RU2533202C2 - Method and system for positioning of mobile terminal inside buildings based on glonass-type signal - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to communication equipment and can be used in mobile communication systems. Stationary beacons consisting of several transmitters and one receiver serving for synchronisation of transmitters are used. Transmitters and the receiver contained in the beacon are synchronised with a common clock generator, and their position is fixed by means of radio transparent beacon housing. As navigation noise-like signals, GLONASS-type signal is used, the beginning of M-sequence of which for different signals transmitted on one and the same carrying frequency, is shifted as to delay by different values. Before the position is calculated, information on expected shift of M-sequence and other information is loaded to mobile terminal memory. Signals of transmitters are accompanied in the mobile terminal, angles of radiation of signals sent by transmitters tuned to one and the same carrier frequency, as well as pseudo-distances to all transmitters are determined, and the position is calculated.

EFFECT: improvement of accuracy and reliability of positioning inside buildings, which allows for arrangement inside rooms of a large number of positioning transmitting devices, requires no major changes to satellite navigational receivers or other components contained in mobile devices, such as for example a smart phone, as well as in non-admission of disturbances to existing navigation receivers.

19 cl, 7 dwg

Description

The invention relates to navigation based on radio signals (to radio navigation) and can be used to determine the position in conditions when the reception of signals from global satellite navigation systems (GNSS) is difficult or impossible, for example, when located inside buildings.

State of the art

There are a large number of methods for determining the position of the receiver using radio signals. There is no single radio navigation method suitable for positioning under any conditions. The most universal means for determining the user's location is satellite navigation. The basic principles of satellite navigation are described in [1]. Unfortunately, satellite navigation, despite the claimed global character, guarantees positioning accuracy of the order of units of meters only in open areas, and may not be available indoors. The low quality and limited availability of indoor satellite navigation are associated with two fundamental factors: a significant weakening of the power of the satellite signal inside the premises by the ceilings and walls of the building and reflection of the signal from walls and other objects. The latter factor leads to multipath propagation of radio waves.

Technologies for determining the location of an object, other than traditional satellite navigation, are called alternative navigation methods. It is these technologies that are gaining more and more popularity due to the increased demand for indoor navigation.

Of particular interest are the alternative navigation methods available for use in mobile devices, such as, for example, a smartphone. The popularity of an alternative positioning technology depends on a number of factors. Among them: the achieved accuracy and reliability, the complexity of support in a mobile device, affecting the cost, the need for additional specially deployed infrastructure. In some cases, such as navigation in large stores, airports, train stations, museums, exhibition centers, the desired positioning accuracy is tens of centimeters. At the same time, with accuracy in navigation in these places, other requirements are presented, such as reliability and minimal peak errors. An integral part of indoor navigation is a detailed building plan, usually downloaded by a mobile device via the Internet.

To improve the accuracy and reliability of navigation in an area where a satellite signal can be partially or completely blocked, several methods have been proposed to supplement the satellite constellation with ground-based transmitters, whose signal fully or partially resembles a satellite signal and can be received by conventional or specialized receivers. A known method is to supplement the satellite constellation with the so-called pseudosatellites (in English terminology pseudolite). An example of a system that implements this method is described in the patent [2]. The proposed system consists of traditional navigation satellites, ground-based transmitters (pseudosatellites), corrective base stations and organized communication channels between transmitters and base stations for transmitting corrective data. The patent [2] lists a large number of radio frequency ranges within which it is possible to organize communication channels for data exchange. It is assumed that the signal from the ground transmitters is synchronized with the signal from the navigation satellites according to the same principles that are used for synchronizing satellite signals. The advantage of this method is to improve the navigation coverage of a given territory and bring navigation accuracy to a level comparable to outdoor navigation. Among the shortcomings of this approach, the infrastructural complexity and high cost of the system should be noted in the first place. The complexity and high cost of the system are caused by the need to deploy special base stations with support for a special type of signal, based on which pseudo-satellites are synchronized. Another significant drawback of the system is the unsolved problem of multipath propagation. The third serious drawback is the problem of cross-correlation interference created by the C / A signals of GPS satellites to each other (in the English literature this problem is often called the “near / far problem”). The essence of this problem is that a short (1023 chip) pseudo-random code used in GPS for code separation of satellite signals (the English term Code Division Multiple Access or CDMA) leads to crosstalk of GPS signals at the level of -21 dB. Thus, the relatively weak signal of one of the satellites, as well as the pseudo-satellites, can be suppressed by a noise comparable to it or superior to it caused by the signal of another satellite or pseudo-satellite ([1], chapter 4.3.4. “Cross-Correlation Functions and CDMA Performance”) . The cross-correlation problem when using GPS pseudo-satellites is compounded by the relatively small distance between the pseudo-satellite and the receiver, as well as its large relative variability. When working with pseudo-satellites, the distance from the receiver to one of the transmitters that transmit the navigation signal can be many times smaller than the distance to the other transmitter, which inevitably leads to a large difference in the power of the signals of the pseudo-satellites at the input of the receiver and, accordingly, to strong interference caused by one of signals. The problem of a large dynamic range of the signal also arises with the simultaneous reception of signals from a pseudo-satellite and a conventional satellite. Too close to the pseudo-satellite transmitter will block the relatively weak signal emitted by the real GPS satellite, and too much distance will block the relatively weak signal from the pseudo-satellite by the signal from the real satellite. Using a GLONASS signal with frequency division multiplexing reduces the level of interference caused by one satellite or pseudo-satellite to another satellite. So, if the carrier frequencies of the satellites are located on adjacent letters, the maximum level of cross-correlation interference is 26 dB, and if the carriers are separated by a double frequency step, then 34 dB. An obvious disadvantage of the frequency separation of channels in accordance with the GLONASS standard is the insufficient number of channels within the frequency band allocated for them. Concluding the enumeration of the shortcomings of the system [2] and the method underlying it, it should also be noted the problem of synchronization with satellites in those buildings where it is not possible to bring an external antenna to the roof.

The problems described above are partially solved due to the rejection of global synchronization of pseudo-satellites by signals from real satellites. A known example of the implementation of such a system described in the patent [3]. According to this idea, the system works autonomously and does not imply the presence of real navigation satellites. The pseudo-satellites included in the system are divided into one master and the other slaves (in English terminology master and slave). The clock of the slave pseudo-satellites is synchronized with the clock of the master. To ensure synchronization, a wired interface or other method is used that is beyond the scope of the patent. The advantage of this method is the somewhat greater ease of installation, since the system does not imply synchronization of pseudosatellites with real satellites. The disadvantages of this method, as in the previous case, are the infrastructural complexity that is inevitable for any method of synchronizing pseudosatellites with an accuracy comparable to the accuracy of GPS synchronization. In addition to the requirement for high accuracy of synchronization, the infrastructure costs of deploying the described system are compounded by the lack of a convenient synchronization channel. The problem of multipath and a limited dynamic range of pseudo-satellite signals (described near / far problem), which leads to serious limitations in the location of the transmitters and to a relatively small coverage area based on them, is also not solved in the described system. Separately, it is worth noting the potential incompatibility of the deployable pseudo-satellite system with existing standard receivers. Incompatibility is associated with a number of dangers of pseudo-satellite transmission of a signal exactly equivalent to the signal of real satellites, in particular transmitted on the same carrier frequency and formed on the basis of the same pseudo-random sequence. The potential algorithmic incompatibility of the pseudo-satellite signal with the software of existing receivers further limits the widespread use of pseudo-satellites.

Several methods are known to significantly simplify the infrastructural complexity of deploying a positioning system based on pseudo-satellites. One of these methods is described, for example, in the patent [4]. According to this method, the transmitters work asynchronously, and the additional receiver present in the system, which calibrates the transmitter signals, is designed to generate corrections to the transmitter ephemeris, which are then taken into account in user receivers during the navigation task. The advantage of this method is a significant reduction in the cost of the system. Among the disadvantages of the method are the same problems with a limited dynamic range of the transmitter signal, and as a result, with a limited area of the system. In addition, due to multipath in an additional stationary receiver, it is not possible to accurately calculate corrections to the signal emitted by asynchronous transmitters. Together with the multipath problem that appears in the user navigation receiver, the latter circumstance leads to a serious deterioration in the quality of navigation. Another drawback is incompatibility with existing receivers. Although the infrastructural complexity is reduced compared to the previous method, it remains quite high, since it is necessary to ensure the prompt delivery of ephemeris corrections to user receivers. An additional disadvantage of this method is the reduced positioning accuracy associated with delays in transmitting corrections to user receivers. Also, the need for constant updating of amendments through their transmission over a mobile or other other network leads to additional traffic and power consumption of the user receiver.

Another method is known that further simplifies the infrastructure of the indoor navigation system. In this case, attempts to synchronize or calibrate asynchronous transmitters are not made at all. This principle formed the basis of GPS-like IMES (Indoor Messaging System) beacons, standardized in the framework of the QZSS (Quasi-Zenith Satellite System) interface document, a navigation system developed by JAXA, Japan's aerospace agency [5]. The interface document contains two patents [6,7] that describe the basic principles for constructing this and similar systems for local positioning indoors. These patents, as well as their analogues, for example [8], describe a system consisting of at least one transmitter emitting a signal in the band used by the satellite navigation system, while the transmitter reports its coordinates as short ephemeris. The system does not involve the use of transmitters to calculate navigation in rangefinder or phase mode. Another major difference between these transmitters and pseudo-satellites is the transfer of alternative positioning information. In fact, the IMES transmitter is not a pseudo-satellite, but a beacon transmitting a Cell-ID. It is assumed that the hardware of traditional navigation receivers, originally designed to receive only a GPS signal, can nevertheless receive a QZSS / IMES signal, since modulation of the listed signals are similar. The advantage of the described approach is the smallest infrastructural complexity of the placement of transmitters, as well as compatibility with the hardware design of receivers developed before the advent of the IMES standard. An obvious drawback of the system is a sharp deterioration in positioning accuracy, since the accuracy of determining the position is actually equal to the coverage of the IMES transmitter. Another disadvantage of the IMES system is that the GPS bandwidth is filled with a signal correlated to -21 dB with traditional GPS satellite signals. As a result, standard receivers perceive cross-correlation crosstalk of IMES signals as a signal from real navigation satellites. More broadly, an IMES signal can be perceived by existing receivers as interference that mimics satellite signals.

A number of local positioning methods are known that describe a system that is fundamentally different and incompatible with the principles used in navigation receivers. These methods, such as navigating traditional Wi-Fi access points, cellular base stations, radio and television transmitters, etc., provide positioning accuracy comparable to or worse than IMES navigation accuracy. The main advantage of these methods is the lack of additional efforts to deploy a positioning system. Using these methods, it is assumed that base stations and / or Wi-Fi access points are already present in the required quantity for navigation inside buildings. This fact may lead to the fact that navigation will be unwarranted, random in nature. It should be emphasized separately the lack of navigation on intermittent signals, or on signals scanned at the same time (a typical example of such navigation is positioning on Wi-Fi access points on the basis of the "fingerprint" principle), which consists in the difficulty or inability to navigate the positioned object in motion.

