JPH0868659A - Signal detector - Google Patents

Abstract

PURPOSE: To enhance the detection probability of target signal by providing a comparison circuit at the post-stage of an envelope detection circuit, taking out only a signal having strength higher than a threshold after detection of the envelope and then performing noncoherent integration. CONSTITUTION: An output signal from an envelope detection circuit 9 is compared through a comparison circuit 13 with a predetermined threshold T1 and only a signal having strength higher than the threshold T1 is fed to a noncoherent integration circuit 10 which then delivers an integration result to a CFAR (erroneous alarm probability) detection circuit 11. The detection circuit 11 determines a threshold for making constant the erroneous alarm probability from a preset erroneous alarm probability Pfa and the number of output signals passed through the comparison circuit 13 (number of times of integration at the integration circuit 10) through CFAR processing. The threshold is compared with the strength of output signal from the integration circuit 10 and '1' is delivered to a display means 12 if the former is lower otherwise '0' is delivered thereto. The display means 12 delivers target information based on the output signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal detecting device for detecting a desired signal from a received signal containing noise and a method of determining a secondary false alarm probability used in the device, and more particularly, to a second false alarm probability determining method after envelope detection. The present invention relates to a signal detection device capable of improving a detection probability of a desired signal by extracting only a signal having high intensity from a signal and performing integration.

[0002]

2. Description of the Related Art FIG. 16 shows, for example, JVDiFranco, WL.
Rubin, "Radar Detection", 1980, pp339-344.
FIG. 3 is a configuration diagram of a pulse radar device using a signal detection device that integrates (noncoherent integration) the output signal after performing the envelope detection described in FIG.

In FIG. 16, 1 is an antenna, 2 is a transmission / reception switching circuit, 3 is a transmission pulse generation circuit, 4 is a frequency mixing circuit, 5 is a reference signal generation circuit, 6 is an intermediate frequency amplification circuit, and 7 is a 90-degree hybrid circuit. , 8a is an in-phase component phase detection circuit, 8b is a quadrature component phase detection circuit, 9 is an envelope detection circuit, 10 is a non-coherent integration circuit, and 11 is a CF.
The AR detection circuit, 12 is a display means.

The operation of the conventional pulse radar device is shown in FIG.
6 will be described.

First, the high frequency transmission pulse signal generated by the transmission pulse generation circuit 3 passes through the transmission / reception switching circuit 2 and is radiated from the antenna 1 to space. The reflected signal from the target is received by the antenna 1, passes through the transmission / reception switching circuit 2, is input to the frequency mixing circuit 4, is converted into an intermediate frequency, and is amplified by the intermediate frequency amplifier circuit 6. The output signal of the intermediate frequency amplifier circuit 6 is divided into two and input to the in-phase component phase detection circuit 8a and the quadrature component phase detection circuit 8b.

The signal generated by the reference signal generation circuit 5 is separated by the 90-degree hybrid circuit 7 into two signals having a phase difference of 90 degrees, and the in-phase component phase detection circuit 8a is separated.
And the quadrature component phase detection circuit 8b. In the in-phase component phase detection circuit 8a and the quadrature-component phase detection circuit 8b,
From the output signal of the intermediate frequency amplifier circuit 6 and the output signal of the 90-degree hybrid circuit 7, a video signal (video signal I component) in phase with the reference signal and a video signal (video signal Q component) orthogonal to the reference signal are output, respectively. To do.

The output signals of the in-phase component phase detection circuit 8a and the quadrature-component phase detection circuit 8b are input to the envelope detection circuit 9, converted into the amplitude value of the envelope, and output to the noncoherent integration circuit 10. The non-coherent integrator circuit 10 integrates the output signal of the envelope detection circuit 9 in order to improve the probability of detecting the desired signal, and outputs the result as CF.
Output to the AR detection circuit 11.

In the CFAR detection circuit 11, from the false alarm probability and the number of integrations, for example, Matsuo Sekine, "Radar Signal Processing Technology", 1991, pp96-157. CFAR described in
By the (Constant False Alarm Rate) process, the threshold for making the false alarm probability constant and the intensity of the output signal of the noncoherent integrator circuit 10 are compared, and when the intensity of the output signal of the noncoherent integrator circuit 10 is larger, “1” is output to the display unit 12 when it is smaller. The display means 12 outputs target information based on the output signal of the CFAR detection circuit 11.

[0009]

Therefore, in the pulse radar device using the conventional signal detection device, in order to improve the detection probability of the desired signal, in the non-coherent integration circuit, the output signals of all envelope detection circuits are used. Is used to perform the integration. Therefore, if the fluctuation of the received signal strength is large, the output signal of the envelope detection circuit with weak strength is used to perform the integration, and the detection probability of the desired signal decreases. There was a problem.

The present invention solves the above problems,
An object of the present invention is to provide a signal detection device capable of improving the detection probability of a desired signal by extracting only a signal having high intensity from the signal after envelope detection and performing integration.

[0011]

In order to solve the above-mentioned problems, the signal detecting apparatus of the first feature of the present invention comprises an envelope detection circuit, an output signal of the envelope detection circuit and a predetermined threshold (T1). ), And a non-coherent integration for performing non-coherent integration using the output signal of the comparison circuit, which outputs only the output signal of the envelope detection circuit having a higher intensity than the threshold (T1). And an integrating circuit.

A second aspect of the signal detecting apparatus of the present invention is the signal detecting apparatus according to claim 1, wherein the A / D converting circuit converts a predetermined analog signal into a digital signal, and the A / D converting circuit. And a Fourier transform circuit that performs a Fourier transform on the output of the transform circuit. The envelope detection circuit performs envelope detection of the output of the Fourier transform circuit. A third aspect of the signal detecting apparatus of the present invention is the envelope detecting circuit of the signal detecting apparatus according to claim 1 or 2, which is determined to be larger than a predetermined threshold (T1) in the comparing circuit. False alarm probability (secondary false alarm probability) for each number of output signals of the comparator circuit based on the number of output signals, that is, the number of output signals of the comparator circuit, the false alarm probability, and the value of the threshold (T1). And a second false alarm probability determining circuit for determining.

Further, a signal detecting device having a fourth characteristic of the present invention is the signal detecting device according to claim 1 or 2, wherein
An S / N calculation circuit for obtaining a signal-to-noise power (S / N) ratio using the output signal of the envelope detection circuit, and the envelope curve judged by the comparison circuit to be larger than a predetermined threshold (T1). The number of output signals of the detection circuit, that is, the number of output signals of the comparison circuit, the false alarm probability, the value of the threshold (T1), and the number of output signals of the comparison circuit based on the result of the S / N calculation circuit. And a secondary false alarm probability determining circuit for determining the false alarm probability (secondary false alarm probability) for each.

A fifth aspect of the signal detecting apparatus according to the present invention is the signal detecting apparatus according to any one of claims 1, 2, 3 or 4, wherein a signal-to-noise is obtained by using an output signal of the envelope detection circuit. An S / N calculation circuit for obtaining the electric power (S / N) ratio, a memory for storing the optimum threshold (T1) value for each S / N ratio, and the S / N for referring to the memory.
The optimum threshold (T1 based on the result of the N calculation circuit
) And a threshold T1 determining circuit for selecting the value of (1).

A sixth aspect of the signal detecting apparatus of the present invention is the signal detecting apparatus according to any one of claims 1, 2, 3, 4, or 5, wherein the comparison circuit and the noncoherent integrating circuit are N-type. Is a predetermined positive integer, the number of output signals of the envelope detection circuit having a higher intensity than the predetermined threshold (T1) in the comparison circuit, that is, the number of output signals of the comparison circuit is N. When the N
It has a function of repeating the process of performing non-coherent integration using the output signals of all the comparison circuits each time the output signals of the N comparison circuits are obtained.

The signal detector of the seventh aspect of the present invention is the signal detector according to claim 1, 2, 3, 4, or 5, wherein the comparison circuit and the noncoherent integration circuit are N. Is a predetermined positive integer, N + 1
When the output signals of the first or more comparison circuits are obtained, α
Each time the output signals of the (1 ≦ α <N) comparison circuits are obtained, a function of performing integration using the past output signals of the N comparison circuits is provided.

An eighth aspect of the signal detecting apparatus of the present invention is the signal detecting apparatus according to any one of claims 1, 2, 3, 4, or 5, wherein the comparison circuit and the noncoherent integrating circuit are N. Where N is a predetermined positive integer, among the output signals of the N envelope detection circuits, the output signal of the envelope detection circuit which is judged to be stronger than the predetermined threshold (T1) in the comparison circuit. It has a function of repeating the process of performing non-coherent integration using only each time the output signals of the N envelope detection circuits are obtained.

A ninth aspect of the signal detecting apparatus according to the present invention is the signal detecting apparatus according to any one of claims 1, 2, 3, 4, or 5, wherein the comparison circuit and the noncoherent integrating circuit are N. Is a predetermined positive integer, N + 1
When the output signal of the envelope detection circuit more than the number is obtained,
Every time the output signals of α (1 ≦ α <N) envelope detection circuits are obtained, the envelope whose strength is larger than the predetermined threshold (T1) among the output signals of the past N envelope detection circuits. It has a function of performing non-coherent integration using the output signal of the line detection circuit.

