RU2285935C2 - Method for multi-positional determining of position of decametric transmitters - Google Patents

Abstract

FIELD: radio engineering, possible use for determining position of objects using radiations of their decametric transmitters with use of two or more receiving stations (range and direction finders).

SUBSTANCE: method is based on using additional information about rules of ionosphere distribution of decametric signals. This information is considered at each receiving station when determining assumed coordinates of objects by one-positional method with use of ionosphere model. In central calculator, connected to all stations, by comparing results of physically different methods of estimation of spatial coordinates (one-positional and multi-positional) indeterminacy of unification of measurement results is removed and position of objects is determined unambiguously with use of two or more stations.

EFFECT: increased precision of determining position of a set of one-typed decametric transmitters by wider class of signals, including complex signals with low spectral density of power.

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Description

The invention relates to radio engineering and is intended for passive location of objects from the radiation of their DKMV transmitters using two or more receiving stations (direction finders-rangefinders).

With the advent and improvement of communication systems and radio equipment using complex signals with a low spectral power density, problems arise associated with the determination with high accuracy of the location of many similar DKMV transmitters with multi-position systems. These problems are based on a contradiction: on the one hand, due to the increased energy secrecy of complex signals, it is necessary to minimize the number of receiving positions of the measurement system, and, on the other hand, to preserve the uniqueness of the results, an increase in the number of positions is required.

A known method of multi-position location of objects from the radiation of their DKMV transmitters [1], including direction finding of radio transmitters using ground direction finding stations distributed at certain points on the earth’s surface, using triangulation using a central calculator associated with direction finding stations, the position of the transmitters on the earth’s surface, direction-finding stations, visualization on the screen of the graphic remote control associated with the central computer, corresponding their position of the transmitter relative to the direction-finding stations.

The main disadvantage of this method is the need to use at least three direction finding stations to determine the location.

A known method of multi-position location of objects from the radiation of their DKMV transmitters [2], free from this drawback and adopted as a prototype, including:

- reception and synchronous conversion at several stations of the received radio signals into digital signals;

- restoration from digital signals of the moment of arrival and azimuth bearing of each received radio signal;

- determination in the central computer associated with all stations of the difference in the moments of arrival of the coincident radio frequency signal at two stations and the corresponding position line difference on the Earth’s surface;

- calculation of coordinates of the point of intersection of the position line and bearing of one of the stations;

- identification of the coordinates of the intersection point as preliminary coordinates of the location of the radio signal source;

- repeating the operations of determining the preliminary coordinates of the source with all possible pairs of stations;

- calculation of the location of the source of the radio signal by combining the preliminary coordinates.

This method when determining the location of many of the same type of DKMV radio transmitters loses its effectiveness. It is known that surface waves of a DKMV transmitter decay sharply at distances of more than 15 km when propagating along the earth's surface and at distances of more than 200 km when propagating along the water surface. In this regard, the main propagation mechanism of DKMV on paths up to 10,000 km is multi-hop ionospheric propagation, in which, due to the difference in the group propagation velocity of the signal, the actual difference in the moments of arrival of the radio signal at two stations can significantly differ from the case of propagation in free space.

Thus, the use of the prototype method for determining the coordinates of the DKMV transmitters, based on a combination of the goniometric and difference-ranging methods and implemented by at least two receiving stations, can lead to significant location errors due to the presence of:

- anomalous measurement errors of the azimuthal bearing caused by the slopes of the reflecting layer of the ionosphere;

- anomalous errors in determining the position line caused by the difference in the group velocity of propagation of radio waves in the ionosphere and free space.

Improving the accuracy of multi-position location of DKMV transmitters using the prototype method can be provided by histogram processing or averaging of measurement results to suppress the influence of slopes of the reflecting layer of the ionosphere on the accuracy of positioning. However, this way does not solve the problem, since it requires at least a daily observation cycle, which leads to the loss of its practical value.

The technical result of the invention is to increase the accuracy of determining the location of many of the same type of DKMV transmitters for a wider class of signals, including complex signals with a low spectral power density, by eliminating anomalous measurement errors based on a combination of single-position and multi-position methods for determining coordinates.

