JPH058480U - Radar receiver - Google Patents

Abstract

(57) [Summary] [Purpose] The low noise amplifier placed at the input of the radar receiver becomes oversaturated due to the leakage of the transmitted wave to the radar receiver side when the radar transmitter transmits, and the output video (EN) A radar receiver that prevents an unnecessary wave having a 0 Doppler frequency component from being superimposed on a signal. [Structure] A bias signal of the low noise amplifier 3 is cut off only during a period when a radar transmitter generates a transmission pulse, and a low noise amplifier driving circuit 13 for receiving the low noise amplifier driving circuit 13 for preventing the low noise amplifier 3 from being saturated is received by the radar. It is provided inside the machine 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a technique for removing unnecessary waves in a receiver for radar.

[0002]

[Prior Art]

 FIG. 2 is a block diagram of a conventional radar receiver. In the figure, 1 is a receiver, 2 is a high frequency attenuator, 3 is a low noise amplifier, 4 is a mixer, 5 is an intermediate frequency amplifier, 6 is an intermediate frequency attenuator, 7 is a crystal filter, 8 is a phase detector, 9 Is an attenuator drive circuit, 10 is a high frequency signal input terminal, 11 is a video signal output terminal, and 12 is a local signal input terminal.

A conventional radar receiver will be described below. The radar receiver receives the high-frequency pulse transmission signal radiated from the radar transmitter through the transmission / reception signal switching circulator and the antenna, reflects the Doppler frequency shift corresponding to the target speed, and receives the above-mentioned antenna and circulator. The pulse reception signal that is input via is received.

In FIG. 2, the high frequency pulse reception signal is input from the high frequency input terminal 10. The high frequency pulse reception signal is attenuated by the high frequency attenuator 2 by a predetermined level. At this time, the amount of attenuation is determined by the output power of the attenuator drive circuit 9. The output signal of the high frequency attenuator 2 is input to the low noise amplifier 3, amplified, and input to the RF terminal of the mixer 4. On the other hand, the local oscillator signal input from the local oscillator signal input terminal 12 is input to the LO terminal of the mixer. In the mixer 4, the intermediate frequency signal of the frequency difference between the input signal of the RF terminal and the input signal of the LO terminal is output from the IF terminal. The intermediate frequency signal, which is this pulse signal, is input to the intermediate frequency amplifier 5 and the intermediate frequency attenuator 6, and is amplified and attenuated. At this time, the amount of attenuation is determined by the output voltage of the attenuator drive circuit 9. The amplified and attenuated intermediate frequency signal is then input to the crystal filter 7 which is a narrow band filter. The crystal filter filters only the carrier component of the intermediate frequency signal, which is a pulse signal, and removes other frequency components of the signal and unnecessary waves such as an input signal and clutter due to the ECM. The intermediate frequency signal, which is a CW wave that has passed through the filter 7, is phase-detected by the phase detector 8 (usually I, Q vector detector), and the video signal is obtained as a video signal having a Doppler frequency corresponding to the target speed. It is input to the signal processor via the output terminal 11.

The band of the crystal filter 7 is a band of a few fractions to a few hundredths of the repetition frequency of the received pulse signal. Therefore, in order to pass the carrier component of the received pulse in the band of the crystal filter 7, the frequency of the local signal normally input from the local signal input terminal 12 is changed. This amount of change is determined by the control of the signal processor in the variable frequency exciter that is the oscillation source of the local signal.

The above-mentioned video signal, which is the output signal of the radar receiver, enables the radar to detect the position and velocity of the target.

[0007]

[Problems to be solved by the device]

 When the transmitter outputs the transmission pulse signal, part of the power of the transmission pulse signal leaks to the receiver side in the transmission / reception switching circulator described above. The level of this leakage is larger than the target received signal that is normally input to the receiver, the input signal by the ECM, and the clutter received signal. Therefore, in the conventional radar receiver, the leaky pulse signal causes the low-noise amplifier to be in a supersaturated state, and the width of the leaky pulse signal increases backward. Therefore, there is a problem that the 0 Doppler frequency component of the transmitted wave is detected as an unnecessary wave larger than the target during the reception period between the transmissions.