The relevance of guaranteed high-precision navigation in buildings (indoor) encourages the industry to add support for local positioning in communication standards that were not initially oriented towards solving navigation problems. In the most serious way, local positioning is supported in the IEEE 802.15.4 standard [9], as well as in the ISO standard on RTLS (Real-Time Locating Systems) [10]. One of the undoubted advantages of the IEEE 802.15.4 standard is the use of a special type of modulation - UWB (Ultra-Wide Band) with a bandwidth of 499.2 MHz. The use of an ultra-wide signal band allows one to increase the resolution of distance measurement to 1.2 m, which, when navigated by the rangefinder method, theoretically allows achieving accuracy of 0.6 m even in multipath conditions (in the presence of a direct beam). The standard provides both a measurement of pseudorange (by measuring the arrival time of a signal in one direction), and determining the full range to positioning transceivers (measuring the total delay of signal propagation in both directions). The disadvantages of this technology are the operational limitations imposed by the IEEE 802.15.4 standard (first of all, the limited coverage of the transmitter is up to 10 m), and a lot of additional work is necessary to support the UWB navigation receiver, which is optional in the IEEE 802.15.4 standard. In addition, the positioning accuracy in real receivers can significantly deteriorate due to the problematic procedure for self-calibration of transmitters when measuring absolute distances ([9], chap. EL.6) and because of the problems of constant time calibration using the traditional navigation method based on the calculation of pseudorange to positioning transceivers. It should also be noted technological problems associated with an ultra-wide bandwidth of the signal, which makes the application of this standard in portable devices problematic.

Known methods for improving the accuracy of satellite and pseudo-satellite navigation both outside and indoors due to additional complication of the infrastructure. The main method for increasing navigation accuracy to a centimeter level is the Real Time Kinematic or RTK method ([1], chapter 8.4. "Carrier-Based Techniques"). In a number of RTK implementations, in addition to the cost of infrastructure, the cost of a user receiver also increases (a dual-frequency GPS signal reception in the L1 and L2 bands is required). In addition, the effectiveness of RTK is directly related to the possibility of primary (approximate) determination of the location of the receiver, which is then specified. The basis of RTK is the phase method for determining coordinates, as well as phase tracking and correction of the pseudorange of satellites. Navigation using the phase tracking method is described, for example, in the patent [11]. This patent describes a mobile platform that extracts various measurement data from a GPS signal and adjusts one type of data for other types of data. It is proposed, for example, to adjust the delay of a satellite signal (delay) in response to a phase change and so on. Phase tracking allows you to position the receiver with centimeter accuracy relative to the starting point from which the movement began. Another advantage of the phase navigation method is significantly better accuracy in multipath conditions. At the same time, determining the exact coordinates of the starting point by the phase method is a non-trivial task, since the phase of the signal without the use of special methods of resolving phase ambiguity allows one to determine only a fraction of the number of wavelengths that fit into the pseudorange determined by the receiver to the transmitter. The specific application of the RTK method in pseudosatellites was comprehensively considered in [12]. In this paper, a number of suggestions are given on how to solve the RTK phase ambiguity problem (determining the integer number of wavelengths in pseudorange), various self-calibration algorithms are proposed. The undoubted advantage of the RTK method in its well-known implementations is the increase in navigation accuracy to a centimeter level and relatively high protection against multipath (with strong direct beam). The main drawback of the well-known RTK implementation techniques is the aggregate rise in the cost of the positioning system noted above, as well as the problem of determining the starting position.

A known positioning method based on phase measurements on the principle of an interferometer, which is one of the options for implementing the principle of triangulation. This method is also one of the options for determining the angle of arrival of the signal (in the English literature - Angle of Arrival (AoA), as well as Direction Finding). An example of the implementation of such a method is described in the patent [13]. The patent describes a system of two or more base stations with an array of antennas, receiving a mobile transmitter signal and calculating a direction angle based on the phase difference of the carrier of this signal received at the output of each of the antennas. According to the method proposed by the patent, phase measurements are additionally weighted using linear and non-linear functions, and the reception of a mobile transmitter signal is provided by a special protocol or a set of messages transmitted by a mobile transmitter to base stations. Determining the location of the receiver in the plan is carried out by finding the intersection point of the rays corresponding to the direction of the signal from the mobile device defined by each base station. The advantage of this method is the absence of a phase ambiguity problem due to the small distance between the antenna elements (it is recommended to place the antenna elements in increments of half the wavelength). The disadvantage of this method is the increase in positioning error as the positioned object moves away from the array of antennas, as well as the need for constant signal emission from the positioned object.

A known positioning method based on phase measurements according to the Direction Finding principle, according to which several transmitter antennas and one antenna in the navigation receiver are used to determine the direction to the object. Unlike the previous method, the position of the receiver is determined through the angles of radiation (IM) of the positioning transmitting devices. This method in the English literature has the abbreviation AoD (Angle of Departure). The method of determining the coordinates of an object from the angles of radiation (IM) from two or more transmitters is well known in aviation (used in directional radio beacons). The determination of UI is possible in various ways, among which the most accurate and resistant to multipath for local positioning is the method based on measuring the phase difference of the signals coming from the antenna elements of the transmitter. This means that signals from various antenna elements of the transmitter are separated in a certain way at the receiver. In the case of frequency separation of signals (the English term Frequency Division Multiple Access (FDMA)), the measurement of the phase difference of the received signals can be complicated by the nonlinearity of the phase characteristics of the receiver. When dividing signals by time (the English term Time Division Multiple Access (TDMA)), the measured phase difference can be distorted by the instability of the Doppler shift, the cause of which is the movement of the object with acceleration, as well as the noise of the reference oscillation source (for example, Temperature Compensated crystal Oscillator (TCXO) ) With Code Division Signal Separation (CDMA), strong near-far crosstalk is possible, which can also significantly affect phase measurements. The advantage of this method is the passive mode of operation of the positioned navigation device, since all signals are emitted by beacons, and not by the device itself. The disadvantage of the method, as in the previous case, is the degradation of positioning accuracy proportional to the distance from the beacons, as well as reduced reliability in motion. Another serious drawback of the method is its inoperability with a weak direct beacon signal and a strong reflected signal.

The known method and positioning system in the building on the basis of the measurement of MD, allowing to reduce the number of multi-antenna transmitting beacons up to one device. These method and system are described in the patent [14]. According to the patent, the system contains transmitters, each of which transmits an individual signal and is connected to a separate antenna, as well as a receiver that can distinguish between transmitter signals and uses additional restrictions on the system (for example, a certain vertical location of the receiver) to calculate the position. Due to additional restrictions, the described method and the system that implements it are theoretically capable of determining not only the angular coordinates of the object relative to each of the lighthouses, but also the distance to the lighthouse. The system, thus, allows you to determine the coordinates of the object even by one beacon. The advantage of this method is the reduction in the number of beacons. The disadvantage of the system is the inability to guarantee compliance with additional restrictions - first of all, a certain height of the navigation receiver, which can be in a mobile phone. If the restrictions (conditions) imposed on the system are not observed, the accuracy of positioning of the objects deteriorates in proportion to the deviation from the a priori assumed conditions. Another serious drawback of the described goniometric navigation systems oriented to the phase measurement method is, as in the previous case, their inoperability with a weak direct beacon signal and a strong reflected signal.

An analysis of the currently known indoor positioning techniques shows that positioning using pseudo-satellites transmitting a continuous noise-like signal theoretically allows you to achieve the best accuracy, both in statics and dynamics, but to achieve reliable meter and submeter accuracy in a room with large by the number of radio-reflecting and radio-tight objects it is required to place a large number of beacons. At the same time, the placement of a large number of beacons in addition to the price factor leads to strong cross-correlation interference inherent in the GPS C / A code. Also, the installation of a large number of beacons in the room inevitably affects the accuracy of determining the location and when using alternative positioning methods. The presence in the visibility range of the receiver of a large number of transmitting beacons leads to a deterioration in the quality of navigation associated with the inevitable mutual interference caused by the signal emitted by the beacons.

A number of methods are known aimed at reducing cross-correlation noise created by signals identical or similar to the GPS C / A signal. In the patent [15], it is proposed to model the interference caused by a noise-like signal generated on the basis of one pseudo-random code to a signal generated on the basis of another pseudo-random code, then subtract the predicted value of the interference from the results of correlation of the input signal with the second code. The advantage of this method is the reduction of the cross-correlation effects of signals separated by the CDMA principle, and, as a result, a partial solution of the “near / far problem”. The main drawback of the method as applied to navigation through a strong pseudo-satellite signal is the need to track all “subtracted” pseudo-satellite signals, the number of which can exceed the number of tracking channels available in the receiver.

A known method that reduces mutual cross-correlation interference noise-like signals by increasing the length of the code sequence and at the same time the frequency band occupied by the navigation signal. An example of such a method is the GPS P-code. This method can be considered the most promising for the implementation of new indoor pseudo-satellite navigation systems, however, it is impossible to use this method with existing civilian navigation receivers, since the GPS P-code is not supported in them. Another example of the implementation of this method is the El Galileo signal, the code length of which is four times the length of the C / A GPS code. The advantage and at the same time the disadvantage of solving the cross-correlation problem in the E1 signal is a 6 dB reduction in the cross-correlation coefficient between navigation signals, but this value cannot be considered sufficient for indoor navigation using a large number of beacons.

A known method that reduces mutual cross-correlation interference noise-like signals due to the emission of these signals according to the principle of TDMA. This method is described in the patent [16]. A more detailed description of the method and the system that implements it is given in the patent [17]. The main idea of this method is alternating emission of navigation signals, similar to TDMA time slots. As in other pseudo-satellite based positioning systems described above, the system according to the patent [17] includes a mobile terminal capable of receiving a pseudo-satellite signal and containing a database with information about the location of the pseudo-satellite constituents in the system. By analogy with radar, such a radiation mode is called a pulsed mode. The advantage of this method and system is the solution of the cross-correlation problem at the level of the signal-code structure. The disadvantages of this method and system are: the need for a large number of time slots to separate the corresponding number of pseudosatellite signals, energy losses for each of the shared signals, proportional to their duty cycle, worsening phase tracking of intermittent signals, especially manifested in motion.

An analysis of the currently known methods of positioning inside buildings shows the lack of a high-precision, reliable and at the same time low-cost solution that can be easily integrated into existing products.

The method and the system that implements it, described in the patent [17], are closest to the proposed ones and are selected as a prototype.

Disclosure of invention

An object of the present invention is to propose a method for accurately and reliably positioning inside buildings, providing for placement of special transmitting devices (beacons) inside buildings and not requiring major changes in satellite navigation receivers or other components contained in mobile devices, such as, for example, a smartphone, as well as systems to implement this method. The second part of the task is to minimize the cost of deploying infrastructure in large rooms, such as an airport, shopping mall or office center, as well as eliminating interference with existing navigation receivers. An important feature of the problem being solved is to increase the protection against cross-correlation interference between noise-like signals transmitted at the same carrier frequency and to ensure compatibility with existing navigation receivers.

To solve the problem in the known positioning method, which consists in synchronized emission by stationary transmitters of navigation noise-like signals at one or several carrier frequencies, their reception by a mobile terminal and the subsequent calculation of the position of a mobile terminal, an M-sequence is used as navigation noise-like signals, the beginning of which for different signals transmitted at the same carrier frequency are shifted in time by a different amount, differing by two or more th element of the M-sequence.

