JP2002181925A - Passive radar apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that, in a conventional radar apparatus, the position of an own station is searched by radio waves in a monostatic radar apparatus whose transmission-reception is performed by the same antenna and that direct waves and reflected waves must be received respectively by separate antennas in order to receive faint reflected waves from a target in the case of a bistatic radar apparatus using radio waves whose transmission factor is unclear. SOLUTION: The direction of the direct waves and that of the reflected waves are estimated by using an ultraresolution algorithm such as MUSIC or the like for a received signal. After that, the direct waves and the reflected waves are separated and extracted from the received signal. Even when transmitted waves are used as the direct waves and even when the direct waves and the reflected waves are received by the same antenna, the distance and the direction of the target can be found, and the position of the own station can not be searched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and specifies a target position such as an azimuth and a distance by using an existing radio wave such as a TV or a radio without performing transmission or synchronization with the transmission device. To a passive radar device.

[0002]

2. Description of the Related Art Conventional radar devices include a monostatic radar in which transmission and reception are performed by the same antenna and a bistatic radar in which a transmission antenna and a reception antenna are arranged at different positions. The transmitting station has a problem that its position is detected by performing transmission.

[0003] Further, signal processing of a normal bistatic radar apparatus requires synchronization of transmission and reception, and a target position cannot be calculated without radio wave data on the transmission side. Further, this point is solved, for example, in Japanese Patent Laid-Open No. 6-148318.
In the case of using a transmission source whose radio wave specification is unknown, as in the bistatic radar device disclosed in Needs to be processed separately. FIG. 11 shows a bistatic radar device disclosed in JP-A-6-148318. In the figure, TX is a transmission source, RX is a receiving device, 31 is an antenna system for receiving a direct wave, 32 is an antenna system for receiving a reflected wave, 33a and 33b are receivers, 34 is a correlation filter, 35 is a characteristic change unit, 36
Is an indicator.

In the bistatic radar device shown in FIG. 11, a radio wave transmitted from a transmission source is reflected on a target and received by a reflection receiving antenna system 32, and at the same time, a direct wave is received by a direct wave receiving antenna system 31. You. The signals received by the direct wave receiving antenna system 31 and the reflected wave receiving antenna 32 are passed through the receivers 33a and 33b, respectively, and subjected to target detection by a filter adapted to the reception-processed transmission wave system. Is displayed. At this time, in order to receive the weak radio wave transmitted from the transmission source, separate antennas for the direct wave and the reflected wave were required.

[0005]

As described above, in a conventional radar apparatus, in the case of a monostatic radar apparatus in which transmission and reception are performed by the same antenna, the position of its own station is detected by a radio wave at the time of transmission. There was a problem that it would.

Further, in a bistatic radar device in which a transmitting station and a receiving station are arranged at different positions, there is a problem that a receiving process cannot be performed for a radar device using a radio wave whose transmission data is unknown. . Furthermore, even when using a radio wave whose transmission data is unknown, it is necessary to receive the direct wave and the reflected wave from the target with separate antennas, which causes a problem that the device becomes large. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. Various types of existing radio waves whose transmission characteristics are unknown are used as transmission waves, and a direct wave and a reflected wave from a target are the same. A passive radar device that can obtain the target distance and azimuth even if it is received by the antenna, and cannot detect the position of its own station.

[0008]

A passive radar device according to the present invention is a radar device independent of a transmission source, and includes a plurality of element antennas for receiving a direct wave from the transmission source and a reflected wave from a target. An antenna device comprising:
A receiving device that performs reception processing of a signal received via the antenna device, an azimuth estimating device that estimates an arrival azimuth of the reflected wave from a received signal output from the receiving device, and the reception based on the estimated azimuth. A signal separation device that separates and extracts the components of the direct wave and the reflected wave from the signal, and performs correlation processing on the extracted direct wave and the reflected wave,
The target position is detected from the result of the correlation processing.

A radar device independent of the transmission source, the antenna device comprising a plurality of element antennas for receiving the direct wave from the transmission source and the reflected wave from the target, and receiving the signal via the antenna device A receiving device that performs a receiving process of the received signal, a direction estimating device that estimates an arrival direction of the reflected wave from a received signal output from the receiving device, and a direct wave and a reflected wave from the received signal based on the estimated direction. And a position correcting device for storing position information of a moving transmission source and / or a moving own station, and correlating the extracted direct wave and reflected wave. , A target is detected from the result of the correlation processing, and the moving transmission source and / or
Alternatively, the detected target position is corrected in accordance with the position information of the moving own station.

