JPS59501922A - Method and device for determining pseudorange from earth orbiting satellite - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Calculate pseudo range from earth orbiting satellite method and apparatus Invention contractual relationship American Aerospace Layer and California Institute of Technology - Contract box NAS7 signed with Jet Propulsion Laboratory 100, the United States Government has rights in this invention.

Background of the invention The present invention provides platform positioning, i.e., tracking and tracking of points relative to the earth coordinate system. More specifically, it relates to methods of positioning and positioning, and more specifically, Relates to a method and device for setting a pseudo-microwave oven.

The U.S. Navy's TRANS IT navigation satellite system operates in large numbers in near-Earth polar orbits. Consists of satellites. The satellite sends the satellite position estimator information modulated toward the user station. It transmits carrier waves of 150 MHz and 400 MHz. The user receives The frequency of the signal is measured and the Doppler frequency shift and satellite signals observed by the user are Calculate the range from the transmitting satellite based on the star position estimation table information. Specifically, If the position of the satellite to be measured and its transmission frequency are known, the satellite can pass over the receiving station. The Doppler frequency shift of the signal received from the satellite at one point within 15 minutes is Allows determination of the position of said point in the earth coordinate system. For more information on TRANSIT , Jones Hopkins APL Technica, published from January to March 1981 H, D published in Le Digest, Volume 2, No. 1, pp. 3-13. , 7 Uyuri (H, D, Black)'s paper Passatellite for Earth Sa - Vaving and Ocean Navigating''.

NAVSTAR G-D- consists of multiple coded signal transmitting satellites in telegeometric orbits. The PAL positioning system provides access to authorized users who have been assigned codes. provides greater accuracy and flexibility than TRANSIT. At the moment, Although there are only 6 NAVSTARs in orbit, 4 It is planned to increase the number of satellites to 18, arranged so that 100 satellites can be seen. Each N AVSTAR satellites do not have the so-called L1 band with a center frequency of approximately 1575.42 MHz. Transmits line signals and L2 band wireless signals whose center frequency is approximately 12216MHz. . The L+ band has a protection information channel called P code and C/A code. The coarse acquisition channel to be transmitted has a suppressed carrier L1 modulated in the form of double sidebands. Ru. The L2 band has a suppressed carrier L2 on which the P code is modulated in the form of double sidebands. do. Both the P code and C/A code channels are i.e. 10.230M l-IZ for P code, C/A code In the case of 1.0230 MHz, it carries a binary information signal. P code The sequence is known only to authorized users of the NAVSTAR system. P-co Because the code sequence is known, authorized NAVSTAR users can ensure that the signal is moving at the speed of light. Based on the fact that the P-code sequence is transmitted between the satellite and the user from the satellite at the observation location by measuring the time it takes to pass the You can set the pseudorange of . The true range from the satellite to the user is the pseudorange the satellite clock and the user relative to a time reference, e.g. a universal time harmonized clock. -Equal to the difference in clock offsets. In this way, the pseudorange is measured. If so, the user can measure the offset of the user clock and the satellite clock. A series of tracking functions called platform positioning can be performed using well-known techniques. and position measurements. Persons not informed of P-code sequence The NAVSTAR satellite system will be used simultaneously to establish a high-precision pseudorange. It is impossible to use it.

Summary of the invention The present invention enables Allows users to determine pseudoranges from transmitting satellites. transmitted from satellite A modulated radio frequency signal with a given frequency content is intercepted at a user station. Ru. The components are recovered from the intercepted signals. Also, the phase and frequency of the component are be measured. From these measurements and similar measurements from other satellites, the pseudorange of the satellite can be used. Specifically, it can be determined from the measured phase and frequency of the intercepted signal. Several phases are observed. The Doppler range value is also determined from the satellite's measurement frequency. de Divide the Zuppler range value by the wavelength of the given frequency and calculate the integer and remainder.

Add an integer to the fractional phase to obtain a value proportional to the -pseudorange.

From the pseudorange, various platform positions, e.g. earth coordinates, can be determined using known techniques. Positioning of user points in the system, differential positioning of users with respect to fixed points, satellite positioning calibration and ion layer calibration.

