RU2271019C1 - Method of compensation of signal phase incursions in onboard radar system and onboard radar system with synthesized aperture of antenna for flying vehicles - Google Patents

Abstract

FIELD: radar systems; aircraft or helicopter onboard radar systems for observation of ground or water surface and detection of objects in radar cartography modes.

SUBSTANCE: for compensation of phase incursions at synthesizing, use is made of information pertaining to parameters of antenna motion received from inertial navigational system and linear acceleration sensors; procedure consists in treatment of signals reflected from ground objects when magnitude of phase incursions caused by errors of sensors is brought to permissible level dictated by quality criterion of radar information.

EFFECT: reduction of errors of measurements of acceleration; improved characteristics of radar image (resolving power, contrast range, dynamic range).

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Description

The present invention relates to radar systems and is intended for use as a helicopter or aircraft airborne radar station (radar) for viewing the earth or water surface and detecting objects on it in the modes of radar mapping.

Foreign and domestic airborne and helicopter radars are known in which the antenna aperture synthesis mode is used for high-resolution radar mapping of the earth's surface.

High azimuth resolution in such radars is achieved as a result of the aircraft using a segment of the path, called the synthesis interval, as an artificial antenna.

The synthesized aperture of the antenna is realized as a result of summing the reflected signals during coherent radiation. To obtain a high azimuth resolution, the synthesized antenna aperture (SA), like the optical system, focuses on a specific surface area at a given range. As in optics, the focusing process consists in the fact that signals from all points on the surface are in phase in one point (focus).

The process of synthesizing the antenna aperture, receiving a signal characterizing radar information (RLI), is reduced to the implementation of the relationship (Itogi Nauki i Tekhniki. Radio Engineering, Volume 36, M., 1986)

- аддитивная смесь полезного сигнала и шума в комплексной форме;Where:

- additive mixture of useful signal and noise in a complex form;

- опорная функция системы обработки,

- reference function of the processing system,

t is the time

Tc is the time interval for synthesizing the antenna aperture,

α is the angular coordinate of a point on a site in a normal coordinate system.

Signal processing in a radar system with a synthesized antenna aperture (SAR) is based on matching the reference function with the signal reflected from a point target:

where: A (t) is a function that characterizes the intensity of the reflected signal;

r (t, α) is the current distance between the aircraft and the target;

λ is the length of the emitted wave;

φ is a random initial phase in the synthesis interval.

As a reference function, a weighted function is selected that ensures focusing of the antenna aperture, coupled to a signal reflected from a point target accurate to the initial phase.

where: H (t) is the weight function that provides the required level of the side lobes of the synthesized aperture of the antenna.

To focus a surface point at a given range, the reference function must be complexly coupled with the reflected signal and calculated up to the initial phase.

As is known (Itogi Nauki i Tekhniki. Radio Engineering, Volume 36, M., 1986), the law of the phase change of the received trajectory signal (signal when the aircraft moves along the trajectory) from a point target can be represented (with the restriction of the series of decomposition):

where: V _r , α _r - radial velocity and acceleration of the phase center to the point; φ ₀ is the initial phase of the signal.

To focus a surface point at a given range using the support function on board the aircraft, these parameters are measured with an accuracy determined by allowable focusing (obtaining a given element resolution in azimuth) and allowable geometric distortions (obtaining a minimum azimuth shift).

In the general case, when synthesizing the antenna aperture, the CA is controlled using the reference function. The SA control law is determined by the view of the irradiated surface. However, regardless of the type of review, the nature and parameters of control signals are calculated based on a priori data on the flight mode, or using measured values of the aircraft motion parameters.

With an arbitrary trajectory, when it changes from one synthesis interval to another, the support function is determined for each interval separately during the flight of the aircraft. With a uniform horizontal straight flight of the carrier, the SAR functions normally. However, during actual flight of the carrier (fighter or helicopter), trajectory instabilities arise due to angular fluctuations, random changes in speed, environmental influences, noise caused by the aircraft control system, etc.

Such trajectory instabilities lead to amplitude and phase distortions of the reflected signals and, with a fixed reference function, violate the optimality of the processing of radio signals, disrupt the focus of the reflected signal and ultimately degrade the quality of mapping.

In order to obtain high resolution azimuth in real-time RSA, special measures are taken to reduce the influence of trajectory instabilities.

The most common approach to solving this problem is to use a method of compensating for phase distortions of the received signal in the synthesis interval based on measuring the parameters of the aircraft’s motion. Measuring the motion parameters of the aircraft in a normal inertial coordinate system X, Y, Z - values of the velocity components V _X , V _Y , V _Z and acceleration components a _X , a _Y , a _Z on the synthesis interval, calculate the motion parameters of the phase center of a real antenna - speed "V _r " and acceleration "a _r ", directed along the line of sight to the object. Based on these measurements, the phase changes in the trajectory reflected signal are calculated and, using the reference function (see formula (1)), these phase incursions during signal processing are compensated.

In aircraft, inertial navigation systems (ANNs) are used to measure motion parameters, while an additional special ANN installed at the antenna’s location is used to measure the motion parameters of the phase center of the antenna installed in the bow.

In addition, to improve the characteristics of measuring motion parameters, special accelerometers are used that measure linear accelerations along three axes in an inertial coordinate system.

In the known compensation method when processing a signal by harmonic analysis by Fourier transform, the signals of the radar image of one gated range strip at the output of the processing system can be described:

where S _BX (t; α _i ) is the complex signal at the input of the processing system reflected from the object located at an angle α _i relative to the velocity vector;

t is the current time on the interval of movement of the antenna,

T _c - synthesis time

S _in (t; α _i ) = A (t; α _i ) e ^{jφ (t; αi)}

A (t; α _i ) is the signal amplitude,

φ (t; α _i ) is the phase of the signal,

h (t) is the reference function, complex conjugate with the signal reflected from the object (with the restriction of the series of decomposition), calculated on the basis of measuring the motion parameters of the antenna phase center;

where H (t) is a weight function that determines a given level of side lobes,

V _r - component of the velocity of the phase center of the antenna in the direction of the object,

where: V _X is the velocity component along the OX axis,

V _Y is the velocity component along the OY axis,

V _Z is the velocity component along the OZ axis,

τ is the time interval

α _r - component of the acceleration of the phase center of the antenna in the direction of the object,

α _i is the angle in the azimuthal plane,

ε is the angle in the elevation plane,

Where:

α _x - acceleration along the axis OX,

α _y is the acceleration along the OY axis,

α _Z - acceleration along the OZ axis,

From equation (1) it follows that the second term of the equation has a quadratic time dependence and, in the presence of an acceleration measurement error, “da _r ” has a parabolic character:

The maximum phase incursion at the ends of the synthesis interval will be:

приводит к ухудшению разрешения более чем на 10%. (Итоги науки и техники. Радиотехника. Том 36. М., 1986 г.)It is known that, depending on the magnitude of the error on the acceleration "da _r ", which leads to a phase incursion, an expansion of the spectrum of reflections from the focused point appears. So the phase incursion in the synthesis interval,

leads to a deterioration in resolution of more than 10%. (Results of science and technology. Radio engineering. Volume 36. M., 1986)

With coherent filtering, such acceleration errors also lead to a decrease in the signal amplitude, leading to a loss of brightness and a decrease in contrast. The most noticeable effect on the synthesized radiation pattern is from low-frequency acceleration measurement errors.

