RU2052836C1 - Method of and device for selecting signals of radar targets in tracking strobe - Google Patents

Abstract

FIELD: radars. SUBSTANCE: method for selecting radar targets occurring in tracking strobe involves selection of signal whose time position relative to strobe center is minimal; in addition, doppler-offset frequency of detected signal of aerial target is measured and aerial target signals in which absolute value of doppler-offset frequency does not exceed desired threshold value are sampled. Device has target position detecting unit 1, selecting unit 2, target position comparison unit 3, target position smoothing unit 4, extrapolated target position computing unit 5, storage unit 6, target path detecting unit 7, radial velocity metering unit 8, and threshold unit 9. EFFECT: improved design. 2 cl, 3 dwg

Description

 The invention relates to radar and can be applied in automated systems for processing radar information of pulse-Doppler surveillance radars.

There is a method of selecting radar targets in the tracking strobe, which consists in receiving and receiving radar signals reflected from targets in each radar scan period, accumulating the energy of received signals, detecting target signals based on comparing the signal energy with a threshold, measuring the time delay τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{zi}}$ the signal of the i-th target followed, i 1, 2, l, and the time delay τ _{sj of the} signal of the j-th air target, j 1, 2, P, relative to the moment of emission of the probe signal of a given viewing period, storing signals that have a relative delay value temporary position τ _zij defined by the value of τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{zi}}$ - τ _zj | does not exceed the specified value of the tracking half-gate Δτ _i , comparing all the stored signals by the value of τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{zi}}$ - τ _zij in the strobe of the signal for which this value is minimal.

 A device for selecting radar targets in the tracking strobe is known that implements a method for selecting radar targets in the tracking strobe, consisting of series-connected units for comparing target coordinates, the inputs of which are the input to a device for selecting radar targets in the tracking strobe, a block for smoothing target coordinates, a unit for calculating extrapolated target coordinates, a memory block and a block for constructing target trajectories with two outputs connected to the inputs of the memory block, while the second input The s of the target coordinate comparison block and the target coordinate smoothing block are connected to the output of the memory block, to which the input of the target path construction block is connected to the second output of the target coordinate comparison block.

 The method for selecting radar targets in the tracking strobe, selected as a prototype, and the device for selecting radar targets, make it possible to isolate from signals from air targets that have entered the tracking strobe a signal whose temporal position value relative to the current target location (center of the tracking strobe) is minimal, for continuation of the trajectory of the followed air target.

 A disadvantage of the known method for selecting radar targets in the tracking strobe is that if there are signals from false targets in the tracking strobe caused by passive interference (intentional and natural) uncompensated by the radar receiver’s SDC circuit, the probability of selecting signals from false targets to continue trajectories and as a result, the accuracy and reliability of target tracking is reduced.

 The aim of the invention is to increase the accuracy and reliability of tracking targets by reducing the likelihood of signal selection from false targets due to passive interference (intentional and natural) uncompensated by the radar receiver receiving circuit.

This is achieved by the fact that with the known method of selecting radar targets in the tracking strobe, which consists in receiving and receiving radar signals reflected from targets in each radar scan period, accumulating the energy of received signals, detecting target signals based on comparing the signal energy with a threshold, measuring the time delay τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{zi}}$ the signal of the i-th target followed, i 1, 2, l, and the time delay τ _{sj of the} signal of the j-th air target, j 1, 2, P, relative to the moment of emission of the probe signal of a given viewing period, storing target signals for which the relative delays in the temporary position τ _zij determined by the value of τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{zi}}$ - τ _Зj does not exceed the specified value of the tracking half-gate Δτi, comparing all stored signals in magnitude τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{zi}}$ - τ _zij in the strobe of the signal for which this value is minimal, in addition, in each period of the radar survey, the Doppler frequency shift of the detected signal of the j-th air target, j 1, 2, P, relative to the carrier frequency of the sounding signal is measured and the air target signals are gated, which the absolute value of the Doppler frequency shift does not exceed a predetermined threshold value.

