JP2002131423A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of tracking errors which occur due to distance deviations superposed on an observation value caused by the approach speed of a target in the case of using frequency modulation for transmission waves in a radar for detecting and tracking an air target. SOLUTION: In the radar for detecting and tracking an air target through the use of frequency modulation for transmission waves, the approach speed of the target is computed from the amplitude differences among target detection signals after demodulation by a plurality of demodulation reference signals to correct an observation distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar for detecting and tracking an anti-aircraft target.

[0002]

2. Description of the Related Art FIG. 8 shows an operation state of a general conventional radar apparatus. In FIG. 8, reference numeral 1 denotes a target, 2 denotes a radar, and 3 denotes a beam. The beam 3 is periodically emitted to detect and track the target. Here, for the received reflected wave from the target, calculate the target smooth position and velocity using a tracking filter based on the observation value of the target detected by the signal processing device, to obtain the target predicted position, Update using the observation value at the next sampling time. This process is repeated to continue tracking the target.

At this time, when pulse compression is performed on a transmission wave by linear frequency modulation, if the target has a velocity in the distance direction, it is known that the observation distance shifts due to the Doppler effect. Have been. For this reason, when a large modulation is applied or when the target moves at high speed, the deviation of the observation distance may increase.

FIG. 9 is a diagram showing a configuration of a conventional radar device. In FIG. 9, reference numeral 4 denotes an antenna device, 5 denotes a transceiver, 6 denotes a signal detector, and 7 denotes a tracking filter. The operation of the conventional radar device will be described below.

[0005] First, the transmitter / receiver 5 outputs a frequency-modulated transmission waveform to the antenna device 4. Here, FIG.
An example of a transmission wave frequency-modulated to 0 is shown. In FIG. 10, reference numeral 8 denotes a transmission time, which is generally called a transmission pulse width. 9 is the time when the reflected wave from the target is received. Reference numeral 10 denotes a transmission start frequency of the modulated wave, 11 denotes a transmission center frequency, and 12 denotes a transmission end frequency.
Hereinafter, regarding the parameter indicating the transmission waveform of the modulated wave,
The transmission pulse width is represented by Tp, the transmission start frequency is represented by f1, the transmission end frequency is represented by f2, and the transmission center frequency is represented by f0.

[0006] A beam is emitted from the antenna device 4 to the target, and the signal of the received reflected wave is transferred to the transceiver 5, where the received signal is amplified and then output to the signal detector 6. The signal detector 6 performs pulse compression demodulation and detection processing on the modulated target signal, and converts the target observation values of the distance Ro (k), the elevation angle Eo (k), and the azimuth angle Az (k) to a tracking filter 7. Output to Here, after demodulating the frequency-modulated signal by pulse compression, the target observation distance Ro (k) observed at the sampling time k is the Doppler frequency due to the approach speed component DMr (k), which is the target motion data. Under the influence of change, a shift appears. FIG. 11 shows this state, in which 13 is the true position of the target, 14 is a line indicating the distance direction, 15 is the deviation of the observation distance due to the approach speed DMr (k) of the target, and 16 is The observed distance Ro (k). The relationship is as shown in Equation 1.

[0007]

(Equation 1)

Here, Ro (k) is the observed distance, Rt (k) is the true distance of the target, and ΔT is the component of the shift time determined by the constant of the transmitted wave. Further, ΔT is affected by the transmission pulse width Tp, the transmission center frequency f0, the transmission start frequency f1, and the transmission end frequency f2, and has the relationship shown in Expression 2.

[0009]

(Equation 2)

The tracking filter 7 receives the observation of the distance and the angle, and calculates a target predicted position and a target speed at the next sampling time according to Equation 3. This tracking filter 7 is generally called a kalman filter.
Here, a brief description will be given. Note that the observation value is assumed to be three-dimensional, that is, distance, azimuth angle, and elevation angle, but can be implemented in two dimensions, that is, distance and azimuth angle.

[0011]

(Equation 3)

Here, Z _k is an observation value which is an input parameter, and is a 3 × 1 vector including components of distance Ro (k), elevation angle Eo (k) and azimuth angle Az (k). X _{k (+)} is a vector of smoothed values, and X _{k (−)} is a vector of predicted values which are output specifications of the tracking filter. Each is a vector of 6 rows and 1 column including components of distance, elevation angle, azimuth angle, and respective velocities. K _k is a 6-by-6 Kalman gain matrix that serves as a smoothing coefficient, H is a 3-by-6 matrix that converts observed values, and P _{k (+)}
Is a matrix of 6 rows and 6 columns indicating a smooth error covariance, P _{k (-)} is a matrix of 6 rows and 6 columns indicating a prediction error covariance, and Φ _(k) is a matrix of 6 rows and 3 columns indicating transition of prediction time. It is. Q _k is a driving noise constant indicating the instability of the target movement, and is a value set at the start of operation. Γ _{1 (k)} converts this driving noise to 6
This is a matrix with 6 rows and 6 columns. Further, R _k is a 6-by-6 matrix indicating the magnitude of random observation noise by the radar.
This is a constant set at the start of operation. Γ _{2 (k)} is a matrix for converting the observation noise.