A tenth feature of the present invention is the signal detecting device according to any one of claims 3, 4, 5, 6, 7, 8 or 9, wherein the secondary false alarm probability determining circuit is used. Where N is a predetermined positive integer, among the output signals of the N envelope detection circuits, j (0 ≦
j.ltoreq.N) signals are judged to be larger than a predetermined threshold (T1), that is, when the number of output signals of the comparison circuit is j, false alarm probability and N noise only signals Among the output signals of the envelope detection circuit of FIG. 1, the false alarm probability (secondary false alarm probability) corresponding to the number of output signals of the comparator circuit is based on the probability that the threshold (T1) is exceeded in the comparator circuit j times. ).

Further, an eleventh feature of the signal detecting device of the present invention is the signal detecting device according to any one of claims 3, 4, 5, 6, 7, 8 or 9, wherein the secondary false alarm probability determining circuit is used. Where N is a predetermined positive integer, among the output signals of the N envelope detection circuits, j (0 ≦
j.ltoreq.N) signals are judged to be larger than a predetermined threshold (T1), that is, when the number of output signals of the comparison circuit is j, false alarm probability and N noise only signals Of the output signals of the envelope detection circuit of, the probability that the threshold (T1) will be exceeded j times in the comparison circuit, and the output signals of the envelope detection circuit of N received signals (desired signal + noise). Then, the false alarm probability (secondary false alarm probability) according to the number of output signals of the comparison circuit is obtained based on the probability that the threshold (T1) will be exceeded j times in the comparison circuit.

[0021]

In the signal detecting device of the first feature of the present invention, the comparison circuit at the subsequent stage of the envelope detection circuit compares the predetermined threshold T1 with the intensity of the output signal of the envelope detection circuit, and the envelope detection circuit. Among the output signals, only the signal having a higher intensity than the threshold T1 is output to the non-coherent integrator circuit, and only the envelope detection circuit output signal having a higher intensity than the threshold T1 is used to perform integration in the non-coherent integrator circuit. I am trying.

As a result, signals weaker in intensity than the threshold T1 are eliminated, and integration is performed only by signals stronger in intensity than the threshold T1, which improves the detection probability of the target signal as compared with the conventional signal detecting apparatus. Can be made.

Further, in the signal detecting apparatus of the second feature of the present invention, the input signal is classified into frequency components for each band by the A / D conversion circuit and the Fourier transform circuit in the preceding stage of the envelope detection circuit and output. The processing after the envelope detection circuit is performed for each band. Accordingly, it is possible to realize a signal detection device that achieves the same effect as that of the signal detection device of the first feature even if the received signal is divided into bands and handled.

Further, in the signal detecting apparatus of the third feature of the present invention, the number of output signals of the envelope detection circuit, that is, the number of output signals of the comparison circuit judged by the comparison circuit to be larger than the predetermined threshold T1. And the value of the threshold T1 are output to the second-order false alarm probability determining circuit, and the second-order false alarm probability determining circuit determines the number of output signals of the envelope detection circuit determined to be larger than the threshold T1 and the threshold. Based on the value of T1 and the false alarm probability, the false alarm probability (secondary false alarm probability) corresponding to the number of output signals of the comparison circuit is obtained and output.

By adding the secondary false alarm probability determining circuit in this way, it is possible to realize a signal detecting device capable of obtaining a false alarm probability according to a change in the number of integrations in the noncoherent integrating circuit.

Further, in the signal detector of the fourth feature of the present invention, the S / N calculation circuit calculates the S / N ratio of the received signal and outputs it to the secondary false alarm probability determination circuit. Further, the number of output signals of the envelope detection circuit determined to be larger than the threshold T1 by the comparison circuit and the value of the predetermined threshold T1 are output to the secondary false alarm probability determination circuit.

In the secondary false alarm probability determination circuit, the number of output signals of the envelope detection circuit, that is, the number of output signals of the comparison circuit and the threshold signal which are judged to be larger than the calculation result of the S / N ratio and the threshold T1. From the value of T1 and the false alarm probability, the false alarm probability (secondary false alarm probability) corresponding to the number of output signals of the comparison circuit is obtained and output.

By adding the S / N calculating circuit and the secondary false alarm probability determining circuit in this way, the false alarm probability is obtained according to the change of the S / N ratio and the change of the number of integrations in the noncoherent integrating circuit. It is possible to realize a signal detection device capable of doing so.

In the signal detecting apparatus of the fifth feature of the present invention, the S / N calculation circuit calculates the S / N ratio of the received signal by using the output signal of the Fourier transform circuit for each band. , Threshold T1 output to the decision circuit.

In the threshold T1 decision circuit, S / N
By using the ratio value, the threshold T1 is called from the memory which stores the optimum value of the threshold T1 for each S / N ratio and is output to the comparison circuit.

Thus, by adding the S / N calculation circuit, the threshold T1 determining circuit, and the memory storing the value of the threshold T1 that maximizes the detection probability for each S / N ratio, Even if the N ratio changes, it is possible to realize a signal detecting device that can always obtain the optimum threshold T1 that maximizes the detection probability.

Further, in the signal detecting device of the sixth feature of the present invention, the output signals of the envelope detection circuit are sequentially input to the comparison circuit. The comparison circuit compares a predetermined threshold T1 with the strength of the envelope detection circuit output signal, and outputs only the envelope detection circuit output signal having a higher strength than the threshold T1 to the noncoherent integration circuit.

In the non-coherent integrator circuit, when the number of output signals of the envelope detection circuit having a higher intensity than the threshold T1, that is, the number of output signals of the comparison circuit becomes a predetermined positive integer N, N comparisons are made. Integration is performed using the output signal of the circuit. This process is repeated every time the output signals of the N comparison circuits are obtained.

As a result, even if the non-coherent integrator circuit is used to perform integration using only the output signal of the envelope detection circuit, which is judged to be stronger than the threshold T1 in the comparison circuit, the number of integration times is arbitrary. It is possible to realize a signal detection device that can perform non-coherent integration in.

In the signal detector of the seventh feature of the present invention, the output signals of the envelope detection circuit are sequentially input to the comparison circuit. The comparison circuit compares a predetermined threshold T1 with the strength of the envelope detection circuit output signal, and outputs only the envelope detection circuit output signal having a higher strength than the threshold T1 to the noncoherent integration circuit.

In the noncoherent integrator circuit, when the number of output signals of the envelope detection circuit having a higher intensity than the threshold T1, that is, the number of output signals of the comparison circuit becomes a predetermined positive integer N, N comparisons are made. When the number of output signals of the comparison circuit is N + 1 or more when integration is performed using the output signals of the circuit, the number of output signals of the comparison circuit is α (1 ≦ α
Every time <N), integration is performed using the output signals of the past N comparison circuits.

As a result, even when the non-coherent integrator circuit is used to perform integration using only the output signal of the envelope detection circuit whose strength is judged to be greater than the threshold T1 in the comparison circuit, an arbitrary number of integrations can be performed. A non-coherent integration can be performed and a signal detection device with a short processing time can be realized.

Further, in the signal detecting apparatus of the eighth feature of the present invention, N is a predetermined positive integer, the number of output signals of the envelope detection circuit is N, and the number of output signals of the noncoherent integrating circuit is N. Among the output signals of the envelope detection circuit, integration is performed using the output signals of the j (0≤j≤N) comparison circuits whose signal strength is judged to be larger than the predetermined threshold T1 in the comparison circuit, This process is repeated every time the output signals of the N envelope detection circuits are obtained.

As a result, even when the non-coherent integrator circuit is used to perform integration by using only the output signal of the envelope detection circuit whose strength is judged to be greater than the threshold T1 in the comparison circuit, an arbitrary time interval is obtained. It is possible to realize a signal detection device that can obtain the result of the signal detection judgment.

Further, in the signal detecting apparatus of the ninth feature of the present invention, N is a predetermined positive integer, the number of output signals of the envelope detection circuit is N, and in the noncoherent integrating circuit, N is Among the output signals of the envelope detection circuit, integration is performed using the output signals of the j (0≤j≤N) comparison circuits whose signal strength is judged to be larger than the predetermined threshold T1 in the comparison circuit, When the number of output signals of the envelope detection circuit is N + 1 or more, the number of output signals of the envelope detection circuit becomes α (1 ≦ α <N) each time the number of output signals of the past N envelope detection circuits is increased. Among the output signals, the output signal of the comparison circuit, which is judged to have a signal strength higher than that of the threshold T1, is used to perform the integration.

As a result, even when the comparator circuit is configured to perform integration by the noncoherent integrator circuit using only the output signal of the envelope detection circuit whose strength is judged to be greater than the threshold T1, it is possible to set an arbitrary time. It is possible to realize a signal detection device in which the result of signal detection determination is obtained at intervals and the processing time is short.