Further, the apparatus further includes a radar information correlating device for accumulating target position information detected by the other station, averaging the target position information detected by the other station and the target position information detected by the own station, and performing final processing. This is for calculating target position information.

[0011] Further, the plurality of transmission sources are independent radar devices, each corresponding to a plurality of frequencies,
A plurality of or one antenna device including a plurality of element antennas for receiving a direct wave from each transmission source and a reflected wave from one target, and a plurality of reception devices for performing a reception process of a signal received via each of the antenna devices A plurality of azimuth estimating devices for estimating the direction of arrival of the reflected wave from a received signal output from each of the received signals, and a direct wave and a reflected wave from the plurality of received signals based on the estimated directions. And a plurality of signal separation devices for separating and extracting the components, respectively, and performing target detection using direct waves and reflected waves from a plurality of transmission sources.

A transmitting device for transmitting data to another station, and transmitting an output of the transmitting device to another station;
Further, an antenna device including a plurality of element antennas that receive a direct wave from another station and a reflected wave from a target, a receiving device that performs reception processing of a signal received through the antenna device, and an output signal that is output from the receiving device. A direction estimating device for estimating the direction of arrival of the reflected wave from the received signal, and a signal separating device for separating and extracting components of the direct wave and the reflected wave from the received signal based on the estimated direction, respectively. The transmitted wave from the own station to the other station and the received wave from the other station are made direct waves, and the direct wave and the reflected wave are subjected to correlation processing to detect a target position.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram illustrating a configuration of a passive radar device according to Embodiment 1 of the present invention. In the figure, reference numeral 1a denotes a transmission source such as a broadcasting satellite which is not controlled by its own station or a ground station for broadcasting TV, radio, etc., 2 denotes a target, 3 denotes a direct wave from the transmission source 1a and a reflected wave from the target. , An antenna device composed of a plurality of element antennas for receiving a signal, 4 a receiving device for performing reception processing of a signal input via the antenna device 3, 5 an azimuth estimating device for estimating the azimuth of a received signal, and 6 a receiving device. Device 4
Is a signal separation device that separates and extracts the output signal of the above into a direct wave from the transmission source 1a and a reflected wave from the target, 7 is a correlation processing device that performs a correlation process using the separated direct wave and the reflected wave, and 8 is a correlation processing device. The signal after the correlation processing is integrated and the signal-to-noise ratio (S /
N) is an integration processing device, 9 is a target detection device that detects a target position using the output of the integration processing device 8, and 10 is a display device that displays the detected target position.

Next, the operation will be described. First, the position of the transmission source 1a is determined in advance using the azimuth estimating device 5 of the passive radar device, and does not move. The signal transmitted from the transmission source 1a is received by the antenna device 3 as a direct wave, is reflected by the target 2, and is received by the antenna device 3 as a reflected wave.
The mixed signal of the direct wave and the reflected wave input via the antenna device 3 is received by the receiving device 4 and input to the azimuth estimating device 5. The azimuth estimating device 5 estimates the azimuth of the reflected wave using a super-resolution algorithm such as MUSIC.

For example, as a super-resolution algorithm, MU
The case where the SIC is used will be described. The basic principle of MUSIC is that in an array antenna, a correlation matrix R is calculated from received signals of each element of the array antenna,
And an eigenvector corresponding to each eigenvalue are obtained. Then, the number K of incoming radio waves is estimated from the distribution of the eigenvalue λ, and the eigenvector corresponding to the minimum eigenvalue is calculated. Then, an azimuth evaluation function is obtained from the eigenvectors and the like, and the azimuth evaluation function is scanned for all angles, and the azimuth corresponding to the K peak values is estimated as the arrival azimuth. Therefore, when MUSIC is used, it is necessary to use an array antenna. At this time, a configuration in which a plurality of antennas such as a parabolic antenna or a Yagi antenna are used as element antennas may be used.

After the direction of the reflected wave is estimated by a super-resolution algorithm such as MUSIC, the received signal from the receiving device 4 is output to the signal separating device 6, and the reflected wave and the direct wave in the direction where the target exists are detected. Are separated and extracted.
The extracted direct wave and reflected wave are sent to the correlation processing device 7, and the cross-correlation is calculated. S / N by cross-correlation
Are integrated in the integration processing unit 8 to further improve the S / N ratio. The target detection device 9 detects a target position by using the integrated signal. At this time, the azimuth of the target has already been obtained by the azimuth estimating device 5, and the distance of the target is obtained from the difference in arrival time of the direct wave and the reflected wave to the antenna device 3. The target position information obtained as described above is displayed on the display device 10.