 To a device for selecting radar targets in the tracking strobe, comprising sequentially connected unit for comparing target coordinates, the inputs of which are inputs of the device for selecting radar targets in the tracking strobe, block for smoothing the coordinates of targets, a unit for calculating extrapolated target coordinates, a memory block and a block for detecting target trajectories with two outputs connected to the inputs of the memory block, while the second inputs of the block comparing the coordinates of the targets and the block smoothing the coordinates of the targets are connected to the input the memory block, the second inputs of the target trajectory detection unit are connected to the second output of the target coordinate comparison unit, additionally connected are the target detection and measurement coordinates unit, the radial velocity measurement unit, the second input of which is connected to the second output of the target coordinate detection and measurement unit, the threshold block , a selection unit, the second input of which is connected to the output of the threshold unit, and the first inputs are connected to the first input of the unit for detecting and measuring target coordinates, while detection and measurement of target coordinates at the inputs, and a selection block at the output is connected between the input of the radar target selection device in the tracking strobe and the first inputs of the target coordinate comparison block, respectively, the first inputs of the radial velocity measuring block being the second input of the radar target selection device in the tracking strobe.

In FIG. Figure 1 shows timing diagrams, where diagram 1 shows the temporary position of signals from air targets relative to the moment of radiation of the probe signal: τ ₁ , τ ₂ , τ ₃ , τ ₄ for four signals, respectively;
diagram 2 the position of signals from air targets, shown in diagram 1, on the frequency axis relative to the carrier frequency of the probe signal (f _n ): f _n + f _D1 , f _n + f _D2 , f _n + f _D3 , f _n + F _D4 for four signals, respectively, where f _{D is the} Doppler frequency shift of the a-th signal from air targets (a 1, 2, 3, 4);
figure 3 the position of the threshold signal on the frequency axis relative to the carrier frequency of the probing value of the Doppler frequency offset;
Figure 4 shows the temporary position of signals from air targets (first, third, fourth), whose Doppler frequency shift exceeds a threshold value;
diagram 5 is the temporary position of the signal of the target being followed (the first target) relative to the moment of radiation of the probe signal, which determines the center of the tracking strobe of the given dimensions Δτ ₁ ;
diagram 6 the temporary position of the first and third signals from air targets that satisfy the condition τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{s1}}$ - τ _zij ≅Δτ ₁ , i.e., trapped in the tracking gate;
diagram 7 temporary position of the third signal from air targets, the value of the temporary position of which relative to the center of the tracking strobe (τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{s1}}$ ) is minimal.

 As follows from the time and frequency diagrams shown in FIG. 1, the second signal from air targets after selection by Doppler frequency offset is excluded from further operations of the selection of signals from air targets in the tracking strobe. Otherwise, that is, in the absence of selection by Doppler frequency offset (which corresponds to the prototype), the second signal from air targets will be selected to continue the trajectory of the target being tracked.

 Thus, the proposed method allows you to compensate for signals caused by passive interference.

 In FIG. 2 shows a functional diagram of a device for selecting radar targets in the tracking strobe.

 A device for selecting radar targets in the tracking strobe that implements a method for selecting radar targets in the tracking strobe consists of series-connected block 1 for detecting and measuring target coordinates, block 2 for selection, block 3 for comparing target coordinates, block 4 for smoothing target coordinates, block 5 for calculating extrapolated coordinates targets, memory unit 6, target trajectory detection unit 7 with two outputs connected to the inputs of the memory unit 6, while the second inputs of the unit 3 comparing the coordinates of the targets and bl 4, the smoothing of the coordinates of the targets is connected to the output of the memory unit 6, the second inputs of the target tracing unit 7 are connected to the second output of the target coordinate comparing unit 3, connected in series to the radial velocity measurement unit 8, the second input of which is connected to the second output of the detection and measurement unit 2 the coordinates of the targets, the threshold block 9, the output of which is connected to the second input of the selection block 2, and the inputs of the block 1 for detecting and measuring the coordinates of the targets and the first inputs of the block 8 for measuring radial velocity tsya respectively the first and second input selection device of radar targets in the tracking gate.

 The device for selecting radar targets in the tracking strobe in the steady state works as follows.