The above method of compensating for phase incursions of a signal is implemented in well-known aircraft and helicopter radars operating in the mode of synthesizing an aperture of an antenna, such as radar with a synthesized aperture of the antenna for detecting ground objects of the company "Hughes" APG-65, placed on an F-16 fighter plane or radar APG-70, installed on a US F-15 aircraft, as well as in an airborne ground-based radar station for mapping the Earth’s surface (USA, application No. 756455 dated 3/1-1977 MKI G 01 S - 13/90). These radars with a synthesized aperture of the antenna due to the movement of the aircraft provide mapping of the earth's surface with high angular resolution.

As follows from the description, the last radar is designed to map the earth's surface in both lateral and anterolateral view. The closest technical solution to the proposed compensation method is a method of compensating for phase incursions of a signal using an inertial navigation system in a helicopter radar system described in patent RU N 2147136, G 01 S 13/00, 13/90 with priority dated 03/12/1997.

This radar provides mapping of the underlying surface in the synthesis mode of the antenna aperture.

In this station, when synthesizing the antenna aperture, the above-described method of compensating the phase incursion of a signal using the measurement of the motion parameters of the carrier V _{x is used} ; V _y ; V _z and a _x ; a _y ; a _z using an inertial platform.

Figure 1 presents a block diagram of a prototype helicopter radar system, where:

Antenna - 1;

antenna angle sensor - 2;

azimuth antenna engine - 3;

antenna control unit - 4;

master oscillator 5;

frequency synthesizer - synchronizer - 6;

circulator - 9;

transmitter - 10;

receiver - 11;

signal processor - 12;

indicator - 13;

radar data and control processor - 30;

inertial platform - 52;

angular velocity meter 56;

calculator of the flight-navigation complex (PNK) - 57;

Executive helicopter control device - 64.

As follows from the description of the prototype radar, the synthesized aperture of the antenna when the helicopter hangs is formed due to the rotational movement of the phase center of the antenna installed in the bow of the helicopter. In this case, the length of the trajectory along the chord of the circle of motion of the phase center is taken as the antenna aperture.

With the rectilinear motion of the helicopter, the synthesized aperture of the antenna is formed by moving the phase center on a segment of the antenna path perpendicular to the direction of the object. In the process of helicopter movement to obtain a synthesized aperture, the signals reflected from ground objects are coherently summed. The possibility of coherent summation of signals received during the movement and evolution of a helicopter is provided by compensating for phase changes in the received Doppler frequency signals. Compensation is based on measurements of the parameters of the movement of the helicopter inertial platform 52.

During the movement of the helicopter during the operation of the radar in the data processor 30 with the synchronized signal "f _pd " coming from the frequency synchronizer 6, a reference function is formed to compensate for the phase incursions of the signal, which is complex conjugate with the signal reflected from the object for each range element and each repetition period two quadrature signal, and accumulates in memory. The coefficients of the support function for each element of the range and each repetition period are calculated on the basis of measurements of the parameters of the carrier’s movement, components of the carrier’s speed V _x , V _y , V _z and components of the carrier’s accelerations a _x , a _y , a _z , course angle ψ, determined inertial platform 52 and the angle of direction to the object "ε _g ". At the end of the collection of the signal array at a given synthesis interval, the signal array of two quadrature accumulated in the processor signal memory 12 for each element of the range and each repetition period is multiplied in multipliers with the same samples of each element of the range and the repetition period of the reference function coming from the processor 30. From the outputs After multiplication of the difference and sum schemes, the array of signals of two quadratures enters the fast Fourier transform processor (FFT), where it undergoes harmonic analysis the study. The result of the conversion of signals from the time domain to the frequency domain is the frequency (azimuthal) samples of two quadratures of radar information in each element of the range.

Then, from the samples of the signal array of the two quadratures, the signal modules are formed, which enter the indicator 13. As follows from the construction of the radar of the prototype, measures were taken to reduce the effect of trajectory instabilities in radars of high resolution in azimuth in real flight. The solution to this problem is provided by compensating for the phase incursions of the received signal in the synthesis interval based on measuring the parameters of the aircraft’s motion.

To do this, measure the motion parameters of the aircraft in a normal inertial coordinate system - the values of the velocities V _x , V _y , V _z and accelerations a _x , a _y , a _z on the synthesis interval and calculate the motion parameters of the phase center of the real antenna - speed "V _r " and accelerations a _r directed along the line of sight. Based on these measurements, the phase changes of the trajectory reflected signal are calculated and, using the reference function (see formula (1)), these phase incursions during signal processing are compensated. However, as analysis of the SAR operation using an inertial platform shows, in a number of parameters the latter does not satisfy the requirements for reproducing the law of phase change of the reflected signal to obtain high-resolution azimuth in SAR (Results of science and technology. Radio engineering, vol. 36, M., 1986; Foreign radio electronics, No. 3, 1983, M .: "Radio and communication").

The use of special accelerometers for measuring accelerations along three axes additional to the inertial platform improves the characteristics of measuring motion parameters, however, due to the finite value of the measurement accuracy and the inability to place them near the antenna phase center, it does not solve the problem of obtaining the required high resolution in azimuth during maneuvers of the aircraft. Thus, the characteristics of domestic accelerometers produced by measurement accuracy are more than an order of magnitude inferior to the required accuracy to obtain the required high, and even superhigh linear resolution in azimuth (0.5 m) (for example, according to the technical conditions of operation for a sensor manufactured by NPP Temp- AVIA "Arzamas, the measurement error is 1.5% of the measured value, while to obtain high resolution the error should not exceed 0.05%). This circumstance is the main disadvantage of the phase change compensation method used in the radar of the prototype and the above analogs, using linear acceleration sensors, the measurement errors of which determine the magnitude of the phase incursions of the signal and do not allow to obtain the required high resolution in azimuth.

The objective of the invention is to obtain high resolution in azimuth in radar from the SA on aircraft with sensors for measuring linear accelerations by compensating for phase incursions of a signal during evolution and acceleration of a carrier.

To solve this problem, an array of signals reflected from ground objects, received and stored in the synthesis interval, is processed in two stages in the signal processor. At the first stage, the array of signals is multiplied by the support function complex conjugate to the signal, as a result of which phase incursions of signals associated with the movement and accelerations of the antenna phase center are compensated.

