JP4836928B2 - Pulse Doppler radar device - Google Patents

Description

  The present invention relates to an electronic scanning type pulse Doppler radar apparatus that performs scanning with a high resolution beam.

  A pulse Doppler radar mounted on an aircraft is known as a radar that can obtain a radar visibility downward by cutting the ground surface approaching at the same speed as the own aircraft using the Doppler effect. In particular, those installed in fighters have the ability to distinguish and distinguish aircraft flying at an altitude lower than their own from ground reflected waves. In this type of pulse Doppler radar, an improvement in Doppler frequency resolution is required in order to perform target number determination by a formation flight that is close to the radar distance, azimuth, and elevation resolution. This will be described next.

In the pulse Doppler radar, a received data sequence (distance vs. frequency) can be calculated by performing coherent integration on the received pulse signal sequence (distance vs. time) received by the irradiated beam. At this time, even if multiple targets in the beam exist at the same distance from the radar, if the Doppler frequency components (velocity) of each target are different, multiple targets exist from the amplitude distribution of the received data sequence (distance versus frequency). I understand that. In the case of the amplitude distribution example of the received signal shown in FIG. 4, it is estimated that the bank 2 and the bank 7 have amplitude peaks as different targets. The longer the observation time (irradiation time), the better the frequency resolution. Therefore, the purpose was to improve the Doppler frequency resolution used for determining the number of target aircraft by formation flight close to the radar distance, azimuth and elevation angle resolution. The high-resolution beam is composed of a large number of transmission pulses and has a feature that the irradiation time is long. The irradiation time may be longer in units of orders compared to other search beam and tracking beam specifications.
In the conventional beam control method in electronic scanning pulse Doppler radar, the transmission pulse width, PRT (Pulse Repetition Time; transmission repetition period + reception interval), transmission / reception directivity azimuth, elevation angle, etc. are specified for each beam. Since beam control is complicated and difficult, beam control combining a plurality of beam specifications and beam specification control for each pulse are not performed.

  Regarding the beam control of the electronic scanning pulse Doppler radar, in a radar having a plurality of antenna surfaces, the beam irradiation time is limited while synchronizing the beam PRT and the number of hits on each surface according to the target position. There is a technique (see Patent Document 1, for example).

Japanese Patent Laid-Open No. 9-243741

For the above-described reason, in the conventional pulse Doppler radar device, during the period in which the high resolution beam is applied, it is not possible to scan other beams other than the azimuth / elevation angle at which the high resolution beam is directed. For this reason, when a high-resolution beam is applied, the number of other beams to be applied is reduced, so that the search area is reduced and the tracking target number is reduced. Alternatively, there is a problem that the entire beam scanning time becomes long (decrease in data rate). The higher the Doppler frequency resolution is obtained, the longer the beam irradiation is required, and the greater the influence on the radar system.
Further, the beam control method described in Patent Document 1 sets an upper limit value of the irradiation time of the tracking beam according to the position of the tracking target, thereby performing a PRF synchronization process between the antenna surfaces with respect to the short-range target. In this invention, the beam irradiation time is not increased more than necessary and the number of short-distance targets that cannot be tracked due to PRF synchronization processing with the long-distance target is reduced. It is different from the beam control method.

  The present invention has been made to solve the above problems, and an object of the present invention is to obtain a pulse Doppler radar device that can scan a high resolution beam and other beams in parallel.

The pulse Doppler radar apparatus according to the present invention is an electronic scanning type pulse Doppler radar apparatus that performs scanning with a high resolution beam that requires a long irradiation time. in the interval, PR T low resolution one other search beam requiring shorter irradiation times than high-resolution beam, is also properly, low resolution one other tracking beam requiring shorter irradiation times than the high-resolution beam by interrupting the PRT, and high resolution beam, other search beam, it is also properly, is obtained so as to scan in parallel other tracking beam.

