JP3394465B2 - Signal processing method and device - Google Patents

Description

Detailed Description of the Invention

The present invention relates to a signal processing method and apparatus for removing a clutter and detecting a target in radar signal processing.

TECHNICAL FIELD OF THE INVENTION

[0002]

2. Description of the Related Art Conventionally, in radar signal processing, a CFAR (Constant False Alarm Ra) is performed in a distance (range) direction.
te) processing was performed to remove the clutter and detect the target. FIG. 16 is a block diagram of a signal processing device that performs such an operation. In FIG. 16, 1 is a moving target detection (Moving
Target indicator; hereinafter referred to as MTI) Fixed clutter removing device that removes unnecessary signals (clutter) reflected from an object that does not move by processing, 2-1 to 2-n are fixed clutter removing devices with filters centered on different frequencies. Doppler filter for separating the output signal of No. 1 into each frequency component, 3-1 to 3-n is a clutter removing device for removing clutter having a spread in the range direction from the signals of each Doppler filter 2-1 to 2-n, 4 is a maximum value selection device that selects and outputs a frequency component signal having the maximum amplitude when there are a plurality of signals in the same range from the signals detected by the clutter removal devices 3-1 to 3-n.
Reference numeral 13 denotes a target detection device that detects the target by setting a threshold value for the input signal and outputs position information of the target. In the following, when the individual operations of the Doppler filters 2-1 to 2-n and the clutter removing devices 3-1 to 3-n are described, they are simply referred to as the Doppler filter 2 and the clutter removing device 3. .

The clutter removing device 3 generally includes LogCFAR and CA-CFAR. FIG. 17
Is a block diagram in the case where the clutter removing device 3 is configured by LogCFAR. 5 is a logarithmic amplifying device for converting an input signal into a logarithm, 6-1 and 6-2 are delay devices for delaying the input signal, and 7 is an attention. A signal extraction device for extracting the signal of the selected portion, 8 is an average calculation device for calculating the average of the right N range bin and the left N range bin of the range bin of interest, 9
Is an arithmetic unit that subtracts the average value of the two N range bins from the value of the range bin of interest, and 10 is an antilogarithmic amplifier that calculates the antilogarithm of the input signal.

Next, the operation of the signal processing apparatus having the above configuration will be described. The received signal is input to the fixed clutter removing device 1, and the fixed clutter is removed by MTI processing. The signals from which the fixed clutter has been removed are Doppler filters 2-1 and 2-2 centered on different frequencies.
Each frequency component is separated by -n and input to the clutter removing devices 3-1 to 3-n. The clutter removing device 3 converts the signal for each frequency into a logarithm by the logarithmic amplifying device 5, and then extracts the values of the right N range bin and the left N range bin of the focused range bin by the delay devices 6-1 and 6-2. Then, the signal extraction device 7 extracts the value of the range bin of interest and sends it to the arithmetic device 9. Further, the average calculation device 8 calculates the average of the two input N range bins and sends it to the calculation device 9.
The arithmetic unit 9 performs a process of subtracting the average value of the N range bins from the value of the noted range bin. The result obtained by this subtraction is converted into antilogarithm by the antilogarithmic amplifier 10, and is output as a signal from which clutter has been removed. The signals from which the clutter has been removed by the clutter removing devices 3-1 to 3-n are processed by the maximum value selecting device 4 as follows.
The signals in the same range bin are compared with each other, and when there are a plurality of signals in the same range bin, the output from the frequency filter (Doppler filter) having the maximum amplitude is selected and output. This output is then sent to the target detection device 13, and those exceeding the threshold are detected as targets.

[0005]

However, although the above-mentioned conventional signal processing apparatus can remove the clutter that spreads in the range direction to some extent, since the CFAR processing is performed, the clutter that spreads in the range direction is small. Could not be removed. Further, in the conventional device, when two or more targets are detected in the same range bin,
Since the target having the largest amplitude is determined to be the target, if there are two or more targets, the targets cannot be detected separately. As a method of removing the clutter having a small spread in the range direction, it is conceivable to perform the clutter process using the cross CFAR in consideration of both the continuity in the range direction and the continuity in the Doppler direction. Not only is it complicated, but so is the hardware.

