JP2674397B2 - Radar equipment - Google Patents

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 more particularly to a multifunctional three-dimensional radar device having an active phased array antenna.

[0002]

2. Description of the Related Art In recent years, with the remarkable development of semiconductors, active phased array radars having a structure in which solid-state transceiver modules are arranged in one-to-one correspondence with antenna elements are being developed. In this active phased array radar, the beam is synthesized by controlling the amplitude and the phase of the microwave for each antenna element, so that the beam having a relatively high degree of freedom in the direction and the directional characteristics is formed depending on the control contents of the amplitude and the phase. can do.

By controlling the amplitude and phase, the azimuth and elevation can be adjusted to 2
A radar system that electronically forms and scans a beam in a three-dimensional space is called a two-dimensional electronic scanning system. By causing a computer to perform such beam scanning control, various functions such as adaptive beam scanning and transmission energy control can be realized in the radar in addition to the basic functions of the conventional three-dimensional radar such as search and tracking. The evolution from functional radar to multi-functional radar can be achieved.

Incidentally, adaptive beam scanning means that instead of scanning the beam regularly in accordance with the mechanical rotation of the antenna, the adaptive beam scanning responds to changes in the target detection situation and flight direction / speed.
It is designed to improve the detection performance and tracking performance by irradiating the beam in the required direction when needed. In addition, transmission energy control is to increase the number of microwave irradiations (hits) to irradiate these existing areas at once in order to suppress clutter or interfering waves and improve target detection performance in them. Then, the target-to-clutter power ratio (S / C ratio) and the target-to-interference signal power ratio (S / C) are processed by signal processing.
J ratio) is improved.

With the practical use of the functional radar as described above, the performance of the radar for the purpose of early warning is being dramatically improved. However, the radars currently in practical use are beyond the scope of remote sensing for detecting and tracking an intrusion target. That is, the basic functions of the radar such as search, detection and tracking have been dramatically improved, but the ultimate function of the remote sensing device, which is identification, has not been put to practical use in the radar device.

[0006] A radar apparatus that employs an active phased array, which is currently in practical use, is provided with a transmitter / receiver called a T / R module (transmission / reception module) for each antenna element, and a beam is formed and scanned under the control of a computer. Searching, detecting, and tracking are performed by means of, and the configuration is basically as shown in FIG. That is, in FIG. 3, generally, N element antennas 1
01 to 10N are connected to the T / R modules in a one-to-one manner. Then, the microwave signal supplied from the T / R module is radiated into space during transmission, and the received microwave signal is output to the T / R module during reception.

For beam formation, the beam controller 800 indicates the beam forming direction, and in response to this, the antenna controller 4
This is performed by transmitting the amount of microwave rotation phase (phase shift) and the amount of power attenuation to the N T / R modules 201 to 20N. In the T / R module 201, when receiving these control signals from the antenna controller 410, the phase shift amount and the attenuation amount are instructed to the transmission circuit 211 at the time of transmission and to the reception circuit 221 at the time of reception.

The transmission circuit 211 includes an excitation pulse generator 30.
The microwave signal distributed from 0 is subjected to phase / amplitude modulation as instructed and output to the element antenna 101 via the circulator 231. Receiver circuit 221
Is the element antenna 101 through the circulator 231.
The received signal input from the
After the amplitude modulation, it outputs to the beam combiner 400.

The beam combiner 400 combines the phase-amplitude-modulated microwave signals from the N element antennas 101 to 10N. The combined microwave signal is output to the mixer 5
At 00, the signal is converted into a predetermined intermediate frequency signal, and at the filter 511, only the signal within the reception band defined by the design passes. The in-band received signal that has passed is subjected to phase detection in the phase detector 521 based on the reference signal.
Then, after being converted into a digital signal by the A / D converter 601, it is compressed by correlation processing in the pulse compressor 631 and shaped into a narrow pulse. The signal processor 640 removes unnecessary signals such as clutter and detects target signals. The tracking data processor 700 also performs tracking processing on the detected target signal and displays the result on the display 710.

The beam controller 800 performs control for forming a search beam on the basis of a beam scanning program prepared in advance, and, in accordance with a request from the tracking data processor 700, an adaptive tracking beam corresponding to a target flight. The control for forming is performed in real time. Further, the timing controller 810 supplies a timing signal to each device constituting the radar device according to an instruction from the beam controller 800, and also transmits a transmission pulse width to the pulse expander 320 and the pulse compressor 631. To function.