Further, in the signal detecting device of the tenth feature of the present invention, in the secondary false alarm probability determining circuit, N is a predetermined positive integer, and among the output signals of the N envelope detecting circuits, When it is determined in the comparison circuit that j (0≤j≤N) signals are larger than a predetermined threshold T1,
False alarm probability and noise-only signal will cause threshold T1
The false alarm probability (secondary false alarm probability) according to the number j of output signals of the comparison circuit is determined based on the probability of crossing.

This makes it possible to obtain the false alarm probability (secondary false alarm probability) according to the number of output signals of the comparison circuit, that is, the change in the number of integrations in the noncoherent integration circuit.

Further, in the signal detecting apparatus of the eleventh feature of the present invention, in the secondary false alarm probability determining circuit, N is a predetermined positive integer, and among the output signals of the N envelope detecting circuits, When it is determined in the comparison circuit that j (0≤j≤N) signals are larger than a predetermined threshold T1,
The probability that a noise-only signal will exceed the threshold T1 j times and the probability that the output signal of the received signal envelope detection circuit will exceed the threshold T1 j times using the S / N ratio calculated by the S / N calculation circuit. And the false alarm probability (secondary false alarm probability) corresponding to the number j of output signals of the comparison circuit is determined from the result and the false alarm probability.

This makes it possible to obtain the false alarm probability (secondary false alarm probability) according to the number of output signals of the comparison circuit, that is, the number of integrations in the non-coherent integration circuit, and the change in the S / N ratio of the received signal. You can

[0046]

Embodiments of the present invention will now be described with reference to the drawings.

(Embodiment 1) FIG. 1 shows a block diagram of a pulse radar apparatus using a signal detection apparatus according to Embodiment 1 of the present invention. In the figure, the same parts as those of the conventional example shown in FIG.

Referring to FIG. 1, the pulse radar device of this embodiment includes an antenna 1, a transmission / reception switching circuit 2, a transmission pulse generation circuit 3, a frequency mixing circuit 4, a reference signal generation circuit 5, an intermediate frequency amplification circuit 6, and a 90-degree hybrid. The circuit 7, the in-phase component phase detection circuit 8a, the quadrature component phase detection circuit 8b, the envelope detection circuit 9, the comparison circuit 13, the noncoherent integration circuit 10, the CFAR detection circuit 11, and the display means 12.
It is configured with.

That is, a new part in comparison with the conventional example is a comparison circuit 13 added between the envelope detection circuit 9 and the noncoherent integration circuit 10, and the other components are the same as those in the conventional example.

The comparison circuit 13 compares the output signal of the envelope detection circuit 9 with the strength of a predetermined threshold T1 and outputs only the output signal of the envelope detection circuit 9 having a higher strength than the threshold T1. Further, the noncoherent integration circuit 10 performs noncoherent integration using the output signal of the comparison circuit 13.

The operation of the pulse radar device of this embodiment is shown in FIG.
It will be described based on. In the figure, the operation up to the comparison circuit 13 is the same as in the conventional example.

That is, the high frequency transmission pulse signal generated by the transmission pulse generation circuit 3 at a constant repetition period passes through the transmission / reception switching circuit 2 and is radiated from the antenna 1 to space. The reflected signal from the target is received by antenna 1,
After passing through the transmission / reception switching circuit 2, it is input to the frequency mixing circuit 4, converted into an intermediate frequency, and amplified by the intermediate frequency amplification circuit 6.

The output signal of the intermediate frequency amplifier circuit 6 is divided into two and input to the in-phase component phase detection circuit 8a and the quadrature phase detection circuit 8b. Further, the signal generated by the reference signal generation circuit 5 is separated by the 90-degree hybrid circuit 7 into two signals having a phase difference of 90 degrees and input to the in-phase component phase detection circuit 8a and the quadrature-component phase detection circuit 8b. To be done.

In the in-phase component phase detection circuit 8a and the quadrature phase detection circuit 8b, the output signal of the intermediate frequency amplification circuit 6 and 9
Based on the output signal of the 0-degree hybrid circuit 7, a video signal I component (a video signal in phase with the reference signal) and a video signal Q component (a video signal orthogonal to the reference signal) are output. The output signals of the in-phase component phase detection circuit 8a and the quadrature phase detection circuit 8b are input to the envelope detection circuit 9 and converted into the amplitude value of the envelope.

The output signal of the envelope detection circuit 9 is compared in strength with a threshold T1 which is appropriately determined in advance in the comparison circuit 13, and only the output signal of the envelope detection circuit 9 larger than the threshold T1 is output. Output to the coherent integration circuit 10.

In the coherent integration circuit 10, the comparison circuit 13 performs integration using the output signal of the envelope detection circuit 9 determined to be larger than the threshold T1, and outputs the integration result to the CFAR detection circuit 11.

In the CFAR detection circuit 11, the false alarm probability pfa set appropriately in advance and the number of output signals of the envelope detection circuit 9 which is judged by the comparison circuit 13 to have a signal strength larger than the threshold T1, that is, the comparison circuit From the number of output signals of 13 (the number of integrations in the non-coherent integration circuit 10), a threshold that makes the false alarm probability constant by CFAR processing is obtained, and the obtained threshold and the intensity of the output signal of the non-coherent integration circuit 10 are calculated. A comparison is made. When the intensity of the output signal of the non-coherent integrator circuit 10 is larger, it is "1", and when it is smaller, it is "
0 "is output to the display means 12, respectively.
Then, the target information is output based on the output signal of the CFAR detection circuit 11.

As described above, according to the configuration of the present embodiment in which the comparison circuit 13 is added to the conventional example, a weak signal can be excluded when the pulse integration is performed, so that detection with respect to the target signal is performed. The probability can be improved.

(Embodiment 2) FIG. 2 shows a block diagram of a pulse radar apparatus using a signal detecting apparatus according to Embodiment 2 of the present invention. In the figure, the same parts as those in the first embodiment shown in FIG. 1 are designated by the same reference numerals.

In FIG. 2, a new part in comparison with the first embodiment (FIG. 1) is an A / D conversion circuit 14 and a Fourier transform circuit 15 provided in the preceding stage of the envelope detection circuit 9, and other parts. The constituent elements are the same as in the first embodiment. In the case of this embodiment, a fast Fourier transform (FFT) circuit is used as the Fourier transform circuit 15.

The operation of the pulse radar system of this embodiment is shown in FIG.
It will be described based on. In the figure, the operations up to the in-phase component phase detection circuit 8a and the quadrature phase detection circuit 8b are the same as in the first embodiment.

Video signals I output from the in-phase component phase detection circuit 8a and the quadrature component phase detection circuit 8b, respectively.
The component and the video signal Q component are input to the A / D conversion circuit 14, converted into a discrete time signal, and input to the fast Fourier transform circuit 15.

The fast Fourier transform circuit 15 outputs to the envelope detection circuit 9 complex signals of the number Fp of points of the fast Fourier transform, which are separated into components for each band determined by the reciprocal of the observation time of the input signal.

The envelope detection circuit 9 outputs the absolute values of the Fp complex signals to the comparison circuit 13. The output signals of the Fp envelope detection circuits 9 are compared in strength with the threshold T1 determined in advance in the comparison circuit 13, respectively, and only the output signals of the envelope detection circuit 9 larger than the threshold T1 are output. Output to the non-coherent integration circuit 10.

In the non-coherent integrator circuit 10, the comparator circuit 13 performs integration for each band using only the output signal of the envelope detection circuit 9 determined to be larger than the threshold T1, and the integration result for each band. To the CFAR detection circuit 11.

In the CFAR detection circuit 11, an appropriate false alarm probability pfa is set in advance, and in the comparison circuit 13,
The CFAR processing is performed based on the number of output signals of the envelope detection circuit 9 determined to have a signal strength higher than that of the threshold T1, that is, the number of output signals of the comparison circuit 13 (the number of integrations in the noncoherent integration circuit 10). Find the threshold that keeps the false alarm probability constant. Further, the intensity of the calculated threshold and the output signal of the non-coherent integrator circuit 10 are compared. When the intensity of the output signal of the non-coherent integrator circuit 10 is large, "1" is displayed, and when it is small, "0" is displayed respectively. Output to 12. The display means 12 outputs target information based on the output signal of the CFAR detection circuit 11.

As described above, the A / D conversion circuit 1 is added to the first embodiment.
According to the configuration of this embodiment in which 4 and the Fourier transform circuit 15 are added, not only the pulse radar device but also the so-called pulse Doppler radar device that handles the received signal by dividing it into bands is the same as the first embodiment. A similar effect can be expected, that is, an improvement in detection probability for the target signal can be expected.

(Embodiment 3) FIG. 3 shows a block diagram of a pulse radar apparatus using a signal detection apparatus according to Embodiment 3 of the present invention. In the figure, the same parts as those of the second embodiment shown in FIG.

