RU2564523C1 - Method of angular object orientation using spacecraft radio navigation signals - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: in conditions of noise situation before measurement of phase shifts the vector of correction weight coefficient is determined for each of reception channels by their calibration by reference pilot noise. The noise signal of each of reception channels is summarized with the noise signals of other channels which are compensatory for it, previously multiplied by the respective vector of weight coefficient. Each vector of weight coefficient is calculated on the basis of recurrent assessment of inverse noise correlation matrix taking into account vectors of correction weight coefficients. Then the radio navigational signals are distinguished from n navigation spacecrafts and their initial parameters are restored in each reception channel.

EFFECT: increase of overall performance of multichannel goniometric navigation equipment in a difficult noise situation.

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Description

The present invention relates to the field of satellite navigation and can be used to determine the angular position of objects in space or on a plane under the influence of intentional broadband interference.

The most modern methods are recognized for combating interference based on spatial selection provided using multi-element antenna systems. The principle of interference compensation is based on the use of correlation properties of interference oscillations received by various channels. The protection equipment against active noise interference of the navigation equipment of consumers is a multi-channel quadrature correlation auto-compensator with an algorithm for the formation of weighting coefficients and compensation digital summation. To effectively suppress interference, it is necessary to take into account all delays and decorrelating factors that occur in the receiving paths, which can be of various kinds: in the form of differences in the bandwidth and tuning frequency (center frequency), differences in the form of a complex frequency response (CFC), the spread of the compensation channels in terms of gain and phase shift.

A known method of compensating for interference received on the main and additional (compensation) antenna, which should not contain a useful signal [1]. The signal of the main channel is fed to the adder with a unit weight, and the oscillations of the compensation channels are weighed based on the interference environment. At the same time, the goal of adjusting the weight coefficients is to provide minimum noise power at the output of the adder. The disadvantage of this method is the inability to determine the angular position of the object.

Also known is a method of angular orientation of an object according to the radio navigation signals of spacecraft, taken as a prototype, based on the reception of signals from n spacecraft by two or more antenna-receiving devices located parallel to one or two axes of the object, isolating a signal with a Doppler frequency, determining phase incursion for the measurement time interval and determining the angular position of the object [2]. This method is designed to receive only radio navigation signals, without taking into account the possible received interference signals of both natural and intentional origin, therefore, in a difficult interference environment, determining the angular orientation of an object becomes extremely difficult.

The basis of the invention is the task of increasing the efficiency of the goniometric navigation equipment in a complex jamming environment by compensating digital interference suppression taking into account preliminary calibration of the receiving channels for a given error and measurement time of the angular orientation of the object.

The problem is solved in that in the method of angular orientation of the object by the radio navigation signals of spacecraft, based on the reception of radio navigation signals from n navigation spacecraft with two or more receiving channels, the antennas of which are located so that the lines drawn through the phase centers of the antennas are parallel to one or two axes of an object, measuring phase shifts between signals from each of n navigation spacecraft between pairs of receiving channels and determining the angular position of an object according to the invention in an interference environment, before measuring the phase shifts, the correction weight factor vector for each of the receiving channels is determined by calibrating them with a reference pilot noise, the interference signal of each of the receiving channels is summed with the interference signals of the remaining channels, which are compensated for it, previously multiplied to the corresponding vector of the weight coefficient, which is calculated on the basis of a recursive estimate of the inverse correlation matrix of interference, taking into account the vectors in correcting weighting coefficients, select radio navigation signals from n navigation spacecraft and restore their initial parameters in each receiving channel by solving a system of equations

где

Where

- выделенный радионавигационный сигнал, принятый от i-го навигационного космического аппарата в m-м приемном канале;

- a dedicated radio navigation signal received from the i-th navigation spacecraft in the m-th receiving channel;

- принятый радионавигационный сигнал от i-го навигационного космического аппарата в m-м приемном канале;

- received radio navigation signal from the i-th navigation spacecraft in the m-th receiving channel;

- вектор весового коэффициента k-го компенсационного канала в m-м приемном канале;

is the vector of the weight coefficient of the k-th compensation channel in the m-th receiving channel;

- вектор поправочного весового коэффициента k-го компенсационного канала в m-м приемном канале;

is the vector of the correction weight coefficient of the k-th compensation channel in the m-th receiving channel;

i is the number of the navigation spacecraft, i = 1, 2, ..., n;

m is the number of the receiving channel, m = 1, 2, ..., p;

k is the number of the compensation channel, k = 1, 2, ..., (p-1).