The present invention has been made in view of the conventional problems, and eliminates clutter having a small spread in the range direction by using clutter without requiring complicated equipment configuration and performing complicated processing. An object is to provide a signal processing device that reduces the false alarm rate.

[0007]

According to the signal processing method of the present invention, the input signal is separated into frequency components centered at different frequencies by a plurality of Doppler filters, and then the signal of interest is detected. Calculate the ratio of the amplitude and the amplitude of the signal separated by the Doppler filter adjacent to the Doppler filter separating the signal, and if the ratio is smaller than the preset threshold, the signal of interest as clutter. The feature is that it is removed.

According to a second aspect of the present invention, there is provided a signal processing device for measuring the amplitude of a signal from each Doppler filter, and the signal of the Doppler filter adjacent to the Doppler filter separating the signal of interest and the signal. Is calculated, and if the ratio is smaller than a preset threshold value, it is provided with an adjacent Doppler / amplitude calculation means for removing the signal of interest as clutter, and the clutter is extracted from the input signal. It removes and detects a target.

A signal processing apparatus according to a third aspect of the present invention compares signals output from adjacent Doppler / amplitude calculation means within the same range bin, outputs signals in discontinuous Doppler bins as signals from different targets, and outputs continuous signals. The output data control means for outputting the signal in the Doppler bin as a signal from the same target is provided.

According to a fourth aspect of the signal processing apparatus of the present invention, the amplitude ratio is calculated only for the signals of the adjacent Doppler filters whose amplitude is equal to or larger than a predetermined threshold value.

According to a fifth aspect of the present invention, there is provided a signal processing device, wherein buffer means for storing the amplitude value output from each amplitude measuring means is provided, and the amplitude value of the signal of interest and the signal stored in the buffer means. In the signal of the Doppler filter adjacent to the separated Doppler filter, the ratio of the amplitude value of the signal of the range bin of the signal and the adjacent range bin is calculated, and when the ratio is smaller than the preset threshold value, The signal of interest is removed as clutter.

According to a sixth aspect of the present invention, there is provided a signal processing device which measures an amplitude of a signal, an integral calculating means for integrating the signal, an integral value of the signal from the integral calculating means and the amplitude measuring means. It is provided with a comparison operation means for comparing the amplitude value of the signal from the above, and the target and the clutter are discriminated based on the comparison result.

According to a seventh aspect of the present invention, there is provided a signal processing apparatus, wherein the range width measuring means for measuring the spread of the signal in the range direction and the comparison calculating means for comparing the range width measured by the range width measuring means with a predetermined threshold value. And, when the range width is larger than the threshold value, the signal is removed as clutter.

According to another aspect of the signal processor of the present invention, the amplitude measuring means for measuring the amplitude of the signal, the range width measuring means for measuring the spread of the signal in the range direction, and the range measured by the range width judging means. A comparison operation means for comparing a product of the width and the amplitude value of the signal from the amplitude measuring means with a predetermined threshold value, and if the product is larger than the threshold value, the signal is removed as clutter. It was done.

In the signal processing method according to the ninth aspect, when a target is detected, the resolution of the Doppler filter separating the target is increased and the clutter removal process is performed again for the input signal. It is characterized by