In FIG. 3, a new part in comparison with the second embodiment (FIG. 2) is a comparison circuit 13 and a CFAR detection circuit 11.
It is the secondary false alarm probability determination circuit 16 added between and, and the other components are the same as in the second embodiment.

The operation of the pulse radar device of this embodiment is shown in FIG.
It will be described based on. In the figure, the operation up to the envelope detection circuit 9 is the same as in the second embodiment.

In the non-coherent integrator circuit 10, for example, when N is a predetermined positive integer, among the output signals of the N envelope detection circuits 9, the threshold value which is appropriately determined in advance in the comparator circuit 13 is selected. When performing integration using only the output signal of the envelope detection circuit 9 determined to be larger than T1, the number of output signals of the envelope detection circuit 9 determined to be larger than the threshold T1 in the comparison circuit 13, that is, The output signal of the comparison circuit is 0
There can be from 1 to N. That is, the number of integrations in the noncoherent integration circuit 10 may be 0 to N.

In such a case, in the configuration of the second embodiment, C
The value of the false alarm probability pfa input to the FAR detection circuit 11 was constant regardless of the number of output signals of the comparison circuit 13, that is, the number of integrations in the noncoherent integration circuit 10. On the other hand, in this embodiment, the number of output signals from the comparison circuit 13 and the value of the threshold T1 are set to 2
Output to the next false alarm probability determination circuit 16.

In the secondary false alarm probability determining circuit 16, the output signal of the comparator circuit 13 is determined based on the number j (0≤j≤N) of output signals of the comparing circuit 13, the value of the threshold T1 and the false alarm probability pfa. The false alarm probability (secondary false alarm probability) pfa2, j corresponding to the number j of is calculated, and the result is output to the CFAR detection circuit 11. The method of calculating the secondary false alarm probability will be described in detail in Example 10 described later.

In the CFAR detection circuit 11, the comparison circuit 13
Number of output signals of the non-corrent integrating circuit 10
2 from the secondary false alarm probability determination circuit 16
From the value of the next false alarm probability pfa2, j, the threshold for making the false alarm probability constant by CFAR processing is obtained. Further, the calculated threshold is compared with the intensity of the output signal of the non-coherent integrator circuit 10, and when the intensity of the output signal of the non-coherent integrator circuit 10 is larger,
1 "and" 0 "when smaller are output to the display means 12. The display means 12 outputs target information based on the output signal of the CFAR detection circuit 11.

As described above, according to the configuration of this embodiment in which the secondary false alarm probability determination circuit 16 is added to the second embodiment, the number j of output signals of the comparison circuit 13, that is, the integration in the noncoherent integration circuit 10 is performed. False alarm probability (2
Next false alarm probability) pfa2, j is obtained.

(Embodiment 4) FIG. 4 shows a block diagram of a pulse radar apparatus using a signal detecting apparatus according to Embodiment 4 of the present invention. In the figure, the same parts as those of the third embodiment shown in FIG. 3 are designated by the same reference numerals.

In FIG. 4, a new portion as compared with the third embodiment (FIG. 3) is an S / N calculation circuit 17 added between the envelope detection circuit 9 and the secondary false alarm probability determination circuit 16. And other components are the same as those in the third embodiment.

The operation of the pulse radar system of this embodiment is shown in FIG.
It will be described based on. In the figure, the operation before the input of the envelope detection circuit 9 and the operation after the secondary false alarm probability determination circuit 16 are the same as those in the third embodiment.

The output signal of the envelope detection circuit 9 divided into Fp components for each band is output to the comparison circuit 13 and the S / N calculation circuit 17.

The S / N calculation circuit 17 calculates the S / N ratio of the received signal using the output signal of the envelope detection circuit 9, and outputs the result to the secondary false alarm probability determination circuit 16.

In the secondary false alarm probability determination circuit 16, the number of output signals of the envelope detection circuit which is judged to be larger than the threshold T1 by the comparison circuit 13, that is, the comparison circuit 1
From the number of output signals of 3 and the value of the threshold T1, the false alarm probability pfa and the value of the S / N ratio from the S / N calculation circuit 17, the false alarm probability (2 Next false alarm probability) pfa2, j is calculated, and the result is CFA
Output to the R detection circuit 11. The method of calculating the secondary false alarm probability will be described in detail in Example 11 described later.

As described above, the S / N calculation circuit 1 is added to the third embodiment.
According to the configuration of this embodiment in which 7 is added, the number j of output signals of the comparison circuit 13, that is, the noncoherent integration circuit 1
The false alarm probability (secondary false alarm probability) pfa2, j according to the number of integrations at 0 and the change of the S / N ratio is obtained.

(Embodiment 5) FIG. 5 shows a block diagram of a pulse radar apparatus using a signal detecting apparatus according to Embodiment 5 of the present invention. In the figure, the same parts as those of the fourth embodiment shown in FIG.

In FIG. 5, a new part in comparison with the fourth embodiment (FIG. 4) is a threshold T1 decision circuit 18 and a memory 19 added between the S / N calculation circuit 17 and the comparison circuit 13. The other components are the same as those in the fourth embodiment.

The memory 19 holds the optimum threshold value T1 for each S / N ratio.

The operation of the pulse radar device of this embodiment is shown in FIG.
It will be described based on. In the figure, the S / N calculation circuit 17
The operations up to are the same as those in the fourth embodiment.

The value of the S / N ratio obtained by the S / N calculation circuit 17 is output to the secondary false alarm probability determination circuit 16 and also to the threshold T1 determination circuit 18.

In the threshold T1 decision circuit 18, S
Using the result of the / N calculation circuit 17, the threshold value T1 from the memory 19 holding the optimum threshold value T1 for each S / N ratio obtained in advance.
And outputs the value to the comparison circuit 13.

As described above, in Example 4, Threshhold T
By adding the 1 decision circuit 18 and the memory 19, the optimum value of the threshold T1 can be obtained even when the S / N ratio changes.

(Embodiment 6) FIG. 6 is a flow chart showing the operation of the comparison circuit 13 and the noncoherent integration circuit 10 used in the signal detecting apparatus according to claim 6 of the present invention, and FIG. 7 is an envelope curve. The output signal of the detection circuit 9, the output signal of the comparison circuit 13, and the noncoherent integration circuit 10
3 is a conceptual diagram of the output signal of FIG.

The configuration of the pulse radar device using the signal detection device of this embodiment may be any of the configurations of the first to fifth embodiments.

In FIGS. 6 and 7, xi represents the output signal of the envelope detection circuit 9 and sj represents the output signal xi of the envelope detection circuit 9 having a higher intensity than the threshold T1 set appropriately beforehand. Signal, that is, the output signal of the comparison circuit 13, and wh indicates the output signal of the noncoherent integration circuit 10.

As shown in FIG. 7, in the present embodiment, the number of output signals xi of the envelope detection circuit 9 is not fixed and the comparison circuit 13
When the number of the output signals sj of the above becomes a predetermined positive integer N, the non-coherent integrator circuit 10 performs integration using the output signals of the N comparator circuits 13. Then, the output signal of the comparison circuit 13 used once for integration is not used twice, and integration is performed every time N output signals of the comparison circuit 13 are obtained.

The operation of the comparison circuit 13 and the noncoherent integration circuit 10 will be described with reference to FIG.

First, in step S50a, counters i, j, and k indicating the number of signals are initialized.

In step S50b, the envelope detection circuit 9
Of the output signal xi is larger than the threshold T1. If the output signal xi is smaller than the threshold T1, the process proceeds to step S50h. In step S50h, the counter i of the output signal xi is set to 1
Then, the process goes back to step S50b to judge whether the output signal xi is larger than the threshold T1.

In step S50b, the output signal xi
Is greater than threshold T1, step S
Go to 50c. In step S50c, the value of the output signal xi is substituted into sj indicating the output signal of the comparison circuit 13, the counter j of the output signal sj is incremented by 1, and step S50d
Go to.

In step S50d, the value of the counter j of the output signal sj and the predetermined positive integer N
When the counter j is less than N, the process returns to step S50h. When the counter j is N or more,
It proceeds to step S50e.

In step S50e, N comparison circuits 1
The sum (integration) of the output signals s0 to sN-1 of 3 is taken and substituted into wh showing the output signal of the noncoherent integrator circuit 10, and the process proceeds to step S50f.

In step S50f, the counter h of the output signal wh is incremented by 1, and the process proceeds to step S50g.

In step S50g, the counter h of the output signal wh is compared with a predetermined positive integer hmax which indicates the maximum number of times of the signal detection processing, and h is hma.
If it is less than x, the process proceeds to step S50i.

In step S50i, the counter j of the output signal sj is returned to 0, the process returns to step S50h, and the above processing is repeated.

In step S50g, the output signal wh
If the counter h of is greater than or equal to hmax, the process ends.

By using the non-coherent integrating circuit 10 having such a function, it is possible to realize a signal detecting device capable of performing non-coherent integration with an arbitrary number of integrations.

In the present embodiment, the case where N has a constant value has been described, but the value of N may change each time integration is performed.