In FIG. 1 shows a structural diagram of a device for determining the angular orientation of an object under the influence of broadband interference, which implements the proposed method with correction of the frequency response of the receiving channels, FIG. 2 shows the radiation pattern of the antenna system after adaptation to two jammers according to the results of modeling the operation of the proposed device.

A device for determining the angular orientation of an object that implements the inventive method under conditions of broadband interference includes m receiving channels, each of which includes serially connected: antenna 1 ₁ (1 ₂ , ..., 1 _m ), analog path 2 ₁ (2 ₂ , ..., 2 _m ) and an analog-to-digital converter (ADC) 3 ₁ (3 ₂ , ..., 3 _m ), the output of which is connected to the corresponding input of the interference suppression equipment 4. The interference suppression equipment 4 contains m interference suppression units 5 ₁ (5 ₂ , ..., 5 _m ), the inputs of each of which are connected to the m inputs of the interference suppression equipment 4. Each of the blocks 5 ₁ (5 ₂ , ..., 5 _m ) of the interference suppression contains an adder 6, m-1 of the multipliers 7 and an adaptive processor 8. The first inputs of the multipliers 7 and the inputs of the adaptive processor 8 are connected respectively to the 2nd through mth inputs block 5 _m (each of blocks 5) of interference suppression, and the remaining inputs (other inputs of multipliers 7) are connected to the corresponding outputs of processor 8. Adder 6 is connected to the first input of the corresponding interference suppression unit 5 by the first input, and the rest, respectively, to the outputs of multipliers 7 in this block. The output of the adder 6 is connected to the control input of the adaptive processor 8, to the corresponding input of the digital signal processing unit 9 and to the corresponding input of the PC 11. The outputs of the digital signal processing unit 9 are connected to the corresponding inputs of the phase recovery unit 10, and the phase corrections input of the phase recovery unit 10 connected respectively to the outputs of the adaptive processors 8 of each of the blocks 5. The device for determining the angular orientation of the object also includes an interference generator 12, which is connected to the input the analog paths 2 ₁ (2 ₂ , ..., 2 _m ) and a spectrum analyzer 13. To analyze the compensation of the reference noise level, the output of the spectrum analyzer 13 is connected to a PC 11, the output of which is connected to the correction input of the adaptive processor 8 of each of the blocks 5. The outputs of the block recovery phase 10 is connected to the corresponding inputs of the block measuring the angular orientation 14.

The essence of the proposed method can be illustrated by the example of the device for determining the angular orientation of an object under the influence of intentional interference, containing 3 receiving channels.

для ее компенсации на основе рекуррентной оценки обратной корреляционной матрицы помех адаптивными процессорами 8Before determining the angular orientation of the object in an interference environment, the receiving channels are pre-calibrated by correcting their frequency characteristics, for which only a reference pilot noise is established by the interference generator 12, which is fed to the input of the analog paths 2, where it is amplified and converted into intermediate signals frequency, and then goes to the ADC 3. The pilot noise when passing through the analog paths of different receiving channels is distorted and, as a result, inter-channel decorrelation in their channels. From the outputs of the ADC 3, digital pilot interference signals are fed to the inputs of the interference suppression equipment 4 and then to three interference suppression units 5 ₁ , 5 ₂ , 5 ₃ , which are correlation auto-compensators, to form weight coefficients, multiplying them with interference signals of the compensation channels and digital summation. In each of the blocks 5 interference suppression is the calculation of the vector of weights $${\stackrel{•}{R}}_k$$

for its compensation on the basis of a recursive estimate of the inverse correlation matrix of interference adaptive processors 8

- вектор весового коэффициента k-го компенсационного канала на l+1 шаге адаптации.

is the vector of the weight coefficient of the kth compensation channel at l + 1 adaptation step.

