JP2000111646A - Doppler detecting display method and system thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Doppler detecting display method for enabling an operator to easily and accurately judge whether it is an echo or not. SOLUTION: An echo sounder transmitter array 3 radiates a transmission signal having detecting resolution of a desired Doppler shift, and while a phase matching unit 5 form a directional beam having directivity with every constant azimuth and constant time on the basis of a received signal received by an echo sounder receiver array 4. A replica correlating unit 6 calculates a correlation level with plural replica signals being the same waveform as the transmission signal or a waveform compressed or extended in time with every directional beam to decide a display color and display lightness by a maximum value selected on the basis of the correlation level and a relative speed detected on the basis of the maximum value to display the correlation level in a corresponding position on two-dimensional coordinates in the decided display color and display lightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting a signal from a transmitter array, detecting a reflected signal from a target target from a received signal received by a receiver array, and detecting the presence of the target and determining the position of the target. The present invention relates to a method for displaying an estimated position of a target in a system having an active sonar for estimation.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a system for explaining a flow of a detection process of Doppler shift or the like in a conventional active sonar. The transmission signal generator 21
For example, LFM (Li
near Frequency Modulation) and PCW (Pu
lsed Continuous Wave). Here, the transmission signal transmitted into the sea is an acoustic signal (for example, a sound wave,
And ultrasonic waves). The amplifier 22 amplifies each of the LFM and PCW transmission signals. The transmitter array 23 is L
Each of the FM and PCW transmission signals is transmitted into the sea.

On the other hand, the receiver array 24 receives an underwater acoustic signal while sampling it at predetermined time intervals (hereinafter, this signal is referred to as a received signal). The phase adjuster 25 forms a beam having directivity for each fixed direction based on the received signal. The band-pass filter 26 filters out only the LFM transmission band components transmitted by the transmitter array 23 for each of the formed beams. The normalization processor 28 performs normalization between each beam at each time. The normalized output, which is the normalized result, is transmitted to the signal detector 31 and the display processor 32.

On the other hand, in the band-pass filter 29,
For each of the formed beams, only the transmission band component of the PCW transmitted by the transmitter array 23 is filtered. The frequency analyzer 30 analyzes the frequency of the transmission band component of the filtered PCW. The transmission band component of the PCW whose frequency has been analyzed is transmitted to the signal detector 31 as a frequency analysis output.

[0005] The signal detector 31 compares the output of the normalization process with a preset threshold value, and if it determines that the value exceeds the threshold value, the signal reflected by the target signal (hereinafter referred to as echo). Here, it is a reverberation sound) (this detected echo is called an event). Then, interpolation (reproduction from a discrete signal to a continuous signal) is performed based on the normalization processing output in the vicinity of the azimuth of the event, and the azimuth and the distance are precisely measured. Also, based on the frequency analysis output near the event, the Doppler shift is detected and converted to a relative speed. Further, interpolation is performed based on the normalization processing output in the vicinity of the detected azimuth and relative speed of the event to calculate event information. The azimuth, distance, and relative speed of the echo calculated in this way are transmitted to the display processor 32 as event information.

[0006] The display processor 32 displays the correlation output level in the azimuth and the distance on a screen such as a CRT based on the normalized processing output. The azimuth and distance are represented by position display using two-dimensional coordinates on the screen, and the correlation output level is represented by shading. Further, based on the signal of the event information transmitted from the signal detector 31, the event is displayed on a two-dimensional coordinate by a symbol or the like. When the operator designates an event displayed on the display processor 32 with a cursor or the like, the event information is displayed as numeric data or the like.

The conventional system processes the above-mentioned display based on the acoustic signal received by the receiver array and provides information to the operator. The operator
In addition to the events detected by the system, it is confirmed on the screen whether there is an echo, and a final judgment of echo detection is made.
This is because signal detection is performed mechanically, and echo detection based on only system processing cannot be said to be 100% reliable.

[0008]

However, when an operator attempts to detect an echo other than an event detected by the system on the screen, conventionally, the criterion for determining whether the echo is an echo is a correlation output displayed on the screen. Only the shading of the level. The correlation output level has many effects such as reverberation. Therefore, it is difficult for an operator to accurately determine whether an echo is present and to detect it.

Therefore, it has been desired to realize a Doppler detection display method or the like that enables an operator to easily determine whether an echo is accurate.

