JPH09159752A - System for automatically detecting moving target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the erroneous alarm issuing ratio of a system for automatically detecting moving target and to improve the detection ratio of the system when the system automatically detects a moving target. SOLUTION: A frequency analyzing section 1 analyzes the frequency of input signals received from an underwater moving target, calculates the frequency component and spectral level of the signals, and outputs the calculated results to an time-change-not- requiring reflected wave eliminating section 2 and the section 2 outputs the signals to a spectral level threshold processing section 3 after eliminating a reverberation component. The section 3 performs a threshold process with the spectral level threshold corresponding to a background noise level and outputs the processed results to a signal length threshold processing section 4. The section 4 discriminates whether the input signals are the same received signal divided by the spectral level threshold process. A Doppler frequency variation threshold processing section 5 calculates the Doppler frequency variation of the input signal and performs a threshold process on the input signal by using a Doppler frequency variation threshold indicating the upper limit of the Doppler frequency by the real moving target and an azimuth threshold processing section 6 integrates the scattered azimuths and directions of an input signal group and outputs the integrated results as a moving target signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving target automatic detection method, and more particularly to a moving target automatic detection method for automatically detecting a moving target using reflected wave data from the target by a transmission pulse of a sound wave or an electromagnetic wave.

[0002]

2. Description of the Related Art Conventionally, this type of automatic detection method of a moving target transmits a pulsed sound wave in water, a pulsed radio wave in the air, and a received signal reflected back from the target. In order to detect the shift of the Doppler frequency including, frequency analysis is performed to obtain the frequency component and spectrum level, and this is compared with the threshold obtained from the background noise level of the received signal after frequency analysis, and the threshold is exceeded. A received signal having a spectral level is detected as a moving target signal.

In the target detection in such an automatic detection system, the false alarm rate (fa) of the rate at which a false signal is judged to be a true signal is determined.
It is one of the important issues to improve the detection rate without increasing the lse alarm rate), and the prior arts described below are known.

For example, as disclosed in Japanese Unexamined Patent Publication No. 4-52584, there is used a technique of removing a transmission reverberation component as an unnecessary reflected wave component causing the false alarm rate in order to reduce the false alarm rate.

FIG. 7 is a block diagram showing a configuration example of a dereverberation unit in the conventional moving target automatic detection method. The speed detection circuit 101 detects its own speed. Next, based on the transmission frequency of the pulse signal and its own speed, the band stop filter control circuit 102 calculates a filter coefficient that constitutes an adaptive filter characteristic for suppressing the reverberation spectrum, and outputs it to the variable band stop filter 103. To do.

Thus, the reverberation of the received signal in which the target signal and the reverberation signal are mixed is blocked by the variable band stop filter 103, and passes through the detection circuit 104 and the gate circuit 105.
At, a target signal in which reverberation is suppressed is extracted by spectrum level threshold processing that determines whether or not a threshold value (threshold) set based on background noise is exceeded.

As described above, although consideration is given to the change of the input signal level and the speed of oneself, dereverberation is ensured. However, after this processing, FFT (Fast) as a frequency analysis method that is normally used subsequently is performed. In the Fourier Transform (Fast Fourier Transform) processing, the correspondence of the spectral level of the Doppler frequency with harmonic frequencies other than the transmission frequency is not particularly considered.

The spectrum level of the harmonic frequency is closely related to the transmission signal waveform. For example, in the case of a rectangular wave, the level is gently lowered as compared with the spectrum of the transmission frequency, and both are level in the time (distance) direction. It shows the characteristic of going down.

Further, as a conventional technique for removing reverberation in the vicinity of the transmission frequency, there is also used a technique for performing threshold processing with all received signals in a certain set range around the transmission frequency as reverberation.

Further, as disclosed in Japanese Patent Laid-Open No. 56-127685, there is also used a technique for reducing false alarms caused by sea surface reverberation.