[0013] By the operation of the tracking filter, the random error of the observation distance can be suppressed by calculating the smoothed value. However, the tracking filter cannot suppress the distance deviation. The target position and speed are calculated while leaving the error. This process is performed every time an observation value is input, the target predicted position and the smoothing speed are calculated, and tracking is continued.

In the conventional radar apparatus, the observation and tracking of the target are performed in this manner.

[0015]

In the conventional radar apparatus, since the above operation is performed, an accurate distance cannot be observed when tracking a high-speed target while using a frequency modulation signal for a transmission wave.

The present invention has been made to solve such a problem, and calculates a target approach speed based on an amplitude ratio of a target signal demodulated by a plurality of reference signals, thereby obtaining a distance deviation. The shift can be corrected.

[0017]

According to a first aspect of the present invention, there is provided a radar apparatus for transmitting and receiving a beam, a transceiver for inputting and outputting a frequency-modulated transmission / reception signal to and from the antenna apparatus, A parallel demodulation type target signal detector that performs target detection based on the received output signal of the detector and a plurality of demodulation reference signals, and calculates the amplitude of the target signal, and an observation value of a distance and an angle. ,
An approach speed calculator that calculates a target approach speed based on the amplitude of the detected target signal, an observation distance corrector that corrects the observation distance based on the calculated target approach speed, and a target observation angle and corrected observation By providing a tracking filter that performs tracking calculation of the target based on the distance, the approach speed of the target is determined based on the amplitude of the target signal obtained by performing pulse compression demodulation on the received signal using a plurality of reference signals. By calculating and correcting the observation distance, the tracking performance is improved.

According to a second aspect of the present invention, in the radar apparatus according to the first aspect, the clutter determination remover removes unnecessary observation values from the fixed target based on the calculated target approach speed to improve tracking performance. The configuration is as follows.

The radar device according to a third aspect of the present invention is the radar device according to the first aspect, wherein a target speed initial value setting unit sets the target speed as an initial value calculated by a tracking filter to improve tracking performance. .

A radar apparatus according to a fourth aspect of the present invention is the radar apparatus according to the first aspect, wherein the velocity correlation determiner determines an optimum combination at the time of detecting a multi-target based on the target velocity being tracked.
It is configured to improve tracking performance.

According to a fifth aspect of the present invention, in the radar apparatus according to the first aspect, the turning determination is performed based on the approach speed observed by the turning determiner and the filter setting selector, and the Kalman gain matrix of the tracking filter is set. The tracking performance is secured by increasing or decreasing the distance, and the tracking performance is improved.

The radar apparatus according to a sixth aspect of the present invention is the radar apparatus according to the first aspect, wherein the gate correlation type tracking filter performs a correlation process between the wake and the observed value based on the information on the position and the approach speed to detect a multi-target. The tracking performance is improved.

According to a seventh aspect of the present invention, in the radar apparatus according to the first aspect, the turning value determiner, the filter setting selector, and the multiple motion model tracking filter use the tracking filter based on the prediction method of the multiple motion model to obtain the observation value. And a motion model are subjected to a correlation process based on information on the position and the approach speed, so as to improve the tracking performance for the turning target.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing Embodiment 1 of the present invention. In FIG. 1, reference numeral 4 denotes an antenna device, 5 is a transceiver, 19 is a parallel demodulation type target signal detector, 20 is an approach speed calculator, and 21 is an approach speed calculator. The observation distance corrector 7 is a tracking filter.

The operation principle of the radar device configured as described above will be described with reference to FIG. First, in the transceiver 5,
The frequency-modulated transmission waveform is output to the antenna device 4. Here, regarding the parameters indicating the transmission waveform of the modulated wave, the transmission pulse width is represented by Tp, the transmission center frequency is represented by f0, the transmission start frequency is represented by f1, and the transmission end frequency is represented by f2.