Brief description of the drawing The structure of the most preferred embodiment of the invention is shown in the accompanying drawings.

Drawing: FIG. It is an explanatory diagram showing a single artificial satellite of Figure 2 shows three satellites orbiting the earth to clarify the Doppler frequency shift. FIG. 3 is an explanatory diagram showing an artificial satellite, and FIG. 3 shows an outline of a receiving device incorporating the principle of the present invention. This is an abbreviated block diagram. 4, 6 and 8 are sketches for explaining the present invention, 5, 7 and 9 are schematic block diagrams of the signal processor of FIG. gram, and FIG. 10 is a schematic block diagram of the integer generator of FIGS. 5, 7, and 9. is a block diagram, FIG. 11 is a schematic diagram of a differential positioning system incorporating the principles of the present invention. It is.

Detailed description of examples Although the invention is applicable to other types of earth orbit transmitting satellite systems, , the NAVSTAR globe provides a very useful signal for pseudoranging measurements according to the present invention. This will be explained below in connection with the global positioning system.

FIG. 1 shows a transmitting NAVSTAR satellite 10 orbiting Earth 12 along an orbit 14. show. The user is located at point 16 on the earth's surface. The earth with its origin at the center of the earth 18 The seat position based on is ρ8. The distance from the user to the satellite 10 is ρ.

The point 16 is located in the observation horizontal plane 2 orthogonal to the radial line 22 passing through the point 16 and the center 18. Located within 0. As shown by the solid line part of the orbit 14, what is the earth 12 on the plane 20? In the opposite part of the orbit 14, the satellite 10 is visible to the user at point 16. I can recognize it. While the satellite 10 is visible, the user at point 16 receives the radio signal from the satellite. is being intercepted. From the maximum of the user from the satellite 10, when crossing the radial line 22 If the satellite is in the plane 20 It changes to another maximum value when sinking below .

This relationship is shown by curve 24. For NAVSTAR, this range is approximately 20, It varies between 000,000m and 25,000,000m. doppler frequency Due to the number shift, the frequency intercepted at point 16 is different from the frequency transmitted from satellite 10. is different from the measured frequency at point 16 when satellite 10 rises above plane 20. Several fM becomes the maximum, and the satellite 10 moves below the plane 20 in the range of wave numbers as shown by the curve 26. Indicated.

Figure 2 shows how the satellite position affects the frequency shift of the signal intercepted by the user at point 16. Indicate what the impact will be.

The satellite velocity component VS located on the imaginary line passing through the satellite and point 16 is the velocity vector of the satellite. The angle between the tor and the imaginary line passing through the satellite and point 16 is α, and it is proportional to COS α. do. In other words, the first satellite that has just risen above the observation horizontal plane has an angle α1, that is, , at a position of about 77°, and its Doppler frequency shift is maximum. At closest approach The second satellite at point has an angle α2 of 90' and a Doppler frequency shift is O. The third satellite, located between the point of closest approach and the observation horizontal plane, has an angle α3 of approximately 103°, and the Doppler frequency shift is negative. Generally, point 16 is the vertex must be located at the satellite position on an imaginary conical surface whose apex angle is α. No. In the case of another dimension, the cones of the two satellites determine the position of point 16, so point 1 2 to determine the location of point 16 by Doppler frequency shift measurements at 6 satellites are sufficient. In the case of 3D, the frequency standard on the receiving side is NAVSTAR If the frequency standard on the satellite side is exactly the same, three satellites are required.

When implementing the present invention, it is possible to reproduce any frequency component of a signal transmitted from a satellite. Ru. To understand how the present invention establishes a pseudorange from the user to the satellite , the distance between them is expressed as an integer of the wavelength of the selected frequency component. It can be thought of as consisting of numbers expressed by numbers. Below, it is called fractional phase and is denoted by φ. , a portion of the wavelength is defined by the frequency fM and the time T between a given point of the selected component and the reference signal. It can be determined by measuring the Specifically, the measurement frequency [M multiplied by time T By doing so, an accurate fractional phase φ can be obtained. Accuracy depends on the wavelength of the selected component. Ru. The total number of wavelengths is the selected component (7) i' coupler frequency spectrum from separate satellites. Based on this, the total doppler range ρD, hereinafter referred to as Doppler range ρD, is determined. Doppler and range values can be estimated by measuring the Doppler distance measurement technique. It will be done. Pseudorange is the number of wavelengths expressed as an integer between the satellite and the user and the number of wavelengths. There is a Japanese talk with some of them. Therefore, the pseudorange can be expressed by the following formula.