In this case, the support function is formed on the basis of measuring the motion parameters of the phase center of the antenna, components of the velocity V _x ; V _y ; V _z measured by an inertial navigation system (ANN) and accelerations a _x ; a _y ; a _z measured by linear acceleration sensors.

At the second processing stage, the signal array obtained at the first stage and accumulated in the signal processor memory is sequentially multiplied by the complex conjugate correction functions found by the specified criterion for assessing the quality of radar information based on determining the maximum errors of linear acceleration measurement a _x ; a _y ; a _z ; sensors on the synthesis interval. As a result of processing the signal array at the second stage, the phase incursions of the signal caused by errors in measuring linear accelerations by sensors to an acceptable (given) value are compensated. At the same time, the quality of the radar information meets the specified criterion (resolution, contrast, dynamic range, etc.).

When phase compensation is performed, due to the presence of trajectory instabilities, the acceleration measured by the sensors of the antenna phase center along the line of sight to the object will be:

где:

Where:

da _x - error of the acceleration sensor along the axis OX,

da _y - error of the acceleration sensor along the OY axis,

da _z - error of the acceleration sensor along the OZ axis.

, гдеIf there are measurement errors by the sensors, the phase incidence remaining after compensation of the maximum phase incursion due to acceleration is determined by the following formula:

where

da _r , is the error of measuring acceleration by sensors in the radial direction;

To ensure the required resolution, the sensor error da _r must not exceed the permissible value da _{r additional}

When the permissible value of the phase shift Δφ _additional allowable value will be:

To reduce the influence of measurement errors by sensors and bring this error to an acceptable value, the sensor property is used to correlate measurement errors with the measured value of acceleration. For example, in an AT-1104 sensor at ambient temperature t ° = const at short synthesis intervals T _c ≤5 s. the law of change in the measurement error of acceleration by the sensor repeats the law of change in acceleration measured by the sensor (with the acceleration limited): da (t) = ξ · a (t);

Where

da (t) is the law of change of error;

a (t) is the law of change of acceleration;

ξ is a coefficient that determines the value of the error in measuring acceleration by the sensor.

Under technical conditions, only the maximum value of the measurement error is set for the sensor, while the real error of the sensor during measurements in flight, which determines the residual uncompensated phase, is unknown. However, using the property of the sensor, it seems possible to compensate for phase incursions caused by actual sensor errors in flight to allowable values for a specific measurement on the synthesis interval.

This possibility is ensured by the fact that the real measurement error in flight lies in the range of maximum values of the acceleration measurement errors and the solution of the problem in the proposed compensation method can be provided by the proposed processing of the received signal. For this, the maximum range of measurement errors in time determined by the acceleration sensor is divided into "2n" subbands (see Fig.6). After that, the array of reflection signals from the surface, received and stored in the processor’s memory, is sequentially multiplied by each phase-correcting signal by a function in which, to calculate the compensating phase, the error values of the sensors are accelerated sequentially in time to accelerate the corresponding subband.

After each multiplication of the array by each correction function, a fast Fourier transform is carried out, the signal module is found, and the obtained radar information is placed in the processor memory.

After each of the 2n phase distortion compensations of the initially accumulated signal array, the quality of the radar image is evaluated according to one of the selected criteria: resolution, dynamic range, or contrast. The selection of the criterion is determined by the conditions of use of the radar and the statement of the problem.

Based on the results of 2n iterations, based on the obtained values of the selected criterion, an array of radar images corresponding to the best criterion value is determined and displayed on the indicator screen, while phase changes are compensated to a predetermined allowable value.

The proposed method of compensating for phase incursions of a signal in a radar from a satellite determines the following algorithm for the operation of the equipment in the synthesis interval:

1. When moving an aircraft with radar in the radiation and reception mode, a set of received signals of reflections from the surface is set and stored.

2. Measure the motion parameters of the phase center of the antenna, components of the velocity V _x ; V _y ; V _z and linear accelerations a _x ; a _y ; a _z in the normal coordinate system X, Y, Z, for example, by means of an inertial navigation system (ANN) and sensors for measuring linear accelerations, and their values are stored in time.

3. According to the measured parameters of the motion of the phase center of the antenna V _x ; V _y ; V _z and a _x ; a _y ; a _z calculate the phase coefficients of the support function:

4. A preliminary (first stage) multiplication of the signal array by the support function complexly conjugated with the signal is carried out, while the result of the multiplication of the signals by the support function is stored in the memory and the fast Fourier transform operation is performed on the signal array.

5. According to the results of the Fourier transform, the most contrasting elements in each element of the range are selected. For each signal in each element of range find the maximum value of the amplitude of the signal U _max and calculate the contrast:

where U _max - the maximum value of the amplitude of the signal of a point object,

U _cp is the average signal value in neighboring elements, respectively.

If C≥A, then the object is a contrast

where: A is the accepted value of contrast.

6. From the entire array of signals, by means of comparative estimates, the range element n _d and the azimuth element l, in which the signal has a maximum contrast of "C _max " (C _{maxn + 1} ≥C _maxn ), are _revealed .

7. According to the accelerations measured by each of the three sensors, determine the maximum value of the acceleration errors in time according to the formula:

where ξ is the coefficient that determines the value of the error in measuring acceleration by the sensor.

8. Based on the required resolution, with an allowable change in the phase Δφ _add on the synthesis interval, determine the allowable error value for acceleration:

9. The maximum number of correction functions is determined by the permissible uncompensated acceleration value along the X, Y, Z axes for their use in the compensation mode:

The procedure is performed for each of the sensors along the axes OX, OY, OZ.

10. On the synthesis interval, based on the recording of the acceleration values along the OX, OY, OZ axes, the values of the acceleration errors in time along the corresponding axes for each correction function are calculated:

Where

11. Calculate the error values of the component accelerations for each corrective function, measured by each of the sensors, in the direction to the object (radial direction).

12. Arrays of values of the correction functions h _{nx; y; z} in time (along the axes OX, OY, OZ) are calculated:

where, Δφ _{x, y, z} (t) are the values of the phase incursion due to acceleration errors measured by the sensors. Values of arrays of correction functions along the axes OX, OY, OZ in time are stored in memory.

13. The array of signals reflected from the surface, multiplied by the reference function in the range element n _d , where the signal with the maximum contrast in the memory was determined, is multiplied by the complex correction function h _nx conjugated to the signal.

In this case, successively for all 2n correction functions along the coordinate "X" find:

гдеbut)

Where

U _m - the amplitude of the array signal after multiplying by the reference function;

m is the reference number of the reflection signal and the acceleration value in the synthesis interval;

ψ {t) - values of uncompensated phase incursion due to errors in the measurement of acceleration by the sensor.

