JPH0697259B2 - Radar receiver - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radar receiver having a CSLC (Coherent Side Lobe Canceler) circuit, and particularly to an improvement of an AGC pilot pulse signal injection method to the radar receiver. It is about.

[Prior Art] The basic function of an ordinary radar receiver is to receive a reflected signal from a target object, amplify it by a predetermined amount, detect the amplified signal, and convert it into a video signal, which is used as an indicator, etc. Output to the radar target detecting device. Here, especially when the radar target detection device is of an automatic processing type, it is important to handle various gain fluctuation factors and keep the receiver output noise level, in other words, the receiver gain constant. ,
For this reason, AGC circuits are often used.

There are various known AGC systems for radar receivers, but a relatively popular one is to inject a pilot pulse signal of a specified level from the receiver input end during the radar idle period (also called dead time). However, there is a method of configuring an automatic gain control loop so that the pilot pulse signal level becomes constant at the receiver output end.

Also, for the purpose of suppressing unnecessary interference waves input to the radar device, if there is a correlation between the input signal from the auxiliary antenna and the input signal from the main antenna, the input signal from the auxiliary antenna is the main antenna. Suppress unwanted input signals from
A CSLC circuit is used. FIG. 3 shows a systematic diagram of a conventional system relating to such a system. FIG. 4 is an explanatory diagram of the operation.

In FIG. 3, reference numeral 1 is a reference signal oscillator in the intermediate frequency (IF) band, and 2 is a local oscillator in the radio frequency (RF) band. The outputs Vc and Vl of both oscillators 1 and 2 are mixed by a mixer 3, divided into a transmission pulse by a power amplifier 4 and amplified in power to form a transmission pulse signal Vt, a duplexer 5, a directional coupling. It is adapted to be radiated into the air from the main antenna 7 via the vessel 6a. Reference numeral 9 is a pulsing circuit for generating pilot pulse signals Vpa and Vpb by dividing the output of the mixer 3 into pulses, and 6a and 6b are main receiving system 30 and auxiliary receiving system with the same amplitude of the pilot pulse signals at the same time. A directional coupler for injecting into 40.

The reflected signal and the interference wave from the object to the main reception system 30 are received on the route opposite to the transmission pulse signal, that is, on the main antenna 7, and then, through the directional coupler 6a and the transmission / reception switcher 5, to the wide band. R
It is amplified by the F amplifier 10a. After that, it is mixed with the local oscillation signal Vl of the local oscillator 2 by the mixer 11a for reception, and the difference frequency
The IF reception signal Vm is sent to the CSLC circuit 12.

Further, the reflected signal and the interference wave from the object to the auxiliary reception system 40 are received by the auxiliary antenna 8 and then the directional coupler 6b, RF.
The IF received signal Vs is sent to the CSLC circuit 12 via the amplifier 10b and the mixer 11b. Where IF received signal
Vm and Vs are equal to the frequency of the reference signal oscillator output Vc.

Reference numerals 13a and 13b denote AGC circuits that perform the AGC processing by receiving the output signal Vo of the CSLC circuit 12 and the IF reception signal Vs, respectively, and 14a and 14b detect the output signals of the AGC circuits 13a and 13b and detect the target as a video signal. It is a detection circuit that outputs to the device 20.

Next, the operation will be described.

The time relationship between the transmission pulse signal Vt and the pilot pulse signals Vpa and Vpb is set as shown in FIGS. 4 (a) and 4 (b). The pilot pulse signals Vpa and Vpb are the transmission pulse signals V
It is injected into the so-called radar dwell time, which is longer than the radar maximum detection distance immediately before t, and does not overlap with the reflected signal from the target. Here, in addition to the reflected signal from the object and the interference wave, pilot pulse signals Vpa and Vpb of the same amplification are injected into the auxiliary reception system 40 and the main reception system 30 at the same time by directional couplers 6a and 6b, respectively. . These signals are received and processed by the individual reception systems 30 and 40, and are input to the CSLC circuit 12 as IF reception signals Vm and Vs shown in FIGS.

Here, the purpose of the CSLC circuit is to suppress the unnecessary interference wave input from the main antenna 1 by the unnecessary interference wave input from the auxiliary antenna 8 as described above, and
A signal having a correlation with Vm is suppressed as an unnecessary wave by using the signal Vs. Due to this action, the main and auxiliary receiving systems 30,40
The pilot pulse signal injected into the
Since they have a correlation with each other, they are suppressed together with the above-mentioned interference waves. The reflected signal has no correlation and is not suppressed due to the difference in each antenna pattern.