FIG. 8 is an explanatory view of the conventional operation of removing the reverberation from the sea surface. For detection at a long distance targeting the target signal level such as 8b2, the reverberation level is relatively low and only the target signal can be detected.
In particular, the sea surface reverberation level due to side lobes and the like increases as in 8a, causing false alarms due to sea surface reflection.

In order to eliminate such a false alarm of sea surface reflection, at the time of initial detection, the level of the received signal after transmission is set as shown in the level threshold value 8c at the time of initial detection, and at the second and subsequent detections, the target signal level is set. The received signal level immediately before the signal is used as a threshold, and a signal exceeding such a threshold is output as a target signal. By these processes, the reverberation of the sea surface reflection is removed.

Regarding the calculation of the direction of the moving target, as disclosed in Japanese Patent Laid-Open No. 5-302970,
There is also used a technique of calculating an average value of the reception azimuths of a reception signal group that exceeds the signal level for determining whether or not the signal level is the target azimuth.

[0014]

A method for improving the false alarm rate in the above-described conventional moving target detection method is disclosed in Japanese Patent Laid-Open No. 4-206.
The dereverberation method disclosed in Japanese Patent No. 52584 considers the speed of itself and the change of the input signal level, but the harmonics other than the transmission frequency of the FFT processing result usually used as a frequency analysis method. No consideration is given to the influence of the harmonic spectrum level of the Doppler frequency including the wave frequency.

Therefore, in this conventional dereverberation system, since no consideration is given to the temporal change of the harmonic spectrum other than the above-mentioned transmission frequency, it is attempted to eliminate the false alarm due to the unnecessary harmonic spectrum at a short distance. Attempts to widen the dereverberation band will cause distant targets to enter this rejection band, resulting in undetected target.

Further, if such a removal band is set to be narrow in order to prevent such non-detection of a target at a long distance, an unnecessary harmonic spectrum at a short distance is erroneously detected as a target, resulting in an increase in false alarm rate. Will lead to.

The signal detection method disclosed in Japanese Patent Laid-Open No. 56-127685 is to adaptively detect the sea surface reverberation by automatically correlating the Doppler frequency contained in the detected signal during the detection. Although it is supposed that the detection rate can be improved and the false alarm rate can be reduced by calculating the determination threshold value in signal detection, this detection method simply applies a threshold value to each input of input data and simply Since the signal exceeding the threshold is targeted, all signals exceeding the threshold are detected as targets including noise, which inevitably leads to an increase in false alarm rate.

Regarding the method of calculating the azimuth of the detection target according to Japanese Patent Laid-Open No. 5-302970, in the method of taking the average value of the individual signal detection azimuths, noise spreading in the azimuth direction such as reflected waves from the sea bottom and the sea surface. Is also detected as a target, which inevitably leads to an increase in false alarm rate.

Further, since none of these prior arts pay attention to the influence based on the fluctuation amount of the Doppler frequency, the fluctuation amount of the Doppler frequency is large, and it can be determined that the received signal is not clearly from the moving target. Even a signal may be extracted as a target signal.

The object of the present invention is to solve the above-mentioned problems,
When a moving target is automatically detected from a received signal obtained by transmitting a pulse signal in water or in the air, the frequency analysis result applied to the received signal is wide at a short distance around the transmission frequency and narrower at a longer distance. The unnecessary reflected wave component is removed in such a band, and the moving target is detected by focusing on the temporal continuity of the signal that exceeds the signal determination threshold calculated from the received signal from which the unnecessary reflected wave component is removed, A false alarm is generated by determining whether the target is a true moving target from the amount of temporal Doppler frequency fluctuation, receiving the output signal thus output, and determining whether the target is a moving target based on the azimuth direction spread of the detection signal. An object of the present invention is to provide an automatic detection method of a moving target with a significantly improved rate.

