RU2586623C2 - Method of processing radar information with low probability of beginning of false routes - Google Patents

Abstract

FIELD: radar ranging and radio navigation.

SUBSTANCE: invention can be used to reduce probability of initiating of false routes at moving targets (MT) in presence of signals from powerful local objects (LO). Technical result is achieved by fact that method involves combined spatial-time and routing processing using obtained from space-time processing information during initiating and tracking routes, space-time processing is supplemented with operation generating false alarm (FA), which marks uncompensated signal from local object (LO), wherein LO feature is also used in secondary processing at initiating and tracking of routes. Operation of moving targets (MT) detecting includes formation of detection threshold and comparison with MT-signal amplitude, and operation for FA-feature generating involves selection of maximum amplitude of MT signal, optimum processing of LO-signals, suppression of FA-signals and determining of FA-feature. When determining FA-feature accumulation of data volume takes place, which corresponds to half of azimuthal packet multiplication factor depending on stability of transceiving channel, and comparison of delayed maximum amplitude of MT-signal with level of residue from LO-signal. FA-feature receives nonzero value in case of excess residue from LO-signal above delayed maximum amplitude value of MT-signal and zero if otherwise. Then formed feature, which is result of comparison is used in route processing, which performs accumulation of values for spatial coordinates, radial speed and FA-feature on several reviews. At that, FA-feature informs route processing system, that target with non-zero value of that feature at route initiation is to be eliminated from consideration, while during tracking is to lower target selection priority (in presence of several targets).

EFFECT: reduced probability of false routes initiation at moving targets (MT) in presence of signals from powerful local objects (LO) while reducing cost of method and reduction of time for making decision on rejecting of false route.

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Description

The invention relates to the field of radar and can be used to reduce the likelihood of tying false trails on moving targets (DC) in the presence of signals from powerful local objects (MP).

Linking and tracking of tracks takes place in the secondary (track) processing system. One of the main indicators of the quality of processing radar information (RLI) is the probability of tying a false track, which depends on the accuracy of measuring the coordinates of the targets, the criteria for tying tracks, the probability of false alarm (LT) at the output of the primary (spatio-temporal) processing system, using additional parameters for targets (radial speed, signal-to-noise ratio and other informational signs). In this case, the probability of LT is one of the most significant factors affecting the likelihood of a tie. The causes of RT can be different - mutual interference, uncompensated signals from the magnetic field, intrinsic noise of the receiving device, etc. The most negative effect is exerted by the LT, which are uncompensated signals from the magnetic field due to the fact that their location is correlated.

There are known analogues of the proposed method [1, 2], where the task of reducing the probability of false tracing is solved at the stage of primary processing of radar data.

In the primary radar processing, the detection of target signals is carried out by comparing the echo signal with the detection threshold. Basically, the Neumann-Pearson test is used to form the detection threshold, according to which the detection threshold of the target signal is determined so that the probability of LT is constant.

It is determined on the basis of the assumption that the probability density of the echo signal is of the same type within a certain moving range analysis window. This approach does not allow us to exclude from the processing an uncompensated signal from the magnetic field due to insufficient statistics, since this signal is concentrated in one or two elements in range. To exclude RT caused by insufficient suppression of powerful MP signals, it is necessary to increase the detection threshold. This leads to a loss of sensitivity, which is a significant drawback.

The closest in purpose to the claimed invention is a method that reduces the likelihood of tying false trails and based on the joint work of primary and secondary processing systems [3]. It allows one to reduce the probability of false tracing by taking into account differences in a priori distributions of radial velocities independently measured by echo signals from moving and stationary objects, as well as by accumulating and recording information about the magnitude of radial velocities obtained in several radar measurements of several locators, by which formed the path of a moving object.

The main disadvantages of the prototype method are:

- a distorted measurement of the values of spatial coordinates and radial velocities, in the event that DC signals are found against a background of powerful MP signals (within the pulse area or pulse volume and with a small ratio of the DC signal to the uncompensated remainder of the MP signal);

- the need for multiple locators (at least 2) to ensure the independence of radial velocity measurements for moving and stationary objects;

- limitation of the effective work area to the area of intersection of the scan zones of different locators;

- a long time for making a decision on screening a false track, due to the need to tie the track.

The low reliability of measuring the spatial coordinates and the radial velocity of the DC leads to an increase in the probability of tying false paths, as well as to an increase in the likelihood of a breakdown of the path.

The technical result of the invention is to reduce the likelihood of tying false trails on moving targets (DCs) in the presence of signals from powerful local objects (MP) while reducing the cost of the method and reducing the time it takes to drop a false trail.