Each time, after multiplying by the values of one of the 2n correction functions, a fast Fourier transform (FFT) is performed and its result is stored in the memory, while the result of multiplying the signals by the phase coefficients of the correction function is also stored. After multiplying by all 2n the correcting functions h _nx (under the influence of accelerations along the "X" axis) and performing an FFT, compensated by phase distortion (for example, by maximum contrast) according to the criterion for assessing the quality of radar images (due to acceleration errors along the "X" axis) an array of signals in the range element "n _d " is stored.

b) The array of signals stored in the memory in the range element n _d , corrected by the function "h _nx ", multiplied by the correcting functions, the coordinates "Y""h _ny " with the above processing process.

c) Similarly, the processing is carried out with multiplication by the correction function of the coordinate "Z""h _nz ".

Thus, the radar signal array determined in the range element by the criterion of maximum contrast “C _max ” at the last multiplication is compensated for by acceleration with a valid error “da _{r extra} ” for a given radar quality criterion (for example, contrast, resolution, dynamic range) .

And the correction functions h _nx , h _ny , h _nz found by the quality criterion of radar information take into account real errors in measuring linear accelerations by sensors (with a given tolerance) and can be used to correct an array of signals in all range elements.

The following is an airborne radar system that implements the above compensation method that solves the problem of obtaining high (preset) azimuth resolution in the synthesized aperture of the antenna mode using acceleration measurement sensors.

1) Figure 1 shows a block diagram of a prototype.

2) Figure 2 presents a block diagram of the proposed radar. The proposed radar includes:

- antenna - 1;

- circulator - 2;

- transmitter - 3;

- master oscillator - 4;

- frequency synthesizer - synchronizer - 5;

- receiver - 6, consisting of pos. 7-12 (see figure 3);

- signal processor - 13, consisting of pos. 14-28 and 30-53 (see figure 4);

- indicator - 29;

- data processor - 54, consisting of pos.61-104 (see figure 5);

- linear acceleration sensor along the axis "OX" - 55;

- analog-to-digital converter - 56;

- linear acceleration sensor along the axis "OY" - 57;

- analog-to-digital converter - 58;

- analog-to-digital converter - 59;

- linear acceleration sensor along the axis "OZ" - 60;

- inertial navigation system - 69.

3) Figure 3 shows the detailed structural diagram of the radar receiver:

- receiver - 6;

- microwave receiver - 7;

- UPCH - 8;

- phase detector - 9;

- phase detector 10;

- ADC - 11;

- ADC - 12.

4) Figure 4 presents a detailed block diagram explaining the operation of the signal processor 13 in the synthesis mode:

- memory device - 14;

- memory device - 15;

- switch - 16;

- switch - 17;

- the multiplier is 18;

- the multiplier is 19;

- the multiplier is 20;

- the multiplier is 21;

- difference device - 22;

- the device of the amount - 23;

- memory device - 24;

- memory device - 25;

- FFT processor - 26;

- device module - 27;

- switch - 28;

- indicator - 29;

- switch - 30;

- memory device - 31;

- computer - 32;

- threshold device - 33;

- memory device - 34;

- memory device - 35;

- calculator - 36;

- device for evaluating the parameters - 37;

- switch - 38,

- switch - 39;

- control device - 40;

- control device - 41,

- formation device - 42,

- memory device - 43;

- memory device - 44;

- memory device - 45;

- memory device - 47;

- memory device - 48;

- memory device - 49,

- memory device - 50;

- control device - 51;

- control device - 52;

- address management device - 53;

- point target address calculator

and the numbers of the correcting function are 106, it is formed by elements 30-37, 40-42.

5) Figure 5 presents a detailed block diagram explaining the operation of the data processor in the synthesis mode:

- data processor - 54, includes:

- memory device - 61;

- computer - 62;

- computer - 63;

- memory device - 64;

- the multiplier is 65;

- computer data and management - 66;

- calculator of radial acceleration - 67;

- calculator of radial speed - 68;

- inertial navigation system - 69;

- memory device - 70;

- calculator - 71;

- computer - 72;

- memory device - 73;

- the multiplier is 74;

- memory device - 75;

- calculator - 76;

- computer - 77;

- memory device - 78,

- the multiplier is 79;

- the multiplier is 80;

- the multiplier is 81;

- the multiplier is 82;

- the multiplier is 83;

- the multiplier is 84;

- the multiplier is 85;

- the multiplier is 86;

- adder - 87;

- the multiplier is 88;

- device sin - 89;

- cos device - 90;

- device sin - 91;

- cos device - 92;

- device sin - 93;

- cos device - 94;

- device sin - 95;

- cos device - 96;

- memory device - 97;

- memory device - 98;

- memory device - 99;

- memory device - 100;

- memory device - 101;

- memory device - 102;

- memory device - 103;

- memory device - 104;

- calculator of corrective functions - 105, it is formed by elements 61-82, 84-86, 89-94, 97-102.

6) Figure 6 shows, as an example, a graphical dependence of the acceleration measurement errors of the sensor in time over the synthesis interval.

The onboard radar system with a synthesized antenna aperture for aircraft consists of an antenna 1, a circulator 2, a transmitter 3, a receiver 6, a master oscillator 4, a frequency synchronizer synthesizer 5, a data processor 46, a signal processor 13, an indicator 32, an inertial navigation system 61 , three sensors for measuring linear accelerations 55, 57, 60 with analog-to-digital converters 56, 58, 59. In this case, for transmitting a radiating pulse to antenna 1, the output of transmitter 3 through a circulator 2 is connected to the input of antenna 1, for transmission the reflected signal received by the antenna 1, the output of the antenna 1 through the circulator 2 is connected to the first input of the receiver, to form a radiating microwave signal of the carrier frequency "f", the first input of the transmitter is connected to the first output of the synthesizer frequency synchronizer 5, to start the transmitter 3, its second input is connected to the second the output of the synthesizer frequency synchronizer 5 by the signal of the pulse repetition frequency F _p .

The operation of the radar in coherent mode provides the master oscillator 4, the frequency of which "f _g " is the base and is used in the synthesizer to generate the radiation signal "f", as well as the local oscillator and other signals that synchronize the operation of units and processors. All high-frequency signals are generated in the frequency-synchronizer synthesizer 5 by multiplying the frequency of the master oscillator, and low-frequency synchronizing signals by dividing the frequency "f _g ". To form the intermediate frequency of the received signal "f _pr " in the receiver 6, the third output of the frequency synchronizer synthesizer 5 is connected to the second input of the receiver 6 by the heterodyne frequency signal f _c .

To generate the frequency of the receiving signal in the range of Doppler frequencies "f _d " the fourth output of the synthesizer frequency synchronizer 5 by the intermediate frequency signal "f _CR " is connected to the third input of the receiver 6.

To generate the sampling frequency of an analog-to-digital converter (ADC) in receiver 6, the fifth output of the frequency-synchronizer synthesizer is connected to the fourth input of receiver 6 by the reference frequency signal "f _ca ".