[0021]

In order to achieve the above-mentioned object, the present invention has the following means configuration. That is, the first configuration of the present invention regarding the automatic detection method of the moving target is characterized in that the moving target is automatically detected by processing the input reception signal obtained by transmitting the pulse signal of the sound wave or the electromagnetic wave into the water or the air. A method of automatically detecting a moving target, which comprises the following configurations (a) to (f). (A) A frequency analysis unit for performing frequency analysis on an input reception signal obtained by transmitting the pulse signal to detect a spectrum level for each frequency component. (B) Inputting the frequency analysis result of the frequency analysis unit and inputting a bandwidth. Is a time-variable unnecessary reflected wave elimination process that outputs the received signal from which the unnecessary reflected wave component is eliminated through the elimination band that is changed corresponding to time so that it is wide at a short distance and narrow at a long distance from the transmission frequency. Unit (c) a spectrum level threshold processing unit for extracting a received signal exceeding a spectrum level threshold set based on the background noise level of the received signal output from the time variable unnecessary reflected wave removal processing unit (d) the spectrum level threshold process Received the output of the department,
Signals that are continuously input on the time axis for each frequency component are judged to be received signals by the same moving target, and the signal of the received signal is based on the signal start time and signal end time of this received signal on the time axis. A signal length calculation unit that calculates the length and outputs it as a signal length calculation signal, and a rear part of the signal length calculation signal that is output by this signal length calculation unit include multiple propagation that occurs due to the distance to the moving target and the environmental conditions. A signal long-distance gate set in advance in consideration of the apparent division of the target signal caused by noise is provided, and the other signals included in the signal long-distance gate are regarded as the same received signal, and The signal integration unit that integrates the signal long-distance gate into one set signal and the signal integration unit that has been set in advance in consideration of the assumed length of the moving target and the extension by the signal processing among the signals integrated by the signal integration unit. Signal length threshold processing unit including a signal length determination unit that extracts, as a target candidate signal, a signal included in the signal length range set by the maximum value and the minimum value (e) Output of the signal length threshold processing unit The Doppler frequency fluctuation amount calculation unit that calculates the fluctuation amount of the Doppler frequency included in the target candidate signal, and the fluctuation amount of the Doppler frequency calculated by this Doppler frequency fluctuation amount calculation unit, take into consideration the motion parameters of the assumed moving target. Doppler frequency fluctuation amount threshold value processing unit including a Doppler frequency fluctuation amount determination unit that outputs the target candidate signal as a target signal that does not exceed the Doppler frequency fluctuation upper limit as a Doppler frequency fluctuation amount threshold value that has been preset (f) The Doppler frequency fluctuation Continuity is recognized in the detection direction of the target signal output from the quantity threshold processing unit, and the detection position is within the preset fluctuation range. The target azimuth unifying unit that judges the included signals as received signals from the same target and integrates them, and the azimuth direction spread of the target signal integrated by this target azimuth unifying unit, take into consideration the motion parameters of the assumed moving target. Azimuth threshold processing unit that sends as the movement target signal a signal that does not exceed the preset azimuth range threshold value

A second configuration of the present invention is the same as the first configuration, except that the frequency analysis of the received signal by the frequency analysis unit is performed based on a high-speed Fourier transform process.

Further, in a third configuration of the present invention, in the first or second configuration, the removal target of the time variable unnecessary reflected wave removal processing unit is a reverberation caused by transmission of a pulse signal of a sound wave. It has the configuration described above.

Further, in a fourth configuration of the present invention, in the first or second configuration, the removal target of the time variable unnecessary reflected wave removal processing unit is a clutter generated by the pulse signal transmission of the electromagnetic wave. It has the configuration described above.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION A spectrum level threshold value as a signal determination standard which is obtained by frequency-analyzing an input reception signal obtained by transmitting a pulse signal by a frequency analysis method such as FFT and setting based on the background noise level of the analysis result. Reduction of the false alarm rate for increasing the detection rate is the most important issue in extracting the target signal depending on whether or not the value exceeds.