To achieve the technical result, a method for multi-position location of objects from the radiation of their DKMV transmitters is proposed, which includes receiving and synchronously converting received radio signals to digital signals at several receiving stations, according to the invention, from the digital signals, the pulse signal flow is described, which describes the state of radiation and pauses in radiation transmitters at the receiving frequency, and the azimuthal and elevation bearings corresponding to each pulse transform the reconstructed stream of pulsed signals to the streams of individual transmitters, which differ in electronic addresses (frequency, azimuth, elevation angle), for each address simulate the path of the reverse multi-hop propagation of the radio signal from the receiving point through the ionosphere and restore the coordinates of the points of arrival of the model trajectory on the Earth's surface, consider them as assumed radiation points of the radio signal of an individual transmitter, convert the signal flow of an individual transmitter with an address (frequency, azimuth, elevation) a stream with a detailed address (frequency, coordinates of possible radiation points), and in a central computer connected with all stations, the streams received at different stations are compared in pairs with a detailed address and those pairs of flows that have the same coordinates of possible points of signal emission are selected for the orthodromes are built for each selected pair of streams and the coordinates of the intersection point of the orthodrome are calculated, the coordinates of the intersection point of the orthodrome and the coordinates of the coincident points of the selected pair of streams are compared and at Ichii coincidence points operate their union and determine coordinates of a point, which is identified as the transmitter coordinates corresponding to a selected pair of flow streams for different pairs of coordinates of points are compared, as the coordinates of the identified transmitter, and if there is a match determined by combining the refined location of the transmitter points coincident coordinates.

The proposed set of features allows us to use additional information about the patterns of ionospheric propagation of DCMV signals when determining the location of objects. This information is taken into account at each station when determining the estimated coordinates of objects in a one-way manner using the ionosphere model. In the central computer, which can be part of any station, by comparing the results of physically different methods of estimating spatial coordinates (single-position and multi-position), the uncertainty of identifying the measurement results obtained at different stations is eliminated, and the location of objects when using two or more stations is uniquely determined, which leads to the achievement of a technical result.

The operation of the method is illustrated by drawings:

Figure 1. Block diagram of a device for positioning DKMV transmitters.

Figure 2. The signal flows generated at one of the receiving stations of the positioning system:

A _f ⁽¹⁾ (z) - after amplitude demodulation of signals at a frequency f;

X _f ⁽¹⁾ (z) - after converting the stream of demodulated signals A _f ⁽¹⁾ (z) into a stream of pulse signals of unit amplitude, describing the radiation flux at a frequency f without reference to a specific transmitter;

- после преобразования потока X_f ⁽¹⁾(z) в потоки сигналов, отличающиеся электронными адресами (частота f, азимут α, угол места β) и описывающие состояния излучения и паузы в излучении первого и второго передатчика.

- after converting the flux X _f ⁽¹⁾ (z) into signal streams that differ in electronic addresses (frequency f, azimuth α, elevation angle β) and describe the radiation states and pauses in the radiation of the first and second transmitters.

Figure 3. The operation scheme of the positioning system using two receiving stations (direction finders-rangefinders).

Figure 4. Features on-off location.

Figure 5. Features of combining possible points of signal emission.

6. Location display form.

The device (figure 1) contains K receiving stations (PS), each of which includes a series-connected antenna system 1, a multi-channel radio receiving device (RPU) 2, a multi-channel analog-to-digital converter (ADC) 3, a discrete Fourier transform (DFT) 4 and a radio modem 5. Each station is connected via a radio link 6 to a central computer (CV) 7, including serially connected radio modems 8, a memory (memory) 9, an identification unit 10, an orthodrome processing unit 11, a coordinate comparison unit 12, and an indie unit ation 13.

The registration of signals at all stations is synchronized in time from an external source (the receiver of the synchronization signal is not shown), which ensures the simultaneous start of the ADC 3 of all stations. Synchronization is necessary for correlation of the high-frequency fields of transmitters coherently received by different array antennas at optimal time-frequency signal localization and two-dimensional direction finding [3]. In addition to the external signal of a highly stable clock emitted, for example, from a satellite, it is possible to synchronize time from an internal clock with a highly stable reference source installed on a central computer 7 and at each station. In the latter case, it is necessary to periodically compare the hours, for example, using a reference source.