To process the radar information, the output of the receiver 6 is connected to the first input of the digital signal processor 13. (A 2 × 16 bit line is used to transmit signals from the receiver 6 to the digital signal processor 13). To synchronize the operation of the signal processor 13, the sixth output of the frequency synchronizer synthesizer 5 by the signal of the clock frequency f _{cn is} connected to the second input of the digital signal processor 13. To synchronize the operation of the data processor 54, the seventh output of the synthesizer of the frequency synchronizer 5 by the signal f _{nd is} connected to the first input of the digital data processor 54.

To control the operating modes and output the initial parameters, the first output of the digital data processor 54 is connected to the third input of the digital signal processor 13. (To transfer signals from the digital data processor 54 to the digital signal processor 13, the standard main parallel interface (MPI) GOST 26765.51-86 )

To control the operating modes of the frequency synthesizer of the synchronizer 5, its second input is connected to the second output of the data processor 54. To output the processed radar information, the output of the digital signal processor 13 is connected to the input of the indicator 13.

To calculate the reference function relative to the antenna phase center to compensate for phase changes in the signal, the fifth input of the data processor 54 is connected to the inertial navigation system 69 by the signals of the carrier velocity components V _x , V _y , V _z. Three acceleration sensors with analog-to-digital converters are introduced into the radar located on the platform of the antenna 1 near its phase center along the axes OX, OY and OZ to calculate the phase coefficients of the reference and correction functions. In this case, the first, second and third outputs of the first, second and third acceleration measurement sensors via analog-to-digital converters are connected respectively to the third, fourth and fifth inputs of the data processor 54 (lines a, b, c in figure 2).

For the operation of analog-to-digital converters 56, 58, 59 of acceleration sensors 55, 57, and 60, the second input of each ADC receives the sampling frequency signal “f _d ” from the frequency-synchronizer synthesizer 5 along the “d” line (Fig. 2).

In order to significantly reduce the influence of errors of linear acceleration measurement sensors, a signal target calculator 106 and a correction function number are introduced into the signal processor 13, and a correction function calculator 105 is introduced into the data processor, while the output of the correction function calculator of the data processor 54 is connected to the third input of the signal processor 13 (according to MPI GOST 26765.51).

The airborne radar system operates as follows.

In the process of moving the carrier of the antenna 1, the transmitter 3 amplifies and modulates the high-frequency signal "f" coming from the synthesizer of the frequency synchronizer 5, and generates pulses having a given duration τ _{and a} repetition period T _p defined by a unique range. The microwave pulses generated in the transmitter 3 are transmitted through the circulator 2 to the antenna 1.

Antenna 1, these pulses are radiated into space and propagate in the direction of the selected area.

The coherence of the signal is determined by the master oscillator, highly stable in frequency 4. The high-frequency signal f and the synchronizing pulses are generated by the frequency synthesizer-synchronizer 5, developed by well-known design methods and manufactured using a well-known element base.

From the master oscillator 4, the input frequency "f _g " enters the frequency synthesizer-synchronizer 5, is multiplied to a higher frequency and is used as the carrier frequency of the radar signal emitted by the antenna, as well as the local oscillator and clock signals. In addition, by dividing the frequency f _g , synchronizing and triggering pulses are formed. During the movement of the carrier, the signals reflected from the surface of the objects are received by the antenna and fed through the circulator 2 to the receiver 6. In the microwave receiver 7 (see Fig. 3), this signal in the receiver mixer is mixed with the signal of the frequency-synchronizer synthesizer 5 "f _c ", resulting in the formation of an intermediate frequency signal "f _CR ". The intermediate frequency signal in the intermediate frequency amplifier UPCH 8 is amplified and fed to synchronous detectors 9 and 10, which receive a signal from the synthesizer with a frequency equal to the intermediate frequency f _pr Moreover, to one of the phase detectors, the synthesizer signal f _pr enters with a shift by π / 2.

Due to the movement of the antenna 1, in-phase "I" and quadrature "Q" Doppler frequency signals are generated at the outputs of the phase detectors. Further, both signals "I" and "Q" using the analog-to-digital Converter 11 and 12, clocked using the clock signal "f _ca ", from the synthesizer frequency synchronizer 5, are accumulated in the memory 14 and 15 for each element of the range and each repetition period .

In the proposed radar, the compensation of phase incursions of signals is carried out in two stages (see figure 5). At the first stage, using the reference function, the maximum phase incursions of the signals associated with the presence of acceleration are compensated.

At the second stage, using the correction function, phase incursions associated with measurement errors by linear acceleration sensors are compensated.

At the first stage, in the data processor 54 with the synchronized signal "f _pd " of the frequency-synchronizer synthesizer 5, the coefficients of the reference function are formed, which are complexly coupled to the signal reflected from the object in accordance with formula (1).

For this, a linear term of the phase change "Δφ _l " of the support function and its quadratic term "Δφ _q " are formed (see formula (1)).

и управления на один из входов умножителя 83 поступает коэффициент и его умножают на значение радиальной скорости V_r, поступающее на другой вход из вычислителя 68, где оно рассчитывается по формуле (2) для каждого элемента дальности "n" и "к"-го периода повторения на основе измеряемых инерциальной навигационной системой (ИНС) составляющих скорости V_x, V_y, V_z и поступающих из вычислителя 66 данных и управления углов α_i и ε_i. На выходе умножителя 83 будет:To form a linear term from the calculator 66 data

and control one of the inputs of the multiplier 83 receives a coefficient and it is multiplied by the value of the radial velocity V _r supplied to the other input from the calculator 68, where it is calculated by the formula (2) for each element of the range "n" and "to" of the period repetitions based on the measured components of the inertial navigation system (ANN) velocity components V _x , V _y , V _z and coming from the computer 66 data and control angles α _i and ε _i . The output of the multiplier 83 will be:

где k - номер периода повторения "Т_п"

where k is the number of the repetition period "T _p "

и умножается на значение а_r, поступающее из вычислителя 67 радиального ускорения. Величина радиального ускорения "а_r" вычисляется в вычислителе 67 по формуле (3). Значения углов "α" и "ε" для вычисления поступают из вычислителя 66 данных и управления.To form a quadratic term from the data calculator 66 and control, a coefficient is supplied to the multiplier 88

and multiplied by the value of a _r coming from the radial acceleration calculator 67. The magnitude of the radial acceleration "a _r " is calculated in the calculator 67 according to the formula (3). The values of the angles "α" and "ε" for calculation come from the computer 66 data and control.