The false alarm rate is a rate at which a false signal that is not true is judged as a true target signal and a false alarm is issued. The main cause of the false signal is an unnecessary reflected wave. Is mixed in. This unnecessary reflected wave is called reverberation due to reflection from the sea surface and the bottom of the sea mainly in water using pulse signals of sound waves, and is called clutter in the air using pulse signals of electromagnetic waves. The reverberation is very similar though the names are different.

Taking the case of a sound wave as an example, it is caused by a reverberation component due to sea surface reflection near the transmission source where the influence of side lobes is emphasized, a propagation condition governed by the distance to the target and environmental conditions. Due to the apparent dispersion of the received signal from the moving target caused by multiple propagation and noise, the assumed length of the moving target and the extension of the received signal at the signal processing stage, the FF of the received signal
Examples include those caused by harmonic components of the Doppler frequency included in the frequency analysis result using T, and those caused by noise spread in the azimuth direction caused by reflected waves from the seabed and the sea surface.

In the case of electromagnetic waves, there are fixed target clutter due to structures near the transmission source, weather clutter affected by weather, etc., and further, influence of propagation path, influence of Doppler frequency fluctuation, and azimuth direction caused by clutter. Variations and the like are conditions that should be taken into consideration in the same manner as in the case of sound waves.

The present invention is intended to improve the false alarm rate by eliminating various factors that cause the deterioration of false alarms, and unnecessary reflection such as reverberation contained in a received signal corresponding to a short distance and a long distance. A time-variable unnecessary reflected wave removal processing unit that suppresses the wave component, and a moving target received signal is determined based on the time continuity of the spectrum component with respect to the received signal on which the unnecessary reflected wave removal processing is performed, and the signal length is After the calculation, the apparent dispersion of the received signal due to multiple reflections and noise that occur based on the distance to the moving target and the environmental conditions is integrated, and further the length of the moving target and the expansion of the received signal by signal processing (elonga
signal length threshold processing unit that determines the target candidate signal by determining the signal length based on the maximum and minimum values set in consideration of A Doppler frequency fluctuation amount threshold value processing unit that determines the target signal by eliminating the influence, and an azimuth threshold processing unit 6 that further eliminates the azimuth direction decentralization influence from the target signal determined in this way to obtain a true moving target signal. Is provided as an embodiment.

[0030]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, and also exemplifies a case of transmitting a pulse signal by a sound wave to detect a moving target in water. Referring to FIG. 1, in the embodiment of the present invention, a frequency analysis unit 1 that performs a frequency analysis of an input reception signal and a time variable unnecessary reflection wave removal processing unit 2 that performs a dereverberation process as an unnecessary reflection wave component of the reception signal.
A spectrum level threshold processing unit 3 for extracting a spectrum exceeding a threshold value set based on background noise, and a signal length threshold processing unit 4 for selecting a received signal having a correct signal length.
A Doppler frequency fluctuation amount threshold processing unit 5 that eliminates the influence of the received signal due to the Doppler frequency, and an azimuth threshold processing unit 6 that eliminates the influence of the dispersion of the received signal in the azimuth direction.

The signal length threshold processing unit 4 also determines a signal length, a signal length calculating unit 41 for calculating a signal length, a signal integrating unit 42 for unifying received signals expanded by propagation conditions and signal processing. And a signal length determination unit 43 that operates.

The Doppler frequency fluctuation amount threshold processing unit 5 is composed of a Doppler frequency fluctuation amount calculation unit 51 for calculating the Doppler frequency fluctuation amount and a Doppler frequency fluctuation amount judgment unit 52 for judging the validity of the Doppler frequency fluctuation amount. To be done.
The azimuth threshold processing unit 6 includes an azimuth unifying unit 61 that unifies the azimuth direction variances of the same received signal and an azimuth judging unit 62 that judges the true azimuth of the received signal.