To solve this problem, the signal of the transmitters, in addition to the mobile terminal, is received in stationary receivers with a known location, where information about the actual shift of the beginning of the M-sequence, frequency and phase shift of the carrier in the signal emitted by each transmitter relative to other transmitters is extracted from the received signal. Then, the selected information is reported to the transmitters. The transmitters compare the required and actual information about the shift of the beginning of the M-sequence, the shift of the frequency and phase of the carrier relative to other transmitters. Based on the difference obtained, the beginning of the M-sequence, the frequency and phase of the carrier in the transmitted signal are corrected, and thus the identity of the required and actual shifts is ensured.

To solve this problem, before calculating the position of the mobile terminal, information about the expected shifts of M-sequences in the signals of all transmitters is loaded into its memory. Based on the indicated information, the signals of the transmitters to be followed are selected, among which there are signals transmitted at the same carrier frequency, the signals of the selected transmitters are received, the actual shift of the beginning of the M-sequence is calculated, the frequency and phase of the carrier are compared, the actual shift is compared with the expected, calculated discrepancy between actual and expected shifts. Then, based on the calculated errors, the angles of radiation of the signals transmitted by the transmitters operating at the same frequency are determined, as well as the pseudorange to these transmitters.

There are various options for implementing the above method, as well as their combination. In one embodiment of this method, it is proposed to use an M-sequence identical to the pseudo-random rangefinding code of a GLONASS standard-accuracy signal with a period of 1 ms and a symbol rate of 511 kbit / s, while the digital information contained in the navigation signal is transmitted at a speed of 1000 / N bits / s, where N is an integer greater than 3. Such a signal is hereinafter referred to as GLONASS-like.

In another embodiment of this method, the carrier frequency of the transmitters is determined by the formula:

F _carrier = F ₀ + K _L dF _L + K _SubL dF _SubL

where F ₀ is the base carrier frequency of the L1 band of the GLONASS system, equal to 1602 MHz, K _L is the frequency letter, dF _L is the GLONASS frequency interval equal to 562.5 kHz, K _subL is the index of the additional subcarrier, taking the value 0, ± 1, ± 2, dF _subL is the interval between additional subcarriers in kHz equal to K / N or K / (N-2), where K is an integer satisfying the relation: N <K <2 · N.

In another embodiment of this method, navigation signals are transmitted at free letter frequencies of the GLONASS satellite navigation system, not occupied by satellite signals.

In the next variant of this method, the bit boundary of the digital information transmitted in the navigation signal of the transmitter does not coincide with the beginning of the M-sequence.

In another embodiment of this method, the bit boundaries in the navigation signal transmitted by several transmitters coincide in time.

In another embodiment of this method, each transmitter is assigned a synchronization zone with a certain rank, with the beginning of the M-sequence, the phase of the carrier and the carrier frequency of transmitters with a lower synchronization rank adjusted in accordance with the beginning of the M-sequence, phase of the carrier and the value of the carrier frequency transmitters with a higher synchronization rank.

In addition, in one embodiment of this method, the signal emitted by the transmitters contains additional digital information designed to provide mutual synchronization of the transmitters.

In another embodiment of this method, a signal containing additional digital information is transmitted on a carrier frequency and modulated with a pseudo-random code that does not match the carrier frequency and pseudo-random code emitted by the transmitter of a GLONASS-like navigation signal, while a signal containing additional digital information is transmitted synchronized with GLONASS-like navigation signal.

In the positioning system of a mobile terminal inside buildings based on a GLONASS-like signal that implements this method, compared with the known system containing several stationary transmitters of navigation noise-like signals with a predetermined location connected to the corresponding antennas, as well as a mobile terminal with an unknown location, capable of receive a satellite navigation signal and determine its location based on the received signal, the following changes are made and lneny. Stationary transmitters of noise-like signals are capable of emitting a GLONASS standard-accuracy signal, and the mobile terminal is capable of receiving a GLONASS standard-accuracy signal. The system also contains one or more stationary receivers with a known location, capable of receiving the specified signal, connected to the respective antennas, and the number of stationary receivers is less than the number of stationary transmitters.

Stationary transmitters and receivers, together with corresponding antennas, are combined into devices called beacons, while one beacon contains one receiver, one or more transmitters, a clock generator and a communication module. The output of the communication module is connected to the first input of the receiver and the first input of all the transmitters located in the beacon, the output of the receiver is connected to the second input of all transmitters located in the beacon, the output of the clock generator is connected to the third input of all transmitters located in the beacon, and to the second input receiver.

Each lighthouse contained in the system is an autonomous device, all of the listed components of which (transmitters, receiver, communication module and clock) are located inside the radio-transparent case of the lighthouse, which acts as a single supporting structure for all components of the lighthouse, while the antennas of the transmitters and receiver are placed on a certain distance relative to each other.

In addition, in one embodiment, this system includes a server with a database accessible to the mobile terminal containing the coordinates of the beacons, the set shifts of the beginning of the M-sequence, the phase of the carrier and the carrier frequency of the transmitter signals, as well as the synchronization zone and the interaction scheme between the master and slave transmitters .

In another version of the system, the connection of the receiver and the beacon transmitters is carried out through a special interface converter having one input and one or more outputs according to the number of transmitters contained in the beacon. The interface converter may also contain a data converter designed to extract from the output of the receiver pieces of data intended for a separate transmitter, modifying this piece of data and transmitting it to the corresponding output of the interface converter.

In one embodiment of this system, the antennas of the stationary receiver and each stationary transmitter contained in one beacon are located relative to each other at a distance of at least a quarter of the wavelength, while the coordinates of the antennas of the stationary transmitters and the stationary receiver are entered into the database stationary receiver.

In the next embodiment of this system, the components of the stationary transmitters and the stationary receiver, with the exception of the antennas, are arranged arbitrarily. Including these components can be combined into a single chip.

In another embodiment of the implementation of this system, stationary receivers are implemented in a truncated form, and are only able to accompany a GLONASS standard accuracy signal in the L1 range. At the same time, stationary receivers and stationary transmitters are not able to work at some carrier frequencies allocated to the signal of GLONASS satellites.

In another embodiment of this system, stationary noise-like signal transmitters are capable of emitting a GLONASS standard-accuracy signal in the L1 band corresponding to the frequency range 1595 ... 1609 MHz, and the mobile terminal is capable of receiving the GLONASS standard-accuracy signal in the L1 band corresponding to the frequency band 1595 ... 1609 MHz.

To solve this problem, the principle of time synchronization of signals has been changed in comparison with the known positioning system: instead of a system with interleaving signals based on TDMA, a continuous or quasi-continuous noise-like signal based on the M-sequence is used as navigation noise-based signal, the beginning of which is for different signals transmitted on one and the same carrier frequency, delayed by a different amount. In particular, the M-sequence used in the GLONASS standard accuracy signal can be used. The specific shift of the M-sequence in the beacon transmitter is established by entering the indicated shift through the beacon input into the communication module, from where the shift amount is transmitted to the first input of the beacon transmitters. The first input of the transmitter and receiver contained in the beacon also receives information about the required shift in the carrier frequency of the beacon transmitters. This information is also transmitted to the beacon through the input of the communication module. The operation of the stationary receiver and transmitters of each beacon is synchronized by a single beacon clock.

In the further discussion, transmitters are considered whose signal is based on the GLONASS M-sequence. For brevity, GLONASS-like signal transmitters are called IGLONS transmitters, the signal emitted by them is called an IGLONS signal, and modules assembled on the basis of several IGLONS transmitters and a stationary IGLONS receiver are called IGLONS beacons. The abbreviation IGLONS stands for Indoor Geo LOcation Navigation System.

Next, we will consider how, due to the above distinguishing features, an improvement in navigational characteristics is achieved.

A feature of the proposed solution is the use of special IGLONS beacons emitting a signal with a modulation principle identical to the modulation principle of a GLONASS standard accuracy signal in the L1 frequency range. An arbitrary number of user navigation receivers can be positioned (in a particular case, one navigation receiver, hereinafter referred to as a mobile terminal) capable of receiving a civil navigation signal of standard accuracy GLONASS L1 and adapted to work with beacon signals. For navigation receivers not adapted to work with IGLONS beacons, the IGLONS signal is transparent. This means that the IGLONS signal does not lead to the finding of false navigation satellites by traditional GLONASS receivers, prevents long-term tracking of false satellites, and excludes their use in the navigation solution.

Positioning by the proposed IGLONS signal can be carried out in various modes. In the main mode, several beacons are assumed, in each of which several transmitters are installed. A single beacon positioning system with multiple transmitters is also possible. In case of positioning on two or more beacons, the transmitters are synchronized.

According to the proposed solution, IGLONS transmitters emit two types of signal: one, hereinafter referred to as S1, is most compatible with existing GLONASS receivers, the other, optional, hereinafter referred to as S2, is incompatible with the GLONASS standard. Signal S2 is provided for additional data exchange between beacons. Each active transmitter transmits both signals simultaneously, while the signals of different transmitters are synchronized. The signals S1 and S2 are synchronized with each other.

In addition to signals S1 and S2, transmitters can emit a noise signal S3 at the GLONASS carrier frequencies closest to the frequency S1 from the letter range (-7..6). The S3 signal is designed to guarantee the prevention of the acceptance of the IGLONS signal for the GLONASS satellite by existing navigation receivers that are not adapted to receive the S1 signal.

According to the proposed solution, user receivers determine their location based on signal S1. Navigation measurements are carried out in the rangefinder mode, in the phase tracking mode, and also by determining the angle of the signal radiation by positioning beacons.

The proposed solution has improved navigation characteristics due to the following innovations: frequency and code-position separation of signals is used, positioning by the rangefinder method and the method based on the determination of radiation angles (ID) are simultaneously supported, the determination of the radiation angle can be improved using switchable arrays of transmitter antennas. The proposed method and system ensures maximum compatibility of the navigation signal S1 with the signals of traditional GLONASS satellites, without at the same time exerting a noticeable effect on user receivers not adapted for receiving the IGLONS signal.

The new code-based channel separation proposed in the framework of the invention reduces the peak cross-correlation of S1 transmitter signals to a level of 54 dB, which is 30 dB lower than the peak cross-correlation of C / A GPS code signals, and the S1 signal of each transmitter can be demodulated using a traditional code correlator GLONASS standard accuracy. At the same time, about one hundred orthogonal signals can be emitted at one carrier frequency. The proposed new code-based channel separation allows the use of signal S1, the modulation principle of which is similar to the modulation principle of the GLONASS standard-accuracy signal, to determine the angle of emission of signals S1 by transmitters of a positioning beacon, the radiation angle being determined based on the phase difference of the carriers of these signals.

The use of such a parameter as the S1 signal ID allows one to resolve phase ambiguity and perform high-precision angular measurements using the minimum number of receiver channels.

To prevent cross-correlation effects of the S1 signal on non-adapted GLONASS navigation receivers, special modifications can be introduced into the S1 signal structure: the S1 signal carriers are outside the GLONASS L1 satellite range, which occupies frequency characters from minus 7 to plus 6, the information bit structure is changed, the signal spectrum is limited forming filter.