Antenna system 1 contains a reference antenna with number n = 0 and N antennas with numbers n = 1 ... N, combined in a grid. Multichannel RPU 2 is made with a common local oscillator and with a bandwidth of each channel exceeding the width of the spectrum of the transmitter signal. The common local oscillator provides multi-channel coherent signal reception, which is the main condition for interferometric (holographic) registration of complex signals of the wave fields of the transmitters. A wide bandwidth of the RPU 2 channels is necessary for recording complex signals, most of which have a wide range of frequencies. In addition, RPU 2 provides the connection of a reference antenna (n = 0) instead of all the antennas of the array for periodic calibration of channels using an external signal source in order to eliminate their amplitude-phase non-identity. Calibration by internal signal source is possible. In this case, a noise generator can be used, the output of which can also be connected instead of all antennas for periodic calibration of channels.

Calibration is necessary due to the fact that finding bearings on the real part of the synthesized radiation pattern requires two conditions to be met when it is implemented:

- the exact (with an accuracy of fractions of the minimum wavelength of the working frequency range) coordinates of the antenna elements of the array relative to the reference element must be known;

- phase incursions in feeders should be taken into account if they differ in electric length, and the non-identity and time-varying phase-frequency characteristics of the receiving paths of the applied RPUs.

The first of these conditions is easily satisfied by simple measurements of the geometry of the lattice. The second condition can be fulfilled by aligning the characteristics of the feeders and paths at the stage of manufacturing the device or by special calibration procedures for a special internal or external source of the signal during its operation, which is implemented in the proposed device.

The minimum number of channels of device 2 is two. In this case, one of the channels of the RPU 2 is constantly connected to the reference antenna (n = 0), and the second channel is connected in series in time to each of the N antennas of the array. At the same time, a more economical, from the point of view of the required volume of equipment, but less informative method of sequential synthesis of the angular spectrum is realized.

The DFT block 4 is multiprocessor and provides parallel processing of signals received by the reference antenna (n = 0) and all N antennas of the array.

Radio modems 5 and 8, together with communication lines 6, provide the exchange of information between stations and CV 7.

A device is operating that implements a multi-position location method for DKMV transmitters, as follows.

Signals of direction-finding transmitters arrive at the antenna systems 1 of all stations.

At each station with the help of RPU 2, time signals x _n (t) are coherently received, where n is the number of the antenna element for all bases formed by the reference (n = 0) and all antennas included in the array (n = 1 ... N) .

Using ADC 3, the received RPU 2 signals x _n (t) are synchronously converted at all stations into digital signals x _n (z), where z is the number of the time reference of the signal, and are recorded in the DFT block 4.

At each station in the DFT block 4, the stream of pulse signals of unit amplitude is restored from digital signals, describing the radiation states and pauses in the radiation of the transmitters at the receiving frequency, and the azimuth and elevation bearings corresponding to each pulse. Recovery is possible in various ways, for example [3]. The following operations are performed:

где F_t{...} - оператор ДПФ по времени, а f - номер частотной дискреты;- restore the complex spectra of the signals of each antenna

where F _t {...} is the DFT operator in time, and f is the number of the frequency discrete;

сигнала опорной антенны с порогом обнаружения выбирают f-е дискрета, в которых обнаружен входной сигнал, то есть определяют среднюю частоту

и полосу δf частот, реально занимаемую спектром входного сигнала;- power spectrum comparison

of the reference antenna signal with a detection threshold, select the f-th discrete in which the input signal is detected, that is, determine the average frequency

and a band δf of frequencies actually occupied by the spectrum of the input signal;

- using a digital filter with a passband equal to the found value of the spectrum width δf, a signal is extracted from the digital signal of the reference antenna x ₀ (z)

с помощью программно реализуемого амплитудного детектора

где k=1...K - текущий номер станции;- demodulate the signal

using a software-implemented amplitude detector

where k = 1 ... K is the current station number;

посредством сравнения с порогом U₀ в поток импульсных сигналов единичной амплитуды

Порог выбирают исходя из минимизации вероятности пропуска сигнала. Поток импульсных сигналов

описывает поток излучений на частоте приема

без привязки к конкретному передатчику. Импульс потока сигналов

соответствует наличию излучения на частоте

а пауза потока - отсутствию излучения.- convert signals

by comparing with the threshold U ₀ into the stream of pulse signals of unit amplitude

The threshold is selected based on minimizing the probability of missing a signal. Pulse Flow

describes the radiation flux at the receiving frequency

without reference to a specific transmitter. Signal flow pulse

corresponds to the presence of radiation at a frequency

and pause flow - the absence of radiation.