According to a tenth aspect of the present invention, there is provided a signal processing device comprising a buffer device for storing the signal from the fixed clutter removing means and a data control device for controlling the resolution of the Doppler filter. The resolution of the Doppler filter through which the target passes is increased, and the signal from the buffer device is input to the Doppler filter whose resolution is increased to perform the clutter removal processing again.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. FIG. 1 is a block diagram showing a signal processing method and an apparatus therefor according to Embodiment 1 of the present invention. This signal processing apparatus uses an adjacent Doppler / amplitude arithmetic unit 12 between adjacent Doppler bins. By determining the amplitude ratio of the signal, it is determined whether the received signal is the target or the clutter. In FIG. 1, reference numeral 1 denotes MTI processing on a received signal,
Fixed clutter removing device for removing fixed clutter 2-1
2 to 2-n are Doppler filters for separating the signals from which the fixed clutter has been removed by the fixed clutter removing device 1 into frequency components by filters centering on different frequencies, and 3-1 to 3-n are Doppler filters. 2-1
2-n is a clutter removing device for removing clutter having a spread in the range direction for each frequency separated signal, 11-1 to 11-n are for the signals from which the clutter is removed. An amplitude measuring device which sets a threshold value, gives the amplitude value to a range bin having an amplitude equal to or larger than the threshold value, and gives information (for example, an amplitude value 0) that the threshold value is not exceeded to the range bin that does not exceed the threshold value. ,
For each range bin, 12 obtains the ratio between the amplitude value of the signal of an arbitrary Doppler bin whose amplitude is measured and the amplitude value of the signal of the adjacent Doppler bin, and compares the value of the above ratio with a preset threshold value. If the ratio of the amplitude values is smaller, it is judged as clutter and the amplitude value of the signal is output as 0. If the ratio of the amplitude values is equal to or more than the threshold value, the signal is judged as the target. The adjacent Doppler / amplitude calculation device 21 which outputs the amplitude value as it is, 21 outputs the target data by comparing the output signals from the adjacent Doppler / amplitude calculation device 12 for each same range bin, and outputs two target values in the same range bin. If there is the above, the data control device that outputs the number-of-machines information and target data, 13 determines from the transmitted signal that there is a target at a place having amplitude, and outputs the position information of the target. It is a target detection apparatus. The structure of the clutter removing device 3 is the same as that of the conventional CF shown in FIG.
It is similar to the device that performs AR.

Next, the operation will be described. First, the received signal is input to the fixed clutter removing device 1, and MT
The fixed clutter is removed by the l treatment. This signal is sent to the Doppler filters 2-1 to 2-n and becomes a signal separated for each frequency. The signals separated for each frequency are subjected to CFAR processing by clutter removing devices 3-1 to 3-n, respectively, to remove clutter having a continuous spread in the range direction. The content of this CFAR process is the same as that of the conventional example. Clutter removal device 3-1
The signals from which clutter having a continuous spread in the range direction has been removed by 3 to 3-n are amplitude measurement devices 11-1 respectively.
11-n, as shown in FIG. 2, if the amplitude of the signal does not exceed a preset threshold value, it is output as no amplitude, and if it exceeds the threshold value, the amplitude is output. The value is output.

In the adjacent Doppler / amplitude calculation device 12, as shown in FIG. 3, for each signal output from the amplitude measuring devices 11-1 to 11-n separated for each frequency, within the same range bin, The ratio between the amplitude of the signal whose amplitude is measured and the amplitude of the signals on both sides of the measured amplitude is calculated, and the ratio is compared with a preset threshold value to remove clutter. That is, when the ratio of the amplitude of this range bin and the amplitude of the range bins on both sides is equal to or greater than the threshold value, centering on the range bin of interest, it is determined that the signal is not clutter, and the amplitude value is output as it is. If it is smaller than that, it is judged as clutter and the amplitude is set to zero. For example, in FIG. 3, consider the range bin R2 as the range bin of interest. In the range bin R2, the signal amplitude ratio between the Doppler bin fa and the Doppler bin fb is
The ratio of the Doppler bin fc is also small, that is, assuming that the signal of the Doppler bin fb extends from the Doppler bin fa to the Doppler bin fc, all the signals of the range bin R2 are determined to be clutter, and all the outputs are set to 0. Further, when considering the range bin R3, the ratio between the Doppler bin fb and the Doppler bin fc is large, so that the Doppler bin fb
The signal of is judged as the target and is output as it is. Further, since the Doppler bin fb is 0 in the range bin R4, it is determined that the signal of the Doppler bin fa and the signal of the Doppler bin fc are not continuous, and the processing for obtaining the ratio is not performed and is output as it is.

The signal output from the adjacent Doppler / amplitude calculation device 12 is sent to the data control device 21 and the data in the same range bin are compared. As a result, when there are two amplitudes within the same range, two data are sent to the target detection device 13 as outputs, and when there are three amplitudes, three data are sent as outputs. However, if there are two or more consecutive Doppler bins with amplitude, one target is set. For example, in the case of FIG. 3, the Doppler bin fb is output as the target in the range bin R3, and the range bin R4
Then, it is output that there is a target in each of the Doppler bin fa and the Doppler bin fc.

The target detection device 13 outputs the position information of the target, assuming that the target has the amplitude in the transmitted signal, and the information that there are two or more targets in the same range. Can also be detected.