[0010]

According to the present invention, there is provided a Doppler detection and display method, comprising: a step of radiating a transmission signal having a desired Doppler shift detection resolution by a transmitting means; Based on the above, a directional beam having directivity is formed for each certain direction, and a Doppler shift caused by a relative speed is created by assuming a plurality of patterns in advance. Calculating a correlation level between the plurality of replica signals, which are expanded waveforms, and the received signal for each directional beam, and calculating between the plurality of replica signals in each directional beam of the received signal received simultaneously. Selecting the one having the maximum value from the plurality of correlation levels obtained, and detecting the relative speed indicated by the replica signal corresponding to the maximum value; Display color based on the display speed based on the relative speed, the display color based on the detected relative speed, and the display brightness based on the maximum value. Displaying a correlation level at a corresponding position on the two-dimensional coordinates in color and display brightness. In the present invention, the transmitting unit transmits a transmission signal having a desired Doppler shift detection resolution. On the other hand, based on the received signal received by the receiving means, a directional beam having directivity is formed at a fixed azimuth and at a fixed time, and a correlation level between the received signal for each beam and a plurality of replica signals is determined. calculate. The maximum value of the correlation levels calculated between the plurality of replica signals is selected for each directional beam at the same time, and the relative speed indicated by the replica signal is detected. A correlation level is displayed at a corresponding position on the two-dimensional coordinates with a color predetermined based on the relative speed and a brightness predetermined based on a maximum value. Since the Doppler shift amount of the echo due to the reflection of the target target is different from the Doppler shift amount of the reverberation, this difference is clearly displayed in color, and the operator can easily determine the echo.

In the Doppler detection and display method according to the present invention, instead of determining the display color based on the detected relative speed, the speed component of the movement of the sonar platform including the transmitting means and the receiving means is detected. Subtracting from the calculated relative speed, determining a display color corresponding to the relative speed after the subtraction, and displaying the correlation level at a corresponding position on the two-dimensional coordinate with the determined display color. In order to eliminate the effect of Doppler shift also caused by the movement of the platform, the velocity component due to the movement of the sonar platform is calculated and subtracted from the detected relative velocity. The display color is determined based on the relative speed after the subtraction, and the correlation level is displayed at the corresponding position on the two-dimensional coordinates by the color.

The Doppler detection and display system according to the present invention has a desired Doppler shift detection resolution.
A transmitter array that emits a transmission signal with an acoustic signal that is a sound wave or an ultrasonic wave, a receiver array that receives an acoustic signal as a reception signal at regular intervals, and a reception array that the receiver array receives. A phasing means for forming a beam having directivity for each fixed direction, and a plurality of patterns of Doppler shifts caused by relative speeds are assumed in advance, and the same waveform or time as a transmission signal created based on the Doppler shifts is used. Replica correlation means for preliminarily holding a plurality of replica signals having a compressed or decompressed waveform and calculating a correlation level between a received signal for each beam and a plurality of replica signals at the same time, and a correlation level calculated by the same replica signal And a plurality of replicas in each directional beam of the received signal received at the same time. Data selection means for selecting a maximum value among a plurality of correlation levels calculated between the signals and a relative speed indicated by a replica signal relating to the maximum value, and a reception signal received simultaneously. In each of the directional beams, a maximum value of a plurality of correlation levels calculated between a plurality of replica signals is selected, and the maximum value is compared with a predetermined threshold value. Signal detection means for detecting, based on the comparison, an echo signal which is a signal reflecting the transmission signal from the target target, and transmitting event information data indicating the azimuth, distance and relative speed of the target target using the detected echo signal as an event And a conversion table in which the display brightness based on the correlation level and the display color based on the relative speed are determined in advance, and the relative speed and the maximum value detected by the data selection means are input. And the display color and the display brightness are determined based on the conversion table, the determined display color and the display brightness are used to display the correlation level at the corresponding position on the two-dimensional coordinates, and further, based on the event information data, Display processing means for displaying the event at a corresponding position on the two-dimensional coordinates. In the present invention, the transmitter array transmits a sound wave or ultrasonic wave transmission signal having a desired Doppler shift detection resolution. On the other hand, the receiver array receives a received signal of a sound wave or an ultrasonic wave at regular intervals, and based on the received signal, the phasing means forms a beam having directivity for each constant direction. Replica correlation means having a replica signal calculates a correlation value between the received signal for each beam at each time and a plurality of replica signals. The normalization means normalizes the correlation value, and the data selector selects the maximum value among the correlation values with a plurality of replica signals for each beam at each time,
The relative speed related to the replica signal at that time is also detected. On the other hand, the signal detector detects an event based on the maximum value among the correlation values with a plurality of replica signals for each beam at each time, and obtains event information as information on the relative speed and position of the event. Is calculated. The display processing means has a conversion table, and when the relative speed and the maximum value detected by the data selection means are input, determines the display color and display brightness based on the conversion table, and determines the determined display color and display brightness. Then, the correlation level is displayed at the corresponding position on the two-dimensional coordinates. Further, based on the event information data, the event is displayed at a corresponding position on the two-dimensional coordinates.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. FIG. 1 shows the first embodiment of the present invention.
FIG. 3 is a block diagram of a system for realizing a Doppler detection display method according to the embodiment. In the figure, reference numeral 1 denotes a transmission signal generator. The transmission signal generator 1 generates, for example, a random signal waveform whose frequency band is limited. 2 is an amplifier. The amplifier 2 amplifies the signal waveform generated by the transmission signal generator 1. 3 is a transmitter array. The transmitter array 3 transmits the amplified signal underwater as a transmission signal (in this embodiment, it is assumed to be an acoustic signal).