(Embodiment 7) FIG. 8 is a flow chart showing the operation of the comparison circuit 13 and the noncoherent integration circuit 10 used in the signal detecting apparatus according to claim 7 of the present invention, and FIG. 9 is an envelope curve. The output signal of the detection circuit 9, the output signal of the comparison circuit 13, and the noncoherent integration circuit 10
3 is a conceptual diagram of the output signal of FIG.

The structure of the pulse radar device using the signal detection device of this embodiment may be any of the structures of the first to fifth embodiments.

8 and 9, xi is an output signal of the envelope detection circuit 9 and sj is appropriately set in advance in the output signal xi of the envelope detection circuit 9 in the same manner as in the sixth embodiment. A signal having a higher intensity than the threshold T1, that is, the output signal of the comparison circuit 13, and wh represents the output signal of the noncoherent integration circuit 10.

In the sixth embodiment, when the number of output signals sj of the comparator circuit 13 becomes a predetermined positive integer N, a noncoherent integrator circuit is used by using the output signals of the N comparator circuits 13. The integration is performed at 10, and the output signal of the comparison circuit 13 used for the integration is not used twice, but the integration is performed every time N output signals sj of the comparison circuit 13 are obtained. In the example, it is done as follows.

That is, as shown in FIG. 9, in the first integration, when the number of the output signals sj of the comparison circuit 13 becomes N, the output of the N comparison circuits 13 is output as in the sixth embodiment. Although it is performed using a signal, the second and subsequent integrations are performed by the comparison circuit 13
Each time the number of output signals sj of the above is obtained by a predetermined positive integer α (1 ≦ α <N), integration is performed using the output signals of the past N comparison circuits 13.

The operation of the comparison circuit 13 and the noncoherent integration circuit 10 will be described with reference to the flow chart shown in FIG.

First, in step S51a, the counters i, j, k indicating the number of each signal are initialized, and the number of output signals sj of the comparison circuit 13 at the time of integration in the noncoherent integration circuit 10 is shown. Substitute a predetermined positive integer N into jc.

In step S51b, the envelope detection circuit 9
Of the output signal xi is smaller than the threshold T1. If it is determined that the output signal xi is smaller than the threshold T1, step S51.
Go to h.

In step S51h, the counter i of the output signal xi is incremented by 1, and the process returns to step S51b again.
A determination is made as to whether the output signal xi is greater than threshold T1.

In step S51b, the output signal xi
Is greater than threshold T1, step S
Go to 51c.

In step S51c, the value of the output signal xi is substituted into sj representing the output signal of the comparison circuit 13, the counter j of the output signal sj is incremented by 1, and the process proceeds to step S51d.

In step S51d, the value of the counter j of the output signal sj and the value of jc are compared, and the counter j
If is less than jc, the process returns to step S51h. If the counter j is greater than or equal to jc, the process proceeds to step S51e.

In step S51e, the sum (integration) of the output signals sjc-N to sjc-1 of the past N comparison circuits 13 is calculated from the output signal of the jc-1th comparison circuit 13, and the noncoherent integration circuit 10 outputs the sum. Substitute for wh indicating the output signal, and proceed to step S51f.

In step S51f, the counter h of the output signal wh is incremented by 1, and the process proceeds to step S51g.

In step S51g, the counter h of the output signal wh is compared with a predetermined positive integer hmax that indicates the maximum number of times of the signal detection processing set in advance. If the counter h is less than hmax, the process proceeds to step S51i. .

In step S51i, jc is added with a predetermined positive integer α (1≤α <N) to obtain j again.
Substitute for c, return to step S51h, and repeat the above processing.

In step S51g, the output signal wh
If the counter h of is greater than or equal to hmax, the process ends.

By using the non-coherent integrator circuit 10 having such a function, it is possible to implement a non-coherent integration with an arbitrary number of integrations and to realize a signal detection device with a short processing time.

In the present embodiment, the case where N and α take constant values has been described, but the values of N and α may change each time integration is performed.

(Embodiment 8) FIG. 10 is a flow chart showing the operation in the comparison circuit 13 and the noncoherent integration circuit 10 used in the signal detecting apparatus according to claim 8 of the present invention, and FIG. 11 is the envelope detection. The output signal of the circuit 9, the output signal of the comparison circuit 13, and the noncoherent integration circuit 1
It is a conceptual diagram of the output signal of 0.

The structure of the pulse radar device using the signal detecting device of this embodiment may be any of the structures of the first to fifth embodiments.

Similar to Embodiments 6 and 7, FIG.
In FIG. 11 and FIG. 11, xi is the output signal of the envelope detection circuit 9, and sj is the signal whose intensity is larger than the threshold T1 set in advance in the output signal xi of the envelope detection circuit 9, that is, comparison The output signal of the circuit 13 is shown, and wh is the output signal of the noncoherent integration circuit 10.

In the sixth embodiment, the number of output signals xi of the envelope detection circuit 9 is not fixed, and the output signal sj of the comparison circuit 13 is sj.
When the number of P's becomes a predetermined positive integer N, the non-coherent integrator circuit 10 was integrated using the output signals of the N comparison circuits 13, whereas in the present embodiment, Like this.

That is, as shown in FIG. 11, among the output signals of the N envelope detection circuits 9, the comparison circuit 13 determines that the signal strength is larger than the threshold T1 (j≤0≤j≤N). ) The output signals of the comparator circuits 13 are used to perform integration in the non-coherent integrator circuit 10, and this processing is repeated each time the output signals of the N envelope detection circuits 9 are obtained.

The operations of the comparison circuit 13 and the noncoherent integration circuit 10 will be described with reference to the flowchart shown in FIG.

First, in step S52a, the counters i, j, and k indicating the number of each signal are initialized, and the number of output signals xi of the envelope detection circuit 9 when the noncoherent integrator circuit 10 is integrated. Showing ic
Is substituted with a predetermined positive integer N.

In step S52b, the envelope detection circuit 9
Of the output signal xi is larger than the threshold T1. If it is judged that the output signal xi is smaller than the threshold T1, step S52.
Go to d.

In step S52b, the output signal xi
If it is determined that is larger than the threshold T1, the process proceeds to step S52c.

In step S52c, the value of the output signal xi is substituted into sj representing the output signal of the comparison circuit 13, the counter j of the output signal sj is incremented by 1, and the process proceeds to step S52d.

In step S52d, the value of the counter i of the output signal xi and the value of ic -1 are compared. If the counter i is less than ic -1, the process proceeds to step S52h.

In step S52h, the counter i of the output signal xi is incremented by 1, and the process returns to step S52b to determine whether the output signal xi is larger than the threshold T1.

In step S52d, the output signal xi
If the counter i of is greater than or equal to ic -1, step S
Go to 52e.

In step S52e, j (0≤j≤N)
Sum (integration) of the output signals s0 to sj-1 of the individual comparator circuits 13
Is taken and substituted into wh representing the output signal of the noncoherent integrator circuit 10, and the process proceeds to step S52f.

In step S52f, the counter h of the output signal wh is advanced by 1, and the process proceeds to step S52g.

In step S52g, the counter h of the output signal wh is compared with a predetermined positive integer hmax that indicates the maximum number of times of the signal detection processing set in advance. If the counter h is less than hmax, the process proceeds to step S52i. .

In step S52i, a value obtained by adding a predetermined positive integer N to ic is substituted into ic again, and the process returns to step S52h to repeat the above process.

In step S52g, the output signal wh
If the counter h of is greater than or equal to hmax, the process ends.

By using the non-coherent integrator circuit 10 having such a function, it is possible to realize a signal detection device which can obtain the result of signal detection judgment at an arbitrary time interval.

In this embodiment, the case where N has a constant value has been described, but the value of N may change each time integration is performed.

(Embodiment 9) FIG. 12 is a flow chart showing the operation in the comparison circuit 13 and the noncoherent integration circuit 10 used in the signal detecting apparatus according to claim 9 of the present invention, and FIG. 12 is the envelope detection. The output signal of the circuit 9, the output signal of the comparison circuit 13, and the noncoherent integration circuit 1
It is a conceptual diagram of the output signal of 0.

The pulse radar device using the signal detection device of this embodiment may have any of the configurations 1 to 5.

12 and 13, xi is the output signal of the envelope detection circuit 9 and sj is the output signal xi of the envelope detection circuit 9 as in the sixth, seventh, and eighth embodiments. In the figure, a signal having a higher intensity than the threshold T1 set in advance, that is, the output signal of the comparison circuit 13, and wh represents the output signal of the noncoherent integration circuit 10.

In the eighth embodiment, in the output signals of the N envelope detection circuits 9 which are predetermined positive integers in the noncoherent integration circuit 10, the comparison circuit 13 outputs more than the threshold T1 in the output signals of the N envelope detection circuits 9. J (0.ltoreq.j.ltoreq.N) comparison circuits 13 determined to have a high signal strength
The integration is performed using the output signal of, and this processing is repeated every time the output signals of the N envelope detection circuits 9 are obtained, whereas in the present embodiment, it is performed as follows.