As described above, according to the first embodiment, the amplitudes of the signals from the Doppler filters 2-1 to 2-n are measured by the amplitude measuring means 11-1 to 11-n, and the adjacent Doppler / amplitude calculation is performed. The means 12 calculates the ratio of the amplitude of the signal of interest and the amplitude of the signal of the adjacent Dopbin of the signal, and when the ratio is smaller than a preset threshold value, the signal is removed as clutter. Therefore, it is possible to remove clutter having a small spread in the range direction, and the false alarm probability can be reduced. Further, even when there are two or more targets in the same range bin, the respective information can be output separately. Further, since the clutter can be removed by obtaining the ratio of the amplitudes and comparing it with the reference value, there is an advantage that a complicated equipment structure is not required and the processing is easy.

Embodiment 2. In the first embodiment, the adjacent Doppler / amplitude calculation device 12 is configured to remove the clutter by taking the ratio with the amplitude value of the signal from the adjacent Doppler filter. As shown in the figure, the adjacent Doppler / amplitude calculation device 14 is provided with a threshold-added adjacent Doppler / amplitude calculation device 14 having a function of providing a predetermined threshold (hereinafter, referred to as a threshold value) with respect to an input adjacent Doppler bin signal. ,
By comparing the signal of the Doppler bin next to an arbitrary Doppler bin with the above threshold, the ratio is obtained only for the signal of the signal of the adjacent Doppbin that has an amplitude equal to or more than the above threshold. If the amplitude of the signal of the Dopbin does not reach the threshold value, the amplitude becomes 0. Therefore, the number of processes for obtaining the ratio is reduced, and the target can be determined easily and quickly. For example, as shown in FIG. 5A, in the range bin R3, the Doppler bin fc
If the amplitude value of 1 is 1, the threshold value of 5 is provided, and as shown in FIG. 5B, the amplitude value of the Doppler bin fc is smaller than the threshold value and becomes 0. Therefore, since the amplitude value of the Doppler bin fc becomes 0 in the range bin R3 of the value which is compared with the threshold value, it is not necessary to take the ratio, and immediately the Doppler bin f
The signal of b can be judged and output as a target.

Embodiment 3. In the first embodiment, the amplitudes of the signals of the adjacent Doppler bins in the same range bin are compared. However, as shown in FIG. 6, a buffer device 15 is provided,
The results of the amplitude determination performed by the amplitude measuring devices 11-1 to 11-n are output to the adjacent Doppler / amplitude calculation device 12 and at the same time output to and stored in the buffer device 15 as well. It is also possible to take the ratio with the signal amplitude of the range bin next to the Doppler bin.
At this time, the adjacent Doppler / amplitude arithmetic unit 12 performs the same processing as that of the first embodiment, but after taking the ratio of the signal of the bin and the Doppler bin adjacent to the bin, further refer to the buffer unit 15. Then, the ratio of the signal of the bin to the amplitude of the signal of the range bin adjacent to the bin and adjacent to the range bin is taken. The result of taking the ratio is processed in the same manner as in the first embodiment. FIG. 7 is a diagram showing an example thereof, and when the Doppler bin fa of the range bin R2 is considered, a process of taking the ratio of the next Doppler bin to the next range bin, that is, the range bin R3 to the Doppler bin fb is performed. Alternatively, when the Doppler bin fb of the range bin R2 is considered, a process of taking the ratio with the Doppler bin fa of the range bin R3 is performed. As a result, it is possible to identify clutter having a shape that extends over other range directions, and it is possible to reliably remove clutter that has a small spread in the range direction.

Fourth Embodiment In the third embodiment, as shown in FIG. 5, the adjacent Doppler / amplitude calculation device 1
If the threshold value is set for the amplitude of the adjacent Doppler before calculating the ratio by using the threshold-equipped adjacent Doppler / amplitude calculation device 14 of the second embodiment instead of 2, the other range directions It is possible to determine the clutter of the shape straddling over, and it is possible to determine the target before taking the ratio, so it is possible to reliably remove the clutter with a small spread in the range direction, The goal can be judged easily and quickly.