(фиг.2,а) и

(фиг.2,б), формируемые на первой приемной станции двухпозиционной системы;Figure 2 shows the flows as an example

(figure 2, a) and

(figure 2, b) formed at the first receiving station of the on-off system;

к конкретному передатчику определяют двумерный пеленг излучения (по азимуту и углу места) на частоте

в интервале существования импульса.- to bind each pulse of the radiation flux

to a specific transmitter determine a two-dimensional bearing of the radiation (in azimuth and elevation) at a frequency

in the interval of existence of the impulse.

For what:

в найденной полосе δf частот;- receive the complex amplitudes of the signal of the nth antenna by convolving the complex conjugate spectra of the reference and other antennas

in the found band δf frequencies;

- determine the azimuthal α ₀ and angular β ₀ bearings from the maximum of the real part of the two-dimensional complex angular spectrum

- модельная фазирующая функция, зависящая от конфигурации антенной решетки;where d _n = (m, h) is the radiation pattern of the nth antenna, m = 0 ... M - 1 is the current number of the grid node in azimuth, M is the number of nodes in azimuth, h = 0 ... N - 1 - the current node number of the grid pointing the lattice in elevation, N is the number of nodes in elevation, and

- model phasing function, depending on the configuration of the antenna array;

преобразуют восстановленный поток

импульсных сигналов в потоки отдельных передатчиков

отличающиеся электронными адресами (частота

, азимут α, угол места β) и описывающие состояния излучения и паузы в излучении каждого передатчика.- highlighting groups of pulses with matching two-dimensional bearings at the receiving frequency

convert recovered stream

pulse signals into the streams of individual transmitters

different email addresses (frequency

, azimuth α, elevation angle β) and describing the states of radiation and pauses in the radiation of each transmitter.

(фиг.2,б) преобразовался в два потока

(фиг.2,в) и

(фиг.2,г), совпадающие по частоте, но отличающиеся пеленгами;From figure 2 it follows that the flow generated at the first station

(figure 2, b) was converted into two streams

(figure 2, c) and

(figure 2, g), coinciding in frequency, but different bearings;

сигналов, используя его адрес (f, α, β), моделируют в запеленгованных направлениях траекторию обратного многоскачкового распространения радиосигнала из точки приема (координаты точки приема совпадают с координатами соответствующей приемной станции) через ионосферу и восстанавливают координаты точек прихода модельной траектории на поверхность Земли

где i - номер скачка сигнала после отражения от ионосферы,

- сферические координаты точки на поверхности Земли, причем φ отсчитывается от нулевого меридиана, а θ от оси, проходящей из центра Земли через географический север. Найденные точки рассматривают как предполагаемые точки излучения радиосигнала отдельного передатчика.- for each stream

signals using its address (f, α, β), simulate in the direction-finding directions the trajectory of the reverse multi-hop propagation of the radio signal from the receiving point (the coordinates of the receiving point coincide with the coordinates of the corresponding receiving station) through the ionosphere and restore the coordinates of the points of arrival of the model trajectory on the Earth’s surface

where i is the number of signal jump after reflection from the ionosphere,

are the spherical coordinates of a point on the Earth’s surface, with φ being measured from the zero meridian, and θ from the axis passing from the center of the Earth through geographic north. The found points are considered as the assumed emission points of the radio signal of an individual transmitter.