The antenna device 4 radiates this transmission wave into space and receives a reflected wave from a target. The transceiver 5 amplifies the received signal and outputs it to the parallel demodulation type target signal detector 19. The parallel demodulation type target signal detector 19 demodulates and detects a target by using a plurality of demodulation reference signals, observes a target distance Ron (k), an elevation angle Eon (k), and an azimuth angle Azon (k). The amplitude Aon (n) (k) detected by the demodulation reference signal of
Output to Here, (n) indicates the n-th demodulation reference signal. However, the observation distance Ron (k) at this stage is a distance shifted due to the influence of the approach speed of the target.

The characteristics of the reference signal for demodulation in the parallel demodulation type target signal detector 19 indicate the frequency and delay time with respect to the received signal. When linear frequency modulation is performed on the transmission wave, the signal In demodulation, a time-varying delay is performed for each frequency of the received wave, and the delay is added. If the target reflected wave has no frequency shift due to Doppler, the reference signal for demodulation is the same frequency band as the modulation signal for transmission, that is, the demodulation center frequency is f0, the demodulation start frequency is f1, and the demodulation start frequency is f1. If the end frequency is f2, it is possible to perform demodulation without waste, and it is known that the amplitude of the signal detected in that case is proportional to Equation 4.

[0028]

(Equation 4)

When the received signal is shifted with respect to the transmission frequency due to the target approach speed, the frequency of the demodulation reference signal is shifted by the Doppler fD based on the target approach speed. FIG. 12 shows this state. The received signal 17 without the influence of the target Doppler can be demodulated between the frequencies f1 and f2. At 18, the frequency f1 is changed to f2
, The received signal deviates from the range described above, and the amplitude of the received signal decreases as shown in Expression 5.

[0030]

(Equation 5)

In the present invention, utilizing this property, after a received signal at a certain time is demodulated by a plurality of demodulation reference signals, a target signal is detected, and a target signal is detected by the demodulation reference signal having the maximum amplitude. It aims to calculate the approach speed.

FIG. 13 shows an example of the processing in the parallel demodulation type target signal detector 19, and shows the execution of demodulation using a plurality of demodulation reference signals and detection of the target signal. The demodulation reference signal is obtained by setting a demodulation center frequency in consideration of a target Doppler, and parallel processing is performed using n demodulation reference signals having different settings. Here, it is determined that the reference signal used for demodulation of the target signal having the largest amplitude of the detection target matches the approach speed of the detection target, and the target observation value is output. The approach speed calculator 20 calculates the approach speed DMr (k) of the detection target from the ratio of the plurality of detected amplitudes using the demodulation reference signal at the maximum amplitude.

The observation distance corrector 21 calculates an observation value R (k) corrected from the approach speed DMr (k) of the detection target and the distance observation value Ro (k) of the target in accordance with Equation (6).

[0034]

(Equation 6)

The corrected observation value is output to the tracking filter 7, and the tracking filter is calculated in accordance with the equation (3). This process is performed every time an observation value is input, the target predicted position and the smoothing speed are calculated, and tracking is continued.

According to the present invention, in a radar that modulates the frequency of a transmission wave, even if a deviation of a distance observation value greatly occurs with respect to a target moving at a high speed, the correction of the observation distance is performed before the input of the tracking filter. This has the effect of improving the tracking accuracy.

Embodiment 2 FIG. 2 is a block diagram showing Embodiment 2 of the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals, and the description of the same reference numerals is omitted. In FIG. 2, reference numeral 22 denotes a clutter judgment remover.

The principle of operation of the radar device constructed as described above will be described with reference to FIG. First, in the transceiver 5,
The frequency-modulated transmission waveform is output to the antenna device 4. Here, regarding the parameters indicating the transmission waveform of the modulated wave, the transmission pulse width is Tp, the transmission center frequency is f0, the transmission start frequency is f1, and the transmission end frequency is f2.

The antenna device 4 radiates this transmission wave into space and receives a reflected wave from a target. The transceiver 5 amplifies the received signal and outputs it to the parallel demodulation type target signal detector 19. The parallel demodulation type target signal detector 19 demodulates and detects a target by using a plurality of demodulation reference signals, observes a target distance Ron (k), an elevation angle Eon (k), and an azimuth angle Azon (k). The amplitude Aon (n) (k) detected by the demodulation reference signal of
Output to Here, (n) indicates the n-th demodulation reference signal. However, the observation distance Ron (k) at this stage is a distance shifted due to the influence of the approach speed of the target.

The approach speed calculator 20 calculates the approach speed DMr (k) of the detection target from the ratio of the plurality of detected amplitudes using the demodulation reference signal at the maximum amplitude. The clutter determination and elimination unit 22 removes an observation value that is determined as clutter due to a reflected wave from a fixed target, such as a mountain or a building, for which the calculated approach speed is slower than the tracking target for the detection target, and performs observation. Output to the distance corrector 21.