Embodiment 5. In the first embodiment, the clutter is determined by determining the amplitude after removing the clutter and taking the ratio between the amplitude and the amplitude of the adjacent Doppler. However, the fifth embodiment does not As shown in FIG. 9, integration calculation devices 16-1 to 16-n for integrating the signals in the range bins are connected to the amplitude measuring devices 11-1 to 11-n after the clutter removal devices 3-1 to 3-n. Installed in parallel,
Both outputs are sent to the comparison operation device 17, the amplitude of the signal is measured, and at the same time the range bin is integrated,
The clutter is determined based on the ratio between the amplitude value and the integrated value, which can further improve the accuracy of clutter removal. That is, from the signal from which the clutter has been removed by the clutter removing device 3, the amplitude measuring device 11 measures the maximum amplitude h _k within the range bin Rk, and at the same time, the integral calculating device 16 integrates the integrated value S _k of the signal within the range bin R _k. Is required. In the comparison operation device 17, the ratio (S _k / h _k ) between the integrated value S _k and the maximum amplitude h _k.
And the result is compared with a preset threshold value K. If the ratio (S _k / h _k ) exceeds the threshold value K, the signal is judged to be clutter and removed. For example, as shown in FIG. 10, in the range bin Ra, the maximum amplitude is h _a and the integrated value is S _a , and in the range bin Rb, the maximum amplitude is h a.
Let _b be the integrated value be S _b . At this time, (S _a /
If h _a )> K, it is determined to be clutter, and the comparison arithmetic unit 17 sets the amplitude to 0 for the signal in the range bin Ra.
And If (S _b / h _b ) ≦ K, it is determined that clutter is not present. The maximum amplitude h _k and the integrated value S _k are calculated for the portion where the signal amplitude exceeds a predetermined threshold value.

Sixth Embodiment In the first embodiment, the amplitude is measured for each range bin, but the range width exceeding the threshold is set for the Doppler bin in which the amplitude value equal to or larger than the predetermined threshold is output without providing the range bin delimiter. W _k
The clutter may be determined by measuring.
That is, as shown in FIG. 11, the clutter removing device 3-
A range width measuring device 18 for measuring the length of a portion where the signal from which clutter has been removed exceeds the threshold value is provided at the subsequent stage of 1 to 3-n, and the above-mentioned measurement is performed by the light weight computing device 17. The range width W _k is compared with a preset threshold value W _0, and when the range width W _k is larger than the threshold value W ₀ ,
The above signal is judged to be clutter. For example, as shown in FIG. 12, range widths W _a and W _b (W _a >
In the case of the signal W ₀ > W _b ), the signal of the range width W _a is W _a
Since it is> W _0, it is determined to be clutter, and the comparison calculation device 17 outputs it as having no amplitude. On the other hand, range width W
_Since the signal of _b is W _b ≦ W _0, it is judged as the target, and its amplitude value is output.

Embodiment 7. In the fifth embodiment, the ratio between the amplitude of a certain range bin and the integrated value of the value exceeding the threshold value is obtained. However, as shown in FIG. 13, after the clutter removal device 3, the amplitude measurement device 11 and the range width measurement are performed. A device 18 is provided, and both outputs are sent to the comparison operation device 17, and the product of the range width W _k and the median amplitude h _k (W _k ·
The clutter may be discriminated based on h _k ).
That is, from the output signal from the clutter removing device 3, the amplitude measuring device 11 measures the median value h _k of the amplitude, and at the same time, the range width measuring device 18 measures the range width W _k . The comparison operation device 17 multiplies the two results, and if the result exceeds a preset threshold value P, it is determined as clutter. For example, as shown in FIG. 14, in the range bin Ra, the median amplitude is h _a and the range width is W _a , and in the range bin Rb, the median amplitude is h _b and the range width is W _b.
Suppose At this time, if (W _a · h _a )> P, it is determined that clutter is present, and the comparison arithmetic unit 17 sets the amplitude to 0 for the signal in the range bin Ra. Also, (W
_{If b} · h _b ) ≦ K, it is determined that clutter is not present. It should be noted that the calculation of the median value h _{k of the} amplitude and the range width W _k is performed for the part where the signal amplitude exceeds a predetermined threshold value.