[0008]

[Means for Solving the Problems]

 The radar receiver according to the present invention is provided with a circuit for preventing saturation of the low noise amplifier during a period in which a transmission pulse signal leaks to the receiver side.

[0009]

[Action]

 The radar receiver according to the present invention removes unnecessary waves larger than the target by preventing saturation of the low noise amplifier even if the transmission pulse signal leaks into the receiver side, and only the target reception signal is removed. To detect.

[0010]

【Example】

 Example 1. FIG. 1 is a block diagram showing a first embodiment of a radar receiver of the present invention. In FIG. 1, 1 to 12 are the same as in the conventional example shown in FIG. 2, and 13 is a low noise amplifier drive circuit.

Next, the operation will be described. FIG. 3 is a timing chart showing the timing of the radar receiver, and FIG. 4 is a frequency characteristic diagram of the video signal level of the radar receiver.

In FIG. 1, in order to switch the bias voltage of the low noise amplifier 3 on and off, the above low noise amplifier drive circuit 13 is provided, and the low noise amplifier 3 is pulsed at a predetermined timing. This timing is the transmission leakage blank gate shown in FIG. 3 (for example, TTL driving), and at the portion A, that is, when the transmission pulse signal is generated (when the leakage pulse is input to the receiver side), the above low noise is generated. When the bias voltage of the amplifier 3 is cut off, the oversaturated state disappears, and the pulse width of the output pulse signal does not increase backward (portion in FIG. B). On the other hand, in the portion C, that is, in the reception period, the bias voltage of the low noise amplifier 3 is restored, and the received signal is processed as usual.

FIG. 4 is a frequency characteristic diagram of the video signal of the transmission wave leak signal (carrier component) and the target reception signal (carrier component) described above. An example in which the relative velocity of the target to the own radar is small is shown. That is, the transmitted wave leak signal (carrier component) and the target received signal (carrier component) are close to each other on the frequency axis, and the transmitted wave leak signal, which is an unnecessary wave, is set as a larger target, and It is detected by mistake.

According to the method described above, the unnecessary wave in FIG. 4 is removed and only the target reception signal can be detected.

[0015]

[Effect of the device]

 As described above, even if the transmission signal leaks into the receiver side, a circuit that does not put the low-noise amplifier in the oversaturation state is provided to eliminate unnecessary waves larger than the target and detect only the target reception signal. There is an effect.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a radar receiver according to the present invention.

FIG. 2 is a diagram showing a configuration of a conventional radar receiver.

FIG. 3 is a timing chart showing the timing of the radar receiver.

FIG. 4 is a frequency characteristic diagram of a video signal level of a radar receiver.

[Explanation of symbols]

 1 receiver 2 high frequency attenuator 3 low noise amplifier 4 mixer 5 intermediate frequency amplifier 6 intermediate frequency attenuator 7 crystal filter 8 phase detector 9 attenuator drive circuit 10 high frequency signal input terminal 11 video signal input terminal 12 local signal input terminal 12 13 Low noise amplifier drive circuit

Claims (1)

Claims for utility model registration 1. A variable voltage type high frequency signal attenuator connected to an input terminal of a high frequency pulse reception signal, and a low noise amplifier connected to an output side of the high frequency signal attenuator. A mixer connected to the output side of the low noise amplifier, an intermediate frequency amplifier and a voltage variable intermediate frequency signal attenuator on the output side of the mixer, and an output side of the intermediate frequency signal attenuator, A narrow band crystal filter that filters only the carrier component of the pulse reception signal, a phase detector connected to the output side of the narrow band crystal filter, and a predetermined amount of attenuation of the high frequency signal attenuator and the intermediate frequency attenuator. In a radar receiver configured with an attenuator drive circuit that generates an applied voltage for setting a value, the bias voltage of the low-noise amplifier is turned on and off at a predetermined timing to generate a pulse motion. Radar receiver, characterized in that a low-noise amplifier drive circuit for.