[0011]

The function required for the next generation radar is identification. In general, in order to identify a target from a reflection signal acquired by the radar, it is essential for the radar to realize a sufficiently small resolution with respect to the physical size of the target. 3D radar
It has three resolutions: distance resolution, azimuth resolution, and altitude resolution. Of these, the range resolution is determined by the received pulse width (or the pulse width after compression in the case of radar that performs pulse compression). The azimuth resolution and the altitude resolution are determined by the horizontal beam width and the vertical beam width, respectively. In order to be able to identify the target, it is the minimum necessary that any one of these resolutions must be set sufficiently small with respect to the physical size of the target.

In general, the size of the space irradiated by the beam width expands in proportion to the distance to the target, so it is extremely difficult to make the azimuth resolution or altitude resolution smaller than the target size as compared with the distance resolution. . For example, assuming that the length of an aircraft is about 20 m, and in order to realize a resolution of 1/10 of this, Table 1 below shows indices to be improved with respect to the resolution of a typical radar at present. The typical radar resolution was revised to 150 m (pulse width 1 μs), and the azimuth resolution was revised to 1 degree (beam width: 1 degree).

[0013]

[Table 1]

As can be seen from the above table, it is very difficult to improve the azimuth resolution (or altitude resolution) as compared with the distance resolution and to provide the target identification. Therefore, it is effective to improve the range resolution in order to identify the target. Here, the distance resolution has a relationship with the received pulse width (or the pulse width after compression) as shown in the following formula 1.

[0015]

(Equation 1)

Further, the pulse width has a relationship with the band of the receiver as shown in the following equation (2).

[0017]

(Equation 2)

Therefore, in order to improve the distance resolution,
Expanding the reception band is essential. Table 2 below shows the relationship between the distance resolution and the reception band.

[0019]

[Table 2]

Thus, in order to identify the aircraft,
It requires a reception band of about 100 MHz. However, when the reception band is expanded, there are practical problems such as (1) a sharp pencil beam (plane wave) is not formed, and (2) the processing capacity for pulse compression increases. That is,
With regard to (1), the phased array antenna forms a pencil beam by aligning the phases of the antenna elements, so the amount of phase rotation changes as the frequency changes. As a result, the beam forming direction is shifted, and when the band is widened, a sharp pencil beam is not formed. Regarding (2), if the pulse width after compression is generally 1 / N, the amount of calculation required for one pulse compression will be N times, and the amount of distance data that requires pulse compression processing will be N times. . As a result, the processing capacity required for compression is increased N × N times.

As described above, in the case of the radar apparatus having the conventional structure, if the range resolution is greatly improved to enable the model identification of the aircraft or the like, a sharp pencil beam will not be formed. In order to enable model identification, it is essential to set the resolution in the distance direction to a value that is sufficiently smaller than the target physical size, as described above. It is necessary to increase the pulse compression ratio (about 100 times) as well as increase (about 100 times). Further, if the band is widened, not only the azimuth accuracy and the altitude accuracy are deteriorated but also a pulse compressor having a processing capacity of about 10,000 times is required, which is difficult to realize.

Therefore, an object of the present invention is to provide a radar apparatus capable of identifying the model of an aircraft or the like which is a target without sacrificing the functional performance related to searching which the conventional typical radar apparatus already has. It is in.

[0023]

According to the present invention, a search beam scan for scanning a search space with a search beam based on a predetermined beam scanning program and a target requiring identification by automatic control or manual control are provided. Beam control means for controlling which of the identification beam scanning is performed by the identification beam and narrow beam extension pulse during the search beam scanning, and wideband extension pulse during the identification beam scanning And a filter for selecting a narrow band pass characteristic at the time of the search beam scanning, and a wide band pass characteristic at the time of the identification beam scanning, and a filter having a pass characteristic adapted to the band of the stretched pulse. The phase detection means for performing phase detection on the output signal of, and the sampling frequency adapted to the band of the expanded pulse And, at a lower sampling frequency at the time of the search beam scanning, also performs A / D conversion at a high sampling frequency during the scanning of the identification beam A / D
A radar apparatus comprising a conversion means and a pulse compression means for performing pulse compression suitable for the extension characteristics of the extension pulse can be obtained.