Embodiment 8. FIG. 15 is a block diagram showing a configuration of a signal processing apparatus according to Embodiment 8 of the present invention, in which 1 is an MTI for a received signal.
A fixed clutter removing device for processing and removing fixed clutter, 20 is a data control device, 15 is a buffer device, 2
-1 to 2-n are Doppler filters for separating the signals from which the fixed clutter has been removed by the fixed clutter removing device 1 into respective frequency components by filters centering on different frequencies, and 3-1 to 3-n Doppler filter 2-
A clutter removing device that removes clutter from each of the signals separated by 1 to 2-n for each frequency, 19 is a maximum value selection determining device, and 13 is a threshold value for the input signal to detect the target. , A target detection device for outputting target position information. Next, the operation will be described. The signal from which the fixed clutter has been removed is first input to the data control device 20. The signal input to the data control device 20 is sent to the buffer device 15 and at the same time the Doppler filter 2-1.
~ 2-n. The signal input to the Doppler filter 2 is sent to the maximum value selection determination device 19 after passing through the clutter removal device 3 as in the conventional case. The maximum value selection judgment device 19 selects the signal having the maximum value among the signals of the same range bin among the input signals, outputs the value, and is the target when the above signal is judged to be the target. Information and its range bin information are sent to the data controller 20. The data control device 20 that has obtained the target range bin information reads the signal corresponding to the target range bin from the buffer device 15, sends it to the Doppler filter, and performs the process again. At this time, the data control device 2
0 controls the number of hits of the Doppler filter. For example, what was previously processed using 32 hit data is subjected to Doppler filter processing using 64 hit data at the time of reprocessing to remove clutter.

As described above, according to the eighth embodiment, the buffer device 1 for storing the signal from the fixed clutter removing means.
5 and the data control device 20 are provided to increase the resolution of the Doppler filter 2 through which the target passes when the target is detected, and the signal from the buffer device 15 is added to the Doppler filter with the increased resolution. Since clutter removal processing is performed again by inputting, clutter determination can be performed using finer data in the detected target peripheral portion. Therefore, it is possible to remove clutter having a small spread in the range direction, and the false alarm probability is reduced. Furthermore, since this apparatus only raises the resolution of a specific Doppler filter, it is possible to remove clutter without requiring a complicated equipment configuration and performing a complicated process.

[0031]

As described above, according to the first aspect of the invention, the ratio of the amplitude of the signal of interest to the amplitude of the signal separated by the Doppler filter adjacent to the Doppler filter separating the signal. And the above signal is removed as clutter when the ratio is smaller than a preset threshold value, it is possible to remove clutter having a small spread in the range direction.

According to the present invention, the amplitude measuring means measures the amplitude of the signal from each Doppler filter, and the adjacent Doppler / amplitude calculating means separates the signal amplitude of interest from the signal. Calculate the ratio with the signal amplitude of the Doppler filter adjacent to the Doppler filter,
When the ratio is smaller than the preset threshold value, the signal is removed as clutter, so that the spread in the range direction does not require complicated equipment configuration and complicated processing. Small clutter can be removed to reduce the false alarm rate due to clutter.

According to the third aspect of the present invention, the output data control means is provided, the signals output from the adjacent Doppler / amplitude calculation means are compared in the same range bin, and the signals in the discontinuous Doppler bins are output from different targets. Since signals are output as signals of, and signals in consecutive Doppler bins are output as signals from the same target, even when there are two or more targets in the same range bin, each information is output separately. be able to.

According to the invention described in claim 4, since the ratio of the amplitudes is calculated only for the signals of the adjacent Doppler filters whose amplitudes are equal to or more than the predetermined threshold value, the signals of the small amplitudes are calculated. Therefore, the calculation can be omitted, and the target can be determined easily and quickly.

According to the invention described in claim 5, buffer means for storing the amplitude of the signal separated for each frequency component is provided, and the amplitude of the signal of interest and the signal of the adjacent range bin of the adjacent Doppler filter are stored. Calculate the ratio with the amplitude,
When the above ratio is smaller than the preset threshold value, the above signal is removed as clutter, so it is possible to identify clutter having a shape that spans other range directions, and to spread in the range direction. The small clutter of can be reliably removed.

According to the sixth aspect of the invention, the amplitude measuring means for measuring the amplitude of the signal, the integral calculating means for integrating the signal, the integral value of the signal from the integral calculating means and the amplitude measuring means. Since the comparison calculation means for comparing the amplitude value of the signal from the above is provided and the target and the clutter are discriminated based on the above comparison result, the clutter can be surely removed.