Here, ρ' is the pseudorange, C is the speed of light, and fT is the true value of the selected component transmitted from the satellite. frequency, f is the Doppler frequency shift of the selected component intercepted by the user , where N is the time and N is the number of total wavelengths.

Dividing the total Doppler range value ρ by the wavelength λ of the selected component By calculating, the number of wavelengths N and the remainder can be obtained. Obtain Doppler range ρ The measurement for The gold side of the wavelength is accurate if the wavelength is also made to provide high accuracy. However, the remainder contains inaccuracy, that is, error Z. In principle, this surplus is rounded down. Instead, we can calculate the fractional phase φ, which is extremely accurate, by adding the total number of wavelengths N (adding gives an accurate pseudorange ρ', but the precision m depends on the wavelength λ of the selected component.

(Note that in order to obtain the total number of wavelengths 2, several The measured value must be discarded or the quotient must be rounded up to obtain the next total number. ) Figure 3 shows the selected IRP and minutes of the signal transmitted from the NAVSTAR satellite. This shows the receiving device. For convenience, the signals transmitted from the NAV S T A R satellite are The selected frequency components and their characteristics are shown in the table below.

Selected component Frequency Effective reproduction Doppler’ (MHz) Wavelength (m) K#l C--L+carrier wave 1575.42. 095 ±8.3kHz L2 carrier wave 1 227,6. 122 ±6.5kHzP code Chip rate: 10,230’29.3 ±27Hz NAVSTAR satellite? The signals transmitted from the antenna 30 are intercepted by the antenna 30. As already mentioned, This signal has both the P code channel and the C/A code channel in both side band form. The L1 band of the suppressed carrier L+, which is modulated by the formula, and the P code are in double-side band format. and the L2 band of the suppressed carrier wave L2 that is being modulated. Under figure 3 The number marked with a line is the frequency at the specified location in MH2 units unless otherwise specified. . The numbers in parentheses represent the passband of the filter and the time delay of the associated delay circuit.

The antenna 30 is connected to the L+ band and the 12 band via a bandpass filter 32 and an amplifier 34. connected to the input of a power divider 36 that separates the range. The frequency reference 38 is, for example, a Even a relatively simple crystal oscillator such as the Paracard HP105 will do. The Hewlett Paracard HP5065 is synchronized to the satellite frequency reference. It consists of a stable atomic clock like A.

Frequency reference 38 specifies the eight different frequencies used in the receiver. It is connected to a frequency synthesizer 40 formed by a multiplier and a frequency divider. Therefore , the eight frequencies formed by the synthesizer 40 as shown are the frequencies Accurately synchronize with reference 38. The frequency reference 38 is also a universal time harmonization (UT, C) generates an output that provides a clock time of 1 pulse per second (1 PPS) It is also connected to a clock 41 having an output.

From the output of one of the power dividers 36, the [l band is passed through a filter 42 to a mixer 4 4 and in said mixer by one of the signals from the synthesizer 40. is converted downward. The output of mixer 44 is passed through amplifier 46 to power divider 48. Connect to.

For the L1 carrier component, two of the outputs of power divider 48 are connected to mixer 50. played by. The output of mixer 5° is sent to mixer 5 through filter 52. 4 and is lowered in the mixer 54 by the signal from the synthesizer 40. The direction is converted. The output of the filter 52 has its center set at 10.84MH2. , has a range twice that of the Doppler frequency spread appearing on the LI carrier, and therefore The effective reproduction wavelength is 0.095111. Doppler frequency shift of Lt carrier and A low frequency narrow band sinusoidal signal exhibiting fractional phase is transmitted from mixer 54 to a 1+ carrier. A wave signal processor 56 is provided. The state where the Doppler frequency shift is zero is t ok)-1z is shown in the form of a sine wave.