Reference numeral 4 denotes a receiver array. Receiver array 4
Receives a signal while sampling an underwater acoustic signal at predetermined time intervals (hereinafter, referred to as time) (hereinafter, a received signal is referred to as a reception signal). 5 is a phase adjuster. The phase adjuster 5
Based on the received signal received by the receiver array 4, a beam having directivity is formed for each fixed direction. 6 is a replica correlator. The replica correlator 6 includes the transmission signal generator 1
Holds the same waveform as the signal waveform generated in step 2 and N replicas that have been compressed (same waveform and shorter wavelength) and expanded (same waveform and longer wavelength) in several stages in time and received as replicas A correlation process with a signal is performed, and a correlation process is performed for each beam at each time (this process can be performed in parallel at each replica). Here, the replica is created based on the amount of change in wavelength due to the Doppler shift of the transmission signal (hereinafter referred to as the Doppler shift amount). The fact that the signal waveform is temporally compressed indicates that the wavelength is shortened, and the relative speed with respect to the target is positive (approaching). In addition, the fact that the signal waveform is elongated in time indicates that the wavelength has become longer,
The relative speed with respect to the target is negative (goes away). 7 is a normalization processor. The normalization processor 7 normalizes the correlation level based on the correlation value calculated by the replica correlator 6. The result of the normalization processing is transmitted to the data selector 8 and the signal detector 9.

The data selector 8 outputs the largest (maximum) data among the correlation values calculated by each replica for each beam at each time based on the transmitted normalization processing output. . Further, the data of the relative velocity represented by the replica corresponding to the maximum value is output for each beam at each time. The signal detector 9 detects an event based on the transmitted normalization processing output. In addition, interpolation is performed based on the normalized processing output near the azimuth and relative speed of the detected event, and the azimuth, distance, and relative speed are precisely measured,
Calculate detailed event information.

FIG. 2 is a diagram showing an example of a display data conversion table. The display data conversion table contains the relative speeds v _{1 to} v
Each of _N is assigned a color. In addition, lightness is assigned according to the level of the correlation value. The display processor 10 has a display data conversion table,
Based on the data of the maximum value and the data of the relative speed for each beam at each time, the display data is generated by assigning the corresponding color and brightness of the display data conversion table. Then, based on the generated display data, the level of the correlation value at the corresponding position (representing the azimuth and distance) on the two-dimensional coordinate screen is determined by the color based on the relative speed and the brightness based on the level of the maximum value. indicate. Further, the events detected by the signal detector 9 are displayed in a superimposed manner by symbols or the like.

The present embodiment transmits a transmission signal having a band-limited random waveform, calculates a correlation value between the received reception signal and a plurality of replica signals, and calculates a correlation value among the plurality of correlation values. The relative speed is detected based on the maximum value. Based on the data of the maximum value, the data of the relative speed, and the display data conversion table, the display of the relative speed by color, the brightness of the maximum value level, and the level of the correlation value are performed, and the echo which is the reflected wave of the target target is displayed. It is intended to be easy to detect. When the target target exists, the target target is displayed with a color corresponding to the relative speed (Doppler shift amount) with respect to the coping target and brightness corresponding to the correlation value. Since the color and the lightness are different from the color and the lightness due to the background noise and the reverberation, it is easy to detect the echo by the target (and, consequently, the target itself and its relative speed).