According to the invention described in claim 7, the range width measuring means for measuring the spread of the signal in the range direction and the comparison calculating means for comparing the range width measured by the range width measuring means with a predetermined threshold value. Is provided, and when the range width is larger than the threshold value, the signal is removed as clutter, so that the clutter can be reliably removed.

According to the eighth aspect of the invention, the amplitude measuring means for measuring the amplitude of the signal, the range width measuring means for measuring the spread of the signal in the range direction, and the range measured by the range width judging means. A comparison calculation means for comparing the product of the width and the amplitude value of the signal from the amplitude measuring means with a predetermined threshold value is provided, and when the product is larger than the threshold value, the signal is removed as clutter. As a result, the clutter can be reliably removed.

According to the ninth aspect of the present invention, when the target is detected, the resolution of the Doppler filter separating the target is increased and the clutter removal process is performed again for the input signal. Therefore, it is possible to determine the clutter in the detected target peripheral portion with finer data, and it is possible to remove the clutter having a small spread in the range direction.

According to the tenth aspect of the invention, a buffer device for storing the signal from the fixed clutter removing means,
While controlling the resolution of the Doppler filter, a data control device for allocating the signal from the buffer device to the Doppler filter is provided, and when a target is detected, the resolution of the Doppler filter through which the target has passed is increased and the resolution is Since the signal from the buffer device is input to the Doppler filter having a higher value to perform the clutter removal process again, the clutter removal accuracy can be improved and the false alarm probability can be reduced. Further, since only the resolution of a specific Doppler filter is controlled, clutter can be removed without requiring a complicated equipment configuration and performing complicated processing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a signal processing method and an apparatus thereof according to a first embodiment of the present invention.

FIG. 2 is a diagram showing input / output data of the amplitude measuring device according to the first embodiment.

FIG. 3 is a diagram showing input / output data of the adjacent Doppler / amplitude calculation apparatus according to the first embodiment.

FIG. 4 is a block diagram of a signal processing device according to a second embodiment.

FIG. 5 is a diagram showing input / output data of an adjacent Doppler / amplitude arithmetic unit with a threshold according to the second embodiment.

FIG. 6 is a block diagram of a signal processing device according to a third embodiment.

FIG. 7 is a diagram showing input / output data of an adjacent Doppler / amplitude calculation apparatus according to the third embodiment.

FIG. 8 is a block diagram of a signal processing device according to a fourth embodiment.

FIG. 9 is a block diagram of a signal processing device according to a fifth embodiment.

FIG. 10 is a diagram showing a signal processing method according to the fifth embodiment.

FIG. 11 is a block diagram of a signal processing device according to a sixth embodiment.

FIG. 12 is a diagram showing a signal processing method according to a sixth embodiment.

FIG. 13 is a block diagram of a signal processing device according to a seventh embodiment.

FIG. 14 is a diagram showing a signal processing method according to a seventh embodiment.

FIG. 15 is a block diagram of a signal processing device according to an eighth embodiment.

FIG. 16 is a block diagram showing a configuration of a conventional signal processing device.

FIG. 17 is a block diagram showing a configuration of a clutter removing device used in a conventional signal processing device.

[Explanation of symbols]

1 fixed clutter removal device, 2-1 to 2-n Doppler filter, 3-1 to 3-n clutter removal device, 4 maximum value selection device, 5 logarithmic amplification device, 6 delay device, 7
Signal extraction device, 8 average calculation device, 9 arithmetic device, 10
Inverse logarithmic amplification device, 11-1 to 11-n amplitude measurement device, 12 adjacent Doppler amplitude risk calculation device, 13 target detection device, 14 adjacent threshold Doppler amplitude calculation device, 1
5 buffer device, 16-1 to 16-n integral operation device,
17 comparison operation device, 18-1 to 18-n range width measuring device, 19 maximum value selection judging device, 20 data control device, 21 output data control device.