The P-code chip rate component is routed from one output of power divider 48 to mixer 58. and connect another output of power divider 48 directly to P-code chip rate mixer 58 through a delay circuit 60 that introduces a time delay corresponding to 1/2 period of is played by connecting to. The output of mixer 58 is passed through filter 62. and is supplied to a mixer 64 in which the output from the synthesizer 40 is The signal is converted down. - The output of filter 62 is a P-code chip register. It is a sine wave of the top. Doppler frequency shift of P-code chip rate component and a low frequency narrow band sinusoidal signal exhibiting a fractional phase is output from the mixer 64 to the P code. - Provided to chip rate signal processor 66;

The C/A code chip rate component is output from one output of power divider 48 into a mixer. 68 and further outputs of the power divider 48 to the C/A cord. Via a delay circuit 10 that introduces a delay corresponding to 1/2 period of the chip rate It is played by connecting to mixer 68. The output of mixer 68 is filtered. is supplied to the mixer 14 via the mixer 72, and synthesized in the mixer 14. is downconverted by the signal from the sensor 40. The output of filter 72 is a C/A code. It is a sine wave with a de-chip rate. C/A code chip rate component dot A low-frequency narrowband sinusoidal signal exhibiting a puller frequency shift and fractional phase is mixed C/A code chip rate signal processor 16 from processor 74 .

From the other output of the power divider 36, the L2 band is passed through the filter 78 to the mixer 8. 0 and is fed to the mixer 8o by one of the signals from the synthesizer 40. is converted downward. The output of mixer 80 is passed through amplifier 82 to power divider 84. connected to the input of

The L2 carrier component connects two of the outputs of power divider 84 to mixer 86. played by. The output of mixer 86 is passed through filter 88 to mixer 90. The mixer 90 receives the signal from the synthesizer 40 to converted. The output of the filter 88 is centered at 70.84 MHz. , has a range twice that of the Doppler frequency spread appearing in the L2 carrier, and therefore The effective reproduction wavelength is 0.122 m. Doppler frequency shift and minute of L2 carrier A low frequency narrow band sinusoidal signal exhibiting several phases is output from the mixer 90 as an L2 carrier signal. The signal is supplied to processor 92 . The state where the Doppler frequency is zero is 10kHz sine Indicated by waves.

The P code chip rate component of the L2 channel is output from one output of power divider 84. power directly to the mixer 94 and another output of the power divider 84 to the P code. a delay circuit 96 that introduces a time delay corresponding to 1/2 period of the de-chip rate; It is reproduced by connecting to the mixer 94 via the video signal. The output of mixer 94 is , is supplied to the mixer 100 via the filter 98, and the odor of the mixer 100 is The signal from the synthesizer 40 is used to down-convert the signal. The output of filter 98 is , a sine wave at the P code chip rate.

P-code chip rate component exhibits Doppler frequency shift and fractional phase A low frequency narrowband sinusoidal signal is output from mixer 100 as a P code chip rate signal. The number is supplied to the processor 102.

Figure 4 shows satellite 104 and user 0 for C/A code chip rate components. 6, that is, the range. A large number of C/A code components (N> full waves) Long λ. /AC/A , the fractional phase φ is spread between the satellite 104 and the user 106 a/a Ru. The fractional phase φ is measured, the wavelength number AN is the total c/a c7' The doppler rate component determined by subtracting the Doppler range value ρ obtained from the Doppler frequency shift of . This is because the amplitude S/N ratio is 10:1. Accuracy of 50 m or less, i.e. approximately 1/6 C/A of wavelength λ This is because it can be determined with an accuracy of . Uncertainty of total Doppler range value ρ , i.e., bracketing possible errors This is indicated by arc 107, which indicates where the total Doppler range value ρ is within the parentheses. It means to come to the crab. Total number puller, range value ρ with C/A code chip By dividing by the wavelength λ of the plate component, the integer, remainder, and 0/A Obtain the quotient consisting of . In principle, the remainder is rounded down and the number of complete wavelengths is N. /As A The fractional phase φ is an integer. /A, we obtain the accurate pseudorange value ρ′. Ru. If C/mu The remainder is, for example, a fractional phase φ than a given value that depends on the signal-to-noise ratio. /A is less than a given value, for example, less than 1/6 of the wavelength λ for an amplitude S/N ratio of 10:1. Small C/A If so, either ignore this particular measure of the total Doppler range value or The total number of wavelengths N to be added to the fractional phase φ is calculated by adding Na C/A C! /A Pseudorange and obtain ρ'o/A. If the amplitude S/N ratio is 10:1, the pseudorange value ρ' C/a with an accuracy of 5m or better You can