Next, the processing operation of the system according to the present embodiment will be described in more detail with reference to FIG. The transmission signal generator 1 generates a signal waveform serving as a transmission signal.
The amplifier 2 amplifies the signal waveform, and the transmitter array 3 transmits the signal to the sea as a transmission signal which is an acoustic signal. In the present embodiment, a signal having a random waveform whose frequency band is limited is used as a transmission signal. This signal is a signal for detecting the Doppler shift caused by the relative movement of the target. Therefore, when performing a correlation process between a received signal and a plurality of replicas, it is possible to obtain a received signal that can detect a Doppler shift with a desired resolution.

On the other hand, the receiver array 4 receives an underwater acoustic signal at each time. The phase adjuster 5 forms a beam having directivity in each fixed direction based on the received signal. The replica correlator 6 calculates N replicas based on the change in the wavelength of the transmission signal based on the Doppler shift (hereinafter referred to as the Doppler shift amount) based on the assumed relative speeds v _{1 to} v _N (including the relative speed 0). keeping. When the phasing-processed received signal is input for each beam at each time, the replica correlator 6 performs a correlation process between the received signal waveform and the N replica signal waveforms, and calculates a correlation value. The correlation value is transmitted to the normalization processor 7 at each time as a replica correlation output (two-dimensional data of the Doppler shift amount for each beam).

The normalization processor 7 performs, for example, the following normalization processing, and normalizes the correlation value calculated by performing the correlation processing using the same replica. The process is to determine a certain point (hereinafter referred to as a point of interest), average the correlation values around a certain point around the point of interest (this average is referred to as a representative value), and calculate the difference between the point of interest and the representative value. The value is converted as a relative value at the point of interest. This point of interest is scanned, converted to a relative value, and normalized. As a result, it is possible to calculate the amount of protrusion (this is a relative value) with respect to the value around the point of interest. Although the difference is calculated here, the relative value may be calculated by calculating the attention point / representative value. In addition, for example, a threshold value is set, and a representative value is calculated by defining conditions such as removing an extremely large value. Can be calculated. The normalization processor 7 performs normalization processing for each replica, and outputs normalization processing output data to the data selector 8 and the signal detector 9.

The data selector 8 selects the maximum value among the N correlation values calculated by the N replicas for each beam at each time based on the normalization processing output data. This is selected for each beam at each time and transmitted to the display processor 10 as maximum value data. In addition, the relative speed data corresponding to the replica corresponding to the maximum value is also transmitted to the display processor 10 as relative speed data. The signal detector 9 selects the maximum value among the N correlation values calculated by the N replicas for each beam at each time, and compares the maximum value with a preset threshold value. If the maximum value exceeds the threshold value, the event is determined. Further, interpolation is performed based on the normalized output data in the vicinity of the detected azimuth and relative velocity direction of the event, and event information is calculated in more detail and transmitted to the display processor 10.

The display processor 10 generates display data for displaying the correlation level with the brightness based on the maximum value data and the color based on the relative speed data based on the display data conversion table. Based on the display data, a correlation level is displayed at a corresponding position on the two-dimensional coordinate screen,
The distribution for each color and each brightness is displayed. Also,
Based on the event information, the event detected by the signal detector 9 is superimposed and displayed at a corresponding position on the two-dimensional coordinate screen with a symbol or the like. When the operator designates an event on the screen with a cursor or the like, the event information is displayed in detail by a numeral or the like.

As described above, in the first embodiment, the transmitter array 3 transmits a random waveform whose band is limited as a transmission signal, while the receiver array 4 transmits the received signal received at each time. , The phase adjuster 5 forms a directional beam,
The replica correlator 6 calculates the correlation between the received signal for each beam at each time and N predetermined replicas, and based on the data having the largest correlation, the relative correlation indicated by the replica is calculated. The correlation level is displayed with the brightness based on the speed color and its value. If the sonar platform including the transmitter array 3 and the receiver array 4 is moving, the amount of Doppler shift due to reverberation included in the received signal differs depending on the direction. Therefore, in the present embodiment, the amount of Doppler shift due to reverberation is displayed in a different color depending on the azimuth (a similar color in the distance direction). Furthermore, if the target is moving, its echo will usually be a Doppler shift different from the Doppler shift due to reverberation in that direction. Therefore, the reverberation and the echo are displayed in different colors. Therefore, the operator can easily detect the echo due to the target.