The observation distance corrector 21 calculates an observation value corrected according to Equation 6 from the observation value of the approach speed DMr (k) of the detection target and the target distance. The corrected observation value is output to the tracking filter 7, and the tracking filter is calculated according to Equation 3. This process is performed every time an observation value is input, the target predicted position and the smoothing speed are calculated, and tracking is continued.

According to the present invention, in a radar that modulates the frequency of a transmission wave, when a deviation of a distance observation value greatly occurs with respect to a target moving at a high speed, detection of a plurality of targets including clutter can be performed. Even if it occurs, the correction is performed before inputting to the tracking processing, and the observation value by the clutter is deleted, so that the tracking accuracy is improved.

Embodiment 3 FIG. 3 is a block diagram showing Embodiment 4 of the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals, and the description of the same reference numerals is omitted.

The operation principle of the radar device configured as described above will be described with reference to FIG. First, in the transceiver 5,
The frequency-modulated transmission waveform is output to the antenna device 4. Here, regarding the parameters indicating the transmission waveform of the modulated wave, the transmission pulse width is Tp, the transmission center frequency is f0, the transmission start frequency is f1, and the transmission end frequency is f2.

The antenna device 4 radiates this transmission wave into space and receives a reflected wave from a target. The transceiver 5 amplifies the received signal and outputs it to the parallel demodulation type target signal detector 19. The parallel demodulation type target signal detector 19 performs demodulation and detection of the target using a plurality of demodulation reference signals, and detects a target distance Ron (k), an elevation angle Eon (k), and a target distance detected by the demodulation reference signal having the maximum amplitude. Azimuth angle Az
On (k) is set as an observation value, and the amplitude Aon (n) (k) is further observed and output to the approach speed calculator 20. Here, (n) indicates the n-th demodulation reference signal. However, the observation distance Ron (k) at this stage is a distance shifted due to the influence of the approach speed of the target.

The approach speed calculator 20 calculates the approach speed DMr (k) of the detection target from the ratio of the plurality of detected amplitudes using the demodulation reference signal at the maximum amplitude. The clutter determination and elimination unit 22 removes an observation value that is determined as clutter due to a reflected wave from a fixed target, such as a mountain or a building, for which the calculated approach speed is slower than the tracking target for the detection target, and performs observation. Output to the distance corrector 21.

The observation distance corrector 21 calculates an observation value corrected according to the equation 6 from the approach speed DMr (k) of the detection target and the target distance observation value. The corrected observation value and the calculated approach speed are output to the tracking filter 7, and the tracking filter is calculated according to Equation 3. At this time, the approach speed is set according to Equation 7 as an initial value of the speed in the distance direction.

[0048]

(Equation 7)

This process is performed every time an observation value is input.
The target predicted position and the smoothing speed are calculated, and the tracking is continued.

According to the present invention, in a radar that modulates the frequency of a transmission wave, when the deviation of a distance observation value is large with respect to a target moving at high speed, the calculation of the target speed becomes unstable. Even if it is easy, the observation distance is corrected before inputting to the tracking processing, and the speed specifications calculated by the tracking filter are stabilized, so that there is an effect of improving the tracking accuracy.

Embodiment 4 FIG. FIG. 4 is a block diagram showing Embodiment 4 of the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals, and the description of the same reference numerals is omitted. In FIG. 4, reference numeral 23 denotes a speed correlation determiner.

The operation principle of the radar device configured as described above will be described with reference to FIG. First, in the transceiver 5,
The frequency-modulated transmission waveform is output to the antenna device 4. Here, regarding the parameters indicating the transmission waveform of the modulated wave, the transmission pulse width is Tp, the transmission center frequency is f0, the transmission start frequency is f1, and the transmission end frequency is f2.

The antenna device 4 radiates this transmission wave into space and receives a reflected wave from the target. The transceiver 5 amplifies the received signal and outputs it to the parallel demodulation type target signal detector 19. The parallel demodulation type target signal detector 19 performs demodulation and detection of the target using a plurality of demodulation reference signals, and detects a target distance Ron (k), an elevation angle Eon (k), and a target distance detected by the demodulation reference signal having the maximum amplitude. Azimuth angle Az
On (k) is set as an observation value, and the amplitude Aon (n) (k) is further observed and output to the approach speed calculator 20. Here, (n) indicates the n-th demodulation reference signal. However, the observation distance Ron (k) at this stage is a distance shifted due to the influence of the approach speed of the target. Further, it is possible to cope with a case where detection of multiple targets occurs instead of detection of one target.