FIG. 5 shows a signal processor 76 that performs the operations described in connection with FIG. Mi The output of the kisser 74 (FIG. 3) is sent to a phase detector 108 and a frequency counter 110. supplied to

For the pulse that appears at the timing of 1 pulse per second generated from the clock 41 The phase of the C,/A code chip rate components is determined by the phase detector 108. Detected. The frequency of this component is controlled by the IPPS interface under the control of the clock 41. It is counted by the frequency counter 110 of the bar.

A phase detector 108 and a frequency counter 110 are connected to a multiplier 112 and The calculator has a fractional phase φ at its output. Form 24°. Mixer 64 (Fig. 3 ) is connected to a frequency counter 114. Output of frequency counter 114 The power is connected to a Doppler position finder 116 which receives input from the clock 41. UTC clock time is also provided. As a position finder 116, in 1982 Magnavox Document MX-TM-3346-81 published in February, G, J, Hoar published in issue 10058 Based on the principles described in “Satellite Surveying”, 400MH Magnavox 150 processes data at 10.23 MHz instead of Z A commercially available device such as Type 2 can be employed. The position finder 116 Determine the error range value ρ. The output of the position finder 116 is Connected to a number generator 118, the integer generator 118 forms the value of the total number of wavelengths 2°A. do. The output of the multiplier 112 and the output of the integer generator are provided to a summing circuit 120; The output of the adder circuit 120 is sent to a multiplier 122, which divides the Number phase φ. The total number of wavelengths is N. C without Doppler shift in the sum of A /A code chip rate component frequency f is multiplied by the speed of light C divided by f.

C/A- FIG. 6 shows the satellite 104 and the user for the case of P code chip rate component. 106, that is, the range. Many P-code chip rate components The complete wavelength λ of the number (NP>) and the fractional phase φ are the satellite 104 and the user P p It spreads between 106 and 106. The fractional phase φ is measured, and the wavelength fine number N is Already obtained pseudorange with an accuracy of less than 1/6 of the chip rate component wavelength λa It can be determined by using the value ρ' c/a. Pseudorange value ρ’　O/A failure Certainty, i.e. possible errors, are placed in brackets 10 in the sense that they fall somewhere within the brackets. 9. Pseudorange value ρ′. Divide A by Pl-chip rate component wavelength' By adding the number to be calculated to the fractional phase φ, an accurate pseudo-range value ρ' is obtained. too For example, if the amplitude S/N ratio is 10:1, then the remainder depends on the S/N ratio. is larger than 5/6 of the wavelength λ, and the fractional phase φa is less than a given value, e.g. If the S/N ratio is 10:1 and the wavelength λ is smaller than 1/6, the total Doppler level is Either ignore the quotient value or add 1 to the quotient integer and add it to the fractional phase φa. It is necessary to obtain the total number of wavelengths N, and to obtain an accurate pseudo-range value ρ'a. amplitude If the S/N ratio is 10:1, the pseudo-digital value will be accurate to 30 cm or higher. ρ′a can be set.