Embodiment 2 FIG. FIG. 3 is a block diagram of a system for realizing the Doppler detection display method according to the second embodiment of the present invention. In the figure, those having the same figure numbers as those in FIG. 1 perform the same operations as those described in the first embodiment, and thus the description thereof will be omitted. 11 is a sonar platform speed compensator. The sonar platform speed corrector 11 performs a speed correction to remove a component of the speed by the sonar platform.

In a sonar platform having a transmitter array 3 and a receiver array, the transmitter array 3 transmits a transmission signal while moving, and the receiver array 4 transmits a reception signal while moving. (Ie, movement of the sonar platform) causes a Doppler shift based on that movement. In the present embodiment, the sonar platform speed corrector 11 removes the speed component of the Doppler shift due to the movement of the sonar platform, and attempts to perform color-based display based on the Doppler shift caused only by the movement of the target target. is there.

Next, the operation of the system according to the present embodiment will be described with reference to FIG. The transmission signal generated by the transmission signal generator 1 is transmitted. On the other hand, the received signal received by the receiver array 4 is cleaned, and the replica correlator 6 performs a correlation process for each beam at each time to perform normalization. The processing during the execution is the same as that described in the first embodiment.

The data selector 8 selects the maximum value of the correlation for each beam at each time, and transmits the data of the maximum value to the sonar platform speed corrector 11. The data of the relative speed represented by the replica of the maximum correlation value is also transmitted to the sonar platform speed corrector 11. The speed represented by the relative speed data is denoted by vi. This includes the velocity component of the sonar platform. Here, it is assumed that the movement of the sonar platform is a uniform linear movement.

Let v be the speed of the sonar platform and θ be the received azimuth. Here, θ is a relative azimuth where the movement direction of the sonar platform is 0 degree. Assuming that the speed of the target target is vi ', vi' is expressed by the following equation (1). vi ′ = vi−vcos θ (1)

The calculated vi 'is transmitted to the display processor 10 again as relative speed data. The display processor 10 assigns a color corresponding to the relative speed data transmitted from the sonar platform speed corrector 11 based on the display data conversion table, and assigns a brightness corresponding to the data of the maximum value to 2 It is displayed at the corresponding position (azimuth and distance) on the dimensional coordinates.

As described above, according to the second embodiment, the sonar platform speed compensator 11
Since the velocity component due to the movement of the sonar platform including the transmitter array 3 and the receiver array 4 is removed, the color due to the amount of Doppler shift of the reverberation is displayed in the same color regardless of the direction. become. If the target is moving, the echo will usually be a Doppler shift different from the Doppler shift due to the reverberation in that direction. Therefore, the reverberation and the echo are displayed in different colors, but the color due to the reverberation does not change depending on the direction, so that the operator can more easily detect the echo due to the target. In addition, since the speed of the movement of the sonar platform is removed and the target target itself is displayed in different colors only, the approach or separation speed of the target can be directly determined.

Embodiment 3 In the above-described embodiment, the transmission array 3 and the reception array 4 are configured as separate ones. However, the present invention is not limited to this, and the transmission array 3 and the reception array 4 may be the same array. It may be constituted as.

[0032]

As described above, according to the present invention, the transmitting means transmits a transmission signal having a desired Doppler shift detection resolution, while the receiving means receives the received signal based on the received signal. Based on the calculated correlation value and the amount of change due to the Doppler shift, the correlation level is displayed at a corresponding position on the two-dimensional coordinates with a predetermined color and brightness,
If the sonar platform including the transmitting means and the receiving means is moving, the Doppler shift due to reverberation included in the received signal differs in each direction, and the Doppler shift due to the echo signal reflecting the transmission signal from the target is reflected. The shift is different from the Doppler shift due to reverberation,
All of these can be displayed in different colors, and can be displayed with brightness based on the level, so that the operator can easily detect the echo due to the target.

Further, according to the present invention, the velocity component due to the movement of the sonar platform generated in each direction is calculated and subtracted from the detected relative velocity to determine the color to be displayed. Are displayed in different colors, and the color due to reverberation does not change depending on the direction, so that the operator can more easily detect the echo due to the target. Further, since the speed of the movement of the sonar platform is eliminated and the color display is performed only by the movement speed of the target target itself, the operator can directly determine the approach or separation speed of the target target.