That is, as shown in FIG. 13, in the first integration, as in the eighth embodiment, among the output signals of the N envelope detection circuits 9, in the comparison circuit 13, the signal strength is higher than that of the threshold T1. Is determined to be large, j (0 ≦ j ≦
N) The output signals of the comparator circuits 13 are used for integration, and in the second and subsequent integrations, the output signal xi of the envelope detection circuit 9 is a predetermined positive integer α (1 ≦ α <N).
Every time it is obtained, out of the output signals of the N envelope detection circuits 9 in the past, the output signal of the comparison circuit 13 determined to have a signal strength larger than that of the threshold T1 is used to perform integration.

The operation of the comparison circuit 13 and the noncoherent integration circuit 10 will be described with reference to the flowchart shown in FIG.

First, in step S53a, the counters i, j, k indicating the number of each signal are initialized, and the number of output signals xi of the envelope detection circuit 9 at the time of integration in the noncoherent integrator circuit 10 is initialized. Showing ic
Is substituted with a predetermined positive integer N.

In step S53b, the envelope detection circuit 9
Of the output signal xi is larger than the threshold T1. If it is judged that the output signal xi is smaller than the threshold T1, step S53.
Go to d.

If it is determined in step S53b that the output signal xi is larger than the threshold T1, the process proceeds to step S53c.

In step S53c, the value of the output signal xi is substituted into sj representing the output signal of the comparator circuit 13, the value of the counter i of the output signal xi at that time is recorded in the memory Mj, and the counter j of the output signal sj is recorded. To 1 and proceeds to step S53d.

In step S53d, the value of the counter i of the output signal xi and the value of ic -1 are compared. If the counter i is less than ic -1, the process proceeds to step S53h.

In step S53h, the counter i of the output signal xi is incremented by 1, and the process returns to step S53b again to judge whether the output signal xi is larger than the threshold T1.

In step S53d, the output signal xi
If the counter i of is greater than or equal to ic -1, step S
Go to 53e.

In step S53e, j (0≤j≤N)
Sum (integration) of the output signals s0 to sj-1 of the individual comparator circuits 13
Is taken and substituted into wh representing the output signal of the noncoherent integrator circuit 10, and the process proceeds to step S53f.

In step S53f, the counter h of the output signal wh is incremented by 1, and the process proceeds to step S53g.

In step S53g, the counter h of the output signal wh is compared with a predetermined positive integer hmax which indicates the maximum number of times of the signal detection processing set in advance. When the counter h is hmax or more, the processing is ended.

If the counter h of the output signal wh is less than hmax in step S53g, the process proceeds to step S53i.

In step S53i, the counter i of the output signal xi is incremented by 1, and a value obtained by adding a predetermined positive integer α (1≤α <N) to ic is substituted into ic again, and the process proceeds to step S53j.

In step S53j, it is determined whether the output signal xi is larger than the threshold T1. If it is determined that the output signal xi is smaller than the threshold T1, the process proceeds to step S53l.

If it is determined in step S53j that the output signal xi is larger than the threshold T1, the process proceeds to step S53k.

In step S53k, the value of the output signal xi is substituted into sj indicating the output signal of the comparison circuit 13, the value of the counter i of the output signal xi at that time is recorded in the memory Mj, and the counter j of the output signal sj is recorded. To 1 and proceeds to step S53l.

In step S53l, the value of the counter i of the output signal xi and the value of ic -1 are compared. If the counter i is less than ic -1, the process proceeds to step S53r.

At step S53r, the counter i of the output signal xi is incremented by 1, and the process returns to step S53j again.
A determination is made as to whether the output signal xi is greater than threshold T1.

If the counter i of the output signal xi is greater than or equal to ic -1 in step S53l, the process proceeds to step S53m.

In step S53m, the counter p is initialized, and the flow advances to step S53n.

In step S53n, the value of the memory Mp and the size of i-N are compared, and the value of the memory Mp is i.
When the value is −N or less, the process proceeds to step S53s.

At step S53s, the counter p is set to 1
Then, the process returns to step S53n again to compare the value of the memory Mp with the size of i-N.

If the value of the memory Mp is larger than iN in step S53n, step S5 is executed.
Go to 3o.

In step S53o, the sum (integration) of the output signals sp to sj-1 of the comparison circuit 13 is taken and substituted into wh representing the output signal of the noncoherent integration circuit 10, and the flow proceeds to step S53p.

At step S53p, the counter h of the output signal wh is incremented by 1, and the routine proceeds to step S53q.

In step S53q, the counter h of the output signal wh is compared with a predetermined positive integer hmax indicating the maximum number of times of the signal detection processing set in advance. If the counter h is less than hmax, the process returns to step S53i. ,
The above process is repeated. If the counter h is greater than or equal to hmax, the process ends.

By using the non-coherent integrating circuit 10 having such a function, it is possible to realize a signal detecting device which can obtain the result of signal detection judgment at an arbitrary time interval.

In this embodiment, the case where N and α take constant values has been described, but the values of N and α may change each time integration is performed.

(Embodiment 10) FIG. 14 shows claim 1 of the present invention.
6 is a flowchart showing the operation of the secondary false alarm probability determination method in the secondary false alarm probability determination circuit 16 in the signal detection device according to 0.

The structure of the pulse radar device using the signal detecting device of this embodiment may be any of the structures of the third, fourth and fifth embodiments.

In the secondary false alarm probability determination circuit 16 of this embodiment, N is a predetermined positive integer, and among the output signals of the N envelope detection circuits 9, j (0≤j) in the comparison circuit 13 is output.
≤N) when it is judged that the number of signals is larger than the threshold T1, that is, when the number of output signals of the comparison circuit 13 is j, the false alarm probability (2 Next false alarm probability) pfa2, j is calculated.

The operation of this embodiment will be described in detail below with reference to the flow chart shown in FIG.

Assuming that the noise generated in the receiver has a Gaussian distribution when a linear detection circuit is used as the envelope detection circuit 9, the probability density of the output signal r of the linear detection circuit of the noise-only signal is assumed. The function pn (r) is expressed by the following equation.

[0183]

[Equation 1] First, in step S54a, the probability density function p
From n (r), in the comparison circuit 13, the probability pdn1 that the output signal r of the noise-only linear detection circuit exceeds the threshold T1 is obtained by the following equation, and the process proceeds to step S54b.

[0184]

[Equation 2] In step S54b, the probability qn, j of exceeding the threshold T1 by j times (0≤j≤N) in the comparison circuit 13 among the output signals of the linear detection circuit of N noise-only signals is obtained by the following equation, Proceed to S54c.

[0185]

(Equation 3) In step S54c, in the secondary false alarm probability determination circuit 16, the false alarm probability (second false alarm probability) pfa2, j when the number of output signals of the comparison circuit 13 is j is set to the false alarm probability pfa.
Then, the probability qn, j of the noise-only signal exceeding the threshold T1 j times (0.ltoreq.j.ltoreq.N) in the comparison circuit 13 is obtained by the following equation.

[0186]

[Equation 4] By using such a second-order false alarm probability determination method, in the signal detection apparatus of this embodiment, the false alarm probability according to the number of output signals of the comparison circuit, that is, the number of integrations in the noncoherent integration circuit 10. (Secondary false alarm probability) can be obtained.

(Embodiment 11) FIG. 15 shows claim 1 of the present invention.
3 is a flowchart showing the operation of the secondary false alarm probability determination method in the secondary false alarm probability determination circuit 16 in the signal detection device according to the first embodiment.

The structure of the pulse radar device using the signal detecting device of this embodiment may be any of the structures of the third, fourth and fifth embodiments.

In the secondary false alarm probability determination circuit 16 of this embodiment, among the output signals of the N envelope detection circuits 9, j (0 ≦ j ≦ N) signals are output from the threshold T1 in the comparison circuit. When the number of output signals of the comparison circuit 13 is j, the false alarm probability (second false alarm probability) pfa2, corresponding to the number of output signals of the comparison circuit 13 is determined.
Compute j.

The operation of this embodiment will be described in detail below with reference to the flow chart shown in FIG.

Similar to the tenth embodiment, when a linear detection circuit is used as the envelope detection circuit 9, assuming that the noise generated by the receiver has a Gaussian distribution, the linear detection of a signal containing only noise is performed. Density function p of the output signal r of the instrument
n (r) is represented by Formula (1).

Further, for example, assuming that the desired signal fluctuates according to Rayleigh's probability density function, the probability density function ps (r) of the output signal r of the linear detection circuit of the received signal
Is expressed by the following equation when the S / N ratio of the received signal obtained by the S / N calculation circuit 17 is represented by x.

[0193]

(Equation 5) First, in step S55a, the probability density function p
From n (r), in the comparison circuit 13, the probability pdn1 that the output signal r of the noise-only linear detection circuit exceeds the threshold T1 is obtained from the equation (2), and the process proceeds to step S55b. Further, in step S55c, the probability density function ps
From (r), in the comparison circuit 13, the threshold T
The probability pds1 that the output signal r of the linear detection circuit of the received signal exceeds 1 is obtained by the following equation and the process proceeds to step S55d.