According to the present invention, within the time range caused by the extension of the PRT high resolution beam, also it is properly PR T other search beam by interrupting the PRT tracking beam, parallel high-resolution beams and other beam since so as to scan Te, reduced small also properly the search region becomes possible to prevent decrease in the number of tracked targets, and a reduction in the data rate.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a functional configuration of an electronic scanning type pulse Doppler radar apparatus according to each embodiment 1 of the present invention.
Based on the beam control information from the beam control unit 16, the transmission unit 11 outputs transmission pulses of the high resolution beam and other search and / or tracking beams to the antenna unit 12 via the circulator 10 for each PRT. The antenna unit 12 emits a transmission pulse to the space at the timing output from the transmission unit 11, receives a reception pulse from the target, and outputs it to the reception unit 13 via the circulator 10. The reception unit 13 performs reception processing of reception pulse signals of the high resolution beam and other search / tracking beams, and outputs the reception signal to the signal processing unit 14. The signal processing unit 14 performs target detection processing such as S / N improvement and quantization on the reception signal given from the reception unit 13, acquires target position information, and gives the target position information to the tracking processing unit 15. The tracking processing unit 15 estimates target motion information based on the target position information given from the signal processing unit 14, and manages and updates the track information 17. The beam control unit 16 creates beam control information including the specifications and timing of the beam to be applied, based on the track information 17 managed and updated by the tracking processing unit 15 and a preset search beam schedule. Output to the transmitter 11.
The above is the same as the general configuration of the pulse Doppler radar apparatus, but the beam control of the present invention described below is performed by beam control information set by the beam control unit 16.

FIG. 2 is a time chart showing the beam application timing (b) according to the first embodiment and the conventional beam application timing (a). Here, the PRT of the high resolution beam is A seconds, the number of transmission pulses is M, the search beam PRT is B seconds, the number of transmission pulses is N, the tracking beam PRT is C seconds, and the number of transmission pulses is O. .
In the conventional system shown in FIG. 2A, if the PRT of a high-resolution beam is A seconds and the number of transmission pulses is M, another beam cannot be irradiated for a time of A × M seconds. On the other hand, in the system of the first embodiment shown in FIG. 2B, the PRT of the high resolution beam is extended to D seconds, and the search beam PRT is interrupted in a section of DA (> B or C) seconds. Since the number of pulses of the search beam is smaller than that of the high-resolution beam (M> N or O), when the search beam irradiation ends, the search beam PRT or the target is continued in the section D-A. If so, the tracking beam PRT is interrupted.
By setting the beam application timing in this way, the irradiation completion time of the high resolution beam extends to D × M seconds, but the search beam or the tracking beam can be scanned in parallel with the high resolution beam.

  As described above, according to the first embodiment, the PRT of the high-resolution beam that requires a long irradiation time is extended from the originally required section, and the PRTs of other tracking beams and search beams are set in the extended section. Since the high-resolution beam and the tracking beam are scanned in parallel, the search area, the tracking target number, and the data rate can be prevented from being reduced. In the above example, the other beam that interrupts the PRT in the extended section is the tracking beam and the search beam, but only one of the beams may be applied.

Embodiment 2. FIG.
FIG. 3 is a time chart showing beam application timing according to Embodiment 2 of the present invention. Here, the PRT of the high resolution beam is A seconds, the number of transmission pulses is M, the search beam PRT is B seconds, the number of transmission pulses is N, the tracking beam PRT is C seconds, and the number of transmission pulses is O. .
In the case of the second embodiment, the PRT of the high resolution beam is extended to E seconds, and the PRT of another high resolution beam, search beam or tracking beam is interrupted in the section EA (> A, B or C). . By setting the beam application timing in this way, it is possible to scan other search beams or tracking beams in parallel while applying multiple high resolution beams when there are multiple wakes that are the targets of aircraft number determination. It becomes.

  As described above, according to the second embodiment, the PRT of a high-resolution beam that requires a long irradiation time is extended from the originally required section, and the other high-resolution beam PRTs and other PRTs are included in the extended section. Since the search beam and / or tracking beam PRT is interrupted and the high resolution beam, another high resolution beam, and another search beam and / or tracking beam are scanned in parallel, the search area is reduced, the tracking target It enables the application of high resolution beams to multiple targets while preventing a reduction in number and data rate.

It is a block diagram which shows the function structure of the pulse Doppler radar apparatus of the electronic scanning system which concerns on each Embodiment 1 of this invention. It is a time chart which shows the beam application timing by Embodiment 1 of this invention, and the beam application timing of a conventional system. It is a time chart which shows the beam application timing by Embodiment 2 of this invention. It is explanatory drawing which shows the example of amplitude distribution of the received signal in a pulse Doppler radar.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Transmission part, 12 Antenna part, 13 Reception part, 14 Signal processing part, 15 Tracking processing part, 16 Beam control part, 17 Track information.

Claims (1)

In an electronic scanning pulse Doppler radar apparatus that scans with a high-resolution beam that requires a long irradiation time, the PRT of the high-resolution beam is extended from the originally required section, and the high-resolution beam is included in the extended section. also requires a short irradiation time PR T low resolution one other search beam, is also properly, by interrupting the PRT low resolution one other tracking beam requiring shorter irradiation times than the high-resolution beam, wherein and high resolution beam, the other search beam, is also properly, the pulse Doppler radar device is characterized in that so as to scan in parallel the other tracking beam.

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