точек прихода модельной траектории на поверхность Земли изображены только для трехскачковых траекторий, восстановленных на первой приемной станции (ПС 1).FIG. 3 illustrates, by way of example, model trajectories of multi-hop propagation of a radio signal in a positioning system using two receiving stations (range finders). The azimuthal bearings on RPD 1 and RPD 2 obtained at each of their receiving stations (PS 1 and PS 2) are denoted by α ₁ and α _2, respectively. Carbon bearings β ₁ and β ₂ are not shown hereinafter for simplicity. Coordinates

the points of arrival of the model trajectory to the Earth's surface are shown only for three-hop trajectories restored at the first receiving station (PS 1).

In this case, perform the following actions:

и временному интервалу приема (время, месяц, год) формируют модель ионосферы с использованием Международной справочной модели ионосферы IRI-2001 [4]. В результате вычисляют и запоминают пространственное распределение квадрата отношения плазменной частоты электронов f_p=f_p(φ,θ,r) в ионосфере к рабочей частоте

принимаемого сигнала, которое необходимо для вычисления показателя преломления изотропной плазмы μ=μ(φ,θ,r):1. With reference to frequency

and the reception time interval (time, month, year) form the ionosphere model using the International Reference Model of the Ionosphere IRI-2001 [4]. As a result, the spatial distribution of the square of the ratio of the plasma electron frequency f _p = f _p (φ, θ, r) in the ionosphere to the working frequency is calculated and stored

the received signal, which is necessary for calculating the refractive index of an isotropic plasma μ = μ (φ, θ, r):

процедуры вычислений плазменная частота электронов f_p в ионосфере прогнозируется на трехмерной пространственной сетке и аппроксимируется кубической сплайн-функцией. Шаг пространственной сетки по координатам на земной поверхности не превышает 500 км, а по вертикальной координате составляет 2,5 км. После процедуры аппроксимации запоминают коэффициенты аппроксимирующей сплайн-функции в узлах пространственной сетки.To speed up

calculation procedures, the plasma electron frequency f _p in the ionosphere is predicted on a three-dimensional spatial grid and is approximated by a cubic spline function. The spatial grid pitch in coordinates on the earth's surface does not exceed 500 km, and in the vertical coordinate is 2.5 km. After the approximation procedure, the coefficients of the approximating spline function are stored in the nodes of the spatial grid.

и рабочей частотой

. Компоненты единичного вектора

определяются по измеренному азимутальному α и угломестному β пеленгам луча и в локальной системе координат (начало координат совпадает с точкой расположения пеленгатора (φ₀,θ₀,r₀), ось у направлена на север, ось х - на восток, ось z - вертикально вверх) имеют вид

₀={cos β sin α, cos β cos α, sin β}. Переход от локальной системы координат к глобальной декартовой правой системе координат (начало координат связано с центром Земли, ось z проходит через географический север, ось х - через нулевой меридиан) для компонент вектора

осуществляется с помощью матрицы преобразования А:2. Ideal feedback signals are generated in the measured directions of arrival of the rays. An ideal signal is described by a single wave vector

and operating frequency

. Unit Vector Components

are determined by the measured azimuthal α and elevation β bearings of the beam and in the local coordinate system (the origin coincides with the position of the direction finder (φ ₀ , θ ₀ , r ₀ ), the y axis is directed north, the x axis is east, the z axis is vertical up) have the form

₀ = {cos β sin α, cos β cos α, sin β}. Transition from the local coordinate system to the global Cartesian right coordinate system (the origin is connected to the center of the Earth, the z axis passes through geographic north, the x axis passes through the zero meridian) for the components of the vector

is carried out using the transformation matrix A:

where the coordinates of the direction finder φ ₀ , θ _{0 are} substituted as spherical coordinates φ and θ.

3. Form the trajectories of the reverse multi-hop propagation of ideal signals of each beam in the ionosphere. To do this, find the initial values of the spherical coordinates φ, θ, r of the beam, which are assumed to be equal to the coordinates of the point of entry of the beam into the ionosphere φ ₁ , θ ₁ , r ₁ , calculated by the formulas:

декартовых координат точки входа луча в ионосферу:where x _1x , x _1y , x _1z are elements of the vector

Cartesian coordinates of the entry point of the beam into the ionosphere:

- декартовые координаты точки излучения идеального сигнала с поверхности Земли в глобальной декартовой правой системе координат (начало координат связано с центром Земли, ось z проходит через географический север, ось х - через нулевой меридиан). Для первого скачка (i=1) вектор