[0194]

(Equation 6) In step S55b, the probability pn, j of exceeding the threshold T1 by j times (0≤j≤N) in the comparison circuit 13 among the output signals of the linear detection circuit of N noise-only signals is obtained from the equation (3). Further, in step S55d, the threshold T1 is j times (0≤j≤N) in the comparison circuit 13 among the output signals of the linear detection circuit of the N received signals.
The probability of exceeding qs, j is obtained by the following equation, and step S55
Go to e.

[0195]

(Equation 7) In step S55e, in the secondary false alarm probability determination circuit 16, the secondary false alarm probability pfa2, j when the number of output signals of the comparison circuit 13 is j is the false alarm probability pfa and the noise only signal is compared by the comparison circuit. 13, the probability qn, j of exceeding the threshold T1 by j times (0≤j≤N) and the received signal by the comparing circuit 13 at the threshold T1 j times (0≤j≤N).
N) The probability of exceeding qs, j is calculated by the following equation.

[0196]

[Equation 8] By using such a secondary false alarm probability determination method, in the signal detection apparatus of this embodiment, the number of output signals of the comparison circuit, that is, the number of integrations in the noncoherent integration circuit 10 and the S / N ratio of the received signal. The false alarm probability (secondary false alarm probability) according to the change in the ratio can be obtained.

By the way, in the above-described first to eleventh embodiments, the case where the present invention is applied to the radar device is described, but it goes without saying that the present invention can also be applied to other devices such as sonar.

[0198]

As described above, according to the signal detecting device of the first feature of the present invention, the predetermined threshold (T1) and the envelope detection circuit output signal are provided in the comparison circuit subsequent to the envelope detection circuit. Of the envelope detection circuit output signal, which is stronger than the threshold (T1) above, is output to the non-coherent integrator circuit, and the envelope detection is stronger than the threshold (T1). Since the non-coherent integrator circuit is designed to perform integration using only the circuit output signal, signals with weaker intensity than the threshold (T1) are eliminated, and only signals with stronger intensity than the threshold (T1) are integrated. Therefore, it is possible to provide a signal detection device capable of improving the detection probability of the target signal.

Further, according to the signal detecting apparatus of the second feature of the present invention, the input signal is classified into frequency components for each band by the A / D conversion circuit and the Fourier transform circuit in the previous stage of the envelope detection circuit. Since it is decided to output and perform the processing after the envelope detection circuit for each band, it is possible to provide a signal detection device capable of improving the detection probability of the target signal even when the received signal is divided and handled for each band. You can

Further, according to the signal detecting device of the third feature of the present invention, a predetermined threshold (T1) is output from the comparison circuit.
The number of output signals of the envelope detection circuit determined to be larger than the above, that is, the number of output signals of the comparison circuit and the value of the threshold (T1) are output to the secondary false alarm probability determination circuit, and the secondary false alarm probability determination circuit is output. In the alarm probability determination circuit, the threshold (T
Based on the number of output signals of the envelope detection circuit determined to be larger than 1), the threshold (T1) value, and the false alarm probability, the false alarm probability (2 Since the next false alarm probability) is calculated and output, it is possible to provide a signal detection device capable of obtaining the false alarm probability according to the change in the number of integrations in the non-coherent integration circuit.

According to the signal detector of the fourth aspect of the present invention, in the S / N calculation circuit, the S / N of the received signal is
The ratio is calculated and output to the secondary false alarm probability determination circuit, and the number of output signals of the envelope detection circuit determined to be larger than the threshold (T1) by the comparison circuit and the predetermined threshold (T1) The value is supplied to the secondary false alarm probability determining circuit, and the secondary false alarm probability determining circuit determines the S / N ratio calculation result and the number of output signals of the envelope detection circuit determined to be larger than the threshold (T1). That is, the false alarm probability (secondary false alarm probability) corresponding to the number of output signals of the comparator circuit is calculated from the number of output signals of the comparator circuit, the threshold (T1) value, and the false alarm probability and output. Therefore, it is possible to provide a signal detection device capable of obtaining the false alarm probability according to the change of the S / N ratio and the change of the number of integrations in the noncoherent integration circuit.

Further, according to the signal detecting device of the fifth feature of the present invention, in the S / N calculation circuit, the S / N of the received signal is
The ratio is calculated and output to the threshold T1 decision circuit, and the threshold T1 decision circuit uses the value of the S / N ratio to optimize the threshold (T1) for each S / N ratio.
), The threshold (T1) is called from the memory that stores the value and output to the comparison circuit. Therefore, even if the S / N ratio changes, the optimum threshold (T1) that always maximizes the detection probability is obtained. ) Can be provided.

According to the sixth aspect of the signal detecting apparatus of the present invention, the output signals of the envelope detection circuit are sequentially input to the comparison circuit, and the comparison circuit outputs a predetermined threshold (T1).
) Is compared with the intensity of the envelope detection circuit output signal, and only the envelope detection circuit output signal having a greater intensity than the threshold (T1) is output to the non-coherent integrator circuit. When the number of output signals of the envelope detection circuit having a higher intensity than (T1), that is, the number of output signals of the comparison circuit becomes a predetermined positive integer N, integration is performed using the output signals of the N comparison circuits. Since the above processing is repeated every time the output signals of the N comparison circuits are obtained, only the envelope detection circuit output signals which are judged to be stronger than the threshold (T1) in the comparison circuit are used. Thus, a signal detection device capable of performing non-coherent integration at an arbitrary number of integrations even when configured to perform integration by a non-coherent integration circuit is provided. Door can be.

Further, according to the signal detecting apparatus of the seventh feature of the present invention, the output signals of the envelope detection circuit are sequentially input to the comparison circuit, and the comparison circuit outputs a predetermined threshold (T1
) Is compared with the intensity of the envelope detection circuit output signal, and only the envelope detection circuit output signal having a greater intensity than the threshold (T1) is output to the non-coherent integrator circuit. When the number of output signals of the envelope detection circuit having a higher intensity than (T1), that is, the number of output signals of the comparison circuit becomes a predetermined positive integer N, integration is performed using the output signals of the N comparison circuits. When the number of output signals of the comparator circuit is N + 1 or more, the number of output signals of the comparator circuit is α (1 ≦ 1).
Every time α <N), the output signals of the past N comparison circuits are used for integration, so that the output signal of the envelope detection circuit that is judged to be stronger than the threshold (T1) in the comparison circuit. Even when the non-coherent integration circuit is configured to perform integration using only the non-coherent integration circuit, it is possible to provide a signal detection device that can perform non-coherent integration with an arbitrary number of integrations and has a short processing time.

According to the signal detector of the eighth feature of the present invention, the number of output signals of the envelope detection circuit is N,
In the non-coherent integrator circuit, among the output signals of the N envelope detection circuits, the comparison circuit judges that the signal strength is larger than the predetermined threshold (T1) j.
Since the integration is performed using the output signals of the (0 ≦ j ≦ N) comparison circuits and this processing is repeated every time the output signals of the N envelope detection circuits are obtained, the threshold ( Even if the configuration is such that only the output signal of the envelope detection circuit that is judged to have a higher intensity than T1) is used to perform integration by the noncoherent integration circuit,
It is possible to provide a signal detection device that can obtain a result of signal detection determination at arbitrary time intervals.

According to the signal detector of the ninth feature of the present invention, the number of output signals of the envelope detection circuit is N,
In the non-coherent integrator circuit, among the output signals of the N envelope detection circuits, the comparison circuit judges that the signal strength is larger than the predetermined threshold (T1) j.
When the number of output signals of the envelope detection circuit is N + 1 or more when integration is performed using the output signals of (0 ≦ j ≦ N) comparison circuits, the number of output signals of the envelope detection circuit is α Pieces (1
Every time ≦ α <N), the integration is performed using the output signal of the comparison circuit that is judged to have a signal strength larger than the threshold (T1) among the output signals of the N envelope detection circuits in the past. Therefore, even if the comparison circuit is configured to perform integration by the non-coherent integration circuit using only the output signal of the envelope detection circuit that is judged to be stronger than the threshold (T1), it is possible It is possible to provide a signal detection device that can obtain the result of signal detection determination at intervals and has a short processing time.

According to the signal detecting device of the tenth feature of the present invention, in the secondary false alarm probability determining circuit, among the output signals of the N envelope detection circuits, j is output in the comparison circuit.
(0.ltoreq.j.ltoreq.N) signals are transmitted at a predetermined threshold (T1
), The false alarm probability and the probability of a noise-only signal exceeding the threshold (T1) j times based on the number j of output signals of the comparator circuit (second false alarm probability). Since the alarm probability) is determined, it is possible to provide a signal detection device capable of obtaining the false alarm probability according to the number of output signals of the comparison circuit, that is, the number of integration times in the noncoherent integration circuit. it can.