FIG. 2 is an explanatory diagram of the operation of the time variable unnecessary reflected wave elimination processing section 2 of FIG. FIG. 3 is an explanatory diagram of the operation of the spectrum level threshold processing unit 3 of FIG. FIG.
It is explanatory drawing of operation | movement of the signal length threshold value process part 4 of FIG. FIG.
FIG. 3 is an explanatory diagram of an operation of the Doppler frequency fluctuation amount threshold value processing unit 5 in FIG. 1. FIG. 6 is an explanatory diagram of the operation of the azimuth threshold processing unit 6 of FIG.

The operation of this embodiment will be described below with reference to FIGS. In the present embodiment, in order to detect a moving target in water or in the air, a pulse signal of a sound wave is transmitted, and an input reception signal is input to the frequency analysis unit 1.

The frequency analyzer 1 uses the received signal F
Frequency analysis is performed by FT processing, the frequency and spectrum level of the received signal are calculated, and the time variable unnecessary reflected wave removal processing unit 2
Output to

The time-variable unnecessary reflection wave removal processing unit 2 removes the reverberation component as the unnecessary reflection wave component from the input received signal. Therefore, the band for removing the reverberation component centering on the transmission frequency is wide at a short distance, and far away. Time-variable dereverberation processing in which the dereverberation band changes with time such that the distance becomes narrower is performed, and the received signal from which reverberation has been removed is output to the spectrum level threshold processing unit 3. This is intended to effectively suppress the reverberation in the vicinity of the transmission source due to the side lobe, which has a higher level and a greater influence at a closer distance.

Referring to FIG. 2, two received signals 2a are shown.
If there is a received signal 2b, the short-distance received signal 2a included in the dereverberation band 2c is deleted, and the received signal 2b outside the dereverberation band 2c is output. The spectrum level threshold processing unit 3 calculates a background noise level from the received signal from which reverberation has been removed, sets a threshold for receiving signal determination based on this background noise level, and sets this as a spectrum level threshold. Then, the received signal exceeding the spectrum level threshold is extracted as a target candidate signal and output to the signal length threshold processing unit 4.

Referring to FIG. 3, the reception signal 3a having a spectrum level threshold value less than 3c is deleted from the reception signals 3a and 3b, and the reception signal 3b having a level exceeding the spectrum level threshold value 3c is output.

The signal length calculation unit 41 of the signal length threshold processing unit 4
Is for a received signal exceeding the input spectrum level threshold, and when the received signal continuously enters on the time axis for each frequency component as shown in the received signal 4b of FIG. The signal length of the received signal is calculated from the start time t1 and the end time t2 of the signal and output to the signal integration unit 42.

The signal integration unit 42 considers the possibility that the target signal resulting from the spectrum level threshold processing is divided into a plurality of pieces and dispersed due to multiple propagation, noise, etc. due to the distance to the target and environmental conditions, If they are divided, they are integrated into one signal as shown in FIG.
As shown in, the previously stored signal long distance gate 4h is set on the time axis from the end position of the received signals 4a, 4c, 4f, etc., and the signal group included in this signal long distance gate 4h is Originally, the signal long distance gate 4h is integrated as the same one derived from the set received signal, the signal length is recalculated for the integrated one, and the signal length determination unit 43
Output to

The signal length determination unit 43 stores in advance the assumed length of the moving target, the maximum value and the minimum value of the signal length of the received signal by the moving target estimated from the expansion of the received signal in the signal processing. , That value is set as the maximum threshold value and the minimum threshold value, and the received signal having the signal length included in the range is extracted as the target candidate signal and output to the Doppler frequency fluctuation amount threshold processing unit 5.

Referring to FIG. 4, among the received signals 4a, 4b and 4c, the minimum signal length threshold value 4
The received signal 4a that is less than d and the received signal 4c that is longer than the maximum signal length threshold 4e are deleted, and only the received signal 4b that is within the range of both thresholds is output.

The received signal 4 as a signal length calculation signal
The received signal 4g included in the signal long distance gate 4h set to f is the same as the received signal 4f
integrated into f.

The Doppler frequency fluctuation amount calculation unit 51 of the Doppler frequency fluctuation amount threshold processing unit 5 calculates the fluctuation amount of the Doppler frequency in the input target signal section and outputs it to the Doppler frequency fluctuation amount determination unit 52.