вычисляется по координатам пеленгатора:r ₀ is the radius of the Earth, h ₀ is the initial height of the ionosphere,

- Cartesian coordinates of the point of emission of an ideal signal from the Earth’s surface in the global Cartesian right-handed coordinate system (the origin is related to the center of the Earth, the z axis passes through geographic north, the x axis passes through the zero meridian). For the first jump (i = 1), the vector

calculated by the coordinates of the direction finder:

идеального сигнала на входе в ионосферу определяется по вектору

с использованием унитарной матрицы преобразования В глобальной системы координат к сферической:The initial value of the wave vector

ideal signal at the entrance to the ionosphere is determined by the vector

using the unitary transformation matrix B of the global coordinate system to spherical:

where the values of φ ₁ , θ _{1 are} substituted as spherical coordinates φ and θ.

To construct the ray path of an ideal signal, the Cauchy problem for the system of differential equations is numerically solved:

идеального сигнала в ионосфере, φ, θ, r - координаты луча.where k _φ , k _θ , k _r are the values of the elements of the wave vector

ideal signal in the ionosphere, φ, θ, r - beam coordinates.

сферические φ₂,θ₂,r₂ и глобальные декартовые координаты точки выхода из ионосферы

луча идеального сигнала. В качестве значений сферических координат φ₂,θ₂,r₂ и волнового вектора

выбирается решение задачи Коши, полученное на предыдущем этапе, в точке выхода лучевой траектории из ионосферы.4. Find the wave normal vector at the exit from the ionosphere

spherical φ ₂ , θ ₂ , r ₂ and global Cartesian coordinates of the exit point from the ionosphere

beam perfect signal. As the values of the spherical coordinates φ ₂ , θ ₂ , r ₂ and the wave vector

the solution to the Cauchy problem obtained at the previous stage is chosen at the exit point of the ray path from the ionosphere.

5. Find the spherical coordinates of the arrival of the beam of the ideal signal to the Earth's surface (for the first jump i = 1):

декартовых координат точки прихода волны на поверхность Земли в глобальной системе координат:where x _3x , x _3y , x _3z are elements of the vector

Cartesian coordinates of the point of arrival of the wave on the Earth’s surface in the global coordinate system:

Matrix B is calculated at a point with coordinates φ ₂ , θ ₂ .

6. The spherical coordinates of the point of arrival of subsequent jumps in the radial path are determined by repeating steps 1-5 using updated vectors

после отражения от поверхности Земли определяются с использованием координат

и

полученных на предыдущем скачке.where matrix A and vector components

after reflection from the surface of the earth are determined using the coordinates

and

received at the previous jump.

соответствует оценке истинного местоположения первого радиопередатчика (РПД 1), а точки с координатами

и

являются ложными.Figure 3, in particular for the trajectory of the three-hop propagation of the model signal from the location of the PS 1 in the direction α ₁ , β ₁ , the point with coordinates

corresponds to an estimate of the true location of the first radio transmitter (RAP 1), and the points with coordinates

and

are false.

Thus, operations performed using model signals make it possible to preliminarily estimate the coordinates of prospective points of emission of signal flows from the Earth's surface.

сигналов отдельного передатчика с адресом (частота

азимут α, угол места β) в поток

с детализированным адресом (частота

координаты

, предполагаемых точек излучения).- convert stream

signals of an individual transmitter with an address (frequency

azimuth α, elevation angle β) into the stream

with detailed address (frequency

coordinates

assumed emission points).

.As a result of this operation, an infinite number of possible radiation points, described by a two-dimensional bearing of the transmitter, is compressed to several estimated transmitter location points described by coordinates

.

Thus, a significant reduction in uncertainty regarding the location of the transmitters is possible when using only one receiving station (direction finder-range finder). One direction finder-range finder provides the solution to the problem of estimated (ambiguous) positioning in cases where the DKMV radio signal of the transmitter is energetically available for receiving only one receiving station. To eliminate the ambiguity in measuring the coordinates of the DKMV transmitter due to the multi-hop spatial radio wave propagation mechanism, it is possible to use additional a priori information about the location of the monitored transmitters, for example, the impossibility of placing the transmitter on the water surface of the Earth. A more effective way to eliminate the ambiguity of measurements is to combine the results of single-position and multi-position measurements of coordinates and the use of at least two spatially spaced direction finders.

