JP2010117332A - Bistatic radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform position orientation of a target by a reception side radar device wherein a specification table which is a candidate of a pulse specification is known, by utilizing the fact that a transmission radio wave has a different pulse specification according to an orientation azimuth and an orientation distance. <P>SOLUTION: This device includes a transmission side radar device; and a reception side radar device positioned separately therefrom, for receiving a transmission radio wave. The transmission radio wave has a different pulse specification including a pulse repeating frequency, a pulse width and the number of bits according to the orientation azimuth and the orientation distance, and the specification table which is the candidate of the pulse specification is known on the reception side radar device side, and the position orientation of the target is performed by utilizing the fact that the pulse specification depends on the orientation azimuth and a distance range of the transmission radio wave. In this case, the pulse specification is analyzed from a direct wave signal, and a replica of a transmission pulse is generated and utilized for mutual correlation calculation, to thereby maintain pulse compression efficiency. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bistatic radar apparatus that detects a target by using a radar apparatus on a transmission side and a reception side that are separated from each other.

  FIG. 3 is a configuration diagram of a general bistatic radar apparatus, in which a transmission radio wave is transmitted from a transmission antenna 2 connected to the transmitter 1 of the transmission-side radar apparatus. The reception-side radar device 10 that receives the transmission radio wave includes a first reception antenna 11 and a first detection unit 12 for receiving a direct wave that is a signal directly propagating from the transmitter 1 to the reception-side radar device 10. The second reception antenna 21 and the second detection means 22 for receiving the scattered wave that is a signal in which the transmission radio wave is scattered by the target 30 such as an aircraft, the cross-correlation calculation means 13, and the delay time estimation means 14 It is equipped with. In general, an existing radar station is used as the transmission-side radar apparatus.

  Then, the target 30 is determined by detecting the arrival time difference between the direct wave and the scattered wave by the receiving-side radar device 10. One method is to search for the peak of the absolute value after calculating the cross-correlation between the detection signals of the direct wave and the scattered wave by the cross-correlation calculating means 13 and performing pulse compression on the arrival time difference.

In the conventional apparatus of FIG. 3, the distance between the transmission-side radar apparatus and the target is R ₁ , the distance between the target-reception-side radar apparatus is R ₂ , the distance R between the transmission-side radar apparatus and the reception-side radar apparatus, direct waves and scattering When the wave arrival time difference is t, the following formula (1)
R ₁ + R ₂ −R = ct (where c is the speed of light) (1)
The relationship is established. Therefore, it can be said that the target exists on an ellipse with R ₁ + R ₂ = ct + R (constant) from the arrival time difference t between the direct wave and the scattered wave.

  By the way, in the conventional method of calculating the cross-correlation between the direct wave and the scattered wave, there is a problem that the compression efficiency of the pulse compression is influenced by the reception quality of the direct wave.

  In addition, when performing coherent integration of the pulse that is the result of cross-correlation calculation, it is necessary to perform integration over the entire range corresponding to the pulse repetition period of the transmission pulse (detection signal of the transmission radio wave) and search for the target. There was a problem of excessive load.

  The present invention has been made in recognition of such a situation, and the first object of the present invention is that the transmission radio wave has different pulse specifications including the pulse repetition frequency, the pulse width, and the number of hits depending on the directional direction and the directional distance. In view of the above, when performing positioning of a target in a receiving-side radar device that has a known specification table that is a candidate for the pulse specification (has a specification table), the pulse specification of the transmission radio wave is determined. An object of the present invention is to provide a bistatic radar apparatus that can estimate the approximate range where the target exists by analyzing and using it, and improve the target detection sensitivity and reduce the calculation load.

  The second object of the present invention is to analyze the pulse parameters of the transmitted radio wave from the received direct wave signal and create a replica of the transmitted pulse without noise, thereby maintaining the efficiency of pulse compression and enabling highly sensitive target detection. An object of the present invention is to provide a possible bistatic radar device.

  A third object of the present invention is to provide a bistatic radar device capable of realizing a low calculation load by limiting the target search processing range in the distance and azimuth directions using the analysis result of the pulse specifications of the transmission radio wave. There is to do.

  Other objects and novel features of the present invention will be clarified in embodiments described later.