As described above, in the first embodiment, the direction of the direct wave from the transmission source and the direction of the reflected wave from the target are estimated by using a super-resolution algorithm such as MUSIC on the received signal, and then the received signal is directly estimated from the received signal. By separating and extracting waves and reflected waves, the transmission waves of various existing radio waves are used as direct waves,
And even if the direct wave and the reflected wave from the target are received by the same antenna, the distance and direction of the target can be obtained,
Obtain a passive radar device whose position cannot be detected.

Embodiment 2 FIG. In the first embodiment,
Although the case where the position of the transmission source and the own station is fixed has been described, a case where the transmission source and / or the own station moves will be described in the second embodiment.

FIG. 2 is a block diagram showing a configuration of the passive radar device according to the second embodiment. Reference numeral 1b denotes a transmission source that is not controlled by the own station that moves, and 11 denotes a position correction device that stores movement information of the transmission source and / or the own station.

Embodiment 2 relates to the case where the transmission source and / or the own station moves. First, when the transmission source moves, the position of the transmitting station needs to be clear. For example, in the case of an orbit satellite, movement information such as satellite position information and speed is obtained in advance. The same applies when a radar or the like moving on the ground or in the air is used as a transmission source. As shown in FIG. 2, information related to movement such as Doppler shift conversion is processed in the position correction device 11 according to the movement speed of the transmission source, and the target detection device 9 performs the same processing as in Embodiment 1 based on the movement information. The position of the target obtained in the above manner is corrected, and correct target position information is output to the display device 10.

Next, when the own station moves, the movement information of the own station is obtained by GPS or the like, and the movement information is processed using the position correction device 11 as in the case where the transmission source moves. The target position is corrected by the target detecting device 9 and correct target position information is output to the display device 10.

As described above, in the second embodiment, the position correcting device is provided, and even when the transmission source and / or the own station moves, the movement information of the transmission source is obtained in advance and the Doppler due to the movement is obtained. By performing a correction such as shift, similarly to the first embodiment, the target distance can be obtained even when a direct wave from the transmission source and a reflected wave from the target are received by the same antenna, using various existing radio waves as transmission waves. And a heading can be obtained, and a passive radar device in which the position of the own station cannot be detected is obtained.

Embodiment 3 FIG. In the first and second embodiments, the passive radar device that detects the target position information only by the own station has been described. In the third embodiment, however, the passive radar device is networked and the target from a plurality of passive radar devices is detected. In the first and second embodiments, the detection result of the position information of
A passive radar device with higher accuracy than that described above will be described.

FIG. 3 is a block diagram showing the configuration of the passive radar device according to the third embodiment. 21a, 21
b is another radar device networked with its own station by wire, 12 is another radar information correlating device that stores target position information detected by another radar, and 13 is another radar device 21
a, 21b and a local area network.

In the third embodiment, the own station and the other radar apparatuses 21a and 21b are networked, so that not only the position information of the target 2 detected by the own station but also other radar apparatuses 21a and 21b can be obtained.
The position information of target 2 detected by a and 21b is used. The receiving process, the azimuth estimation, and the direct wave from the transmission source 1a and the reflected wave from the target 2 are received by the antenna device 3 where
The configuration is the same as that of the first embodiment until the integration processing is performed by the integration processing device 8 through signal separation and correlation processing.

In addition, the position information of the target 2 received from the other radar devices 21a and 21b via the LAN 13 is stored in the other radar information correlation device 12. Target detection device 9
In addition to detecting the position information of the target 2 using the integration processing result of the integration processing device 8, the detection result of the own station and the other radar devices 21 stored in the other radar information correlation device 12.
The detection results of “a” and “21b” are compared, processing such as averaging or majority decision is performed, and the result is output to the display device 10. Further, the position information of the target 2 calculated by the own station may be transmitted to the other radar devices 21a and 21b via the LAN 13. In that case, the target 2 detected by the target detection device 9
Is output to the other radar devices 21a and 21b via the LAN 13.

In the above, the other radar devices 21a and 21b and the own station are networked by LAN, and information exchange of the position information of the target 2 is performed. However, the network may be formed by a dedicated line or wireless. For example, in the case of wireless
As shown in the block diagram of FIG.
The position information of the target 2 detected by the own station is transmitted to another radar device 21.
c, 21d. The position information of the target 2 output from the target detection device 9 is output by the transmission device 14 to the other radar devices 21c and 21d. On the other hand, the position information of the target 2 sent from the other radar devices 21c and 21d is received by the receiving device 4, output to the other radar information correlation device 12, and stored. At this time, a reflected wave from the target 2 may be received as a direct wave using the transmission signal of the own station and the transmission signals from the other radar devices 21c and 21d, and used for target detection.