The approach speed calculator 20 calculates the approach speed DMr (k) of the detection target by the demodulation reference signal at the maximum amplitude from the ratio of the detected amplitudes. The speed correlation determiner 23 compares the observed values of the multiple targets with the target speeds calculated at the previous sampling time calculated by the tracking filter 7 based on the target speeds, and calculates the observed values having a small speed difference.
Adopted as the observation value from the tracking target, the observation distance corrector 2
Output to 1. The observation distance corrector 21 calculates an observation value corrected from the target observation value of the approach speed DMr (k) and the distance of the detection target in accordance with Equation (6).

The corrected observation value is output to the tracking filter 7, and the tracking filter is calculated in accordance with the equation (3). This process is performed every time an observation value is input, the target predicted position and the smoothing speed are calculated, and tracking is continued.

According to the present invention, in a radar that modulates the frequency of a transmission wave, when a deviation of a distance observation value is large with respect to a target moving at a high speed, and when a plurality of targets are detected. However, since the correction is performed before inputting to the tracking processing, and the observation value corresponding to the target speed being tracked is selected from the plurality of observation values by the correlation processing, there is an effect of improving the tracking accuracy.

Embodiment 5 FIG. 5 is a block diagram showing Embodiment 5 of the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals, and the description of the same reference numerals is omitted. In FIG. 5, reference numeral 24 denotes a turning determiner, and reference numeral 25 denotes a filter gain selector.

The operation principle of the radar device configured as described above will be described with reference to FIG. First, in the transceiver 5,
The frequency-modulated transmission waveform is output to the antenna device 4. Here, regarding the parameters indicating the transmission waveform of the modulated wave, the transmission pulse width is Tp, the transmission center frequency is f0, the transmission start frequency is f1, and the transmission end frequency is f2.

The antenna device 4 radiates this transmission wave into space and receives a reflected wave from the target. The transceiver 5 amplifies the received signal and outputs it to the parallel demodulation type target signal detector 19. The parallel demodulation type target signal detector 19 performs demodulation and detection of the target using a plurality of demodulation reference signals, and detects a target distance Ron (k), an elevation angle Eon (k), and a target distance detected by the demodulation reference signal having the maximum amplitude. Azimuth angle Az
On (k) is set as an observation value, and the amplitude Aon (n) (k) is further observed and output to the approach speed calculator 20. Here, (n) indicates the n-th demodulation reference signal. However, the observation distance Ron (k) at this stage is a distance shifted due to the influence of the approach speed of the target.

The approach speed calculator 20 calculates the approach speed DMr (k) of the detection target by the demodulation reference signal at the maximum amplitude from the ratio of the detected amplitudes. Turning detector 24
Then, the target approach speed calculated by the tracking filter at the previous sampling time is compared with the approach speed calculated from the observation value.If the difference is small, it is determined that the vehicle is moving at a constant velocity. It is determined that the target is turning. If it is determined that the target is turning, the result is output to the filter gain selector 25.
The filter gain selector 25 appropriately changes the set value of the drive noise parameter Qk of the tracking filter 7 in accordance with the situation during the target turning and the straight traveling.

The observation distance corrector 21 calculates an observation value corrected from the observation values of the approaching speed DMr (k) and the distance of the detection target in accordance with Equation (6). This corrected observation and 2
The approach speed calculated from the two observation values is output to the tracking filter 7, and after setting the approach speed as the initial value of the speed in the distance direction, the tracking filter is calculated according to Equation 3.

During the target turning, the change in the setting of the drive noise increases the filter gain of the tracking filter, thereby automatically improving the tracking performance. This process is performed every time an observation value is input, the target predicted position and the smoothing speed are calculated, and tracking is continued.

According to the present invention, in a radar that modulates the frequency of a transmission wave, even when a deviation of a distance observation value is large with respect to a target moving at a high speed, and when the target performs a turning motion. Since the observation distance is corrected before inputting to the tracking processing, and the tracking filter gain can be selected from the determination result of the turning motion of the target, it is possible to ensure the tracking performance and improve the tracking accuracy. .

Embodiment 6 FIG. FIG. 6 is a block diagram showing Embodiment 6 of the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals, and the description of the same reference numerals is omitted. In FIG. 6, reference numeral 26 denotes a gate correlation type tracking filter.

The operation principle of the radar device configured as described above will be described with reference to FIG. First, in the transceiver 5,
The frequency-modulated transmission waveform is output to the antenna device 4. Here, regarding the parameters indicating the transmission waveform of the modulated wave, the transmission pulse width is Tp, the transmission center frequency is f0, the transmission start frequency is f1, and the transmission end frequency is f2.