This result is achieved by the fact that in the known method for processing radar images, including joint space-time processing, which performs optimal, in terms of increasing the signal-to-noise ratio, processing with selection of moving targets (SDC), detection of moving targets (DC), measuring them spatial coordinates and radial velocity, and route processing, which uses the information obtained when tying and tracking the tracks, spatio-temporal processing is supplemented by the operation of forming a feature false alarm (LT), which marks an uncompensated signal from a local object (MP), and the LT symptom is also used in secondary processing when tying and tracking tracks. The operation of detecting moving targets (DC) performs the formation of a detection threshold and compares the amplitude of the DC signal with it, and the operation of generating the LT sign - selection of the maximum amplitude value of the DC signal, optimal processing of MP signals, suppression of DC signals and determining the sign of LT. When defining the LT sign, data is accumulated, the volume of which corresponds to half the azimuthal packet, multiplied by a coefficient depending on the stability of the transceiver path, and the delayed maximum amplitude value of the DC signal is compared with the level of the remainder of the MP signal. The LT attribute takes a non-zero value if the level of the remainder of the MP signal exceeds the delayed maximum amplitude value of the DC signal and zero otherwise. Next, the generated sign representing the result of the comparison is used in the route processing, which performs the accumulation of the values of spatial coordinates, radial velocity, and the LT attribute for several surveys. Moreover, the LT sign informs the route processing system that goals with a non-zero value of this sign should be excluded from consideration when linking a route, and if accompanied, lower the priority of target selection (if there are several goals). At the same time, it is impractical to exclude such targets at the primary processing level because the signals from targets with a large effective scattering area, having a small radial velocity, can also form an LT sign, which ultimately leads to missed targets.

In addition, depending on the type of locator, there are various options for the implementation of the operation of forming the sign of LT. One of the special cases is the use of criterion processing when suppressing DC signals in the presence of N-fold burst wobble of the period of the probe pulses. In this case, the operation of suppressing DC signals is carried out by accumulating signals and selecting the minimum value from N signals that are adjacent in time, and targets with a non-zero value of the LT sign are also excluded from the consideration when tracing, and when accompanied, the value of the LT sign is not taken into account.

The figure 1 shows an example of a structural diagram of a device that implements the proposed method, where indicated:

1 - space-time processing system;

2 - system of route processing;

3 - channel detection DC;

4 - channel formation of the sign of LT;

5 - channel optimal processing with selection of moving targets (SDC);

6 - the first unit of comparison;

7 - block formation of the detection threshold (FPO);

8 - unit for measuring range, azimuth and radial velocity (R, P, Vr);

9 - block selection of the maximum amplitude value;

10 - channel optimal processing of MP signals;

11 - block suppression of DC signals;

12 - block definition of the sign of LT;

13 - data storage unit;

14 - block multiplication by the coefficient K (X);

15 is a second block comparison;

16 - data storage unit for several reviews;

17 - block tying tracks;

18 - block tracking tracks.

As can be seen from figure 1, a device that implements the proposed method includes a space-time 1 and track 2 radar processing system.

The spatio-temporal processing system 1 comprises a detection channel for DC 3 and a channel for generating the LT 4 feature.

The detection channel for DC 3 contains an optimal processing channel with SDS 5, a first comparison unit 6, a FPO block 7, and a measurement unit R, β, Vr 8.

The channel for the formation of the sign of LT 4 contains a block for selecting the maximum amplitude value 9, a channel for optimal processing of MP signals 10, a block for suppressing DC signals 11 and a block for determining the sign of LT 12.

The sign detection unit LT 12 comprises a data storage unit 13, a multiplication unit by a coefficient K 14, and a second comparison unit 15.

The system of route processing 2 includes a data accumulation unit for several surveys 16, a block for tying tracks 17 and a block for tracking tracks 18.

The proposed method, as an example of the above device, is implemented as follows.

The signal from the output of the phase detector (PD) enters the detection channel of DC 3 to the input of the optimal processing channel with SDC 5, which performs the following operations:

- inter-period coherent processing with SDS;

- amplitude detection.

In addition, this channel can perform operations:

- protection against non-synchronous impulse noise (in the general case, it may contain non-linear operations);

- intra-period coherent processing (consistent filtering);

- incoherent processing, performed depending on the selected level of inter-period coherent accumulation in the processing.

From the first output of the optimal processing channel with SDC 5, the DC signal (S _{SDC link} ) obtained by passing the PD signal through the linear operations of this channel is fed to the second input of the measurement unit R, β, Vr 8 and to the input of the maximum amplitude value selection unit 9. In the general case, this signal is complex.

From the second output of the optimal processing channel with SDC 5, the amplitude of the DC signal (A _{SDC obn} ), obtained by passing the PD signal through the linear and nonlinear operations of this channel, is fed to the first input of the first comparison unit 6 and to the input of the FPO 7 block.