Only when wireless communication is used, the position of the own station can be detected. However, even if a direct wave from the transmission source and a reflected wave from the target are received by the same antenna, the target distance and direction can be obtained. , More accurate target detection.

As described above, in the third embodiment, a network is established by wireless or wired communication with another radar apparatus and the own station, and the target position is determined using a plurality of detection results. Obtain a passive radar device that performs detection.

Embodiment 4 In the first embodiment, target position information is detected using only a single transmission source. In the fourth embodiment, a passive radar that detects target position information using a plurality of transmission sources is used. The device will be described.

FIG. 5 is a block diagram showing the configuration of the passive radar device according to the fourth embodiment. 1c and 1d are transmission sources that generate transmission waves of different frequencies, 3a,
3b is an antenna device composed of a plurality of element antennas corresponding to the frequencies of the transmission sources 1c and 1d, respectively, 4a and 4b are receiving devices connected to the antenna devices 3a and 3b, 5a and 5b are receiving devices 4a and 4b, respectively. The azimuth estimating device to which the received signal is input, 6a and 6b are signal separating devices to which the receiving signals of the receiving devices 4a and 4b are input, and 7a and 7b are the correlations to which the output signals of the signal separating devices 6a and 6b are input. The processing devices 8a and 8b are integration processing devices to which the output signals of the correlation processing devices 7a and 7b are input, and 9d detects the position of the target 2 from the processing results of the integration processing devices 8a and 8b, respectively. Determine the position of target 2 by processing such as average or majority decision,
It is a target detection device that outputs to the display device 10.

Next, the operation will be described. The direct wave from the transmission source 1c and the reflected wave from the target 2
a, the signal processing is performed up to the integration processing device 8a in the same manner as in the passive radar device of the first embodiment. Further, the direct wave from the transmission source 1d and the reflected wave from the target 2 are also received by the antenna device 3b, and are processed in the same manner as in the passive radar device of the first embodiment up to the integration processing device 8b. The results of the integration processes of the integration processing devices 8a and 8b are both input to the target detection device 9, and the target detection device 9 detects the position of the target 2 from each integration processing result,
The detection result is compared, processing such as averaging is performed, and the position of target 2 is determined. The determined position information of the target 2 is output to the display device 10 and displayed on the display device 10.

The case where two transmission sources are used has been described above. However, the number of transmission sources may be increased more. In this case, the receiving device, the azimuth estimating device, and the signal What is necessary is just to increase the number of separation devices, correlation processing devices, and integration processing devices. Although the antenna device has been described as being divided into two for convenience of explanation, an antenna device using an array antenna can be used.
One antenna aperture surface may correspond to a plurality of transmission sources. In that case, the area of the antenna aperture surface of the array antenna may be divided according to the number of transmission sources, or an aperture surface corresponding to each transmission source may be secured by using an aperture sharing technique.

As described above, in the fourth embodiment, a plurality of receiving devices, a plurality of azimuth estimating devices, Equipped with a plurality of signal separation devices, a plurality of correlation processing devices, and a plurality of integration processing devices, and performs target detection using transmission waves from a plurality of transmission sources. The direct wave of the target and the reflected wave from the target are received by the same antenna for each transmission source, and the distance and direction of the target can be obtained with higher accuracy.
Obtain a passive radar device whose position cannot be detected.

[0035]

As described above, the passive radar apparatus according to the present invention estimates the azimuth of the direct wave from the transmission source and the direction of the reflected wave from the target using a super-resolution algorithm such as MUSIC. By separating and extracting the direct wave and the reflected wave from the received signal, the transmission wave of various existing radio waves is used as the direct wave, and even if the direct wave and the reflected wave from the target are received by the same antenna, the target distance and The azimuth can be obtained, and the position of the own station cannot be detected.

In addition, even if the transmission source and / or the own station moves, a position correction device is provided to obtain the movement information of the transmission source in advance and to correct the Doppler shift or the like due to the movement. Even if various existing radio waves are used as transmission waves and the direct wave from the transmission source and the reflected wave from the target are received by the same antenna, the distance and direction of the target can be obtained, and the position of the own station cannot be detected. is there.