According to the present invention, the signal converting means for time-expanding the digital signal A / D converted at a high sampling frequency, the output signal of the A / D converting means during scanning of the search beam, and the identification Signal selecting means for selecting an output signal of the signal converting means during beam scanning;
A radar apparatus further comprising pulse compression means for performing pulse compression on the signal selected by the signal selection means.

That is, the radar device of the present invention comprises a beam control means for controlling scanning of a beam for identification with respect to a target requiring identification based on automatic processing or manual designation by an operator, and the beam control means. Pulse expansion means for generating a wide band pulse expansion signal during the identification beam scanning based on the instruction of the above, and a narrow band pulse expansion signal similar to the conventional radar device for the beam scanning other than the identification beam, and the identification beam scanning. A filter having a bandpass characteristic adapted to the frequency characteristic of the wideband received signal at the time, phase detection means for phase detection of the wideband received signal, and converting the wideband received signal subjected to the phase detection into a digital signal by high-speed sampling D conversion means,
Signal conversion means for time-expanding the high-speed digital signal, and switching means for switching the A / D-converted digital signal and the time-expanded digital signal during beam scanning other than the identification beam in correspondence with beam scanning ing.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention in detail, the gist of the embodiments of the present invention will be briefly described.

The radar apparatus according to the embodiments of the present invention described below can scan three types of beams. That is, scanning with a search beam for uniformly searching within a predetermined coverage area, and for the target detected in the search beam scanning, for the purpose of smoothly continuing tracking according to the flight mode of the target, Scanning by a tracking beam that is scanned based on automatic control of a computer between search beam scanning, and a target model (fighter / bomber / missile, etc., or small machine / large machine) under the assumption of search or tracking. )
Of the identification beam, which scans in the direction of the target of interest. Here, since the tracking beam and the identification beam scan the target whose position has already been grasped, it is not necessary to process all the received signals, and only the received signals within the limited range of the focused distance are processed. Should be processed.

As described above, in the search beam and the tracking beam, similarly to the conventional radar device, a narrow band stretch pulse is generated to modulate the microwave and radiate it into the space. The received signal is subjected to phase detection through a narrow band filter (band-pass filter) after beam synthesis, and A / D conversion is performed at the same sampling frequency as that of the conventional radar device, followed by pulse compression and signal processing to detect a target. .

On the other hand, in the identification beam, a broad-band stretched pulse is generated to modulate the microwave and radiate it into space. The received signal is subjected to phase detection through a wide band filter (band pass filter) after beam synthesis, A / D conversion is performed at a high sampling frequency, and then only a signal in a limited range including the distance at which the target exists is extracted. The time is extended to the full scanning time of the identification beam. As a result, the signal can be converted into a signal having the same sampling frequency as the search beam.

A target is detected by performing pulse compression and signal processing on the received signal which has been time-expanded. Here, the subsequent processing is the same as that of the search beam, except that the pulse compression is subjected to the correlation processing so that it has a complex conjugate relationship with the frequency-time characteristic (for example, chirp characteristic) of the expanded pulse. And
Among the basic functions of the radar, which are search, tracking, and identification, search and tracking have a mission to measure the exact position of the target, but do not necessarily require high resolution. On the other hand, for identification, it is essential to realize a sufficiently high resolution, but considering the operation of the radar, there are only a few situations in which identification of a target is necessary.
Also, maintaining high accuracy and achieving super resolution are contradictory,
When necessary, a computer control is used to irradiate an azimuth of a target target with an identification beam, which is a beam mainly for identification, and the identification beam does not measure the position but only identifies the model.

As described above, if search, tracking, and identification are not performed at the same time, it is possible to achieve both high-accuracy search / tracking and identification with high resolution. Furthermore, by using the identification beam, only the received signal within the limited distance range in which the target is present is extracted, and by time extension after A / D conversion,
The enormous processing capacity required for high-resolution pulse compression can be significantly reduced.

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a radar device according to a first embodiment of the present invention. The same components as those of the conventional radar device shown in FIG. 3 are designated by the same reference numerals or names. A description of these same components will be omitted, and the description will focus on the portions related to the present invention.

In FIG. 1, the beam controller 800 incorporates a beam scanning program determined by design in advance, and based on the target information from the tracking data processor 700, one of a search beam, a tracking beam, and an identification beam is selected. Whether to perform beam scanning is controlled in real time, and a beam type signal and beam scanning specifications are output.