 Information of the current (n) radar survey from the outputs of the phase and amplitude detectors of the receiving device is received synchronously at the inputs 2 and 1 of the radar target selection device in the tracking strobe, respectively, to the first inputs of the radial velocity measurement unit 8 and the inputs of the target detection and measurement unit 1.

 Block 8 measuring radial velocity and block 1 detection and measurement of coordinates of targets can be implemented according to one of the known schemes.

 Unit 8 measuring the radial velocity measures the radial velocity of the detected target by the Doppler shift of the signal frequency relative to the carrier frequency of the probing signal.

 Block 1 detection and measurement of target coordinates performs the detection of the target signal and the measurement of its coordinates. At the same time, the process of measuring the radial velocity of the target by the radial velocity measuring unit 8 detected by the target coordinate detection and measurement unit 1 ends with the signal issued last from output 2 (“log 1”) corresponding to the end of the reflected signal packet from the bearing to input 2 of block 8 radial velocity measurement From the output of radial velocity measurement unit 8, the measured radial velocity value of the detected signal from the target in the form of signal codes arrives at threshold block 9, where the radial velocity value INDICATES with a threshold value corresponding to the maximum possible value of the radial speed of the signal from the passive interference with the maximum radial velocity measurement error.

 The threshold block 9 may be implemented according to one of the known schemes. If the measured value of the radial velocity of the detected signal exceeds the threshold value, then a log signal is generated at the output of the threshold block 9. "1", which goes to the output of threshold block 9. Otherwise, a log signal is generated at the output of the latter. "0". The signal from the output of the threshold block 9 is fed to the second input of the selection block 2, the first inputs of which receive the signal codes of the measured values of the coordinates of the signal from the targets (marks from the target).

 If there is an input 1 block 2 signal selection log. "1" the measured values of the coordinates of the signal from the target, received at the inputs 2, pass to the output of block 2 selection. If there is an input 1 block 2 signal selection log. "0" the measured values of the coordinates of the signal from the target to the output of block 2 of selection do not pass.

 Block 2 selection can be performed on the logical elements AND (for example, elements 555 LI1).

 The functional diagram of block 2 is shown in FIG. 3.

 Signal codes (log. "1" and log. "0") of the measured values of the coordinates of signals from targets whose radial velocity value exceeds a threshold value, from the output of block 2 of the selection are fed to the first inputs of block 3 comparing the coordinates of the targets, to the second inputs of which the output of the memory unit 6 receives the signal codes of the coordinates of the center of the tracking strobe, which determines the current location of the tracked target. The coordinates of the center of the tracking strobe for the current (and) radar survey are determined in block 5 for calculating the extrapolated target coordinates on the (n-1) radar survey and are stored in memory block 6.

 In block 3, the comparison of the coordinates of the targets according to the coordinates of the center of the tracking strobe received at the second inputs, signals are generated that determine the sizes of the tracking strobe at the corresponding coordinates, and the correspondence of the coordinates of the signals from the targets arriving at the first inputs, the dimensions of the tracking strobe relative to its center are checked. The signals from the targets, the distance of the coordinate values of which from the center of the corresponding strobe exceeds the strobe dimensions by the corresponding coordinates, i.e., not falling into the tracking strobe, are fed sequentially to the second output of the target coordinate comparison unit 3. For signals from targets that fall into the tracking strobe, in block 3 comparing the coordinates of the targets, the values of the square of the distance from the center of the tracking strobe are determined by the corresponding coordinates and the signal from the target is determined, the value of the square of the distance of which relative to the center of the strobe is minimal. The coordinates of the selected signal from the target are sent to the first output of the coordinate comparison unit 3. Signals from targets for which the value of the square of the distance is not minimal are excluded from further processing. In the event that no signal from the target falls into the tracking strobe, the coordinates of the tracking strobe center are received as the measured coordinate values for the current radar survey, which are received at the first output of the target coordinate comparison unit 3.

 Block 3 comparing the coordinates of the targets can be implemented according to one of the known schemes.

 According to the signal inputs of the coordinates of the signal from the target, allocated to the first inputs of block 4 for smoothing the coordinates of the targets, allocated in block 3 for comparing the coordinates of the targets, and to the second inputs, the extrapolated values of the coordinates of the trajectory (coordinates of the center of the tracking strobe) for the current radar survey period, in this the block evaluates the coordinates and parameters of the trajectory at the time of measuring the coordinates of the signal from the target.