The navigation signal of the transmitters of IGLONS signal S1 is based on the M-sequence of 511 elements (chips), identical to the standard accuracy signal of GLONASS satellites. Separation of channels (signals of different transmitters) is realized by spacing carrier frequencies and / or moments of the beginning of the era of each transmitter. Due to the unique autocorrelation properties of the M-sequence, on the basis of which the GLONASS standard accuracy code is generated, and also due to the effective relative carrier frequency offset, minimizing the overlapping of the linear spectra of IGLONS signals for different carriers, taking into account the expected coherent accumulation in the receiver, achieved within the cross-correlation of IGLONS signals in a typical system is not more than minus 54 dB with a typical use of the system. In this case, the number of signals with mutual cross-correlation not exceeding minus 54 dB is several hundred. The existence of such a large number of almost orthogonal signals makes it possible to realize high-quality navigation using a large number of beacons, provide navigation coverage in large rooms, and to a large extent solve the near / far problem and thus simplify the system configuration.

The autocorrelation function (ACF) of the GLONASS standard accuracy pseudo-random code is shown in FIG. In contrast to the autocorrelation function of the Gold codes underlying the GPS C / A code, the autocorrelation function of the M-sequence used to generate the GLONASS standard accuracy signal contains a single maximum corresponding to the zero time shift of the autocorrelation. With a time shift of more than one chip (figure 2), the autocorrelation function is constant and equal to 1/511 or - 54 dB relative to the maximum ACF. The aforesaid means that the standard discriminator for delay with the spacing of the Early and Late correlators by half a chip relative to the Prompt position is practically insensitive to another signal, which is the same M-sequence transmitted at the same carrier frequency, but shifted forward and backward by 1.5 and more chip.

Figure 2 presents a fragment of the autocorrelation function of the M-sequence of the GLONASS standard-accuracy signal in the region of the main lobe (it is the only maximum of the autocorrelation function). If the spectrum of the GLONASS signal is not limited, the width of the autocorrelation peak is equal to twice the duration of the chip, while the correlation peak has a regular triangular shape. The unlimited spectrum of the GLONASS satellite signal has side spectral lobes, which leads to a serious value of the cross-correlation coefficient of signals transmitted at adjacent frequencies. The maximum cross-correlation between signals transmitted at neighboring frequencies is -26.6 dB, and when the carrier frequencies are spaced into two interliter intervals -34.1 dB. To reduce the correlation of the signal transmitted at adjacent frequencies, a shaping filter can be used in IGLONS transmitters. An example of the impulse response of such a filter is shown in FIG. 3. The presence of a shaping filter in the transmitter and an (optionally) similar (matched) filter in the receiver increases the width of the autocorrelation peak (the area of influence of the interfering side lobes of the ACF) by twice the length of the filter. Thus, the discriminator of the range tracking signal with half-type spacing of the correlators becomes sensitive to the signal of another IGLONS transmitter with a time shift of one and a half chips plus the length of the shaping filter, i.e., 1.5 + T _FIR , where T _FIR is the length of the pulse characteristic of the filter, expressed in chips. In the framework of the proposed system, the length of the transmitter forming filter is equal to four chips (T _FIR = 4). Thus, the time diversity of the beginning of the M-sequence between the signals of the IGLONS transmitters should be at least 5.5 chips.

An additional factor affecting the minimum permissible time diversity of the initial phases of M-sequences (starting positions of epochs) in IGLONS signals is the physical distance from each other of the transmitters, recounted during the passage of the signal from one transmitter to another - T _{Tx1, Tx2} . In satellite navigation, T _Tx1 , _Tx2 , depending on the relative position of the satellites, can reach several tens of milliseconds. The difference between the time it takes for the signal from different satellites to the antenna of the user receiver also fluctuates in the same range. These factors lead to the fundamental impossibility of code-position separation of satellite signals. In the proposed system of local positioning, it is planned to create a local navigation field, measured in hundreds of meters or units of kilometers. In this case, the relative position of the transmitters, and, consequently, the propagation time of the signal between them is fixed. Therefore, the difference in the signal path of the transmitters to the receiver is predictable. Obviously, the stroke difference will always be less than T _{Tx1, Tx2} . In the worst case, T _{Tx1, Tx2 of} such a system will be equal to the ratio of the length of the navigation field in its greatest geometric size to the distance over which the radio signal propagates during one chip:

T _{Tx1, Tx2max} = S _max / 600, [chip]

where S _max - the longest measurement of the navigation field [m].

The final formula for calculating the relative displacement of the beginning of the epochs of neighboring transmitters is:

$$T_{StartMLS}(i,i-\mathrm{one})=ceil(\mathrm{1,5}+T_{FIR}+T_{i,i-\mathrm{one}}+C_T),[h\mathrm{and}P]\text{(one)}$$

where ceil is the function of rounding to the nearest superior integer,

C _T - additional reserve area of the discriminator, smaller than one chip,

i is the transmitter number.

T_StanMLs=6. Максимальное количество одновременно передаваемых на одной частоте сигналов S1 равно 511/ T_StartMLS - 1=84.When providing navigation coverage in relatively small rooms, T _{i, i-1} is small. Respectively $$$$

T _StanMLs = 6. The maximum number of S1 signals transmitted simultaneously on the same frequency is 511 / T _StartMLS - 1 = 84.

Information bits transmitted in signal S1 are formed from N copies in the M-sequence, each of which, being converted into a two-position phase-manipulated signal, is multiplied by +1 or -1 in accordance with the value of the transmitted information bit and is additionally multiplied by +1 or - 1 in accordance with a binary pattern of N elements providing additional coding. The transmission time of one information bit is thus N milliseconds, and the data rate is 1000 / N bits / s. The duration of the information bit in the chips is N-511. The value of the chip transmitted at each moment of time can be calculated by the formula:

$$$$

$${\text{X}}_{\text{chip}}=\text{PRN (t mod 511)}\cdot \text{BitPattern (t div 511)}\cdot \text{Info}\text{, (2)}$$

where PRN is a pseudo-random code in the form of an M-sequence of 511 elements in accordance with the GLONASS specification,

BitPattern - a special sequence of N elements,

Info - information bit, taking into account possible additional coding,

t is the time relative to the start of transmission of the current information bit, expressed in chips,

mod - integer division operation that returns the remainder of division

div is an integer division operation that returns the integer part of the result.

For ease of calculation, all components of the above formula are represented by values of +1 or -1 in accordance with the on-off phase modulation. A similar operation can be performed on the binary data 0 and 1 by replacing the multiplication with logical elements "exclusive OR" (XOR).

To ensure maximum compatibility with the hardware of existing GLONASS navigation receivers, the BitPattern bit pattern can be defined as a unit repeated N times or as a combination of two alternating sequences:

$$\text{BitPattern (i)}=\forall i\in \mathrm{one..}\text{N (3)}$$

or

$$\text{BitPattern (i)}=\{\begin{array}{l}+\mathrm{one,}i=\mathrm{one..}\frac{N}{2}\\ -\mathrm{one,}i=\frac{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="00000014.png,00000015.png"\; state="\{\{state\}\}">N</figure-callout>}}{2}+\mathrm{one..}N\end{array}\text{(four)}$$

The presence of long alternating sequences in the bit pattern, which additionally converts the original pseudo-random code, allows applying the cyclic convolution operation to the signal S1. The applicability of the cyclic convolution operation means that the transmission of two signals formed by one pseudo-random code (in particular, the M-sequence), differing from each other only by the moments of the beginning of the pseudo-random code, is equivalent to the transmission of two signals formed by different pseudo-random codes, provided that the second pseudorandom code the code is a cyclically shifted first pseudo-random code. The difference in the transmission of the two indicated signals appears only at the moment of violation of the cyclic rule, that is, at the moment of changing the sign of the transmitted M-sequence. In the first case, the change of sign of the M-sequence occurs in each signal with a corresponding relative delay. In the second case, the change of sign in both signals occurs simultaneously. The construction of the system according to the second principle is energetically more profitable and convenient for demodulating the signal in the receiver, however, it may not be feasible due to the design limitations of the navigation receiver. The implementation of the system according to the first principle leads to the impossibility of the receiver processing the epochs falling at the boundary of the sign-constant sections of the BitPattern bit pattern. To reduce energy losses during the implementation of the system according to the first principle, the value of N should be made as large as possible. In the framework of the proposed solution, the value of N> 4. It should also be noted that the reduction of permanent sections in the BitPattern template, as well as its additional randomization (the use of several templates with different sequences of plus / minus units) additionally reduces the cross-correlation coefficient of the S1 signal and the GLONASS satellite signal when they are coherently accumulated by the receiver. In the framework of the present invention provides for the use of different bit patterns BitPattern. Examples of bit patterns were given above in formulas (3) and (4). Other varieties of bit patterns are possible. The principles according to which one or another BitPattern template is selected, as well as the simultaneous or delayed application of the BitPattern template to different signals are beyond the scope of this invention.

To reduce cross-correlation interference in the present invention, in addition to code-position separation of signals S1, frequency separation is provided. It is proposed to use at least two frequencies that are not in the satellite range (letters -7 .. + 6). Such frequencies can be, for example, frequencies with the letters +8 and +9 or -9 and -10. In addition to spacing the S1 signal carriers by an integer number of interliter intervals defined by the GLONASS standard as 562.5 kHz, the invention provides for additional tuning of the S1 signal carrier frequencies to K _SubL · K / N kHz or K _SubL · K / (N-2) kHz, where N is the length of the BitPattern template, and K is an integer, with N <K <2 · N, K _SubL = 0, ± 1 or ± 2 The carrier frequency of each IGLONS transmitter can be determined by the following formula:

$$\text{Fcarrier}=\text{F0}+\text{KL * dFL}+\text{KSubL * dFSubL}\text{, (5)}$$

$${\text{F}}_{\text{carrier}}={\text{<figure-callout id="0" label="F" filenames="00000013.png,00000014.png" state="{{state}}">F</figure-callout>}}_{\text{0}}+{\text{K}}_{\text{L}}\cdot {\text{dF}}_{\text{L}}+{\text{K}}_{\text{Subl}}\cdot {\text{dF}}_{\text{Subl}}\text{, (5)}$$

where F ₀ is the center frequency of the L1 GLONASS range. F ₀ = 1602000 kHz,

K _L - frequency letter,

dF _L - interliter GLONASS interval equal to 562.5 kHz,

K _SubL is the index of the additional subcarrier,

dF _SubL is the interval between additional subcarriers equal to K / N in kHz.

The proposed frequency separation of the channels makes it possible to efficiently orthogonalize S1 signals with coherent accumulation of a multiple of N or N-2. The combination of different K _L and K _SubL gives 10 possible values of the carrier frequency of the signal S1. Given the 84 variants of the M-sequence shift indicated above, the total system capacity is 840 channels with a uniquely low degree of cross-correlation.