Continuation of front page (56) Reference JP-A 64-18083 (JP, A) JP-A 3-261884 (JP, A) JP-A 5-203726 (JP, A) JP-A 5-223918 (JP , A) Japanese Unexamined Patent Publication No. 5-223919 (JP, A) Actual development 4-49886 (JP, U) Actual development 3-63876 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (10)

(57) [Claims] 1. An input signal is separated by a plurality of Doppler filters into frequency components centered on different frequencies, and then separated by a Doppler filter adjacent to the amplitude of the signal of interest and the Doppler filter separating the signals. A signal processing method, wherein a ratio to the amplitude of a signal is calculated, and when the ratio is smaller than a preset threshold value, the signal of interest is removed as clutter. 2. A fixed clutter removing means for removing fixed clutter, a Doppler filter for performing separation for each frequency component centered on different frequencies, and a clutter removing means for removing clutter spread in the distance direction. , A signal processing apparatus for detecting a target by removing clutter from an input signal, an amplitude measuring means for measuring the amplitude of the signal, and a Doppler filter adjacent to the Doppler filter separating the amplitude of the signal of interest and the signal A signal comprising: an adjacent Doppler / amplitude calculation means for calculating a ratio with the amplitude of the signal and removing the signal of interest as clutter when the ratio is smaller than a preset threshold value. Processing equipment. 3. The signals output from adjacent Doppler / amplitude calculation means are compared within the same range bin, signals in non-consecutive Doppler bins are output as signals from different targets, and signals in consecutive Doppler bins are identical in target. 3. The signal processing apparatus according to claim 2, further comprising output data control means for outputting as a signal from the. 4. The amplitude ratio is calculated only for the signals of adjacent Doppler filters whose amplitude is equal to or larger than a predetermined threshold value.
The signal processing device described. 5. A buffer means for storing the amplitude value output from each amplitude measuring means is provided, and the amplitude value of the signal of interest and the Doppler filter adjacent to the Doppler filter stored in the buffer means and separating the signal are provided. The ratio between the range bin of the signal and the amplitude of the signal of the adjacent range bin in the filter signal is calculated, and if the ratio is smaller than a preset threshold value, the signal of interest is removed as clutter. 3. The method according to claim 2, wherein
Alternatively, the signal processing device according to claim 3 or claim 4. 6. A fixed clutter removing means for removing fixed clutter, a Doppler filter for performing separation for each frequency component centered on different frequencies, and a clutter removing means for removing clutter spread in the distance direction. In a signal processing device that removes clutter from an input signal to detect a target, an amplitude measuring unit that measures the amplitude of the signal, an integral calculating unit that integrates the signal, and an integration of the signal from the integrating calculating unit. A signal processing apparatus comprising: a comparison calculation unit that compares a value with an amplitude value of a signal from the amplitude measurement unit. 7. A fixed clutter removing means for removing fixed clutter, a Doppler filter for separating each frequency component centered on a different frequency, and a clutter removing means for removing clutter spread in the distance direction. In a signal processing device that removes clutter from an input signal to detect a target, a range width measuring unit that measures spread of a signal in the range direction, and a range width measured by the range width measuring unit is a predetermined threshold value. A signal processing device, comprising: a comparison calculation means for comparing with the above. 8. A fixed clutter removing means for removing fixed clutter, a Doppler filter for separating each frequency component centered on a different frequency, and a clutter removing means for removing clutter spread in the distance direction. In a signal processing device that detects a target by removing clutter from an input signal, an amplitude measuring unit that measures the amplitude of the signal, a range width measuring unit that measures the spread of the signal in the range direction, and this range width determination A signal processing device, comprising: a comparison calculation means for comparing a product of the range width measured by the means and the amplitude value of the signal from the amplitude measurement means with a predetermined threshold value. 9. An input signal is separated by a plurality of Doppler filters for each frequency component centered on different frequencies, and then clutter removing means removes clutter that spreads in the distance direction to remove clutter that detects a target. In the method, when a target is detected, the resolution of a Doppler filter that separates the target is increased and the clutter removal process is performed again on the input signal. 10. A fixed clutter removing unit for removing fixed clutter, a Doppler filter for separating each frequency component centered on a different frequency, and a clutter suppressing unit for removing clutter spread in the distance direction. In a signal processing device that removes clutter from an input signal to detect a target, a buffer device that stores the signal from the fixed clutter removing means and a data control device that controls the resolution of the Doppler filter are provided. When it is detected, the resolution of the Doppler filter through which the target passes is increased, and the signal from the buffer device is input to the Doppler filter with the increased resolution to perform the clutter removal processing again. Signal processing device.