FIG. 7 shows a signal processor 66 or signal processor that performs one of the operations described in connection with FIG. The number processor 02 is shown. The output of mixer 64 or mixer 100 (Fig. 3) is It is supplied to a phase detector 124 and a frequency counter-14 (FIG. 5). Cloth P code chip rate for pulses generated from block 41 at a rate of 1 pulse per second The phase of the components is detected by phase detector 124 . The frequency of this formation is By the frequency counter -14 of lPP5 interval under the control of lock 41 will be counted. The phase detector 124 and frequency counter 114 have their outputs is connected to a multiplier 126 which presents the fractional phase φ at . Multiplier 122 (Fig. ) is connected to an integer generator 128 which forms a value representing the number of wavelengths λ. . The output of multiplier 126 and the output of integer generator 128 are provided to adder circuit 130. , the output of the adder circuit 130 is supplied to the multiplier 132. , the sum of the fractional phase φ and the number of wavelengths N, P due to the Doppler shift Multiplyed by the value obtained by dividing the speed of light C by the frequency f of the P code chip rate component that does not move. be done.

FIG. 8 shows the distance between the satellite 104 and the user 106 for the case of the L carrier component. , that is, indicates a range. Between the satellite 104 and the user 106 there are a large number of L carrier components ( N) completeness A wavelength λ 1 and a fractional phase φ 1 extend between the satellite 104 and the user 106 . fraction place The phase φ is measured, and the number of wavelengths NF has an accuracy of 1/6 or less of the L carrier component wavelength λ. Already me L It is determined using the pseudorange value ρ'. The uncertainty of the quasi-shinji ρ′a, immediately The parentheses 111 mean that the possible error will be somewhere within the parentheses. It was shown in

However, a relatively high S/N ratio of 230:1 is required. Pseudorange value ρ′ LW! Transmission wave Transmission wave component wavelength sword division p L By doing this, we can obtain the quotient consisting of the total number of wavelengths N and the remainder. Ru. In principle, the remainder is rounded down and the total number of wavelengths N is converted into a fractional phase φ. By adding, an accurate pseudorange value ρ' is obtained. If the remainder depends on the S/N ratio, For example, if the amplitude S/N ratio is 10=1, then 5/6 of the wavelength λ is also large, and the fractional phase φ is larger than the given value L If it is less than 6, the total number of wavelengths to be added to the total Doppler range value. N and must obtain an accurate pseudorange value λ'. Amplitude S/N ratio is 1 If the knee is 0, the pseudorange value ρ' is accurate to 2 mm or better.

can be determined.

FIG. 9 shows a signal processor 56 or 9 that performs the operations described in connection with FIG. 2 is shown. The output of mixer 54 or mixer 90 (FIG. 3) is fed to phase detector 134 and and frequency counter-36. Clock 41 emits one pulse per second The phase of the carrier wave relative to the generated pulse is detected by a phase detector 134. . The frequency of this component is set at a frequency of 1 pps interval under the control of clock 41. It is counted by a counter 36. Phase detector 134 and frequency counter -36 is connected to a multiplier 138 which forms a fractional phase φ at its output. multiplication The output of the generator 132 (FIG. 7) is an integer generator that forms a value representing the total number of wavelengths λa. 140. The output of the multiplier 138 and the output of the integer generator 140 are the addition ports. μm42, and the output of the adder circuit 142 is supplied to the multiplier 144, and the multiplier In the device 144, a Doppler shift is applied to the sum of the fractional phase φ and the total number of wavelengths NL. is multiplied by the value obtained by dividing the speed of light C by the L carrier component frequency fL without .

The explanation will be given again with reference to FIGS. 4, 6, and 8.

The fractional phase φ is measured accurately in all cases, but there is an ambiguity in it. . That is, in addition to the fractional phase φ, the total path length connecting the satellite 104 and the user 06, that is, the pseudo There is a total number N of cycles constituting the range ρ'. For any selected ingredient, Although fractional phase measurements are not very accurate, they are accurate to within about 1/6 of the selected component wavelength. The ambiguity can be resolved and the number of wavelengths N can be accurately determined by the measurements taken.

That is, in the above example, the ambiguity of the C/A chip rate code component is Doppler position measurements resolve ambiguity in P-code chip rate components. Using pseudoranges obtained from measurements related to the C/A chip rate component The carrier component ambiguity is resolved by the P code chip rate The solution is to utilize pseudoranges obtained from measurements associated with the components.