To perform the above code-position and frequency separation of signals, the present invention provides a transmitter synchronization procedure. Synchronization occurs hierarchically: transmitters belonging to the synchronization zone with a higher number are synchronized by transmitters belonging to the synchronization zone with a lower number. To synchronize with other transmitters and (optionally) to calibrate own transmitters, each IGLONS beacon has a receiver capable of accompanying the reference signal, which is synchronizing for this beacon. The transmitters related to adjacent synchronization zones operate on different letters (the K _L parameter of such transmitters does not match). At the same time, the carrier frequencies at which the transmitters operate within the same beacon are always identical. Thanks to synchronization, a precise observance of the carrier difference F _carrier between synchronizing and synchronized transmitters is ensured, as well as time diversity of the M-sequence T _{StartMLS beginnings} , and for transmitters installed in one beacon, phase matching of emitted signals is _achieved .

It should be noted that during time synchronization T _StartMLS , the signal propagation time between the synchronizing and synchronized beacon, phase distortions associated with the separation of signals by frequency, as well as distortions associated with the multipath propagation of the signal of the synchronizing transmitter, may not be taken into account.

Within the framework of the present invention, less accurate synchronization of time information transmitted by IGLONS transmitters for subsequent range-finding measurements in a navigation receiver is allowed than is required in traditional systems based on pseudo-satellites. Less stringent requirements for time synchronization are associated with the simultaneous implementation of two positioning methods in the proposed method: positioning based on the rangefinder method and positioning method based on measurements of radiation angles less affected by multipath.

The ability to simultaneously transmit multiple direction-finding signals with a small correlation coefficient makes it possible to implement a system for determining the emission angles of these signals in the coordinate system of an IGLONS beacon based on simple geometric relationships. At the same time, a limited number of transmitters within a single system, non-zero cross-correlation of the signals emitted by them, as well as a limited number of tracking channels in GLONASS navigation receivers require minimizing the number of simultaneously emitted signals.

The present invention proposes an implementation of a system of IGLONS beacons, providing a three-dimensional angle of signal emission based on the minimum number of simultaneously emitted signals S1. The mobile terminal receives these signals, and based on the measurement of the phase difference determines the direction to the radiation source. The determination of the angle of signal emission is possible both in statics and with moderate dynamics of the mobile terminal. It also ensures continuity of phase monitoring of the carrier of one of the transmitters installed in the beacon.

The optimal implementation of an IGLONS beacon is a structure consisting of several N _tx transmitters, several N _ant antennas connected to the transmitters, and N _ant ≥N _tx , and one receiver (in the case of N _ant = N _tx, signal redirection from one antenna to another does not occur ) Moreover, some transmitter antennas are spaced relative to each other by a distance commensurate with half the wavelength of the GLONASS signal L1, while others are spaced apart at a greater distance. Each transmit antenna is connected to one of the transmitters. At each moment of time, a signal is supplied to one of the antennas connected to the transmitter, but no signal is received to the remaining antennas. Accordingly, at each moment of time, the signal is emitted only by N _tx antennas, and N _ant -N _tx antennas do not emit a signal. Transmitter signals are modulated according to the code position separation described above. Obviously, T _{i, i-1} for such transmitters is negligible. The shift of the beginning of the M-sequence for each of the transmitters will be calculated by the formula:

$${\text{T}}_{\text{startMLs}}\text{(i)}={\text{T}}_{\text{startMLs}}\text{(l)}+\text{ceil (1}\text{.5}+{\text{T}}_{\text{F1r}}+{\text{C}}_{\text{T}}\text{)}\cdot \text{(il)}\text{, (6)}$$

where i = 1 ... N _tx .

With the above T _FIR = 4 we get the expression:

$${\text{T}}_{\text{Startmls}}\text{(i)}={\text{T}}_{\text{Startmls}}\text{(l)}+\text{6}\cdot \text{(il)}\text{. (7)}$$

According to the proposed solution, IGLONS beacons may contain a different number of transmitters. A suitable amount is from one to five (N _tx = 1 ... 5). At the same time, at least one beacon must be present in the system, comprising at least two transmitters. The most appropriate value is the value of three transmitters (N _tx = 3). When implementing a system based on IGLONS beacons with three transmitters on each of the carriers in the general visibility zone, 84/3 = 28 IGLONS beacons can simultaneously work. When using 10 carrier frequencies, the number of simultaneously operating beacons in the zone of general visibility becomes equal to 280.

It should be noted that, based on the described IGLONS beacons, it is possible to implement a compact version of the system with one beacon containing several stationary transmitters. When implementing the system in this way, navigation by the rangefinder method is not performed.

The synchronization of the M-sequence start shifts, carrier phase shifts, and transmitter carrier frequency shifts is ensured by the proposed design features of the IGLONS beacon: the presence of a stationary receiver, a common clock generator, a communication module, and a single carrier structure fixing the location of the transmitter and receiver antennas, which Ultimately, is the lighthouse building.

It is important to note that the placement of transmitter antennas and beacon receiver antennas in a single radio-transparent housing makes it easier to determine the position of the antennas when placing beacons inside buildings. The rigid fixation of the antennas, laid down at the stage of design development of the beacon and ensured by a single body of the product, is of particular importance for ensuring navigation along the radiation angles of the beacons, which requires positioning the phase centers of the antennas with millimeter (in extreme cases, with centimeter) accuracy. This takes into account both the geometric coordinates of the phase centers of the antennas and the coordinated orientation of the antennas relative to each other. The latter circumstance is associated with the variability of the phase center of the antennas depending on the direction of signal emission and with traditional methods of compensating for the variability of the phase centers of antennas in goniometric measurements. High-quality synchronization of phase shifts of the carrier signal emitted by the beacon transmitters is also an indispensable condition for ensuring navigation based on goniometric measurements. The specified synchronization is ensured by the presence in the beacon of a single clock generator and the coordinated configuration of the receiver and transmitters of the beacon through the communication module. The presence of a communication module in the beacon solves the problem of remote configuration of the receiver and transmitters of the device using a portable remote control. Remote configuration of the beacon simplifies the operation of the beacons after they are installed in uncomfortable places for the operator, for example, under the ceiling of a room.

The proposed code-time method for separating navigation signals ensures maximum compatibility with existing GLONASS commercial receivers. The simultaneous use of rangefinder, phase and goniometric principles of positioning allows, based on the proposed method and its implementing system, to provide accurate and reliable positioning of the navigation receiver (mobile terminal) indoors, allowing the placement of a large number of positioning transmitting devices indoors, does not require major changes in satellite navigation receivers, lowers infrastructure costs while not interfering with the existing navigation receiver and does not interfere with the reception of signals of GLONASS satellites.

Brief Description of the Drawings

Figure 1 shows the autocorrelation function (ACF) of the pseudo-random code of standard accuracy GLONASS.

Figure 2 presents a fragment of the autocorrelation function of the M-sequence of the standard accuracy code GLONASS in the region of the main lobe.

Figure 3 shows an example of the impulse response of the forming filter GLONASS-like signal.

Figure 4 presents an example of the proposed system containing three IGLONS beacons (470, 472, 474), a mobile terminal 460 with a navigation antenna 461 located at an unknown position 462, server 463, a communication channel for access to server 464. IGLONS beacon 470 includes a transmitter 401 with an antenna 402 located at position 403 and emitting a signal 404, a transmitter 405 with an antenna 406 located at position 407 and emitting a signal 408, a transmitter 409 with an antenna 410 located at 411 and emitting a signal 412, a receiver 413 with antenna 414 located at position 415 of the converter l interface 416 connecting the output of the receiver to the inputs of the phase-frequency synchronization input, clock generator 417, radio-transparent housing 418, communication module 419. IGLONS-beacon 472 includes a transmitter 421 with an antenna 422 located at 423 and emitting a signal 424 , transmitter 425 with antenna 426 located at 427 and emitting signal 428, transmitter 429 with antenna 430 located at 431 and emitting 432, receiver 433 with antenna 434 located at 435, interface converter 436, s connecting output of the receiver with the inputs of the transmitters intended for inputting the phase-frequency synchronization, clock generator 437, radio-transparent housing 438, communication module 439. The IGLONS beacon 474 includes a transmitter 441 with an antenna 442 located at position 443 and emitting a signal 444, a transmitter 445 s antenna 446, located at position 447 and emitting signal 448, transmitter 449 with antenna 450, located at position 451 and emitting signal 452, receiver 453 with antenna 454, located at position 455, interface converter 456, connecting the output a receiver with transmitter inputs for inputting phase-frequency synchronization, clock generators 457, radio-transparent housing 458, communication module 459. The signals 404, 408, 412 emitted by the IGLONS beacon 470 arrive at the mobile terminal 460 as a combined signal 465. The radiated IGLONS beacon 472 signals 424, 428, 432 arrive at the mobile terminal 460 as an aggregate signal 466. The signals 444, 448, 452 emitted by the IGLONS beacon 474 arrive at the mobile terminal 460 as an aggregate signal 467.

Figure 5 illustrates the principle of determining the radiation angle of IGLONS transmitters, containing two antennas (501 and 502), their idealized phase centers (503 and 504), two-dimensional coordinate system 505, within which positioning is performed, mobile terminal 506, radiation angle 507 , designated β, the distance between the phase centers of the antennas 508 (d), the path difference 509 (a).

Figure 6 presents the proposed method for the distribution of time shifts of the beginning of the M-sequence of GLONASS-like signals emitted on one carrier by transmitters Tx ₁ , Tx ₂ , Tx ₃ , Tx _S-1 , Tx _S.

7, the proposed method for simultaneous positioning based on the rangefinder method, the phase method and the method of angles of radiation is illustrated by the example of a system of three IGLONS beacons containing IGLONS beacon 705 with location 706, beacon 707 with location 708, beacon 709 with location 710 , mobile terminal 701 with unknown position 702. The location of the beacon in the coordinate system 704 is calculated based on the pseudo-ranges 720, 721, 722 (range-finding positioning method), integrable velocity vector 703 (phase position method onirovaniya) emission angles 714, 715, 716, 717, 718, 719 (based on the determination of the radiation angles positioning). For clarity, the angles 714, 716, 718 are displayed relative to the projections of the beacons 711, 712, 713 on the horizontal plane in which the positioned mobile terminal is located.

The implementation of the invention

The inventive method of positioning inside buildings and implementing its system is made as follows.

The system contains several stationary located transmitters of navigation noise-like signals with a predetermined location that can operate on one of several carrier frequencies connected to the corresponding antennas, as well as a mobile terminal with an unknown location containing a database with the location of stationary transmitters capable of receiving a satellite navigation signal and determine based on the received signal its location, while stationary noise-like transmitters with latter is present capable of emitting a signal based on the M-sequence, in particular M-sequence signal used in the GLONASS standard accuracy in the range L1, and the mobile terminal capable of receiving a signal transmitter, in particular signal standard accuracy GLONASS L1 band. The system also contains one or more stationary receivers with a predetermined location, connected to respective antennas capable of receiving the indicated type of signal, the number of stationary receivers being less than the number of stationary transmitters. Stationary transmitters and stationary receivers, together with the corresponding antennas, are combined into devices called beacons, with each beacon containing one stationary receiver and one or more stationary transmitters. Each beacon contains a clock and a communication module. The output of the communication module is connected to the first input of all transmitters located in the beacon, and to the first input of the receiver located in the beacon, the output of the receiver is connected to the second input of all transmitters located in the beacon, the output of the clock generator is connected to the third input of all transmitters located in the beacon , and with the second input of the receiver, and the input of the communication module is the input of the beacon. Each lighthouse contained in the system is an autonomous device, all of the listed components of which (stationary transmitters, stationary receiver, communication module and clock) are located inside the radio-transparent case of the lighthouse.