который поступает на сумматор 87, где суммируется с линейным членом для каждого элемента дальности "n" для каждого периода повторения Т_п.С выхода сумматора 87 изменения фазы опорной функции

для каждого элемента дальности и каждого периода повторения "Т_п" поступают в устройства sin и cos 95 и 96, которые вычисляют фазовые коэффициенты компенсации, затем они накапливаются в устройствах памяти 103, 104.The result of multiplying a _r by a coefficient b is the quadratic term of the support function

which goes to the adder 87, where it is summed with a linear term for each element of the range "n" for each repetition period T _p. With the output of the adder 87 changes the phase of the reference function

for each element of the range and each repetition period, "T _p " are supplied to sin and cos 95 and 96 devices, which calculate phase compensation coefficients, then they are accumulated in memory devices 103, 104.

As the phase coefficients are calculated, their values from the memory devices 103, 104 are sent along lines 103 ₁ and 104 ₁ to the memory device 49 and 50 of the signal processor 13.

For the second stage of compensation of phase incursions, a calculator 105 of correction functions h _nx is introduced into the data processor; h _ny and h _nz (see FIG. 5). Moreover, the first, second, third, fourth, fifth, sixth and seventh inputs of the calculator are connected respectively to the first, second, third, fourth, fifth, sixth and seventh outputs of the data and control computer 66. The eighth, ninth and tenth inputs are connected respectively to the outputs ADCs 56, 58 and 59 of linear acceleration sensors 55, 57 and 60. The outputs of the calculator of the correction functions along the lines 97 ₁ , 98 ₁ , 99 ₁ , 100 ₁ , 101 ₁ and 102 _{1 are} connected to the corresponding inputs of the signal processor (see figure 4 )

Due to the fact that the connection between the data processor 54 and the signal processor 13 is carried out via a standard interface, in FIG. 2 and in the formula the above connections in FIGS. 4 and 5 are shown as output 1.

For the second stage of compensation of phase incursions associated with errors in measuring accelerations, the phase coefficients of the correction function are calculated based on measurements by a linear acceleration sensor (DLU). In this case, the formation of phase coefficients of the correction functions h _nx , h _ny and h _nz (formulas 17, 18, 19) is considered by the example of the formation of the function h _nx when measuring accelerations along the "OX" axis. Formation along other axes (OY and OZ) will be similar.

The measured acceleration value of the accelerator via the analog-to-digital converter (ADC) is supplied to the multiplier 65 of the corrector of the correcting functions 105, to which the coefficient ξ value determines the value of the maximum sensor error (from FIG. 5).

In the multiplier 65, the maximum values of the errors of the acceleration measurement by the sensor in time corresponding to the kth repetition period in the synthesis time interval are determined. These error values through the memory 64 go to the calculator 63, which determines the maximum number of correction functions "2n _max ". For this, from the source data calculator and control 66, the value 63 of the allowable error value "d _{a ext} ", determined by the formula (11), is supplied to the calculator 63. In the calculator 62, the calculation of the acceleration measurement errors "d _ax " for the "2n _max " correction functions by the formula (13) for each time reference is performed.

For this, from the data and control computer 66 for each time reference, the value “n”, corresponding to the number of correction functions n ÷ n _max and -n ÷ -n _{max, is} supplied to the calculator 62. In addition, the value "n _max " is received from the calculator 63, and the value of the acceleration measurement error "d _a " for each time reference is received from the memory 64. The obtained values of "2n _max " errors "d _ax " along the OX axis in the multiplier 80 are converted to the radial direction according to the formula 14. For this, the product of the cosines of the azimuth and elevation angles is input to the multiplier 80 from the data and control computer 66. The obtained error values "d _arx " for each correction function are fed to the multiplier to calculate the phase corrections in the time interval "k · T _p ". For this, the calculator 84 from the calculator 66 data and control for each value of the correction function "h _nx " receives the values of the coefficients (see figure 5). From the multiplier 84, the phase correction values for "2n _max " values of the correction functions are supplied to the sin and cos 89 and 90 devices, respectively, to obtain phase coefficients for two quadrature signals.

Next, the signals are transmitted to the memory devices 97 and 98. From the memory devices 97 and 98 of the data processor 54, the phase coefficients of the correction functions from the calculator 105 of the correction functions along lines 97 ₁ and 98 ₁ are sent to the memory devices 43 and 46 of the signal processor 13.

The channel for the formation of corrective functions "h _ny ", consisting of nodes 74.73, 72, 71, 70, 81, 85, 91, 92, 99 and 100 and the channel "h _nz ", consisting of nodes 79, 78, 77, 76 , 75, 82, 86, 93, 94, 101, and 102 are similar to the "h _nx " channel. In this case, the phase coefficients of the correction functions "h _ny " and "h _nz " along lines 99 ₁ , 100 ₁ and 101 ₁ , 102 ₁ from the calculator 105 of the correction functions are received respectively in the memory device 44, 47 and 45, 48 of the signal processor 13.

At the first stage of compensation, in the mapping mode, upon completion of the array of radar data, the signal samples from each range element, each repetition period, coming from the memory (14 and 15), through the switches 16 and 17 (in the absence of signal j) are sent to the multipliers 18, 19, 20, 21, where they are multiplied with the same samples of each element of the range and the period of repetition of the phase coefficients of the reference function coming from the memory devices 49 and 50 through the switches 38 and 39 (in the absence of signal j). This achieves the initial compensation of phase incursions caused by accelerations of the carrier, which are measured by DLU sensors 55, 57, and 60. After multiplying the signals from the outputs of the difference devices 22 and the sum 23, the samples of the signals of two quadratures arrive at the memory devices 24 and 25 for each range element for each period repetition. At the end of the array of radar images, the samples of the signals from the memory devices 24, 25 are fed to the FFT processor 26, where they are subjected to harmonic analysis using the fast Fourier transform algorithm.

The result of the conversion of signals from the time domain to the frequency domain is the frequency (azimuthal) samples of two quadratures of radar information in each element of the range. Then the readings of the two quadratures arrive at node 27, where a module is formed from them. To ensure the compensation mode at the second stage, a calculator 106 selects a point target and determines the number of the correction function in the signal processor 13. The input of the computer 106 by the reflection signals is connected to the output of the node of the module 27 of the signal processor 13, and the first output of the computer by the signal "j" is connected to the inputs of the switches 16, 17, 28, 38 and 39 of the signal processor 13.

The outputs of the control device of the computer 106 - according to the signals X °; Y °; Z °; X ₁ , Y ₁ ; Z ₁ ; n _x ; n _y ; n _z enter the inputs with the corresponding names in the control device 51, 52 and 53 of the signal processor. To select a point target, the signal samples for each element of the range for each azimuthal sample from the node 27 of the signal processor 13 are transmitted through the switch 30 (in the absence of signal j) to the memory device 31, then the signals from the memory devices are sent to the threshold device 33.

In the threshold device, a threshold is formed for each element of the range in accordance with the formula:

где:

Where:

Where:

l is the azimuthal reference number,

L _max - the maximum number of the azimuthal reference,

U _fc1 - the amplitude of the 1st azimuthal reference.