And _{SDC obn.} and S _{SDC lines} contain information on Doppler channels. In this case, A _{SDC obn.} It is used to detect DC signals, and S _{SDC lin} is used to measure spatial coordinates and radial velocity, and it is also used in the channel for generating the LT 4. sign. Moreover, in special cases:

- And _{SDC obn.} and S _{SDC lin} can be equal when using only linear operations and algorithms for measuring radial velocity and angular directions of the target using real signals in the detection channel;

- And _{SDC obn.} and S _{SDC lin} can contain information about only one channel in which the component corresponding to the stationary objects is excluded.

In the FPO block 7, a detection threshold (P _obn. ) _{Is formed} , which is supplied from the output of this block to the second input of the first comparison unit 6, in which the amplitude of the DC signal (A _{SDC obn} ) is compared with the detection threshold (P _obn ). In this case, in case A _{SDC obn.} > R _obn. a decision is made about the existence of the goal, otherwise - about its absence (1 - yes, 0 - no).

Then the information (1/0) from the output of the first comparison unit 6 is fed to the first input of the measurement unit R, β, Vr 8, where the measurement of the range, azimuth and radial velocity (R, β and Vr, respectively).

The signal from the PD output also goes to the LT 4 sign formation channel to the input of the channel for optimal processing of MP signals 10, which contains the same operations as the channel for optimal processing with SDC 5 with the exception of inter-period coherent processing, where low Doppler frequencies are filtered to isolate MP signals and suppression of DC signals.

Next, the signal from the output of the channel for optimal processing of MP signals 10 is fed to the input of the block suppressing DC signals 11, while the operation of suppressing DC signals is carried out in two stages:

- at the level of inter-period coherent processing due to filtering of low Doppler frequencies in the block of optimal processing of MP signals 10;

- at the level of incoherent processing in the block suppression DC signals 11.

The operation of additional attenuation of the DC signal level, which occurs in the block for suppressing DC signals 11, may not be carried out if it is sufficiently suppressed in the channel for optimal processing of MP signals 10. Therefore, the block for suppressing DC signals 11 may also be absent.

The following operations are carried out in the channel for generating the LT 4 symptom: selection of the maximum amplitude value of the DC signal, optimal processing of the MP signals, suppression of the DC signals, determining the level of the remainder of the MP signal and determining the LT attribute.

The amplitude of the MP signal (A _MP ), selected when the signal passes from the PD output through blocks 10 and 11, comes from the output of the DC signal suppressing unit 11 to the LT 12 sign detection unit to the second input of the data storage unit 13. To the first input of block 13 the maximum amplitude value of the DC signal (A _max ) from the output of block 9 is supplied.

From the first output of the measurement unit R, β, Vr 8, the measured values of the spatial coordinates (R and β are supplied to the third input of the data storage unit 13. The accumulation and delay of data by half the azimuthal packet in block 13 is necessary to align the delay with the data of the measurement unit R, β , Vr 8, where the measurement of spatial coordinates and radial velocity takes into account the presence of a local maximum within the azimuthal packet.

At the input of the unit of multiplication by the coefficient K 14, the amplitude of the MP signal (A _{MP assignment} ) is delayed in the accumulation unit 13. The value of the coefficient K depends on the stability of the transceiver path. It is necessary to determine the level of the remainder of the MP signal. Stability can be measured in advance by the results of experiments, measured dynamically by specially formed test signals or by received echo signals from powerful MPs.

The determination of the level of the remainder from the MP signal (A _{MP stop} ) occurs by filtering low Doppler frequencies in the channel for optimal processing of MP signals 10, suppressing DC signals in block 11, accumulating data in block 13, and multiplying by the coefficient K in block 14 .

Then, the maximum amplitude value of the DC signal (A _{max ass.} ) Delayed in the data storage unit 13 is supplied from the first output of this block to the first input of the second comparison unit 15, and A _{MP stop} is fed to the second input of block 15 _. supplied from the output of the multiplication unit by the coefficient K 14. If the level of the remainder of the MP signal exceeds the delayed maximum amplitude value of the DC signal (A _{MP oc} > A _{max ass.} ), the LT flag takes a non-zero value, otherwise it will be zero.

The result of comparing the values of And _{max back.} and A _{MP ost.} is to obtain the value of the trait LT (S _MP ). It comes from the output of the second block of comparison 15 in the system of route processing 2.

Thus, the additional LT attribute is calculated in the channel of the LT 4 attribute formation by determining the level of the remainder from the MP signal and comparing it with the delayed maximum amplitude value of the DC signal.

The values of R, β and Vr from the second output of the measurement unit R, β, Vr 8 and the value of the LT attribute (S _MP ) from the output of the LT 12 attribute determination unit are supplied to the route processing system 2 to the first and second inputs of the data storage unit for several surveys 16 , respectively.