For a recurrent estimate of the inverse correlation matrix of interference to the control input of the adaptive processor 8, a signal is output from the output of the adder 6 as feedback.

From the interference generator 12, the pilot noise also arrives at the input of the spectrum analyzer 13 for analysis of its power level in the personal computer 11 Due to inter-channel decorrelation, uncompensated residual pilot interference from the output of the adder 6 is fed to the input of the personal computer 11. In the personal computer 11, the value of the correction weight vector is calculated and stored the coefficient of each calibrated compensation channel, which is fed to the correction input of the adaptive processor 8 of the corresponding channel. The purpose of calculating and forming the vectors of correction weighting factors in PC 11 is to achieve the minimum power spectrum of the pilot interference of the calibrated channels.

The determination of the correction weight vectors is performed with the same interference at the input of all receiving channels in the steady state. Thus, an additional adjustment of the channels is performed, providing a reduction in the discrepancy between their frequency characteristics and signal delays.

After calculating the correction weight vectors, an additive mixture of radio navigation signals and intentional interference, which are received by three spaced antennas, is connected to the input of the receiving channels, where further spatial compensation of intentional interference is carried out taking into account the already calculated correction weight vectors and the separation of radio navigation signals from navigation spacecraft to determine the angular position of the object (course, roll, pitch).

Consider the principle of noise suppression on the example of block 51 of the suppression of the first receiving channel.

An additive mixture of signals n of navigation spacecraft and deliberate broadband interference from jammers has the form:

N _mj is the interference signal received in the mth receiving channel from the jth jammer;

Y _mi is the received radio navigation signal from the i-th navigation spacecraft in the m-th receiving channel;

i is the number of the navigation spacecraft, i = 1, 2, ... n;

m is the number of the receiving channel, m = 1, 2, ... p;

The signal at the output of the adder 6 in the first receiving channel will be equal to:

- вектор входных сигналов;

- vector of input signals;

The expression for the vector of weights in this receiving channel is

- вектор весовых коэффициентов компенсационных каналов для первого приемного канала;

- a vector of weighting coefficients of the compensation channels for the first receiving channel;

- вектор поправочного весового коэффициента k-го компенсационного канала;

is the vector of the correction weight coefficient of the k-th compensation channel;

X ₁ is the vector of the input signal of the first receiving channel;

- вектор входного сигнала k-го компенсационного канала, для первого приемного канала, при этом (*) означает комплексно сопряженную матрицу, а (Т) - транспонированную матрицу.

is the vector of the input signal of the k-th compensation channel for the first receiving channel, while (*) means the complex conjugate matrix, and (T) the transposed matrix.

Then the output signal at the output of block 5 ₁ interference suppression in the case of a discrete estimate will be determined by solving the following system of equations [3]:

l is the adaptation step number;

- обратная корреляционная матрица помех k-го компенсационного канала на l+1 шаге адаптации;

- inverse correlation matrix of interference of the k-th compensation channel at l + 1 adaptation step;

- вектор весовых коэффициентов k-го компенсационного канала на l+1 шаге адаптации;

is the vector of weight coefficients of the k-th compensation channel at l + 1 adaptation step;

m is the number of the receiving channel, m = 1, 2, ... p;

k is the number of the compensation channel, k = 1, 2, ... (p-1).

происходит аналогично.In other receiving channels, the calculation of the vector of weight coefficients

happens the same way.

Further, from the output of the adder 6 of each interference suppression unit 5, the radio navigation signals cleared of interference are fed to the input of the digital signal processing unit 9, where the signals of each of the navigation spacecraft are separated, as well as the search, capture of signals by frequency and delay, frequency self-tuning, synchronization by time stamp and bit boundary of service information, reception and decoding of service information and measurement of radio navigation parameters of the signal. In addition to the tasks listed above, the digital signal processing unit 9 solves the problems of secondary processing of the measured parameters, which consist in determining the coordinates of the navigation spacecraft at the time of measurement (the task of multiplying the ephemeris) based on the received service information, and calculating the coordinates of the object.