The communication module contained in each beacon is designed to provide a single external interface and coordinated configuration of stationary transmitters and a stationary receiver. The communication module can support both wired and wireless data entry. Moreover, each beacon contained in the system has an input, which is also the input of a communication module, designed to enter configuration parameters, including the required shift of the beginning of the M-sequence for each transmitter contained within the beacon, a shift of the carrier frequency for all transmitters contained within the beacon, parameters sync transmitter.

The output of the stationary receiver can be connected to the stationary transmitters in various ways. One of the options for implementing such a connection is an interface converter containing one input and one or more outputs. The number of outputs of the interface converter is equal to the number of transmitters contained in the beacon. In this implementation, each transmitter is connected by a second input to one of the outputs of the interface converter. So, if the beacon contains three stationary transmitters, then in the interface converter between the receiver and transmitters there are three outputs and one input, while the first output of the interface converter is connected to the second input of the first transmitter, the second output is connected to the second input of the second transmitter, the third output is connected with the second input of the third transmitter. The interface converter may also contain a data converter that implements several functions: sorting data from the output of the receiver, extracting individual fragments from the receiver data necessary to synchronize only a specific beacon transmitter, modifying data, redistributing the data stream to the transmitter inputs so that each transmitter receives only data required for its synchronization. At the same time, data modification can be expressed both in a change in the data format and in the conversion of data of one type into data of another type.

In the framework of the proposed system, the antennas of the stationary receiver and each stationary transmitter contained in one beacon are located relative to each other at a certain distance. Such a distance may be a quarter of a wavelength or more. In this case, the coordinates of the antennas of the transmitters and the stationary receiver are entered into the database of the location of the transmitters and the stationary receiver. The remaining components of the transmitter and receiver can be arranged arbitrarily, including being combined into a single chip.

The proposed system may also contain a server with a database accessible for the mobile terminal containing the coordinates of the receivers, the coordinates of the transmitters, the set shifts of the beginning of the M-sequence, the phase of the carrier and the carrier frequency of the signals of the transmitters, as well as the synchronization zone of the transmitters.

In the framework of the proposed system, fixed receivers are not designed to determine their location. Because of this, they can only carry out tracking of GLONASS signals in the L1 range. Another significant feature of the proposed system is that stationary transmitters and stationary receivers may not work at some (including all) carrier frequencies allocated to the signal of GLONASS satellites. In this case, stationary transmitters, stationary receivers and a mobile terminal can respectively transmit and receive a signal at a letter carrier frequency that is not used to transmit a GLONASS satellite signal.

The communication module allows both a wireless data input method, for example, using a remote control, and a configuration method through a special connector, such as, for example, UART (Universal Asynchronous Receiver / Transmitter). The output of the communication module is a digital interface with one or more communication lines connected to it, providing the choice of the addressable device (such devices are the receiver and the transmitters contained in the beacon) and allowing the selected device to transmit the necessary digital information. In the communication module, routing of configuration data can also be implemented, which ensures the transfer of input data only to the device or those devices to which this data is intended.

A stationary transmitter is generally a device structurally similar to pseudosatellites. Therefore, the implementation of the transmitter is possible on the same elemental base, which is used in pseudosatellites. At the same time, the transmitters use a third-party clock generator and a third-party control interface. Transmitters may also not have their own housing. The first input of the stationary transmitter is an interface compatible with the output interface of the communication module. In this case, the number of communication lines supplied to the first input of the stationary transmitter may not coincide with the number of communication lines connected to the output interface of the communication module. The second input of the stationary transmitter is an interface compatible with the output of the receiver or with the output of the interface converter. The third input of the stationary transmitter is standard for connecting a clock generator.

A stationary receiver in the general case is a radio frequency module (RFFE) that converts an analog signal into a digital one, as well as a digital module containing a mechanism for searching and tracking IGLONS signals. A receiving antenna is connected to the input of the RF module. The first input of the stationary receiver is an interface compatible with the output interface of the communication module. Moreover, the number of communication lines supplied to the first input of the stationary receiver may not coincide with the number of communication lines connected to the output interface of the communication module. The second input of the stationary receiver is standard for connecting a clock generator. The receiver can be implemented on available microwave and digital components.

As a clock generator connected to the inputs of stationary transmitters and a stationary receiver, TLCO or OXO (Oven-Controlled Crystal Oscillator) can be used.

A mobile terminal within a system is understood to mean any portable device containing a navigation receiver. This may be a mobile phone, smartphone, laptop, tablet computer or specialized equipment.

In one example implementation, a communication module, stationary transmitters, a fixed receiver and an interface converter can be implemented on the basis of discrete elements such as a processor, memory, FPGA (Field Programmable Gate Array) and other digital radio components available on the market. In another example implementation, the communication module, the digital part of the receiver, the digital part of the transmitters, as well as the interface converter can be combined into one chip. In the third embodiment, the radio-frequency components of the transmitter and receiver are also placed in the chip.

A server containing a database for subsequent download to the mobile terminal can communicate with the mobile terminal via the Internet using any wireless communication protocol available inside the building. At the same time, the mobile terminal contains a standard GLONASS navigation receiver in the L1 range, the software firmware of which has been modified to receive GLONASS-like signal (IGLONS signals). According to the proposed solution, additional requirements may be imposed on the mobile terminal: the mobile terminal must receive a signal at carrier frequencies with letters that are not used to transmit a satellite signal, while at carrier frequencies with these letters it must be possible to simultaneously track several GLONASS signals on the same carrier frequency. As an example, we can consider a system with transmitters and receivers (stationary within the beacons, as well as a receiver in a mobile terminal) that can work with carrier letters plus 8 and plus 9. As another example, we can consider a system that can handle carrier letters from minus 12 to plus 12, corresponding to the extended GLONASS lettering range according to some recommendations of GBAS (Ground-Based Augmentation System) and SBAS (Satellite-Based Augmentation System). The last lettering range corresponds to the frequency band 1595 ... 1609 MHz.

Figure 4 presents an example of a positioning system inside buildings based on a GLONASS-like signal. The system contains three IGLONS beacons (470 472 and 474). Each beacon contains three stationary transmitters (401, 405, 409 in the beacon 470; 421, 425, 429 in the beacon 472; 441, 445, 449 in the beacon 474), one stationary receiver (413, 433, 453), a clock generator (417 , 437, 457). In addition, each beacon contains four spaced antennas (in beacon 470, these are antennas 402, 406, 411, 414 with idealized phase centers at positions 403, 407, 410 and 415, respectively, in beacon 472, these are antennas 422, 426, 431, 434 with positions 423, 427, 430 and 435, in beacon 474 these are antennas 442, 446, 451, 454 with positions 443, 447, 450 and 455), as well as a communication module (419, 439, 459). All of these components are enclosed in a housing (418, 438, 458). The system also has a mobile terminal 460 with a navigation antenna 461, the idealized phase center of which is located at position 462, as well as a server 463 and a communication channel for access to server 464. As a mobile terminal in this example, we consider a mobile phone, and as an access channel to the server, the Wi-Fi communication standard or a mobile standard supported in the region, for example, GSM or LTE.

The inventive method lies in the fact that in stationary transmitters of navigation noise-like signals emit an M-sequence, the beginning of which for different signals transmitted on the same carrier frequency, is delayed by a different amount, different from each other by a duration of two or more elements of the M-sequence. In this case, the M-sequence can be shifted both in the usual way and cyclically. In the first case, the shift of the M-sequence is equivalent to earlier or later emission of the signal. In the second case, shifting the M-sequence by a different amount is equivalent to generating noise-like codes according to the principle of synchronous CDMA. The transmission of noise-like codes in this case is considered to start simultaneously. Reception of signals with code division based on a cyclically shifted M-sequence is also carried out in a standard manner for receiving CDMA signals.

In one of the implementations of the proposed method, the signal of the transmitters is also received in stationary receivers with a known location, information about the actual shift of the beginning of the M-sequence, phase of the carrier and the value of the carrier frequency in the signal emitted by the transmitters relative to the beginning of the M-sequence, phase of the carrier, and value are extracted from the received signal the carrier frequency of the signal of the other transmitters, the selected information is transmitted to the transmitters, the transmitters compare the required and actual information about the start shift M-p sequence, the phase of the carrier and the value of the carrier frequency with respect to other transmitters, adjust the beginning of the M-sequence, the phase of the carrier and the value of the carrier frequency in the transmitted signal based on the difference, and thus ensure the identity of the required and actual shifts.

In addition, before calculating the position of the mobile terminal, information about the expected shift of the M-sequence, the phase of the carrier, and the value of the carrier frequency in the signals of the transmitters can be loaded into its memory.

The navigation signal may transmit digital information. In this case, digital information is transmitted at a speed of 1000 / N bit / s, where N is an integer greater than 3. The number N also characterizes the number of epochs per one bit of digital information. It should be noted that in a GLONASS standard-accuracy satellite signal, digital information is transmitted at a speed of 50 bits / s (half the preamble bits are halved and transmitted at a speed of 100 bits / s). Thus, the transmission rate of digital information in a GLONASS-like signal (IGLONS-signal) emitted by stationary transmitters differs from the transmission rate of digital information in the signal of GLONASS satellites. At the same time, within the framework of one era, the signal of stationary transmitters and the signal of GLONASS satellites can be completely identical: the M-sequence of a GLONASS-like signal emitted by stationary transmitters is identical to the pseudo-random rangefinding code of a standard GLONASS signal with a period of 1 ms and a symbol rate of 511 kbit / s.

The carrier frequency of the transmitters can be calculated by the formula (5). In this case, navigation signals can be transmitted at the letter frequencies of the GLONASS satellite navigation system, not occupied by satellite signals.

As already noted, the bit boundary of the digital information transmitted in the navigation signal of the transmitter may not coincide with the beginning of the M-sequence. In particular, if the bit boundaries in the navigation signal transmitted by several transmitters coincide in time, the code division of the signals becomes equivalent to synchronous CDMA. Other principles for synchronizing bit boundaries are also possible. Moreover, the law of synchronization of the boundaries of the bits of the transmitters can be configurable. It is important to note that for any principle of synchronizing bit boundaries of transmitters, the law of synchronizing bit boundaries of transmitters is included in the list of system parameters communicated (or a priori known) to the mobile terminal.

In one of the implementations of the proposed method, each transmitter is associated with a synchronization zone with a certain rank, while the beginning of the M-sequence, the phase of the carrier and the carrier frequency of transmitters with a lower rank are adjusted in accordance with the beginning of the M-sequence, phase of the carrier and the value of the carrier transmitter frequencies with a higher sync rank.

In the inventive method, the signal emitted by the transmitters may contain additional digital information designed to ensure mutual synchronization of the transmitters. In this case, a signal containing additional digital information can be transmitted on a carrier frequency and modulated with a pseudo-random code that does not coincide with the carrier frequency and pseudo-random code emitted by the transmitter of a GLONASS-like navigation signal. In this case, a signal containing additional digital information is transmitted synchronized with a GLONASS-like navigation signal.