 From the output of the target coordinate smoothing block 4, the signal codes of the values of the smoothed coordinate estimates and the rate of their change are fed to the inputs of the extrapolated target coordinates calculation block 5.

 In block 5 for calculating the extrapolated coordinates of the targets, the smoothed estimates of the coordinates of the trajectory are extrapolated to the next (n + 1) radar survey, the values of which are sent in the form of signal codes to the inputs of memory block 6.

 Similar operations for the tracking target are performed on subsequent radar surveys.

 Signal codes of the values of the measured coordinates of signals from targets that did not fall into the tracking gates on the current (n) radar survey, from the second output of the target coordinate comparison unit 3, are sent to the first inputs of the target trajectory building block 7. The second inputs of block 7 for constructing the trajectories of targets from the output of block 6 of the memory sequentially receive signal codes for the coordinates of signals from targets measured on the (n-1) radar survey that did not fall into any of the tracking and acquisition gates and determining the centers of the capture gate of the first type on the current radar review.

 In block 7 detection of target trajectories, the detection of trajectories by two consecutive (in (n-1) and n-radar surveys) measurements of the coordinates of the target.

 In this case, the signal codes of the coordinates of the detected trajectory extrapolated to the next (n + 1) survey, and the values of the trajectory number are sent to the first outputs of the target trajectory detection unit 7. The signal codes of the coordinate values of signals from targets that do not belong to any trajectory in the current overview are supplied to the second outputs of the target trajectory detection unit 7.

 The signal codes from the two outputs of the block 7 detection of target paths are received at the inputs of block 6 of the memory.

 Similar operations for detecting target paths in block 7 of constructing target paths are repeated in subsequent radar surveys.

 Blocks for smoothing target coordinates, calculating extrapolated target coordinates, memory, and detecting target paths can be implemented according to one of the known schemes.

 The invention allows in the General case, to reduce the likelihood of signal selection from false targets due to passive interference (intentional and natural), uncompensated by the circuit of the SLC of the radar receiver.

Claims (2)

1. A method for selecting signals of radar targets in the tracking strobe, which consists in emitting and receiving radar signals reflected from targets in each viewing period, accumulating the energy of received signals, detecting target signals by comparing the signal energy with a threshold, and measuring the time delay τ $\genfrac{}{}{0ex}{}{\text{t}}{\text{zi}}$ the signal of the i-th target followed (i = 1, ..., l) and the time delay τ _{sj of the} signal of the j-th air target (j = 1, ..., p) relative to the moment of emission of the probe signal of a given viewing period, the signals are stored goals, the value of the relative temporary position τ _sij which, determined by the value

does not exceed the specified value of the tracking half- _{gate Δτ i} , all the stored signals are compared in terms of τ _zij and a signal with a minimum value of τ _{zij is selected} , characterized in that in each review period after the signals of the jth air target are detected, the signal energy is coherently accumulated, the Doppler the frequency offset relative to the frequency of the probing signal, the measured Doppler frequency offset is compared with the threshold and, if the threshold is not exceeded, the signal of the corresponding air target is gated.  2. A device for selecting radar targets in the tracking strobe, comprising a target detection and measurement unit, the input of which is an input to the device, a unit for comparing target coordinates, a unit for smoothing target coordinates, a unit for calculating extrapolated target coordinates, a memory unit and a target path detection unit , the two outputs of which are connected to the inputs of the memory unit, the second inputs of the unit for comparing the coordinates of the targets and the unit for smoothing the coordinates of the targets are connected to the output of the memory unit, W the second input of the target path detection unit is connected to the second output of the target coordinate comparison unit, characterized in that a selection block is inserted into it, the first input of which is connected to the output of the target coordinate detection and measurement unit, and the output is connected to the first input of the target coordinate comparison unit, and a radial velocity measuring unit connected in series, the first input of which is an additional input of the device, and the second input is connected to the second output of the unit for detecting and measuring target coordinates, and a threshold block to whose output is connected to the second input of the selection block.

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