In order to achieve the above object, a bistatic radar device according to an aspect of the present invention includes a transmission-side radar device and a transmission radio wave transmitted from the transmission-side radar device at a position separated from the transmission-side radar device. In a configuration comprising a receiving-side radar device for receiving
The transmission radio wave has different pulse specifications including the pulse repetition frequency, the pulse width, and the number of hits depending on the directional direction and the directional distance,
A specification table that is a candidate for the pulse specification is known on the receiving radar device side,
The position of the target is determined by utilizing the fact that the pulse specifications depend on the directivity and distance range of the transmission radio wave.

  In the bistatic radar device according to the aspect, the pulse specification of the direct wave signal, which is a signal directly propagated from the transmission-side radar device to the reception-side radar device, included in the reception signal received by the reception-side radar device is analyzed. Then, a replica of a transmission pulse is created by comparing with known pulse specifications of the transmission radio wave, and a cross-correlation calculation between the replica and a scattered wave signal that is a signal obtained by scattering the transmission radio wave at a target is performed. It is good also as a structure which carries out pulse compression by.

  The bistatic radar device according to the aspect may be configured to improve the signal-to-noise ratio by performing coherent integration of a cross-correlation calculation result using the pulse specifications of the transmission radio wave estimated by collating the pulse specifications.

  In the bistatic radar device of the above aspect, the range processing range of the coherent integration may be limited by a target orientation range corresponding to the estimated pulse specifications to reduce a calculation load.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the bistatic radar apparatus of the present invention, the transmitted radio wave is a candidate for the pulse specifications in view of the fact that the pulse specifications including the pulse repetition frequency, the pulse width, and the number of hits differ depending on the pointing direction and the pointing distance. When the target position is determined by the receiving radar device having the specification table (having the specification table), the pulse specification of the transmission radio wave is analyzed and used to It is possible to estimate the approximate range that exists and to improve the target detection sensitivity and reduce the calculation load. Further, when the pulse specifications are analyzed from the received direct wave signal and a replica of the transmission pulse without noise is generated and used for the cross-correlation calculation, the efficiency of pulse compression can be maintained. Further, when the target search processing in the distance and azimuth direction is limited using the analyzed pulse specifications, a low calculation load can be realized.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a receiving-side radar device of a bistatic radar device that estimates pulse specifications and uses a replica of a transmission pulse. Reference numeral 31 is a reception antenna, 32 is a detection means, 33 is a cross-correlation calculation means, and 34 is a delay time estimation means, which may have the same configuration as the conventional apparatus. 35 is direct wave extracting means, 36 is pulse specification estimating means, 37 is replica creating means, and 38 is coherent integrating means. The transmitter and target of the transmission-side radar apparatus shown in FIG. 3 are not shown.

  A direct wave that is a transmission radio wave directly propagated from a transmitter of a transmission-side radar device (which can use an existing radar station) to a reception-side radar device, and a scattered wave that is a signal in which the transmission radio wave is scattered by a target such as an aircraft Is received by the reception antenna 31 and a reception signal including a direct wave and a scattered wave component is input to the detection means 32 and detected there. The direct wave extracting means 35 is a means for extracting a direct wave signal from the received signal after detection, and the pulse specification estimating means 36 is a pulse specification (pulse repetition frequency (pulse interval frequency) of the transmission radio wave from the extracted direct wave signal. A reciprocal number), a pulse width and a hit number (including the number of pulses transmitted in the same direction). The replica creation means 37 is a means for creating a replica of a direct wave signal (transmission pulse) from the pulse specifications of the transmission radio wave estimated by the pulse specification estimation means 36. The cross-correlation calculation means 33 calculates the cross-correlation between the received signal after detection and the replica of the direct wave signal (transmission pulse). The coherent integration unit 38 receives the estimated pulse specification signal from the pulse specification estimation unit 36, and considers the range (distance and azimuth) where the target may exist from the pulse specification, and the processing range. Is a means for coherent integration of the cross-correlation calculation results.

  The operation will be described with reference to the flowchart of FIG. After the received signal is detected by the detection means 32, the direct wave extraction means 35 detects a pulse exceeding the threshold value with respect to the absolute value of the detection signal. The threshold value is determined in consideration of the effective radiant power of the transmitter of the transmission side radar device and the distance between the transmission and reception side radar devices.

  The pulse width and pulse interval are detected by the pulse specification estimation means 36 for the detected pulse. In addition, the number of hits is calculated by counting the number of pulses with a constant pulse interval for successive pulse trains. Then, based on the detected pulse width, pulse interval, and number of hits, it is checked against the specification table, and the closest pulse specification is estimated as the pulse specification of the direct wave. Since the specification table which is a candidate for the pulse specification of the transmitter is already known on the receiving radar device side, this verification is possible.