The antenna device 4 radiates this transmission wave into space and receives a reflected wave from the target. The transceiver 5 amplifies the received signal and outputs it to the parallel demodulation type target signal detector 19. The parallel demodulation type target signal detector 19 performs demodulation and detection of the target using a plurality of demodulation reference signals, and detects a target distance Ron (k), an elevation angle Eon (k), and a target distance detected by the demodulation reference signal having the maximum amplitude. Azimuth angle Az
On (k) is set as an observation value, and the amplitude Aon (n) (k) is further observed and output to the approach speed calculator 20. Here, (n) indicates the n-th demodulation reference signal. However, the observation distance Ron (k) at this stage is a distance shifted due to the influence of the approach speed of the target. Further, it is possible to cope with a case where detection of multiple targets occurs instead of detection of one target.

The approach speed calculator 20 calculates the approach speed DMr (k) of the detection target from the ratio of the detected amplitudes using the demodulation reference signal at the maximum amplitude. The observation distance corrector 21 calculates an observation value corrected from the target observation value of the approach speed DMr (k) of the detection target and the distance in accordance with Equation 6, and outputs the result to the gate correlation type tracking filter 26. The corrected observation value is output to the gate correlation type tracking filter 26, and a tracking filter calculation is performed according to Equation 8, and the position and approach speed of a plurality of input observation values are determined based on the predicted tracking position and the smoothing speed. Then, an observation value considered to be a target to be tracked is selected and input to the tracking filter 7.

[0068]

(Equation 8)

Here, Z _k is an observation value which is an input parameter, and is a 3 × 1 vector including components of the distance Ro (k), the elevation angle Eo (k), and the azimuth angle Az (k). Also, Sk is a matrix of 3 rows and 3 columns indicating the range of the correlation gate, Pd is the set value of the detection probability, βk, i is the reliability of the observation value calculated by the correlation process, and mk is input. Number of observations.

Further, DMr (k), i is an approach speed component for each observation value, DMrp is a predicted approach speed value, and σDMr is an approach speed observation accuracy. In the formula, g (A; B, C) denotes a probability density function based on a normal distribution, with the predicted value B as the center and the existence range of the observed value as the standard deviation C.
Means that the probability density of the observed value A is obtained. The term of the correlation between the observed position and the predicted position shows the probability density function by the normal distribution of the distance, the elevation angle, and the azimuth angle in the three-dimensional space, and the term of the approach speed shows the probability density function by the one-dimensional normal distribution. ing. With this correlation gate, a plurality of input observation values are weighted according to the probability density and integrated to perform tracking filter calculation. Further, X _{k (+)} is a vector of smoothed values, and X _{k (−)} is a vector of predicted values which are output specifications of the tracking filter. Each is a vector of 6 rows and 1 column including components of distance, elevation angle, azimuth angle, and respective velocities. K _k is a 6-row, 3-column Kalman gain matrix serving as a smoothing coefficient, H is a 3-row, 6-column matrix for converting observation values, and P _{k (+)} is a 6-row, 6-column indicating a smoothed error covariance.
A matrix of columns, P _{k (−)} is a 6-row, 6-column matrix indicating the prediction error covariance, and Φ _(k) is a 6-row, 3-column matrix indicating transition of prediction time. Q _k is a driving noise constant indicating the instability of the target movement, and is a value set in advance. Γ _{1 (k)} is a 6 _× 6 matrix for converting the driving noise. Further, R _k indicates the magnitude of random observation noise by the radar.
This is a matrix of columns, which is a constant set in advance. Γ _{2 (k)}
Is a matrix that converts this observation noise.

This process is performed every time an observation value is input.
The target predicted position and the smoothing speed are calculated, and the tracking is continued.

According to the present invention, in a radar that modulates the frequency of a transmission wave, when a deviation of a distance observation value is large with respect to a target moving at a high speed, and when a plurality of targets are detected. However, it has the effect of improving the tracking accuracy by correcting the observation distance before inputting to the tracking process and selecting the observation value that matches the target predicted position and speed during tracking from among multiple observation values .

Embodiment 7 FIG. 7 is a block diagram showing Embodiment 7 of the present invention. In the figure, the same or corresponding parts as in the first embodiment are denoted by the same reference numerals, and the description of the same reference numerals is omitted. In FIG. 7, reference numeral 24 denotes a turning determiner, 27 denotes a multiple motion model type tracking filter, and 28 denotes a motion model setting selector.