According to the proposed solution, the positioning algorithm of a mobile terminal based on GLONASS-like signals can be reduced to the following sequence of actions:

1) calculate the correlation characteristic between the input signal and the M-sequence of the standard accuracy code GLONASS. The correlation characteristic is calculated for all provided letter frequencies, taking into account the maximum possible subcarrier spacing, as well as taking into account the inaccuracy of the TLCHO beacons and the navigation receiver (mobile terminal);

2) select one or more sets (T _startMLS , F _carrier ) corresponding to the maxima of the total correlation characteristic;

3) for the selected one or more maxima, the expected signal S1 is followed and decoded. If the signal does not have a preamble and other signs of the integrity of the signal S1, tracking is stopped;

4) information about the system and the accompanying transmitter (for example, system ID and transmitter ID) are extracted from signal S1;

5) form a query to the database, in response to which the navigation receiver is informed of the exact coordinates of all the transmitters, as well as the parameters according to which the transmitters generate the signal S1 (the parameters may include digital information transmitted in signal S1, T _startMLS , F _carrier antenna switching schedule, synchronization zone, etc.);

6) start tracking X other transmitters. X is limited by the number of GLONASS channels in the navigation receiver. When choosing X transmitters, their location relative to the first transmitter found, as well as other factors, are taken into account. It is important to note that the search for other transmitters at this stage is not required, since their carriers and the positions of the beginning of the era are synchronized with the signal of the first transmitter already found;

7) perform navigation based on rangefinding measurements;

8) carry out navigation by measuring radiation angles;

9) perform navigation based on phase tracking relative to previously found receiver coordinates;

10) assess the reliability of the obtained navigation results, on the basis of which a final solution to the navigation problem is developed.

The principle of determining the emission angle of IGLONS transmitters is illustrated in FIG. 5 by the example of two transmitter emitting antennas (501 and 502). Between the distances that the radio waves travel in the direction of the mobile terminal 506, there is a travel difference, which, assuming a plane wave front, can be expressed as

where a is the stroke difference (509),

d is the distance between the phase centers of the antennas (508),

β is the angle of radiation in the direction of the mobile terminal (507).

Receiving the signals of the transmitters (501 and 502), in the mobile terminal, the phase difference of the signals is measured, which is associated with the stroke difference by the ratio

where Δφ is the phase difference,

λ is the wavelength of the signal.

From (8) and (9) in the mobile terminal, the radiation angle is determined as

$$\beta =\arccos \left(\frac{\Delta \mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="00000014.png,00000015.png"\; state="\{\{state\}\}">\varphi </figure-callout>}}{2\pi }\cdot \frac{\lambda }{d}\right)\text{(10)}$$

To determine the final location of the receiver in three-dimensional space, a larger number of transmitting antennas and the presence of at least two spaced beacons are required.

Before starting work, the coordinates of the stationary beacons and transmitters of the beacons, the parameters of the transmitters, the synchronization zone and the relationship between the synchronizing and synchronized beacons are entered into a database, which is then loaded into the memory of mobile terminals for subsequent use in navigation. The database can be stored on an accessible public server or other other resource.

To establish the relationships between the synchronization zones, each zone is assigned a certain rank, according to which the transmitters assigned to the synchronization zone with a higher rank synchronize the transmitters assigned to the synchronization zone with a lower rank. In accordance with established practice, the numbering of ranks may be the opposite of their "higher" or "lower" status. It is proposed to designate the highest rank by number 1, lower relative to the highest rank by number 2 and so on. According to the proposed method, there can be one and only one beacon in the system whose transmitters have a synchronization rank of Rang = 1. Another factor influencing the formation of synchronization zones is the condition: transmitters with synchronization ranks differing by one from one another cannot operate at the same letter frequency. The third factor in determining the synchronization zones is the condition: all the transmitters inside one beacon (interacting with one stationary receiver) operate at the same carrier frequency and belong to the same synchronization zone.

The above rules can be illustrated by the example of the already considered system depicted in figure 4. The system contains three IGLONS beacons, each of which has three transmitters. In this case, beacon 472 operates at the letter frequency F1, and beacons 470 and 474 at the letter frequency F2. According to the rules described above, the reference synchronizing beacon with a rank 1 in such a system can only be a beacon 472. Beacons 470 and 474, respectively, belong to a synchronization zone with a rank of 2. Any of the three transmitters of the beacon 472 can be selected as the leading transmitter for synchronizing the second zone. The option of synchronizing some of the transmitters of the second zone with the transmitter 421, parts with the transmitter 425 and parts with the transmitter 429, that is, all the transmitters in the beacon 472, is not ruled out. Moreover, the configuration according to which the transmitters inside the same beacon are synchronized by different transmitters from the zone with a higher rank, is not allowed. To ensure maximum system synchronization, the number of synchronization zones and the master transmitters selected in each of them should be minimal.

For example, the following algorithm for placing beacons and determining synchronization zones can be used:

1. Determine the location of the IGLONS beacon, which represents the synchronization zone of the first rank, proceed with the placement of beacons for the new synchronization zone with a rank of Rang = 2;

2. Place the beacons of the new synchronization zone in such a way that they can be synchronized by beacon transmitters from the synchronization zone with an adjacent higher rank (Rang-1);

3. For each beacon from the new synchronization zone, determine the master beacon synchronizing it from the synchronization zone with an adjacent higher rank (Rang-1), and the number of master beacons in the zone with a higher rank should be minimal;

4. If it is not possible to synchronize the next beacon in a new synchronization zone by transmitters from an adjacent synchronization zone with a higher rank (Rang-1), complete the formation of a new zone with a rank of Rang, declare a new synchronization zone with a rank of Rang = Rang + l, and then go to paragraph 2. A possible algorithm for determining the parameters of signals emitted by beacons is as follows:

1. For the transmitter of the master of the first synchronization zone, set the carrier frequency F = F1, the shift of the beginning of the M-sequence T = 0. For the remaining transmitters, set the same carrier frequency and adjacent shifts of the M-sequence.

2. For all transmitters of the synchronization zone with rank Rang = 2, set F = F2, distribute the M-sequence shifts in the range 0 ... T _end2 in accordance with the rule of the minimum sufficient interval between adjacent shifts T _StartMLS , where T _end2 is the maximum shift of the beginning M- sequences at this stage, such that 0 <T _end2 <511.

3. For all transmitters Rang = 3, set F = F1, distribute the M-sequence shifts in the range T _begin1 ... T _end1 in accordance with the rule of the minimum sufficient interval between adjacent shifts T _stanMLs , where T _begin1 is the maximum shift of the beginning of the M-sequence in the zone synchronization of the first rank, T _end1 - the maximum shift of the beginning of the M-sequence in the synchronization zone of this rank, such that T _begin1 <T _endl <511.

4. For transmitters from the remaining synchronization zones, set for the case of even Rang F = F2, the start of shifts of the M-sequence T _begin2 <T <T _end2 , where T _begin2 is equal to T _end2 for the synchronization zone with Rang = Rang-2, and for the case of odd Rang set F = F1, the start of the shifts of the M-sequence T _begin <T <T _end1 , where T _begin1 is equal to T _end1 for the synchronization zone with Rang = Rang-2.

5. When T _end1 or T _{end2 leaves} the range 0 ... 511, shift the value of F1 or F2 to another subcarrier (change K _SubL ) and declare T _begin1 or T _begin2 equal to zero. If there are more than two letter carriers, also change the number of the letter carrier frequency by switching to the frequency F = F3.

The principle of the distribution of the beginning of the shifts of the M-sequence is explained in Fig.6. Let the beginning of the M-sequence of one of the transmitters (transmitter Tx ₁ ) be T ₁ , with T ₁ = 0. Then the shift of the beginning of the M-sequence of another transmitter (transmitter Tx ₂ ) will be equal to T ₂ = T ₁ + T _StartMLS (2, l). The shift of the beginning of the M-sequence of the third transmitter (TX ₃ transmitter) will be T ₃ = T ₂ + T _StartMLS (3,2) and so on. In total, at the given carrier frequency, the S beginnings of the M-sequence can be arranged. The shift of the beginning of the M-sequence of the S + 1 transmitter would exceed 511, which is unacceptable and, accordingly, is a criterion for the maximum value of S.

After determining the parameters of the signals emitted by the beacons, the parameters are communicated to the transmitters through a specially provided interface for the communication module (419, 439, 459 in FIG. 4). For example, for the system depicted in FIG. 4, it is possible to enter the following information characterizing the receivers and transmitters into the database.

The phase of the carrier signal 404 is equal to the phase of the carrier of the signal 408 and equal to the phase of the carrier of the signal 412. The phase of the carrier of the signal 424 is equal to the phase of the carrier of the signal 428 and equal to the phase of the carrier of signal 432. The phase of the carrier of signal 444 is equal to the phase of the carrier of signal 448 and equal to the phase of the carrier of signal 452.

The carrier frequency of the signals 404, 408, 412, 444, 448, 452 is equal to F2. The carrier frequency of the signals 424 428, 432 is equal to F1.

The start shift of the M-sequence of signal 404 is 0, signal 408 is 6, signal 412 is 12, signal 444 is 18, signal 448 is 24, signal 452 is 30. The shift of the beginning of the M-sequence of signals 424, 428 and 432 is equivalent to the start M shifts -sequences of signals 404, 408 and 412.

The transmitters 401, 405, 409 are synchronized by the signal 432 of the transmitter 429 through the receiver 413. The transmitters 441, 445, 449 are synchronized by the signal 432 of the transmitter 429 through the receiver 453. The transmitters 421, 425, 429 are not synchronized by a third-party signal.

Locations 403, 407, 410, 415, 423, 427, 430, 435, 443, 447, 450, 455 idealized phase centers of antennas 402, 406, 411, 414, 422, 426, 431, 434, 442, 446, 451, 454 are entered into the database in the form of three-dimensional coordinates relative to the selected reference system, tied to the floor plan.

During operation of the system, the receiver 413 monitors the actual shift of the beginning of the M-sequence, the actual shift of the carrier phase and the actual carrier frequency of the signal 432 relative to the beginning of the M-sequence, the phase shift of the carrier and carrier frequency of the signals 404, 408 and 412. The results are reported to transmitters 401, 405 and 409 through an interface converter 416. In this case, within the interface converter 416, the data of the receiver 413 can be further processed and supplemented with other data received from third-party sources. In transmitters 401, 405 and 409, the actual shift of the beginning of the M-sequence, carrier phase and carrier frequency values are compared with the required ones (with the data set via the communication module during system configuration) and, if there is a discrepancy, they correct the signal emitted by them. The transmitters and receiver of beacons 472 and 474 interact in a similar way.

The transmitters shown in FIG. 4 may also emit a signal S2 containing additional digital information. Digital information transmitted in signal S2 is received by receivers 413, 433, 453 and communicated by transmitters connected to them via interface converters 416,436,456.

It is important to note that the transmitters and the receiver inside each IGLONS beacon are clocked by a single source of reference oscillation, which can be used as a TLCO or OXO (Oven-Controlled Crystal Oscillator).