The timing controller 810 generates a timing signal based on the beam type signal and the beam scanning data from the beam controller 800, and distributes the timing signal to each device constituting the radar device. The pulse stretcher 320 receives the beam type signal from the beam controller 800 and the timing signal from the timing controller 810 to generate a stretched pulse in a wide band at the time of scanning the identification beam, and a narrow band at the time of scanning other beams. Generate a stretched pulse of.

The mixer 500 converts the beam type signal from the beam controller 800 into an intermediate frequency signal suitable for a wide band signal at the time of identification beam scanning and converts the signal into a filter 5.
10 and, when scanning other beams, converts the intermediate frequency into an intermediate frequency suitable for a narrow band signal and outputs the intermediate frequency to the filter 511.

The phase detectors 520 and 521 perform phase detection on the wideband received signal or the narrowband received signal, respectively, based on the reference signal. The A / D converter 600 is an A / D converter for a wideband phase detection signal at a high sampling frequency.
Perform the conversion. The A / D converter 601 performs A / D conversion on a narrow band phase detection signal at a normal sampling frequency. The signal converter 610 extends the time of the digital signal A / D converted at the high-speed sampling frequency. The switch 620 selects a signal from the signal switch 610 at the time of scanning the identification beam and a signal from the A / D converter 601 at the time of scanning other beams based on the beam type signal from the beam controller 800.

FIG. 2 shows a radar device according to the second embodiment of the present invention. The same components as those of the radar device shown in FIGS. 1 to 3 are designated by the same reference numerals or names. A description of these same components will be omitted, and a description will be centered on a portion unique to this embodiment.

In FIG. 2, the pulse stretcher 320 generates a wide band stretch pulse signal at the time of scanning the identification beam.
The pulse stretcher 321 also generates a narrow band stretch pulse signal when scanning other beams. The switch 310 switches between two wideband / narrowband stretched pulses based on the beam type signal from the beam controller 800. The pulse compressor 630 corresponds to the pulse expander 320 and inputs the wideband received signal to perform pulse compression. By expanding the wideband received signal in the signal converter 610 after high-speed A / D conversion, the calculation scale in the pulse compression processing can be significantly reduced. Also, switch 6
Reference numeral 20 switches between two wideband / narrowband compressed pulses based on the beam type signal from the beam controller 800.

[0039]

As described above, according to the present invention, there is provided a radar apparatus capable of performing target model identification without sacrificing the functions and performances of the conventional multi-functional three-dimensional radar apparatus. Can be provided.

[Brief description of the drawings]

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

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

FIG. 3 is a block diagram showing a configuration of a conventional active phased array radar device.

[Explanation of symbols]

 101 element antenna 201 T / R module 211 transmitter circuit 221 receiver circuit 231 circulator 241 control circuit 300 excitation pulse generator 310, 620 switcher 320, 321 pulse stretcher 400 beam combiner 410 aerial controller 500 mixer 510, 511 filter 520 521 Phase detector 600, 601 A / D converter 610 Signal converter 630, 631 Pulse compressor 640 Signal processor 700 Tracking data processor 800 Beam controller 810 Timing controller

Claims (2)

(57) [Claims] 1. A search beam scan for scanning a search space with a search beam based on a predetermined beam scanning program, and an identification beam scan for scanning a target requiring identification by automatic control or manual control with the identification beam. Beam control means for controlling which one of the beam scanning is performed, pulse expansion means for generating a narrow band expansion pulse during the search beam scanning, and a wide band expansion pulse during the identification beam scanning, and the expansion A filter having a pass characteristic adapted to a pulse band, selecting a narrow band pass characteristic at the time of the search beam scanning and a wide band pass characteristic at the time of the identification beam scanning, and a phase for performing phase detection on the output signal of the filter. A detection means, having a sampling frequency adapted to the band of the stretched pulse, when scanning the search beam An A / D conversion unit that performs A / D conversion at a low sampling frequency and at a high sampling frequency when scanning the identification beam, and a pulse compression unit that performs pulse compression adapted to the extension characteristics of the extension pulse are provided. A radar device characterized by. 2. A signal converting means for time-expanding a digital signal A / D converted at a high sampling frequency, an output signal of the A / D converting means when scanning the search beam, and the signal when scanning the identification beam. The radar apparatus according to claim 1, further comprising: a signal selection unit that selects an output signal of the conversion unit; and a pulse compression unit that performs pulse compression on the signal selected by the signal selection unit.