Further, from the output of block 16, the information goes, respectively, to the input of the block of ties of the tracks 17 and to the first input of the block of tracking tracks 18. Moreover, the second input of the block 18 receives information from the output of the block of ties of the tracks 17.

In the process of linking the route occurring in block 17, only targets with a zero value of the LT attribute are involved.

When tracking a route (if there are several targets in the capture gate), the work is primarily carried out for targets with a zero value of the LT attribute, since, compared with them, targets with a non-zero value of this attribute have a lower priority.

The figure 2 shows an example of a structural and functional diagram of the channel for the formation of the sign of LT 4, which implements a method of suppressing DC signals by criterion processing under conditions of N-fold burst wobble. On it are indicated:

4 - channel formation of the sign of LT;

9 - block selection of the maximum amplitude value;

10 - channel optimal processing of MP signals;

11 - block suppression of DC signals;

12 - block definition of the sign of LT;

19 - delay line (LZ);

20 - block selection of the minimum value.

The block suppressing DC signals 11 contains a series-connected LZ 19 and block selection minimum value 20.

The channel for the formation of the LT 4 trait under conditions of N-fold burst wobble works as follows.

The operations carried out by the unit for selecting the maximum amplitude value 9, the unit for determining the symptom LT 12 and the channel for optimal processing of MP signals 10 have been described previously.

The signal from the output of the channel for optimal processing of MP signals 10 enters the block of suppression of DC signals 11 at the input LZ 19, in which the accumulation of signals occurs, and the number of taps N (from 0 to N-1, where 0 corresponds to the signal without delay) in LZ equal to the frequency of the wobble period of the repetition of the probe pulses. Next, the signal from the N outputs of the LZ 19 is fed to the N inputs of the selection block of the minimum value of 20, where the selection of the minimum of N adjacent in time signals. After that, the signal from the output of block 20 is fed to the second input of the LT sign determination unit 12. The value of the LT attribute (S _MP ) is then sent from the output of the LT sign determination block 12 to the route processing system 2, where the linking of the route also occurs only for targets with a zero value of the LT sign, and when accompanied, the value of the LT sign is ignored, that is, all targets, regardless of the value of the LT sign, have the same priority.

The introduction of the operation for the formation of the LT trait allows one to take into account the decrease in the reliability of measuring the spatial coordinates and the radial velocity of the DC having a nonzero value of this trait.

To use the proposed processing method, the work of one locator is sufficient, which significantly reduces the cost of the method.

The implementation of the screening of LT at the level of the tie of the route allows you to reduce the time it takes to decide on the screening of the false route.

Thus, the addition of spatiotemporal processing by the operation of generating the LT trait, which is used in secondary processing for tying and tracking traces, has reduced the likelihood of tying false traces along the DC in the presence of signals from powerful MPs simultaneously with reducing the cost of the method and reducing the time for deciding on screening false track.

Information sources

1. Yu.S. Lezin. Introduction to the theory and technique of radio systems. M .: Radio and communications, 1986.

2. P.V. Mikheev, patent No. 2237262 for the invention "Method for distinguishing between useful and interfering radar signals at the output of the primary processing."

3. S.K. Tulipov, A.F. Soprunov, patent No. 2099740 for the invention "A method for selecting information about moving objects to ensure the elimination of false track radar information and a device for its implementation."

Claims (2)

1. A method for processing radar information with a low probability of tying false traces, including joint spatio-temporal and trace processing, using information obtained from spatio-temporal processing for tying and tracking trails, characterized in that the spatio-temporal processing is supplemented by the operation of generating a false alarm sign (LT), which performs the selection of the maximum amplitude value of the signal of a moving target, the optimal signal processing of local objects, suppressing signals of a moving target, data accumulation, multiplication by a coefficient depending on the stability of the transceiver path, comparing the delayed maximum amplitude value of the moving target signal with the level of the remainder of the signal from local objects, and determining the LT sign, while the LT sign takes a non-zero value if the remainder level is exceeded from the signal of local objects over the delayed maximum amplitude value of the signal of a moving target and zero - otherwise, after which the generated recognition used in field processing of performing accumulation of the spatial coordinate value of the radial velocity and the LT characteristic for several surveys, wherein the target with non-zero value of the attribute at the complication tracks are excluded from consideration, and the accompanying - decreases the target selection priority (when there are multiple targets). 2. The processing method according to p. 1, characterized in that the LT sign formation operation is performed under conditions of the presence of N-fold burst wobble of the probe pulse period, while the moving target signals are suppressed by accumulating signals and selecting the minimum of N signals adjacent in time, and when tracking the route, the value of the LT attribute is not taken into account.

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