After comparing the signals with the threshold from the output of the threshold device 33, signals exceeding the threshold level by more than N dB are supplied to the memory device 35, and from it, the signal samples are sequentially fed to the device 37 for estimating the parameters of the radar width in azimuth, where according to the number of azimuthal samples " m "determines the signal width at a level of 3 dB from the maximum value (U _max ). In this device, the width of each subsequent signal is compared with the previous one and with m _last. > m _previous recorded in memory for further comparison, and the previous count is excluded from consideration. With m _after > m _previous. subsequent is excluded. After such a comparative assessment of all signals, a signal with a minimum width of "m _min " is determined and its range number "α" is fixed, the reference number in azimuth is "α", and it is fed to the switching signal generation device 42, where the switching signals "j" are generated, range address number "n _d " and azimuth number "l _a ".

The switching signal "j" is supplied to the switches 16, 17, 28, 30, 38 and 39, the range number "n _d " is supplied to the address control device 40, and the azimuth number "l _a " is supplied to the contrast calculator 32.

When the signal "j" arrives at the switches 16 and 17 from the multipliers 18, 19, 20 and 21, the memory devices 14 and 15 are disconnected and the memory devices 24 and 25 are connected. When the signal "j" is sent to the switches 38 and 39 from the multipliers 18, 19 , 20 and 21 turn off the memory devices 49 and 50 with the values of the phase coefficients of the reference function and connect the memory devices 43, 44, 45, 46, 47 and 48 with the values of the phase coefficients of the correction functions.

From the address control device 40, a range address number "n _d " is supplied to the memory devices 24 and 25. In this case, the samples of the signal array in the range element with the number "n _d " for each repetition period from the memory 24 and 25 through the switches 16 and 17 are fed to the multipliers 18, 19, 20, 21, where they are multiplied with the phase coefficients of the correction functions that take into account accelerations in X-axis, which come from the memory devices 43 and 46 for two quadrature signal.

To connect the memory devices 43 and 46 to the multipliers, the address control device 51 receives a signal “X °” from the control device 41 by the signal “j”. The result of multiplication in devices 18, 19, 20, and 21 from the outputs of devices of difference 22 and sum 23 is fed to memory devices 24, 25 and then to the FFT processor 26, where it is subjected to harmonic analysis using the fast Fourier transform algorithm. Then the readings of the two quadratures arrive at node 27, where a module is formed from them.

Next, the signals of each azimuthal reference in the range element with the number "n _d " are fed to the calculator 106 to determine the number of the correction function. Through the switch 30, switched by the signal "j", the radar signals are transmitted to the computer 32, where in accordance with the formula [5], the contrast "C" is calculated for the signal with the azimuth number "l _a ". Next, the contrast value "C" is received in the memory 34.

In this case, the signal array processing cycle is repeated 2n _maxx · k times, which corresponds to the number of correction functions h _x (along the OX axis) and the number of periods T _p. Next, from the memory 34, the contrast values (for each correction function) are sent to the calculator 36, where it is determined the number n _{x of the} correction function "h _nx " corresponding to the maximum contrast "C _max " for the azimuthal count "l _a ", after which the number "n _x " of the correction function h _{nx is} supplied to the control unit 41. From the control unit 41, the signal "n _x "enters the control device address 51, according to the signals of which the coefficients of the correction function "h _nx " are stored in the memory devices 43 and 46, which provide the best compensation for phase changes in the array of reflection signals in the range element "n _d " at which the maximum contrast "C _{max x} " is realized.

From the control device, the signal "n _x " also enters the address control node 40, with which an array of reflection signals is fixed in the memory devices 24, 25 in the range element "n _d ", in which, by compensating for phase changes in the signal using the correction function " h _nx "the maximum contrast" C _max "is obtained.

Upon receipt of the signal "n _x " from the transmitter 36 to the control device 41, i.e. at the end of the cycle of multiplications by correcting phase coefficients with acceleration parameters along the "OX" axis, the signal "X °" is taken out in the control unit 41 and the signal "Y °" is generated, which enters the address control device 52, which controls the memory devices 44, 47 by the output of the coefficients of the correction function with the acceleration parameters along the OY axis to the multipliers 18, 19, 20, 21 in the cycles of its multiplication by the array of reflection signals in the range element "n _d ".

The task of "n _max · k" cycles of operations when using the acceleration parameters along the "OY" axis is to find the correction function "h _ny ", (similar to finding "h _nx "), when multiplied by which array of reflection signals provides the best compensation for phase incursions of the signal, giving maximum contrast With _maxy for the azimuth reference "l _a ".

In this processing, the array of signals in the range element “n _d ”, which has already been processed by the correction function “h _nx ” with the number “n _x ”, is subjected. The processing procedure is the same as for the signal "X °".

At the end of the processing cycle by the signal "Y °", as a result of which, when calculating the maximum contrast "C _max ", the number of the correction function "h _ny " is determined in the control unit 41, the signal "Y °" is removed by the signal number n _, and a signal "Z °" is generated, which enters the address control device 53 and generates control signals for the memory devices 45 and 48 by transmitting the phase coefficients of the correction functions "h _nz " to the multipliers 18, 19, 20 and 21 in the cycles of multiplication by an array of reflection signals. As an array of reflection signals for processing, an array of signals is also received in the memory device 24 25 in the range element "n _d ", which has already been processed by the signals "X °" and "Y °". The processing operation of the array of signals to find the correcting function for the signal "Z °" is similar to the processing operation for the signals "X °" and "Y °". As a result of three cycles of operations on the signals "X °", "Y °" and "Z °", the phase coefficients of the three correction functions "h _nx ", "h are determined and stored in memory devices 43, 44, 45, 46, 47, 48 _ny "and" h _nz ", when applied as functions of compensating for phase incursions of the signal array, maximum contrast With _max signal is obtained.

At the end of the last cycle of operations, the signal "n _z " coming from the calculator 36 to the control device 41, from the control device 41 to the signal conditioning device 42 receives the signal "ρ", which removes the signal "n _d " supplied to the control device 40 The control device 40 removes the address "n _d " in the memory devices 24 and 25.

At the same time, a signal “X ₁ ” is received from the control unit 41 to the address node 51, through which the phase coefficients of the previously found correction function “h” are received from the memory devices 43, 46 through the switches 38 and 39 to the multipliers 18, 19, 20, 21 _nx ".

From this moment, the second stage of the compensation of phase incursions of the signals of the entire array, associated with errors in measuring accelerations, begins. For each element of the range and each repetition period from the memory devices 24, 25, these multipliers also receive samples of the signal array for each element of the range and each repetition period with a given clock cycle. In this case, in the absence of the address signal "n _d ", in the multipliers 18, 19, 20 and 21, sequentially multiplies the entire array of signal samples for each element of the range for a given card size. The values of the samples of the signal array obtained after multiplication are again recorded in the same memory devices 24 and 25. Thus, the phase changes of the entire array of signals of a given card size are compensated for under the influence of accelerations along the "OX" axis. At the end of the first compensation cycle, the signal "X ₁ " is removed and the signal "Y ₁ " is generated and output to the control device address 52 in the control device 41. The signal "Y ₁ " repeats the cycle of processing the entire array of signals in the memory devices 24 and 25, corrected for the signal "X ₁ " when it is multiplied by the coefficients of the previously found correction function "h _ny " with the number "n _y ". Upon completion of the correction for the signal "Y ₁ " in the control device 40, the signal "Y ₁ " is removed and the signal "Z ₁ " is generated.