The phase detector may, for example, supply pulses to the counter (e.g. at a frequency of 5 MH). 2) A so-called time interval counter that includes a clock pulse source. be.

This counter is clocked when supplied with 1 PPS pulse from clock 41. ・Start counting pulses and clock the phase at the positive zero crossing of the detected component. Stop counting pulses. Similarly, the frequency counter above is cycle of the selected component occurring in one second, for example determined by the clock 41. It consists of a counter that counts the number of files.

FIG. 10 shows integer generator 118 in more detail. (integer generator 128.140 is exactly the same as this. ) Doppler position finder 116 (multiplier 1 in FIG. 22, in FIG. 9, the divider 170 to which the output of the multiplier 132) is connected is connected to the input value is the wavelength value λ (λ in Figure 7, λ in Figure 9) C/A P Divide by. The output of the divider 110 is the transmission gate 112 and the isolation gate Connected to the adder circuit 120 (132 in FIG. 7, 144 in FIG. 9) via 174. Continue. The output of divider 170 is also connected to +1 circuit 116, transmission gate 118 and Addition port 9120 (132 in FIG. 7, 144 in FIG. 9) is connected through isolation gate 174. ). The same signal fed to divider 170 is fed to threshold detector 180. will also be supplied. The output of the multiplier 112 (126 in FIG. 7, 138 in FIG. 9) is , are supplied to the threshold detector 182. The outputs of the threshold detectors 180 and 182 are A It is supplied to the input of ND gate 184. The output of AND gate 184 is the transmission Directly connected to the control filtration gate of gate 112 and via inverter 186 Connect to the control terminal of transmission gate 178. Threshold detector 180 and 182, A While the ND gate 184 and inverter 186 are digital control circuits, , divider 170, +1 circuit 176, transmission gates 112 and 178, and Isolation gate 174 is an analog or digital signal transmission circuit. Threshold test The detector 180 has a signal supplied to its input having a wavelength λ. Remainder greater than 5/6 of 7 Outputs a high binary value if it is greater than a threshold representing the quotient with remainder. threshold detector 182 is such that the signal supplied to its input exhibits a fractional phase less than or equal to 1/6 of the wavelength λ. C/A Outputs a high binary value if When these two conditions are met, the AND) gate 184 outputs a high binary value to open the transmission gate 178, and the divider 110 A value representing the integer quotient of these plus 1 is transmitted. Otherwise, the transmission Gate 172 provides a value representing the integer quotient from divider 170.

The signals and components shown in Figures 5, 7 and 9 may be analog or digital. stomach. In the case of digital, although not shown, a sequential timing circuit is provided. These performances This can also be done with a programmed digital computer.

- For selected components in the L2 band without C/A code channels, Figure 4 and As explained in connection with FIG. 5, the wavelength λ. The total number NP of wavelength λa is not h. The Doppler frequency shift of the P-code component with sufficient precision to allow the derivation of Adjust the Doppler range based on this.

This total number of wavelengths NP is calculated as P-]-domain instead of C/A code chip rate component. ・Add to the fractional phase φa of the chip rate component. In this case, the C/A code position Resolving phase ambiguity, the wavelength λ is not a necessary condition for positioning with 50 m accuracy. A higher SZN ratio is required to solve 1/6 ('5111) of A.

When processing signals from multiple satellites with a directional antenna, it is necessary to process signals from one satellite at a time. Since only those signals are received, processors 56, 66, 76, 92 and 102 All you need to do is install a one-dark signal processor like this. Using an omnidirectional antenna When a satellite is observed at a time, for example, one set of signal programs is assigned to each of four satellites. A separate processor must be installed. Signals received from different satellites are The difference can be determined by the frequency difference caused by the error frequency shift 1~. For example, comb They can also be separated from each other by filters.