. В результате искажения фазовых сдвигов при подавлении помех информация об угловой ориентации искажается и измерения становятся невозможными.However, when suppressing interference, the phase of the signal from each spacecraft changes

. As a result of phase shift distortion during interference suppression, information about the angular orientation is distorted and measurements become impossible.

, которые используются в аппаратуре 4 подавления помех, известны, поэтому есть возможность восстановить исходные фазовые соотношения и, таким образом, измерить угловую ориентацию. Сигналы, принятые от i-го навигационного космического аппарата, на входе блока 10 восстановления фазы в трех основных (измерительных) каналах будут иметь видThis problem is solved by correcting the measured phase shifts in the phase recovery unit 10. Weighting Vectors

that are used in the interference suppression apparatus 4 are known, therefore, it is possible to restore the original phase relationships and, thus, measure the angular orientation. The signals received from the i-th navigation spacecraft at the input of the phase recovery unit 10 in the three main (measuring) channels will be

- выделенный радионавигационный сигнал, принятый от i-го навигационного космического аппарата соответственно в 1, 2, 3 приемном канале;

- a dedicated radio navigation signal received from the i-th navigation spacecraft, respectively, in 1, 2, 3 receiving channel;

- принятый радионавигационный сигнал от i-го навигационного космического аппарата соответственно в 1, 2, 3 приемном канале;

- received radio navigation signal from the i-th navigation spacecraft, respectively, in 1, 2, 3 receiving channel;

- вектор весового коэффициента 1-го компенсационного канала соответственно для 1, 2, 3 приемного канала;

- the vector of the weight coefficient of the 1st compensation channel, respectively, for 1, 2, 3 of the receiving channel;

- вектор весового коэффициента 2-го компенсационного канала соответственно для 1,2,3 приемного канала;

- the vector of the weight coefficient of the 2nd compensation channel, respectively, for the 1,2,3 receiving channel;

- вектор поправочного весового коэффициента соответственно 1,2-го компенсационного канала для соответствующего приемного канала;

- the vector of the correction weight coefficient, respectively, of the 1.2th compensation channel for the corresponding receiving channel;

i is the number of the navigation spacecraft, i = 1, 2, ..., n;

After processing in the phase 10 recovery unit, the signals are sent to the angular orientation measuring unit 14, where the initial phases of the signals received by the antennas are optimally estimated, the phase shifts of the signals received by two spatially separated antennas φ _i for each of the navigation spacecraft are calculated are further used to determine the angular position of the axes of the measured object by solving a system of equations.

The required number of receiving channels is determined by the functional purpose, namely, to determine the angular orientation of the object, at least 3 receiving channels are necessary. On the other hand, to suppress t interference, (t + 1) receive channels are required. Thus, the minimum number of receiving channels is three, and it is possible to suppress interference from two sources. With increasing requirements for the number of suppressed interference, the number of receiving channels will be determined by these requirements. Moreover, all the receiving channels can be used to determine the angular orientation.

The relationship of the interference suppression coefficient with the frequency response of the receiving channels will be considered in a simple scheme using one compensation channel, where the interference suppression coefficient is determined by the well-known expression [4]:

ρ is the correlation coefficient of the input signals;

The correlation moments (covariance) of the input noise can be expressed in terms of the frequency characteristics of the receiving channels K _m (f) and S _in (f) is the energy spectrum of the noise, omitting the effects of nonlinearity and internal noise, then the cross-correlation coefficient can be represented as

Obviously, the covariance, and therefore the suppression coefficient, depends not only on the frequency response of the receiving channels, but also on the spectral density of the input noise. Therefore, the difference in the frequency characteristics of the receiving paths reduces the inter-channel correlation of interference and the effectiveness of their suppression. The greatest contribution to the formation of the frequency characteristics of analog paths is made by intermediate-frequency filters. In addition to the main parameters of the center frequency, passband, selectivity, signal attenuation in the filter band, they are all characterized by the shape of the peak and the squareness coefficient of the amplitude-frequency characteristic. Obviously, the use of filters with the same forms of amplitude-frequency characteristics leads to the identity of the channels and the value of the suppression coefficient of the auto-compensator is determined mainly by the difference in the amplitude and phase frequency characteristics of the reception channels in the signal band, as well as the delay in the channels.