In addition, since another radar apparatus and the own station are networked by radio or wire, and the position of the target is determined using a plurality of detection results, the direct wave from the transmission source and the reflected wave from the target are the same. The target distance and azimuth can be obtained even when the signal is received by the antenna, and the target can be detected with higher accuracy.

Further, a plurality of or one antenna aperture plane is used for a plurality of transmission sources independent of the own station,
It is equipped with multiple receivers, multiple azimuth estimators, multiple signal separators, multiple correlation processors, and multiple integration processors, and performs target detection using transmission waves from multiple transmission sources. Can be used as transmission waves, direct waves from multiple transmission sources and reflected waves from the target can be received by the same antenna for each transmission source, and the distance and direction of the target can be determined with higher accuracy. The location of the station cannot be detected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a passive radar device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a passive radar device according to a second embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a passive radar device according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a passive radar device according to a third embodiment of the present invention, in a case where a network is formed with another radar device wirelessly.

FIG. 5 is a block diagram illustrating a configuration of a passive radar device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram illustrating a conventional bistatic radar.

[Explanation of symbols]

1a, 1b, 1c, 1d source, 2 goals, 3,
3a, 3b antenna device, 4, 4a, 4b receiving device, 5, 5a, 5b direction estimating device, 6, 6a,
6b signal separation device, 7, 7a, 7b correlation processing device,
8, 8a, 8b Integration processing device, 9a, 9b, 9
c, 9d Target detection device, 10 display device, 11
Position correction device, 12 other radar information correlator,
13 LAN, 21a, 21b other radar devices,
31 antenna system for direct wave reception, 32 antenna system for reflected wave reception, 33a, 33b receiver, 34 correlation filter, 35 characteristic change unit, 36 indicator.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J070 AA02 AC02 AC13 AD01 AD08 AE04 AF02 AH04 AH19 AH50 AK13 AK22 AK28 BA01 BD01 BH01

Claims (5)

[Claims] An antenna device comprising a plurality of element antennas for receiving a direct wave from the transmission source and a reflected wave from a target;
A receiving device that performs reception processing of a signal received via the antenna device, an azimuth estimating device that estimates an arrival azimuth of the reflected wave from a received signal output from the receiving device, and the reception based on the estimated azimuth. A signal separation device that separates and extracts the components of the direct wave and the reflected wave from the signal, and performs correlation processing on the extracted direct wave and the reflected wave,
A passive radar device for detecting a target position from a result of the correlation processing. 2. A radar device independent of a transmission source, comprising: a plurality of element antennas for receiving a direct wave from the transmission source and a reflected wave from a target;
A receiving device that performs reception processing of a signal received via the antenna device, an azimuth estimating device that estimates an arrival azimuth of the reflected wave from a received signal output from the receiving device, and the reception based on the estimated azimuth. A signal separation device that separates and extracts components of a direct wave and a reflected wave from a signal, and a position correction device that stores movement information of a transmission source and / or its own station. A passive radar apparatus which performs a correlation process, detects a target from the result of the correlation process, and corrects the detected position of the target according to the movement information of the transmission source and / or its own station. 3. A radar information correlating device for accumulating target position information detected by another station, averaging the target position information detected by the other station and the target position information detected by the own station, The passive radar device according to claim 1, wherein the target position information is calculated. 4. A plurality of element antennas respectively corresponding to a plurality of frequencies and receiving a direct wave from each of the transmission sources and a reflected wave from one target, respectively. A plurality of or one antenna device, and a plurality of receiving devices that perform reception processing of a signal received via each of the antenna devices, and estimate an arrival direction of the reflected wave from a reception signal output from each of the reception signals. A plurality of azimuth estimating devices, and a plurality of signal separating devices that respectively separate and extract components of a direct wave and a reflected wave from the plurality of received signals based on the respective estimated azimuths. A passive radar device for detecting a target by using a direct wave and a reflected wave from a radar. 5. A transmitting apparatus for transmitting data to another station, a plurality of transmitting apparatuses transmitting an output of the transmitting apparatus to another station, and receiving a direct wave from the other station and a reflected wave from a target. An antenna device composed of element antennas, a receiving device that performs reception processing of a signal received via the antenna device, and an azimuth estimating device that estimates the arrival direction of the reflected wave from a received signal output from the receiving device A signal separating device that separates and extracts components of a direct wave and a reflected wave from the received signal based on the estimated azimuth, respectively, and transmits a transmitted wave from the own station to another station and a received wave from another station. A passive radar device, wherein a direct wave is detected, and a target position is detected by performing a correlation process between the direct wave and the reflected wave.