Further, according to the signal detecting device of the eleventh feature of the present invention, in the secondary false alarm probability determining circuit, among the output signals of the N envelope detection circuits, j is output in the comparison circuit.
(0.ltoreq.j.ltoreq.N) signals are transmitted at a predetermined threshold (T1
), The probability that the noise-only signal exceeds the threshold (T1) j times and the S / N ratio calculated by the S / N calculation circuit are used to determine the envelope detection circuit of the received signal. The output signal has the above threshold (T1) j
The probability of crossing is calculated, and the false alarm probability (secondary false alarm probability) corresponding to the number j of output signals of the comparison circuit is determined from the result and the false alarm probability. It is possible to provide a signal detection device capable of obtaining the number of false alarm probabilities according to the number, that is, the number of times of integration in the non-coherent integration circuit and the change of the S / N ratio of the received signal.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a pulse radar device using a signal detection device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a pulse radar device using a signal detection device according to a second embodiment of the invention.

FIG. 3 is a configuration diagram of a pulse radar device using a signal detection device according to a third embodiment of the invention.

FIG. 4 is a configuration diagram of a pulse radar device using a signal detection device according to a fourth embodiment of the invention.

FIG. 5 is a configuration diagram of a pulse radar device using a signal detection device according to a fifth embodiment of the invention.

FIG. 6 is a flowchart showing operations in a comparison circuit and a noncoherent integration circuit of the signal detection device according to claim 6 of the present invention.

FIG. 7 is a conceptual diagram showing an output signal of an envelope detection circuit, an output signal of a comparison circuit, and an output signal of a noncoherent integration circuit in the sixth embodiment.

FIG. 8 is a flowchart showing operations in a comparison circuit and a noncoherent integration circuit of the signal detection device according to claim 7 of the present invention.

FIG. 9 is a conceptual diagram showing the output signal of the envelope detection circuit, the output signal of the comparison circuit, and the output signal of the noncoherent integration circuit in the seventh embodiment.

FIG. 10 is a flowchart showing operations in a comparison circuit and a noncoherent integration circuit of the signal detection device according to the eighth aspect of the present invention.

FIG. 11 is a conceptual diagram showing the output signal of the envelope detection circuit, the output signal of the comparison circuit, and the output signal of the noncoherent integration circuit in the eighth embodiment.

FIG. 12 is a flowchart showing operations in a comparison circuit and a noncoherent integration circuit of the signal detection device according to claim 9 of the present invention.

FIG. 13 is a conceptual diagram showing the output signal of the envelope detection circuit, the output signal of the comparison circuit, and the output signal of the noncoherent integration circuit in the ninth embodiment.

FIG. 14 is a flowchart showing the operation of the secondary false alarm probability determining method in the secondary false alarm probability determining circuit in the signal detecting device according to the tenth aspect of the present invention.

FIG. 15 is a flowchart showing the operation of the secondary false alarm probability determining method in the secondary false alarm probability determining circuit in the signal detecting apparatus according to claim 11 of the present invention.

FIG. 16 is a configuration diagram of a pulse radar device using a conventional signal detection device.

[Explanation of symbols]

1 antenna, 2 transmission / reception switching circuit, 3 transmission pulse generation circuit, 4 frequency mixing circuit, 5 reference signal generation circuit, 6 intermediate frequency amplification circuit, 790 degree hybrid circuit, 8a in-phase component phase detection circuit, 8b quadrature component phase detection circuit , 9 envelope detection circuit, 10 non-coherent integration circuit, 11 CFAR detection circuit, 12 display means, 13 comparison circuit, 14 A / D conversion circuit, 15 fast Fourier transform circuit (Fourier transform circuit), 16 secondary false alarm probability Decision circuit, 17 S / N calculation circuit, 18 Threshold T1 decision circuit, 19 memories.

Continuation of the front page (72) Inventor Watanabe ▼ Shoji Satoshi 325 Kamimachiya, Kamakura City, Kanagawa Mitsubishi Electric Corporation Kamakura Factory

Claims (11)

[Claims] 1. An envelope detection circuit, an output signal of the envelope detection circuit and a predetermined threshold (T1) are compared in intensity, and an output of the envelope detection circuit having a higher intensity than the threshold (T1). A signal detection device comprising: a comparison circuit that outputs only a signal; and a noncoherent integration circuit that performs noncoherent integration using an output signal of the comparison circuit. 2. An envelope detection circuit comprising: an A / D conversion circuit for converting a predetermined analog signal into a digital signal; and a Fourier transform circuit for performing a Fourier transform on the output of the A / D conversion circuit. The signal detection device according to claim 1, wherein the output of the Fourier transform circuit is subjected to envelope detection. 3. The number of output signals of the envelope detection circuit determined to be larger than a predetermined threshold (T1) in the comparison circuit, that is, the number of output signals of the comparison circuit, false alarm probability, and the threshold ( 3. A secondary false alarm probability determining circuit for determining the false alarm probability (secondary false alarm probability) for each number of output signals of the comparison circuit based on the value of (T1). The signal detection device described. 4. An S / N calculation circuit for obtaining a signal-to-noise power (S / N) ratio using the output signal of the envelope detection circuit, and the comparison circuit judges that it is larger than a predetermined threshold (T1). The number of output signals of the envelope detection circuit, that is, the number of output signals of the comparison circuit, the false alarm probability, the value of the threshold (T1), and the S /
2. A secondary false alarm probability determination circuit that determines an false alarm probability (secondary false alarm probability) for each number of output signals of the comparison circuit based on the result of the N calculation circuit. Alternatively, the signal detection device described in 2. 5. An S / N calculation circuit for obtaining a signal-to-noise power (S / N) ratio using the output signal of the envelope detection circuit, and an optimum threshold (T1) value for each S / N ratio 3. A stored memory, and a threshold T1 decision circuit for selecting an optimum threshold (T1) value based on the result of the S / N calculation circuit with reference to the memory. 3. The signal detection device according to 3, or 4. 6. The output signal of the envelope detection circuit, wherein the comparison circuit and the non-coherent integrator circuit have a greater strength than a predetermined threshold (T1) in the comparison circuit when N is a predetermined positive integer. , When the number of output signals of the comparison circuit becomes N, N
4. A function for repeating non-coherent integration using output signals of all the comparison circuits every time output signals of N comparison circuits are obtained. 4. The signal detection device according to 4 or 5. 7. The comparison circuit and the noncoherent integration circuit are N + 1 when N is a predetermined positive integer.
When the output signals of the first or more comparison circuits are obtained, α
3. A function to perform integration using output signals of past N comparison circuits each time output signals of (1 ≦ α <N) comparison circuits are obtained. 3,
4. The signal detection device according to 4 or 5. 8. The comparator circuit and the non-coherent integrator circuit, when N is a predetermined positive integer, among the output signals of the N envelope detection circuits, a predetermined threshold (T1) in the comparison circuit. ), A function of repeating non-coherent integration using only the output signals of the envelope detection circuit determined to have a larger intensity each time the output signals of the N envelope detection circuits are obtained. The signal detection device according to claim 1, 2, 3, 4, or 5. 9. The comparison circuit and the noncoherent integration circuit are N + 1 when N is a predetermined positive integer.
When the output signal of the envelope detection circuit more than the number is obtained,
Every time the output signals of α (1 ≦ α <N) envelope detection circuits are obtained, the envelope whose strength is larger than the predetermined threshold (T1) among the output signals of the past N envelope detection circuits. 3. A function for performing non-coherent integration using an output signal of a line detection circuit,
The signal detection device according to 3, 4, or 5. 10. The secondary false alarm probability determination circuit, when N is a predetermined positive integer, selects j (0 ≦ j ≦) from the output signals of the N envelope detection circuits in the comparison circuit. N)
When it is determined that the number of signals is larger than a predetermined threshold (T1), that is, when the number of output signals of the comparison circuit is j, the false alarm probability and the envelope detection of N noise-only signals are detected. Among the output signals of the circuit, the false alarm probability (secondary false alarm probability) corresponding to the number of output signals of the comparator circuit is obtained based on the probability that the threshold (T1) is exceeded j times in the comparator circuit. The signal detection device according to claim 3, 4, 5, 6, 7, 8, or 9. 11. The secondary false alarm probability determining circuit, wherein N is a predetermined positive integer, among the output signals of N envelope detection circuits, j (0 ≦ j ≦) in the output signals of the N envelope detecting circuits. N)
When it is determined that the number of signals is larger than a predetermined threshold (T1), that is, when the number of output signals of the comparison circuit is j, the false alarm probability and the envelope detection of N noise-only signals are detected. Among the output signals of the circuit, the comparison circuit compares the threshold (T1) with the probability of exceeding the threshold (T1) times in the comparison circuit, and the output signal of the envelope detection circuit of N received signals (desired signal + noise). The false alarm probability (secondary false alarm probability) according to the number of output signals of the comparison circuit is obtained based on the probability that the threshold (T1) will be exceeded j times in the circuit. 5,
6. The signal detection device according to 6, 7, 8 or 9.