The output signal of the CSLC circuit 12 is AGC as Vo in FIG. 4 (e).
It is supplied to the circuit 13a. However, in this AGC circuit 13a,
Since the reference pilot pulse signal is suppressed as described above, normal operation becomes impossible. This AGC circuit 1
The output of 3a is detected by the detector 14a and sent to the target detection device 20, but the function of the radar device is disabled because the operation of the AGC circuit 13a is disabled. Further, the reception signal Vs of the auxiliary reception system 40 passes through the AGC circuit 13b and is detected by the detection circuit 14b,
It is output to the target detection device 20.

[Problems to be solved by the invention]

Since the pilot pulse signal injection method for AGC in the conventional radar receiver is configured as described above, the pilot pulse signals Vpa and Vpb injected as the same signal are C
SLC circuit 12 suppresses the unwanted interference waves along with the AGC circuit in the subsequent stage.
There is a drawback that 13a does not work properly.

This invention was made to eliminate the above-mentioned drawbacks of the conventional ones, and the AGC pilot pulse signal is output to the subsequent stage without being suppressed and can be used as the reference signal of the AGC circuit. It is an object of the present invention to provide a radar receiver with high efficiency.

[Means for solving problems]

In the radar receiver according to the present invention, the levels of the AGC pilot pulse signals injected during the radar down time are made different between the main receiving system and the auxiliary receiving system.

[Action]

In the present invention, AGC pilot pulse signals of different levels are injected into the main receiving system and the auxiliary receiving system, and the pilot pulse signals of each receiving system in the CSLC circuit are made uncorrelated signals on the amplitude axis. Prevents the pulse signal from being suppressed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a radar receiver according to an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 3 denote the same elements. Reference numeral 15 is an attenuator for attenuating the level of the pilot pulse signal Vpb given from the pulse forming circuit 9 to the directional coupler 6b of the auxiliary receiving system, which is a pilot pulse signal Vpa injected into the main receiving system and the auxiliary receiving system. This is for giving an amplitude difference to Vpb.

Next, the operation will be described with reference to FIG.

The time relationship between the transmission pulse signal Vt and the pilot pulse signals Vpa, Vpb is set as shown in FIGS. 2 (a), (b), (c), and the pilot pulse signals Vpa, Vpb are injected into the radar down time. It Here, the main receiving system 30 and the auxiliary receiving system 40
In addition to the reflected signal from the object and the interference wave, pilot pulse signals Vpa and Vpb having amplitude differences (Vpa> Vpb) are injected at the same time, and these signals are processed by each receiving system. IF reception signal shown in Fig. 2 (d) and (e)
Vm and Vs are input to the CSLC circuit 12. Here, the interference wave is suppressed because it has a correlation, but the pilot pulse signal is different on the amplitude axis, and the reflected signal is different depending on the pattern of each antenna, which is suppressed by the CSLC circuit 12. The signal Vo shown in FIG. 4 (f) is sent to the AGC circuit 13a at the next stage without being processed. Therefore, normal AGC processing for keeping the receiver gain constant is performed in the AGC circuit 13a, then detected by the detection circuit 14a, and output to the target detection device 20. Similarly, the signal Vs of the auxiliary antenna passes through the AGC circuit 13b, is detected by the detection circuit 14b, and is output to the target detection device 20.

As described above, in this embodiment, the AGC processing can be performed in the radar receiver having the CSLC circuit, and the AGC accuracy can be remarkably improved.

In the above embodiment, the radar device having the main antenna 1 circuit, the CSLC circuit and the AGC circuit has been described, but the present invention is a radar having the inter-channel gain balance circuit and the inter-channel phase balance circuit in the multi-channel receiver mechanism. The same can be applied to the device as in the above embodiment.

〔The invention's effect〕

As described above, according to the present invention, the injection levels of the pilot pulse signals injected into the auxiliary receiving system and the main receiving system are made different, which enables the AGC processing of the radar device having the CSLC circuit. There is an effect that the AGC accuracy under interference can be improved.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a radar receiver according to an embodiment of the present invention, FIG. 2 is an operation explanatory diagram thereof, FIG. 3 is a block configuration diagram of a conventional radar receiver, and FIG. 4 is an operation explanatory diagram thereof. Is. 12 ... CSLC circuit, 13a, 13b ... AGC circuit, 15 ... attenuator, 30 ... main receiving system, 40 ... auxiliary receiving system. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A radar receiver having a CSLC circuit for suppressing an unnecessary interference wave input to a main reception system by an unnecessary interference wave input to an auxiliary reception system, comprising: a main reception system and an auxiliary reception system during a radar suspension period. A radar receiver comprising means for varying the level of a pilot pulse signal for automatic gain control injected into the main receiving system and the auxiliary receiving system.