[Brief description of the drawings]

FIG. 1 is a block diagram of a system for realizing a Doppler detection display method according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a display data conversion table.

FIG. 3 is a block diagram of a system for realizing a Doppler detection display method according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a system for explaining a flow of a detection process of Doppler shift or the like in a conventional active sonar.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission signal generator 2 Amplifier 3 Transmitter array 4 Receiver array 5 Phase adjuster 6 Replica correlator 7 Normalization processor 8 Data selector 9 Signal detector 10 Display processor 11 Sonar platform speed corrector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J083 AA01 AC29 AD04 AD09 AD17 BA02 BA06 BA12 BC01 BC13 BE10 BE18 BE26 CA02 CA12 DA01 EA31 EA46

Claims (6)

[Claims] 1. A wave transmitting means emits a transmission signal, and a wave receiving means determines a correlation level between the transmission signal and the reception signal based on a reception signal received at a predetermined time interval, in a direction and a distance thereof. And a display method using an active sonar for displaying on a two-dimensional coordinate corresponding to: a step in which the transmitting means emits a transmission signal having a desired Doppler shift detection resolution; and a step in which the receiving means receives Based on the signal, a directional beam having directivity is formed for each certain direction, and a Doppler shift caused by a relative velocity is created by assuming a plurality of patterns in advance. Calculating a correlation level between a plurality of replica signals, which are compressed or expanded waveforms, and the received signal for each of the directional beams; For each directional beam of the signal,
Selecting a maximum value among a plurality of correlation levels calculated between the plurality of replica signals, and detecting a relative speed indicated by the replica signal according to the maximum value; and Display brightness based on the level and the display color based on the relative speed are determined in advance, the display color is determined based on the detected relative speed, and the display brightness is determined based on the maximum value, Displaying the correlation level at a corresponding position on a two-dimensional coordinate with the determined display color and display brightness. 2. Instead of determining a display color based on the detected relative velocity, a velocity component of the movement of the sonar platform including the transmitting means and the receiving means is subtracted from the detected relative velocity. The display color corresponding to the relative speed after the
The Doppler detection display method according to claim 1, wherein the correlation level is displayed at a corresponding position on two-dimensional coordinates. 3. In each directional beam of a received signal received at the same time, a maximum value of a plurality of correlation levels calculated between a plurality of replica signals and a predetermined threshold value are compared, Based on the comparison, the target target detects an echo signal that is a signal reflecting the transmission signal,
3. The Doppler detection display method according to claim 1, wherein a symbol is displayed at a corresponding position on the two-dimensional coordinates. 4. The Doppler detection and display method according to claim 1, wherein the transmission signal is a signal having a random waveform whose frequency band is limited. 5. The transmission signal and the reception signal are sound waves or ultrasonic waves.
Doppler detection display method described. 6. A transmitter array that emits the transmission signal with an acoustic signal that is a sound wave or an ultrasonic wave having a desired Doppler shift detection resolution, and receives the acoustic signal as a reception signal at regular intervals. A receiver array, phasing means for forming a beam having directivity in each fixed direction based on a reception signal received by the receiver array, and a plurality of patterns of Doppler shift caused by relative velocity are assumed in advance. , Created based on the Doppler shift, having in advance a plurality of replica signals having the same waveform as the transmission signal or a waveform compressed or expanded in time, the reception signal for each beam and the plurality of replicas at the same time. Replica correlation means for calculating the correlation level with the signal, and normalization processing on the correlation level calculated with the same replica signal And normalization processing means, each directional beam of the received signals received at the same time,
Data selecting means for selecting a maximum value among a plurality of correlation levels calculated between a plurality of replica signals and detecting a relative speed indicated by the replica signal relating to the maximum value; In each directional beam of the received signal
A maximum value is selected from among a plurality of correlation levels calculated between a plurality of replica signals, and the maximum value is compared with a predetermined threshold value. Signal detection means for detecting an echo signal which is a signal reflecting the transmission signal, and transmitting event information data which is the azimuth, distance and relative speed of the target target, using the detected echo signal as an event, and the correlation level A display table based on the relative brightness and the display color based on the relative speed, and based on the conversion table, when the relative speed and the maximum value detected by the data selection unit are input. Determining the display color and the display brightness, and displaying the correlation level at the corresponding position on the two-dimensional coordinates with the determined display color and the display brightness. Display processing means for displaying the event at a corresponding position on two-dimensional coordinates based on the information data.