  Based on the estimated pulse specifications, a replica of a direct wave signal (a transmission wave detected, that is, a transmission pulse) is created by the replica creation means 37.

  The cross-correlation calculation unit 33 performs cross-correlation calculation on the received signal after detection and the replica of the direct wave signal.

  The transmission radio wave transmitted by the transmission-side radar device is estimated because the pulse repetition frequency (reciprocal of the pulse interval), the pulse width, and the number of hits differ depending on the three-dimensional directivity (azimuth angle and elevation angle) and directivity distance. Since the range of the target in which the transmission-side radar apparatus is directed is determined from the pulse specifications, the coherent integration of the cross-correlation result is performed only within this range.

Then, the delay time estimation means 34 estimates the delay time from the difference between the reception times of the direct wave and the scattered wave. From the relationship of the formula (1), it can be said that the target exists on an ellipse with R ₁ + R ₂ = ct + R (constant) from the arrival time difference t between the direct wave and the scattered wave. Further, a range range where the target directed by the transmission-side radar apparatus exists is obtained from the estimated pulse specifications, and the target position can be determined by narrowing down to the range range.

  According to the present embodiment, the following effects can be achieved.

(1) A specification table that is a candidate for the pulse specification, considering that the transmission radio wave from the transmission-side radar device has different pulse specifications including the pulse repetition frequency, the pulse width, and the number of hits depending on the pointing direction and the pointing distance. When the position of a target is determined by a receiving-side radar apparatus that has a known (having a specification table), by analyzing and using the pulse specifications of the transmission radio wave, the existence of the target It is possible to improve the target detection sensitivity and reduce the calculation load.

(2) Analyzing pulse specifications from the received direct wave signal, creating a replica of the transmitted pulse without noise and using it for cross-correlation calculations, eliminating the effects of noise components contained in the direct wave and pulse compression Can maintain efficiency.

(3) Utilizing the fact that the pulse specifications of the transmission radio wave transmitted by the transmission-side radar device are changed by the distance and direction from the transmission-side radar device of the target that the radar device is or is trying to locate, There is an effect of reducing the calculation load by limiting the processing range of the coherent integration of the correlation processing result. In addition, since coherent integration can be performed using the estimated pulse specifications, it is possible to improve the signal-to-noise ratio of the received signal.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way.

It is a block diagram which shows embodiment of the bistatic radar apparatus which concerns on this invention. It is a flowchart which shows operation | movement description of embodiment of this invention. It is a block diagram which shows the conventional bistatic radar apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmitter 10 Receiving side radar device 11, 21, 31 Reception antenna
12, 22, 32 Detection means
13, 33 Cross-correlation calculation means 14, 34 Delay time estimation means
35 Direct wave extraction means 36 Pulse specification estimation means 37 Replica creation means 38 Coherent integration means

Claims (4)

In a bistatic radar apparatus comprising: a transmission-side radar apparatus; and a reception-side radar apparatus that is located at a position separated from the transmission-side radar apparatus and that receives a transmission radio wave transmitted from the transmission-side radar apparatus.
The transmission radio wave has different pulse specifications including the pulse repetition frequency, the pulse width, and the number of hits depending on the directional direction and the directional distance,
A specification table that is a candidate for the pulse specification is known on the receiving radar device side,
A bistatic radar apparatus, wherein a target position is determined by utilizing the fact that the pulse specifications depend on a directivity direction and a distance range of the transmission radio wave.   Analyzing pulse specifications of a direct wave signal, which is a signal directly propagated from the transmission side radar device to the reception side radar device, included in the reception signal received by the reception side radar device, The pulse compression is performed by creating a replica of a transmission pulse by collating with a pulse specification, and performing a cross-correlation calculation between the replica and a scattered wave signal that is a signal obtained by scattering the transmission radio wave at a target. Bistatic radar device.   3. The bistatic radar device according to claim 2, wherein the pulse specifications of the transmission radio wave estimated by collating the pulse specifications are used to improve the signal-to-noise ratio by performing coherent integration of the cross-correlation result.   4. The bistatic radar device according to claim 3, wherein a range processing range of the coherent integration is limited by a target orientation range corresponding to the estimated pulse data to reduce a calculation load.

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