The operation principle of the radar device configured as described above will be described with reference to FIG. First, in the transceiver 5,
The frequency-modulated transmission waveform is output to the antenna device 4. Here, regarding the parameters indicating the transmission waveform of the modulated wave, the transmission pulse width is Tp, the transmission center frequency is f0, the transmission start frequency is f1, and the transmission end frequency is f2.

The antenna device 4 radiates this transmission wave into space and receives a reflected wave from the target. The transceiver 5 amplifies the received signal and outputs it to the parallel demodulation type target signal detector 19. The parallel demodulation type target signal detector 19 performs demodulation and detection of the target using a plurality of demodulation reference signals, and detects a target distance Ron (k), an elevation angle Eon (k), and a target distance detected by the demodulation reference signal having the maximum amplitude. Azimuth angle Az
On (k) is set as an observation value, and the amplitude Aon (n) (k) is further observed and output to the approach speed calculator 20. Here, (n) indicates the n-th demodulation reference signal. However, the observation distance Ron (k) at this stage is a distance shifted due to the influence of the approach speed of the target. Further, it is possible to cope with a case where detection of multiple targets occurs instead of detection of one target.

The approach speed calculator 20 calculates the approach speed DMr (k) of the detection target from the ratio of the detected amplitudes by using the demodulation reference signal at the maximum amplitude. Turning detector 24
Then, the target approach speed calculated by the tracking filter at the previous sampling time is compared with the approach speed calculated based on the observed value, and based on the difference, it is determined whether the target is turning, and the determination result is determined by the motion. Output to the model setting selector 28.

The motion model setting selector 28 appropriately changes the set values of the multiple motion model parameters of the multiple motion model type tracking filter 27 according to the situation during the target turning and the straight traveling. The observation distance corrector 21 calculates an observation value corrected from the target observation value of the approach speed DMr (k) and the distance of the detection target in accordance with Equation (6). The corrected observation value and the observed approach speed are used as the multiple motion model type tracking filter 27.
The tracking filter calculation of the multiple motion model is performed according to Equation 9.

[0078]

(Equation 9)

Here, Z _k is an observation value which is an input parameter, and is a 3 × 1 vector including components of the distance Ro (k), the elevation angle Eo (k), and the azimuth angle Az (k). In addition, in this multiple motion model type tracking filter, prediction accuracy is improved by assuming a plurality of motion models such as “the target is going straight” or “1G turning” and taking into account the calculation of the predicted position. Let me.

Here, Sk is a matrix of 3 rows and 3 columns indicating the range of the motion model correlation gate, and is a constant acceleration vector in each motion model of Uk, n, and a conversion matrix of a constant acceleration vector of Γ _(k) motion model. It is. DMr, n (k) is the predicted approach speed for each motion model, DMr (k) is the observed approach speed, σ
DMr is the observation accuracy of the approach speed, Βkp is the reliability of the motion model calculated by correlation processing of the motion model, and n is the number of motion models.

In the equation, g (A; B, C) represents a probability density function based on a normal distribution, and the predicted value B of each motion model is centered, and the existence range of the predicted value Means the probability density of the observed value A with the standard deviation C. As a result, the reliability of the motion model is obtained. By this correlation gate, the prediction values calculated by a plurality of motion models are weighted according to the probability density and integrated,
Perform tracking filter calculation.

Further, X _{k (+)} is a vector of smoothed values, and X _{k (−)} is a vector of predicted values which are output specifications of the tracking filter. Each is a vector of 6 rows and 1 column including components of distance, elevation angle, azimuth angle, and respective velocities. K
_k is a 6-by-3 Kalman gain matrix that serves as a smoothing coefficient,
H is a matrix of 3 rows and 6 columns for converting observation values, P _{k (+)} is a matrix of 6 rows and 6 columns indicating a smooth error covariance, and P _{k (-)} is a 6 row and 6 column of prediction error covariance. The matrix, Φ _(k), is a 6-row, 3-column matrix indicating transition of prediction time. Q _k is a driving noise constant indicating the instability of the target movement, and is a value set in advance. Γ _{1 (k)} is a 6 _× 6 matrix for converting the driving noise. Further, R _k is a matrix of 6 rows and 6 columns indicating the magnitude of random observation noise by the radar, and is a constant set in advance. Γ _{2 (k)} is a matrix for converting the observation noise.

During the target turning, since the position predicted by the multiple motion model is set in accordance with the target motion, the prediction accuracy is automatically improved. This process is performed every time an observation value is input, the target predicted position and the smoothing speed are calculated, and tracking is continued.

According to the present invention, in a radar that modulates the frequency of a transmission wave, even when a deviation in a distance observation value is large with respect to a target moving at a high speed, and when the target performs a turning motion. The correction of the observation distance is performed before inputting to the tracking processing, and the tracking filter prediction method suitable for the target motion can be selected from the determination result of the target turning motion. The suppressed predicted position can be calculated, which has the effect of improving tracking accuracy.