The signal "Z ₁ " coming from the control device 41 to the address control device 53 from the memory devices 45 and 48 through the switches 38 and 39 to the multipliers 18, 19, 20 and 21 receives the phase coefficients of the correction function "h _nz " with the number "n _z ". These multipliers from memory devices 24 and 25 receive an array of signals from each element of range already adjusted by fluctuations "h _nx " and "h _ny ". As a result of multiplication, an operation is performed to compensate for phase incursions of the signal due to accelerations along the "OZ" axis. These operations are repeated for each range element of a given map size.

As a result of three cycles of operations, the phase changes of the entire array of signals of a given card size are compensated due to the influence of acceleration errors by sensors along the three axes OX, OY and OZ, and which, in the corrected form, is stored in memory 24 and 25.

It should be noted that the compensation of phase changes was carried out with a predetermined allowable value of the residual phase incursion, at which the required characteristic of the quality of the card (contrast, resolution, etc.) is provided. At the end of the cycle of operations with an array of signals of a given card size in the device 41, the signal "Z ₁ " is removed. By removing the signal Z ₁ in the control device 41, a signal for removing the correction mode "B" is generated, which is supplied to the device for generating the switching signals 42, by which the commands "l _a " and "j" are removed. In this case, the switches 16, 17, 38, 39, 30 and 28 are installed in the initial position in which they were before the start of adjustments. After removing the signal "j", the Fast Fourier Transform (FFT) mode is activated, which converts the corrected array of signals of the entire card located in memory devices 24 and 25 from the time domain to the frequency one.

Then, the frequency (azimuthal) readings of two quadratures are sent to the device of module 27, where the module is formed from them, then through the switch 28 (in the absence of signal j) the signals for each range element for each azimuthal readout are sent to indicator 29.

The technical result in the proposed radar is to reduce the influence (according to preliminary estimates, by more than an order of magnitude) of acceleration measurement errors, which leads to a significant improvement in the characteristics of the radar image (resolution, contrast, dynamic range, etc.).

Claims (2)

1. A method of compensating for phase incursions of a signal in an airborne radar station with a synthesized aperture of an antenna for aircraft, which consists in measuring movement parameters in a normal coordinate system - X, Y, Z: when moving an aircraft with an airborne radar: components of the speed of movement V _x ; V _y ; V _z aircraft linear acceleration components a _x ; and _y ; a _{z of the} aircraft, measured, respectively, by an inertial navigation system and linear acceleration sensors, and on the basis of these measurements, the radial component of the velocity V _r in the direction of the object is determined, the support function of the compensation of phase incursions of signals reflected from ground objects is complexly coupled to the signal

where H (t) is the weight function; V _r is the component of the velocity of the phase center of the antenna in the direction of the ground object; and _r is the acceleration component of the phase center of the antenna in the direction of the ground object; τ is the time interval; t is the time multiply the reference function by an array of received reflected signals from ground objects in the synthesis interval, characterized in that the compensation of phase incursions of the signal is carried out in two stages: the array of signals obtained in the first stage after multiplying by the reference function is multiplied by the complex correction functions h _{nX; Y; Z} ^{p0 to} the X, Y, Z coordinates corrective functions are determined by the criterion for assessing the quality of radar information based on measurement errors of acceleration by sensors.

where h is the error of the correction function; d _ar - error in measuring linear acceleration by the sensor. 2. An onboard radar system with a synthesized aperture of an antenna for aircraft, consisting of an antenna, a circulator, a transmitter, a receiver, a master oscillator, a frequency synthesizer - synchronizer, a data processor, a signal processor, an indicator, an inertial navigation system, three acceleration sensors with analog digital converters, while for transmitting the radiating signal, the antenna input through the circulator is connected to the transmitter output, and for transmitting the received signal the antenna output through the output of the circulator is connected to the first input of the receiver, for transmitting a carrier frequency signal f and pulse repetition frequency F _{p, the} first and second input of the transmitter are connected respectively to the first and second output of the frequency synthesizer - synchronizer, for generating a signal at an intermediate frequency f _pr , at the Doppler frequency f _d, a sampling frequency f _ca ADC, third, fourth and fifth outputs of the synchronizer of the frequency synthesizer are connected by the signals f, f and f _{ave ca,} respectively, with the second, third and fourth inputs of the receiver, you od which the signals reflected from the surface facilities, connected to the first input signal processor, a second input for a clock signal f _ch is coupled with the sixth output of frequency synthesizer, a synchronizer, a seventh output is to a clock signal f _nd connected to the first input of the data processor, and a first input signal at a frequency f _r synthesizer connected to the output of the master oscillator, the second input of frequency synthesizer-synchronizer for mode control signals connected to the second output of the data processor, the second input koto th coupled to an inertial navigation system, wherein the first, second and third outputs of the first, second and third acceleration measurement sensors via analog-to-digital converters in the parameters of accelerations a _x; a _y ; a _{z are} connected respectively to the fourth, fifth and sixth inputs of the data processor, the eighth output of the frequency synthesizer by a sampling frequency signal is connected to the second input of each analog-to-digital converter, the output of the signal processor by signals of radar information is connected to the indicator input, characterized in that the processor of signals, a calculator for selecting a point target and a correction function number is introduced, while the input of the calculator is connected to the output of the device for forming the module from the frequency samples of two dratur, the first output of the calculator - with the second input of the processor memory devices, the second output of the calculator is connected to the inputs of the processor switches, the third, fifth and seventh outputs of the calculator are connected respectively to the first, second and third inputs of the first control device, the second, fifth and eighth outputs are connected respectively with the first, second and third inputs of the second control device, the third, sixth and ninth outputs are connected respectively to the first, second and third inputs of the third control device, and in the process A data calculator of correction functions is introduced, while the first, second, third and fourth inputs are connected respectively to the first, second, third and fourth outputs of the data calculator and data processor control, the fifth, sixth and seventh inputs are connected respectively to the outputs of the ADC of the acceleration sensor along the axis OX, the ADC of the acceleration sensor along the OY axis, the ADC of the acceleration sensor along the OZ axis, the eighth ninth and tenth inputs of the calculator are connected respectively to the fifth, sixth and seventh outputs of the data calculator and data processor control and control of the data processor, the output of the calculator of the correction functions on a standard main parallel interface is connected to the third input of the signal processor.

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