During the operation of the system, the mobile terminal 460 detects and then receives the signals of several or all nine stationary transmitters, monitors the actual shifts of the beginning of the M-sequence of the received transmitter signals, as well as their carrier phase and carrier frequency values, compares the actual shifts with the expected ones and then based on the received Differences solves the navigation problem. Before the detection of the first of the nine transmitter signals present in the system or after it by the mobile terminal, a database is loaded with information about all parameters of the transmitter signals, the location of the transmitters and receivers, and the transmitter synchronization pattern. Within the framework of a downloadable database, the mobile terminal receives the necessary information to determine the expected shifts of the beginning of the M-sequence of transmitter signals, shifts of their carrier phases and shifts of their carrier frequencies. Based on the knowledge obtained in this way, the mobile terminal decides on the feasibility of accompanying certain available transmitter signals, as well as on the possibility of determining the radiation angles of the transmitters. Based on the decision made, and also having at its disposal the difference between the expected and actual shifts of various parameters of the transmitter signal, the mobile terminal determines the angles of radiation of the transmitters, the pseudorange of the transmitters, changes the pseudorange of the transmitters, determines the degree of reliability of the measurements, uses the measurements as input data for navigation task and in the process of solving the navigation problem determines the current position of the mobile terminal.

To determine the reliability of the measured angles of radiation of the transmitters, the following algorithm can be applied:

1. If the relative position of the transmitters of the IGLONS beacon and the receiver, determined as a result of solving the navigation problem, meets the reliability criterion (for example, the distance between the beacon transmitters and the mobile terminal is less than a certain limit), then the accuracy of the goniometric measurements is considered high, otherwise low.

2. If the relative position of the beacon transmitters with respect to the calculated direction to the receiver meets the reliability criterion (for example, the distance between the transmitters in the projection perpendicular to the direction to the mobile terminal does not exceed certain restrictions above and below), then the accuracy of the goniometric measurements is considered high, otherwise low .

3. If the new position of the mobile terminal obtained as a result of angular measurements has not shifted a considerable distance relative to the previous position obtained in a similar way, then the accuracy of the angular measurements is considered high, otherwise low.

4. If the results of positioning by goniometric measurements are fundamentally different from the results of positioning based on range-finding measurements, then the accuracy of the goniometric measurements is considered low, otherwise high.

5. If all four of the reliability criteria listed above showed a high level of reliability of the goniometric measurements, the final reliability of the goniometric measurements is considered high, otherwise low.

The principle of simultaneous positioning based on the rangefinder method, a method based on phase measurements and measurements of the radiation angles of the signal of the transmitters is illustrated in Fig.7. In the positioning process, the mobile terminal 701 determines its location 702 and the instantaneous velocity vector 703 based on the pseudorange 720, 721, 722, radiation angles 714, 715, 716, 717, 718, 719, as well as the previous velocity vector and the previous determined position. These measurements are performed in the process of processing the signals of beacons 705, 707, 709.

The mobile terminal, IGLONS beacons and server included in the system can be implemented on well-known electronic components.

Information sources

1. "Understanding GPS: Principles and Applications", Second Edition. Elliott D. Kaplan, Christopher Hegarty, 2005.

2. US 5646630. Network of Equivalent Ground Transmitters.

3. US 0015198 Al. Pseudolite-based Precise Positioning System with Synchronized Pseudolites.

4. US 7342538 B2. Asynchronous Local Position Determination and Method.

5. Quasi-Zenith Satellite System. Interface Specification for QZSS (IS-QZSS). VI.4.

6.JP 4296302 B.

7.JP 4461235 B.

8. US 7948437 B2. Positional information providing system, positional information providing apparatus and transmitter.

9. IEEE Std 802.15.4 ^tm -2011. IEEE Standard for Local and metropolitan area networks - Part 15.4: Low-Rate Wireless Personal Area Networks (LR-WPANs).

10. ISO / IEC 24730-2. Information technology - real-time locating systems (RTLS) - part 2: 2.4 GHz air interface protocol.

11. US 4,894,662. Method and System for Determining Position on a Moving Platform, such as a Ship, Using Signals from GPS Satellites.

12. "Self-Calibrating Pseudolite Arrays: Theory and Experiment." Edward Alan LeMaster.

13. US 4,728,959. Direction Finding Localization system.

14. US 2010/0259450 A1. Indoor Position System and Method.

15. US 6282231 B1. Strong Signal Cancellation to Enhance Processing of Weak Spread Spectrum Signal.

16. US 6160837. Method of Avoiding Near-Far Interference Problem in an Array of Navigation Signal Beacons Having Selected CDMA or GPS-like Navigation Signals.

17. WO 99/48233. Pseudolite-Augmented GPS for Locating Wireless Telephones.

Claims (19)

1. A method for positioning a mobile terminal inside a building, which consists in synchronized emission of navigation noise-like signals at one or several carrier frequencies by stationary transmitters, receiving navigation signals by a mobile terminal and then calculating the position of the mobile terminal, characterized in that the M-sequence is used as navigation noise-like signals , the beginning of which for different signals transmitted on the same carrier frequency, is shifted in time by different quantities They differ from each other by the duration of two or more elements of the M-sequence. 2. The method in accordance with claim 1, characterized in that the M-sequence is shifted in a cyclic manner. 3. The method in accordance with claim 2, characterized in that in the process of receiving said signals, code division of the signal is used, wherein the divided codes are obtained on the basis of a cyclically shifted M-sequence. 4. The method in accordance with claim 3, characterized in that in addition to the mobile terminal, the signals of the transmitters are received by one or more receivers with a known location, information on the magnitude of the actual shift of the beginning of the M-sequence, on the frequency and phase of the carrier in the emitted transmitters, is extracted from the sum of the signals the signal relative to the beginning of the M-sequence, the frequency and phase of the carrier signal of other transmitters, report the selected information to the transmitters, the transmitters compare the required and actual information with Vigo beginning of M-sequence, frequency and phase of the carrier relative to other transmitters is corrected based on the obtained difference M-sequence start, frequency and phase of the carrier in the transmitted signal and provide thereby the identity of the desired and actual shifts. 5. The method in accordance with claim 4, characterized in that before calculating the position of the mobile terminal, information about the expected M-sequence shift, carrier frequency and phase in the transmitter signals is loaded into its memory, based on the specified information, the transmitter signals to be tracked are selected, among which there are signals transmitted at the same carrier frequency, receive the signals of the selected transmitters, calculate the actual shift of the beginning of the M-sequence, frequency and phase of the carrier signal of the transmitters, average they take into account the actual shift with the expected one, calculate the mismatch between the actual and expected shifts, then based on the calculated mismatches, determine the radiation angles of the signals transmitted by transmitters tuned to the same carrier frequency, as well as pseudorange to all transmitters. 6. The method according to claim 5, characterized in that the M-sequence used in the formation of the navigation signal is identical to the pseudo-random rangefinding code of the GLONASS standard accuracy signal with a period of 1 ms and a symbol rate of 511 kbit / s, while digital information, contained in the navigation signal is transmitted at a speed of 1000 / N bits / s, where N is an integer greater than 3. 7. The method according to claim 6, characterized in that the carrier frequency of the transmitters is determined by the formula: Fcarrier = F0 + KL · dFL + KSubL · dFSubL, where F0 is the base carrier frequency of the GLONASS L1 band equal to 1602 MHz, KL is the number letters, dFL - interliter GLONASS interval equal to 562.5 kHz, KSubL - additional subcarrier index taking the value 0, ± 1, ± 2, dFSubL - interval between additional subcarriers equal to K / N kHz or K / (N-2) kHz, where K is an integer satisfying the relation: N <K <2 · N. 8. The method in accordance with claim 7, characterized in that the navigation signals are transmitted at the letter frequencies of the GLONASS satellite navigation system, not occupied by satellite signals. 9. The method according to claim 8, characterized in that the bit boundary of the digital information transmitted in the navigation signal of the transmitter does not coincide with the beginning of the M-sequence. 10. The method in accordance with claim 9, characterized in that the bit boundaries in the navigation signal transmitted by several transmitters coincide in time. 11. The method in accordance with claim 10, characterized in that each transmitter is associated with a synchronization zone with a certain rank, while the beginning of the M-sequence, the phase of the carrier and the carrier frequency of transmitters with a lower synchronization rank are adjusted in accordance with the beginning of M -sequences, carrier phase and carrier frequency value of transmitters with a higher synchronization rank. 12. The method in accordance with claim 11, characterized in that the signal emitted by the transmitters contains additional digital information designed to ensure mutual synchronization of the transmitters. 13. The method according to p. 12, characterized in that the signal containing additional digital information is transmitted on a carrier frequency and modulated with a pseudo-random code that does not coincide with the carrier frequency and pseudo-random code of the navigation signal emitted by the transmitter, while the signal containing additional digital information transmit synchronized with the navigation signal. 14. The positioning system of a mobile terminal inside buildings, containing several stationary transmitters of navigation noise-like signals with a known location connected to the corresponding antennas, as well as a mobile terminal with an unknown location, containing a database with the location of these transmitters, capable of receiving a satellite navigation signal and determine based the received signal its location, characterized in that the stationary transmitters of noise-like signals are capable of emit a GLONASS standard accuracy signal, and the mobile terminal is capable of receiving a GLONASS standard accuracy signal, while the system also contains one or more stationary receivers with a predetermined location connected to the corresponding antennas capable of receiving a GLONASS standard accuracy signal, in that the number of stationary receivers is less the number of stationary transmitters, in that the stationary transmitters and stationary receivers together with the corresponding antennas are combined into devices, called beacons, each lighthouse contains one stationary receiver, one or more stationary transmitters, a clock generator and a communication module, while the output of the communication module is connected to the first input of the receiver and the first input of all transmitters located in the beacon, the output of the receiver is connected to the second the input of all transmitters located in the beacon, the output of the clock generator is connected to the third input of all transmitters located in the beacon and to the second input of the receiver, and the input of the communication m The module is the entrance of the beacon, while stationary transmitters, a stationary receiver, a clock generator and a communication module of each beacon are located inside the radio-transparent case of the beacon. 15. The system according to 14, characterized in that the output of the receiver is connected to the second input of all transmitters located in the beacon through an interface converter containing one input and one or more outputs, while the number of interface outputs is equal to the number of transmitters contained in the beacon, the input of the converter The interface is connected to the transmitter output, and each output of the interface converter is connected to the second input of one of the transmitters. 16. The system of clause 15, wherein the interface converter contains a data converter, characterized in that the data converter extracts from the output of the receiver information intended for one of the transmitters contained in the beacon and transmits it to the second input of the corresponding transmitter, when this transmitted information is modified. 17. The system according to clause 16, wherein the antennas of the stationary receiver and each stationary transmitter contained in one beacon are located relative to each other at a distance of not less than a quarter of the wavelength, while in the database as the location of the stationary transmitters and the stationary receiver The coordinates of the antennas of the stationary transmitters and the stationary receiver are entered. 18. The system according to 17, characterized in that the components of the stationary transmitters and the stationary receiver with the exception of antennas are located in one chip. 19. The system according to 17, characterized in that it contains a server with a database accessible to the mobile terminal containing the coordinates of the stationary receivers, the coordinates of the stationary transmitters, the set shifts of the beginning of the M-sequence, the frequency and phase of the carrier signal of the transmitters, as well as the synchronization zone transmitters.

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