Figure 11 shows the differential position determination, i.e. the user's position relative to a fixed point in the earth coordinate system. Finally, a case in which the present invention is applied is shown. NAVSTAR Mamoru 1150G;t, 1st and and a second fixed ground station. The distance from the satellite 150 to the first station is ρ1, and the second Let the distance to the station be ρ2. Let S be the unit vector from the first station to the satellite. No. This is the suspension B that includes the baseline vector from the first station to the second station. At the first fixed station, The star signal is received by an antenna 152 that connects to a receiver and signal processor 154. Intercepted. The receiving device and signal processor 154 performs processing on selected components of the intercepted signal. extracts the frequency and time interval values and transmits this information via transmission line 158. and transmits it to a remote computer 156. However, if these values are As a result, information may be delayed to some extent during transmission. Similarly, the second unit At the user station, the satellite signal is transmitted to the receiver 2 and to the signal processor 162. is intercepted by antenna 160.

The receiver and signal processor 162 determines the frequency and timing for selected components of the intercepted signal. time interval value and transmits this information to the computer via transmission line 164. 156 for transmission, and the computer 156 stores the list in Appendix A. The attached computer program allows you to create a computer program for each group. The computer 156 calculates the following equation: +CT = C/f < f 2 T2 - f r T +)M 10/f (N2-N+) However, ΔT, □ is the clock offset at the first station, and ΔTo2 is the clock offset at the second station. The clock offset, T'T'M, is different for each signal entering each station. The transmission medium error, fl is the measurement frequency of the selected component at the first station, and 1 is the measurement frequency of the selected component at the first station. f2 is the measurement time interval of the selected component at the second station. frequency, ■2 is the measurement time interval of the selected component at the second station, and δ =Δρ−B2/2ρl. The receiving device and signal processor 154, 162 are Frequency counter and phase sensing as described in connection with FIGS. 5, 7 and 9 With the container, it is constructed in the manner described in connection with FIG.

The embodiments of the invention described above are intended as preferred embodiments and as detailed descriptions of the invention. The scope of the present invention is not limited to this example. stomach.

Various modifications will occur to those skilled in the art without departing from the spirit and scope of the invention. can be done. One feature of the present invention is to simultaneously receive modulated radio signals from multiple satellites. transmitting a signal and regenerating a component from said signal for comparison with the frequency of the transmitted component. The purpose is to determine the pseudo range by Doppler positioning using only and.

Based on the comparison, the user position can be determined as described above. Book as Appendix B Although the description of the invention is attached, the disclosure content thereof may be incorporated into the specification of the present application as necessary. It will be done.

international search report

Claims (1)

[Claims] 1. A radio frequency that carries a signal with a suppressed carrier of a given frequency from a user A method of determining a pseudorange to a transmitting satellite in one earth orbit that transmits information, the method comprising: Intercept the signal at the user's location, Regenerate the suppressed carrier wave from the intercepted signal, Determine the phase of the suppressed carrier, Determine the frequency shift of the suppressed carrier for a given frequency A method characterized in that it consists of steps. 2. From the user to the earth orbit transmitting a radio frequency signal with a given frequency component. A method of determining a pseudo range to a transmitting satellite on the road, Intercept the signals from each satellite at the user's location, and extract the components from the intercepted signals from each satellite. and measure the phase of the component, measuring the frequency of the component; Determine the fractional phase from the measured phase and frequency of the intercepted signal from each satellite, Determine the Doppler range value from the measured frequencies from at least two satellites, Integer and remainder by dividing the Doppler range value by the wavelength of a given frequency form and add said integer to said fractional phase A method characterized in that it consists of steps. 3. A radio frequency signal that transmits a radio frequency signal with a given frequency β from the user. A method for determining a pseudorange to a transmitting satellite, intercepting signals from each satellite at the user's location and reproducing said components from the intercepted signals; measuring the phase of the component; Measure the frequency of said component A method characterized in that it consists of steps. 4. Modulated radio frequency transmitted from all satellites and having the same given frequency content A method for determining a user's position in an earth coordinate system from a number signal, the user Intercept signals from multiple satellites simultaneously at the location of regenerating from each intercepted signal the component reflecting the Doppler frequency shift; Measure the frequency of the reproduced component of each intercepted signal and compare the measured frequency with the given frequency Verify the Doppler frequency shift by A method characterized in that it consists of steps.