The Doppler frequency fluctuation amount determining unit 52 stores in advance the maximum value of the Doppler frequency fluctuation amount of the moving target on the basis of the motion data of the assumed moving target, and the like while the transmission signal is hitting the target. Considering the amount of Doppler frequency fluctuation that occurs when the robot moves, only the received signal with the amount of Doppler frequency fluctuation less than the maximum value of the amount of Doppler frequency fluctuation is output as the target signal by the true moving target.

Referring to FIG. 5, of the received signals 5a and 5b, the received signal 5a including the Doppler frequency fluctuation amount 5d exceeding the Doppler frequency fluctuation amount maximum value 5c is deleted, and the Doppler frequency fluctuation amount maximum value is deleted. Only the received signal 5b including the Doppler frequency fluctuation amount 5e of 5c or less is output as the target signal.

The azimuth integrating unit 61 of the azimuth threshold processing unit 6 recognizes continuity in the detected azimuth of the input target signal, and
In order to correct the deviation of the detection position caused by the difference in the received channels, the signals within the detection position fluctuation width stored in advance are integrated as one signal and output to the azimuth determination unit 62. The azimuth determining unit 62 outputs only a signal that is equal to or less than the azimuth range threshold value that is stored in advance as the movement target signal.

Referring to FIG. 6, the received signals 6a and 6
In b and 6c, the detected azimuths are continuous, and since they are both in the azimuth range threshold 6d and the detected position fluctuation range 6e, they are judged to be received signals by the same target, and these signals are integrated. It

Further, the received signals 6f, 6g, 6h, 6i and 6j are continuous because the detected azimuth is continuous and is within the detected position fluctuation width 6e, but the received range 6d is greater than the azimuth range threshold 6d. It is determined that the received signals are not the received signals by the target, and these received signals 6f, 6g, 6h, 6i, 6j are deleted.

Further, the received signals 6k and 6l are judged to be received signals from different moving targets and deleted because the detected azimuths are continuous but exceed the detected position fluctuation width 6e, and the received signals 6k and 6l are also deleted. 6n falls within the detection position fluctuation range 6e, but since it is not azimuthally continuous detection, this is also judged to be a received signal from a different moving target and is deleted.

In this way, it is possible to ensure automatic detection of a moving target with a significantly improved false alarm rate. In the above-described embodiment, the case where the moving target existing in water is automatically detected by transmitting the pulse signal by the sound wave has been described, but the moving target existing in the water is transmitted by the pulse signal by the electromagnetic wave. Even in the case of automatic detection, it is obvious that various clutters corresponding to reverberation can be targeted instead of reverberation and can be similarly performed.

[0052]

As described above, according to the present invention, in the case of automatically detecting a moving target, in addition to the conventional technique, unnecessary reflected waves such as reverberation contained in the received signal are removed, and the signal length and the Doppler frequency change. Detecting a moving target by focusing on the amount and the signal dispersion in the azimuth direction to detect the true target signal, and by adding the integration processing of the same signal originally to detect the moving target. In this case, it is possible to secure a remarkable reduction in false alarm rate and an improvement in detection rate.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of an operation of a time variable unnecessary reflected wave removal processing unit 2 of FIG.

3 is an explanatory diagram of an operation of a spectrum level threshold processing unit 3 of FIG.

4 is an explanatory diagram of an operation of a signal length threshold processing unit 4 in FIG.

5 is an explanatory diagram of an operation of a Doppler frequency fluctuation amount threshold value processing unit 5 in FIG.

FIG. 6 is an explanatory diagram of an operation of the azimuth threshold processing unit 6 in FIG.

FIG. 7 is a block diagram showing a configuration example of a dereverberation unit in a conventional moving target automatic detection method.

FIG. 8 is an explanatory diagram of a conventional sea surface dereverberation operation.