It should be noted that the calibration efficiency decreases during operation, under the influence of destabilizing factors, such as, for example, changes in temperature, humidity, pressure, mechanical vibrations, therefore, measures should be taken to adjust the frequency characteristics of the receiving channels before each turn on of the equipment.

Using the invention will allow to determine the angular orientation of objects when exposed to deliberate broadband interference, taking into account the decorrelating factors of the receiving channels.

Modeling of the method was carried out on a three-channel receiving goniometer equipment when setting two intentional interference from the angular directions β = 0 °, Θ = -54 and β = 0 °, Θ = 72 ° in the steady state mode of operation.

As the simulation results (Fig. 2) show in the direction of the two interference directors, taking into account the CFC correction, narrow dips of the radiation pattern of the three-element antenna array were formed, reaching a level of minus 35-45 dB.

Thus, the proposed method allows measurements of the angular orientation of the axes of the object from the radio navigation signals of navigation spacecraft at a given measurement error under the conditions of receiving interference signals of both natural and intentional origin.

Literature

1. GLONASS. The principles of construction and operation / ed. A.I. Perova, V.N. Harisova. Ed. 4th, rev. and additional .: Radio engineering, 2010. - 800 p.

2. Pat. RU 2122217 Russian Federation, IPC ⁶ G01S 5/02. The method of angular orientation of the object according to the signals of navigation spacecraft / A.M. Aleshechkin, Yu.L. Fateev, Chmykh M.K .; applicant of the State Educational Institution of Higher Professional Education “Krasnoyarsk State Technical University”, - No. 97107921/09; declared 05/15/1997; publ. 11/20/1998.

3. Tyapkin V.N., Lubkin I.A. Using recurrent adaptive algorithms to solve the problem of suppressing active noise interference in satellite communication systems. Bulletin of the Siberian state. Aerospace University named after Acad. M.F. Reshetneva. - 2010. - Issue. 2 (28). - S. 39-43.

4. V.N. Harisov, S.G. Bystrakov, A.V. Pastukhov, R.N. Sizov A method of setting requirements for non-identical channels of interference cancellers. / Radio engineering, No. 7, 2007. - 113 p.

Claims (1)

A method for angular orientation of an object using the radio navigation signals of spacecraft, based on receiving radio navigation signals from n navigation spacecraft with two or more receiving channels, the antennas of which are located so that the lines drawn through the phase centers of the antennas are parallel to one or two axes of the object, measuring phase shifts between signals from each of n navigation spacecraft between pairs of receiving channels and determining the angular position of the object, characterized in that under the interference situation before measuring the phase shifts, the correction weight factor vector for each of the receiving channels is determined by calibrating them with the reference pilot noise, the interference signal of each of the receiving channels is summed with the interference signals of the remaining channels, which are compensation for it, previously multiplied by the corresponding weight coefficient vector, which are calculated on the basis of a recursive estimate of the inverse correlation matrix of interference, taking into account the vectors of correction weighting factors, highlight t n radionavigation signals from navigation satellites and restore their original settings in each receiving channel by solving the system of equations

Where

- a dedicated radio navigation signal received from the i-th navigation spacecraft in the m-th receiving channel;

- received radio navigation signal from the i-th navigation spacecraft in the m-th receiving channel;

is the vector of the weight coefficient of the k-th compensation channel in the m-th receiving channel;

is the vector of the correction weight coefficient of the k-th compensation channel in the m-th receiving channel;
i is the number of the navigation spacecraft, i = 1, 2, ..., n;
m is the number of the receiving channel, m = 1, 2, ..., p;
k is the number of the compensation channel, k = 1, 2, ..., (p-1).

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