поступают в ЦВ 7.Using radio modems 5 and 8, on the communication lines 6 from the outputs of the DFT blocks 4 of all the PS signal flows

arrive at CV 7.

In CV 7, the following actions are performed:

в ЗУ 9.1. Remember the signal flows

in memory 9.

с детализированным адресом и отбирают те пары потоков, у которых есть совпадение координат

предполагаемых точек излучения сигналов. Другими словами, в блоке 10 решается задача устранения неоднозначности определения координат.2. In pairs, in the identification block 10, the streams obtained at different stations are compared

with a detailed address, and those pairs of flows that have a coincidence of coordinates are selected

prospective emission points of signals. In other words, in block 10, the task of eliminating the ambiguity of determining coordinates is solved.

Coincidence of coordinates can be established in various ways. For example, as shown in FIG. 3, according to the affiliation of the alleged emission points of the signals of the overlapping region of the error ellipses [5].

совпавших3. In processing unit 11, using the coordinates

coinciding

points and coordinates of SS 1 and PS 2, for each selected pair of streams, orthodromes are built (the shortest lines connecting each coincident point with the corresponding station on the earth's surface) and the coordinates of the point of intersection of the orthodrome are calculated. To build orthodromes use the coordinates of the station and the azimuth of the coincident point, which is found by the formula

с точкой размещения ПС 1, а также ортодрома с азимутом α_T3, соединяющая точку

c точкой размещения ПС 2.Ha figure 4 as an example shows an orthodrome having an azimuth α _T2 and connecting the point

with the location point PS 1, as well as the orthodrome with azimuth α _T3 connecting the point

with the location of the substation 2.

The coordinates of the intersection point of the orthodrome and the coordinates of the coincident points of the selected pair of streams are combined and the coordinates of the point, which are identified as the coordinates of the transmitter corresponding to the selected pair of streams, are determined.

When combining points, the principle of the center of mass or the principle of weight processing can be used, taking into account:

- the relative position of the receiving stations and transmitters (in the example of Fig. 5, a higher weight should be attributed to the coordinates obtained by the single-position method, see Fig. 5, and, than to the coordinates obtained by the goniometric method, see Fig. 5, b);

- levels of received signals (if at one of the stations for the received signal the signal-to-noise ratio is not enough for accurate measurement, then its one-position coordinates and the orthodrome are used to eliminate the ambiguity, and the same point obtained by the one-way method at another station of the pair is chosen as the coordinates of the RPD) ;

- the relative accuracy of measuring one-position and two-position coordinates (for example, if the simulation uses only the long-term forecast of the ionosphere, then a high accuracy of measuring the azimuth bearing is ensured, and the achievable accuracy of measuring the distance to the RPD does not exceed 15% of the range. In this case, more weight is assigned to the coordinates, obtained by the intersection of the orthodrome of two stations.If the current sounding of the ionosphere is used, then the accuracy of measuring the distance to the RPD increases to 3%. nopozitsionnyh DIP and measurements may be equal).

Figure 4 shows a point with coordinates (φ _RPD1 , θ _RPD1 ), which are identified as the coordinates of the transmitter. In this case, the aforementioned principle of weight processing was used when the maximum weight is attributed to the intersection point of the orthodrome.

As a result of using only two direction finders, rangefinders are provided:

- an increase in the probability of simultaneous reception of weak signals (when using three or more direction finders, this probability is significantly lower) and, as a result, a decrease in the probability of anomalous measurement errors due to an insufficiently high signal-to-noise ratio, typical for multi-position determination of the coordinates of DKMV transmitters using signals with small power spectral density;

- elimination of location errors that occur during lateral displacements of azimuth bearings, due to the construction of the orthodrome;

- elimination of false goals caused by the ambiguity of measurements of the coordinates of the set of the same type of DKMV transmitters.

4. In block 12, for different pairs of streams, the coordinates of the points identified as the coordinates of the transmitter are compared, and if there is a match, the specified location of the transmitter is determined by combining the points with the matching coordinates.