[Explanation of symbols]

 1 frequency analysis unit 2 time variable unnecessary reflected wave removal processing unit 3 spectrum level threshold processing unit 4 signal length threshold processing unit 5 Doppler frequency fluctuation amount threshold processing unit 6 azimuth threshold processing unit 41 signal length calculation unit 42 signal integration unit 43 signal length Judgment unit 51 Doppler frequency fluctuation amount calculation unit 52 Doppler frequency fluctuation amount judgment unit 61 Direction integration unit 62 Direction judgment unit

Claims (4)

[Claims] 1. An automatic moving target, comprising the following configurations, wherein an input received signal obtained by transmitting a pulse signal of a sound wave or an electromagnetic wave into water or air is processed to automatically detect the moving target. Detection method. (A) A frequency analysis unit for performing frequency analysis on an input reception signal obtained by transmitting the pulse signal to detect a spectrum level for each frequency component. (B) Inputting the frequency analysis result of the frequency analysis unit and inputting a bandwidth. Is a time-variable unnecessary reflected wave elimination process that outputs the received signal from which the unnecessary reflected wave component is eliminated through the elimination band that is changed corresponding to time so that it is wide at a short distance and narrow at a long distance from the transmission frequency. Unit (c) a spectrum level threshold processing unit for extracting a received signal exceeding a spectrum level threshold set based on the background noise level of the received signal output from the time variable unnecessary reflected wave removal processing unit (d) the spectrum level threshold process Received the output of the department,
Signals that are continuously input on the time axis for each frequency component are judged to be received signals by the same moving target, and the signal of the received signal is based on the signal start time and signal end time of this received signal on the time axis. A signal length calculation unit that calculates the length and outputs it as a signal length calculation signal, and a rear part of the signal length calculation signal that is output by this signal length calculation unit include multiple propagation that occurs due to the distance to the moving target and the environmental conditions. A signal long-distance gate set in advance in consideration of the apparent division of the target signal caused by noise is provided, and the other signals included in the signal long-distance gate are regarded as the same received signal, and The signal integration unit that integrates the signal long-distance gate into one set signal and the signal integration unit that has been set in advance in consideration of the assumed length of the moving target and the extension by the signal processing among the signals integrated by the signal integration unit. Signal length threshold processing unit including a signal length determination unit that extracts, as a target candidate signal, a signal included in the signal length range set by the maximum value and the minimum value (e) Output of the signal length threshold processing unit The Doppler frequency fluctuation amount calculation unit that calculates the fluctuation amount of the Doppler frequency included in the target candidate signal, and the fluctuation amount of the Doppler frequency calculated by this Doppler frequency fluctuation amount calculation unit, take into consideration the motion parameters of the assumed moving target. Doppler frequency fluctuation amount threshold value processing unit including a Doppler frequency fluctuation amount determination unit that outputs the target candidate signal as a target signal that does not exceed the Doppler frequency fluctuation upper limit as a Doppler frequency fluctuation amount threshold value that has been preset (f) The Doppler frequency fluctuation Continuity is recognized in the detection direction of the target signal output from the quantity threshold processing unit, and the detection position is within the preset fluctuation range. The target azimuth unifying unit that judges the included signals as received signals from the same target and integrates them, and the azimuth direction spread of the target signal integrated by this target azimuth unifying unit, take into consideration the motion parameters of the assumed moving target. Azimuth threshold processing unit that sends as the movement target signal a signal that does not exceed the preset azimuth range threshold value 2. The automatic detection method of a moving target according to claim 1, wherein the frequency analysis of the received signal by the frequency analysis unit is performed based on a high-speed Fourier transform process. 3. The removal target of the time variable unnecessary reflected wave removal processing unit is configured to be reverberation generated by transmission of a pulse signal of a sound wave.
The automatic detection method of the moving target described. 4. The moving target according to claim 1, wherein the removal target of the time-variable unnecessary reflected wave removal processing unit is a clutter generated by the pulse signal transmission of an electromagnetic wave. Automatic detection method.