[0085]

According to the first invention, there is an effect that tracking accuracy is improved by performing distance correction.

According to the second aspect of the invention, there is an effect that the distance correction is performed and the tracking accuracy is improved because the observation value by the clutter is deleted.

According to the third aspect of the invention, since the distance is corrected and the speed data calculated by the tracking filter is stabilized, the tracking accuracy is improved.

According to the fourth aspect of the invention, since the distance is corrected and an observation value corresponding to the velocity during tracking is selected by the correlation processing, there is an effect of improving the tracking accuracy.

According to the fifth aspect, since the distance correction is performed and the tracking filter gain can be selected based on the result of the determination of the target turning motion, it is possible to ensure the following performance.
This has the effect of improving tracking accuracy.

According to the sixth aspect of the invention, there is an effect that the distance correction is performed and the tracking accuracy is improved because an observation value suitable for the target predicted position and the velocity during tracking is selected.

According to the seventh aspect, since the distance correction is performed and the tracking filter prediction method suitable for the target motion can be selected from the determination result of the target turning motion, the error due to the distance shift correction and the target turning can be selected. It is possible to calculate a predicted position in which tracking is suppressed, and there is an effect of improving tracking accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a seventh embodiment of the present invention.

FIG. 8 is a diagram illustrating an operation state of a general radar.

FIG. 9 is a block diagram according to the related art.

FIG. 10 is a diagram showing a transmission waveform subjected to frequency modulation.

FIG. 11 is a diagram illustrating a state of observation of a distance in a single frequency band.

FIG. 12 is a diagram illustrating a received signal changed by a target Doppler.

FIG. 13 is a diagram showing processing of a multiple demodulation type target signal detector.

[Explanation of symbols]

1 target, 2 radars, 3 beams, 4 antennas, 5 transceivers, 6 signal detectors, 7 tracking filters,
8 transmission time, 9 reception time, 10 transmission start frequency,
11 transmission end frequency, 12 transmission center frequency, 13
Target position, 14 distance direction, 15 distance shift, 16 observation distance, 17 received signal without target Doppler, 18
Received signal affected by target Doppler, 19 parallel demodulation type target signal detector, 20 approach speed calculator, 21 observation distance corrector, 22 clutter judgment remover, 23 speed correlation determiner, 24 turning determiner, 25 filter Gain selector, 26 gate correlation type tracking filter, 27 multiple motion model type tracking filter, 28 motion model setting selector.

Claims (7)

[Claims] An antenna device for transmitting and receiving a beam to and from an air target such as an aircraft when detecting and tracking the target, and a transceiver for inputting and outputting a frequency modulated transmission / reception signal to the antenna device A parallel demodulation-type target signal detector for performing target detection based on a reception output signal of the transceiver and a plurality of demodulation reference signals and calculating an amplitude of the target signal, and an observation value of a distance and an angle; For each signal, an approach speed calculator that calculates the target approach speed based on the amplitude of the detected target signal, and an observation distance corrector that corrects the observation distance with the calculated target approach speed,
A radar apparatus comprising: a tracking filter for performing tracking calculation of a target based on a target observation angle and a corrected observation distance. 2. The radar apparatus according to claim 1, further comprising a clutter determination and removal unit that determines and removes an observation value from an unnecessary fixed target based on the calculated target approach speed. 3. The radar apparatus according to claim 1, further comprising a target speed initial value setting device for setting a speed initial value in a tracking filter calculation based on the calculated target approach speed. 4. The radar apparatus according to claim 1, further comprising a speed correlation determiner that determines whether the combination of the observed values is a tracking target based on the calculated target approach speed. 5. A change in the calculated target approach speed,
2. The apparatus according to claim 1, further comprising a turning determiner for determining whether the target being tracked has turned, and a filter setting selector for changing a gain setting of the tracking filter when the target is determined to be turning. The described radar device. 6. The radar apparatus according to claim 1, further comprising a gate correlation type tracking filter for inputting observation angles for a plurality of targets and a corrected observation distance, and performing wake correlation processing and tracking calculation. . 7. A change in the calculated target approach speed,
A turning determiner that determines whether the target being tracked has turned, and a filter setting selector that changes the setting of the multiple motion model of the tracking filter when the target is determined to be turning,
2. The radar apparatus according to claim 1, further comprising a tracking filter that performs tracking calculation of the target by a prediction method of a multiple motion model based on the target observation angle and the corrected observation distance.