Comparison and integration are possible in various ways [5, p. 297-298]. For example, for each pair of points identified as the coordinates of the transmitter, a point is found according to the principle of the center of mass. If the distance from the center of mass to each point is less than a predetermined threshold, then a decision is made on their coincidence and the choice of the center of mass as the specified location of the transmitter. The threshold value is selected based on the operational accuracy of the coordinate measurement. As a result, two points to be compared are replaced by one point of the center of mass. Using the obtained center of mass point and the remaining points previously identified as the coordinates of the transmitter, the process of determining the location of the transmitter continues until there are points that satisfy the described criterion. After that, the next pair of points is selected and the process repeats.

5. To increase the information content in block 13, the detected directions of the arrival of radio signals in the form of an orthodrome connecting the points of the specified location of the transmitters are displayed on an electronic map of the area (Fig.6).

Thus, the above actions on the signals provide high accuracy in measuring the location of the DKMV radio transmitters when using only two spatially separated receiving stations. If the DKMV radio signal of the transmitter is energetically available for reception to more than two stations, the central computer can combine the location results of several pairs of stations and obtain an updated transmitter location using various weighting algorithms that take into account the levels of received radio signals and the relative location of the different stations and the DKMV transmitter.

Improving the accuracy of determining the location of many of the same type of DKMV transmitters for a wider class of signals, including complex signals with a low spectral power density, is achieved by using a combination of physically different methods (single-position and multi-position) for estimating spatial coordinates, realized when using two or more receiving positions, due to:

- reducing the likelihood of anomalous errors due to the signal-to-noise ratio not high enough for accurate measurements;

- elimination of anomalous positioning errors caused by lateral displacements of bearings due to the inclination of the reflecting layer of the ionosphere;

- elimination of anomalous errors in determining the location of many of the same type of DKMV transmitters, due to the ambiguity of the measurements.

INFORMATION SOURCES

1 FR, patent, 2,688,892, cl. G 01 S 3/40, 1989

2 US Patent, 5,719,584, cl. G 01 S 003/02, 1998

3 RU, patent, 2151406, cl. G 01 S 3/14, 2000

4 Bilitza D. Ionospheric Models for Radio Propagation Studies // The review of radio science 1999-2002 / Ed. W. Ross Stone, IEEE Press. 2002. PP. 625-679.

5 Shirman Y.D., Manzhos V.N. The theory and technique of processing radar information against the background of interference. - M .: Radio and communications, 1981. - 416 p.

Claims (1)

A multi-position method for determining the location of objects from the radiation of their decameter transmitters, including receiving and synchronously converting received radio signals to digital signals at several receiving stations, characterized in that the digital signals are converted into a pulse signal stream describing the states of radiation and pauses in the radiation of transmitters at a receiving frequency, and the azimuthal and elevation bearings corresponding to each pulse transform the stream of pulse signals into the streams of individual transmitters, from with electronic addresses (frequency, azimuth, elevation angle), for each address model the trajectory of the reverse multi-hop propagation of the radio signal from the receiving point through the ionosphere and determine the coordinates of the points of arrival of the signal of the model trajectory on the Earth's surface after reflection from the ionosphere, consider them as the supposed points of radiation of a separate radio signal transmitter, convert the signal stream of a separate transmitter with an address (frequency, azimuth, elevation) to a stream with a detailed address (frequency, coor dynats of possible emission points), and in the central computer associated with all stations, in pairs, the streams received at different stations are compared with a detailed address and those pairs of flows that have the same coordinates of the assumed emission points of signals are selected, orthodromes are built for each selected pair of flows - the shortest lines connecting each coincident point with the corresponding station on the Earth's surface, and calculate the coordinates of the intersection point of the orthodrome, compare the coordinates of the intersection point of the orthodrome and the coordinates of the coincident points of the selected pair of streams and, if there is a coincidence of the points, they are combined and the coordinates of the point are determined, which are identified as the coordinates of the transmitter corresponding to the selected pair of streams, for different pairs of streams, the coordinates of the points identified as the coordinates of the transmitter are compared, and if there is a match, the specified transmitter location by combining points with matching coordinates.

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