JPS58780A - Pulse radar receiver - Google Patents

Abstract

PURPOSE:To perform STC control easily only with an external switching control, by making the sensitivity time control STC signal becomes several kinds of stepped fixed pattern signal whose magnitude depends upon only the range. CONSTITUTION:A pretrigger (h) of a radar and a range clock l are applied to a counter 13, and its counted output is outputted to a next memory 14. Didital data are preliminarily stored in the memory 14 so that a specific STC attenuation quantity corresponding to the range is given, and digital data corresponding to range information is read out and is outputted as an STC signal (c) to the first intermediate frequency amplifier through a D/A converter 15 and a buffer amplifier 12. Then, the STC signal becomes several kinds of fixed pattern signal by an external switching control signal (m) for STC stop/weak/middle/strong applied to the memory 14. Thus, the sensitivity time control is performed easily only with the external switching control.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides sensitivity time control (5e
nsitivity Time Control;
The present invention relates to improvements to the STC (hereinafter referred to as STC) circuit.

In a pulsed radar receiver, the strength of the reflected signal entering the receiver is inversely proportional to the fourth power of the distance. Therefore, since the distance from the radar decreases, the sensitivity of the receiver is suppressed for strong signals from a short distance, and the sensitivity is increased as the distance increases. This is the STC circuit.

That is, in the STC circuit, the receiver gain is controlled by adding a waveform such that the receiver gain changes in inverse proportion to the fourth power of the distance to the gain control circuit.

Figure 1 is a block diagram of a typical pulse radar receiver.
(1) is a high frequency amplifier, (2) is a first mixer, (3) is a first intermediate frequency amplifier with gain control function, (4) is a second mixer, and (5) is a second intermediate frequency Amplifier, (6) is divider, (7) is linear detector, (8) is phase detector, (9)
is an STC circuit.

Next, the operation will be explained.

The received signal λ received by the antenna is amplified by a high frequency amplifier (1) via a transmitter/receiver switcher, and then sent to a first mixer (2).
to go into. A first local oscillation signal S is added to the first mixer (2), and the received signal l is mixed here and WIJ1
It is converted to an intermediate frequency and enters the first intermediate frequency amplifier (3). The first intermediate frequency amplifier (3) has a gain control function, and the gain control signal is an STC signal as shown in Figure 3, which is generated by a 570 circuit (9), and The gain of the first intermediate frequency amplifier (3) is controlled to be low for strong signals from. Therefore, the received signal is subjected to amplitude control and enters the second mixer (4), where the second
It is mixed with the local oscillation signal d and converted to the second intermediate frequency, enters the second intermediate frequency amplifier (5), is amplified here, and is distributed by the distributor (81) to the linear detector (7) and phase detector. The received video signals e and f are extracted as received video signals e and f after linear detection and phase detection, respectively.

jl! 21V is 5TCf of a conventional pulse radar receiver!
l! ] This is a block diagram of a circuit that is very commonly used as a circuit, where aa is a monomulti, aI) is an integral circuit,
is a buffer amplifier.

The monomultiple aυ drive and slope adjustment are externally controlled by the radar's pre-trib h, and the buffer amplifier a
2 to the STC signal port 1 intermediate frequency amplifier (3) as shown in FIG.

Since the conventional 570 circuit is configured as above,
Depending on the usage conditions of the pulse radar, the strength of the reflected signal entering the receiver is not necessarily inversely proportional to the fourth power of the distance, and especially when used as a mobile radar, the strength of the reflected signal entering the receiver may vary depending on the topography where the radar is installed. S each time depending on the target signal strength
It is necessary to adjust the STC range, STC strength, and STC slope to externally control the TC circuit.
When the TC intensity is adjusted, the STC slope also changes due to the dependence of the time constant on the signal amplitude of the integrating circuit Cl1l, which has the disadvantage of requiring readjustment of the STC slope.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and instead of converting the STC signal output from the 570 circuit into a continuously variable signal under external control, it is converted into several types of stepwise fixed pattern signals. By doing so, you can easily set the required ST using external switching control according to the radar usage conditions.
The object of the present invention is to provide a radar receiver equipped with a red 570 circuit that outputs a C signal.

An embodiment of the present invention will be described below with reference to the drawings. Fourth
The figure shows a radar receiver according to an embodiment of the present invention.
70 circuit block diagram, α3 in the figure is a counter,
(141 is a memory, (+51 is a D/A converter, and 02 is a buffer amplifier.

Next, the operation will be explained. The radar pre-trigger force h and the range clock l are added to the counter a3, and the number of range clocks t from the pre-trigger h is counted.
Output the counting output to the next memo 'JQ&. Memory α4 is ROM (Read Only Memory
), and as shown in Figure 5, digital data is stored in advance to give a specific STC attenuation amount depending on the distance, so it corresponds to the count output of the counter a3, that is, the distance information. The resulting digital data are compared and output to the next D/A converter α9. The D/A converter α9 converts the digital data into an analog signal, and outputs the STC signal from the buffer amplifier O2 to the intermediate frequency amplifier 11 (3). At this time, STC
The signal has the characteristic characteristics shown in FIG.
In other words, it is possible to use several types of fixed pattern signals that have characteristics that are inversely proportional to the square of the distance for weak STC, to the cube of the distance for medium STC, and to the fourth power of distance for strong STC, depending on the conditions of use of the radar. Easily adjust the required STC by external switching control
It becomes possible to obtain a signal.

In the above embodiment, the 570 circuit was explained as being used in the same way as the conventional #IJ, but as shown in Fig. 6, this 570 circuit sends its output to a high frequency amplifier (1) with a gain control function. Alternatively, it is also possible to add it to both the high frequency amplifier (1) and the first intermediate frequency amplifier (3).

In this case, the STC can also be controlled by external switching control.
The same effects as the above embodiments are achieved.

- Since the signal is made to be a ON signal, the effect can be easily achieved using only STC control or external switching control.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a typical conventional pulse radar receiver, and Fig. 2 is a block diagram of a conventional STC circuit. J
3 is a signal waveform diagram for explaining the operation of the STC circuit in FIG. 2, FIG. 4 is a block diagram of the STC circuit in an embodiment of the present invention, and FIG. 5 is a signal waveform diagram for explaining the operation of the STC circuit in FIG. 4. FIG. 6 is a block diagram of a pulse radar receiver according to another embodiment of the present invention. (1)...high frequency amplifier, (2)...first mixer,
(3)...First intermediate frequency amplifier, (7)...Linear detector, (8)...Phase detector, (9)...ST
C[! ! circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Shin Kuzuno −
Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) A high frequency amplifier that amplifies the received signal at high frequency, a mixer that mixes the output of this high frequency amplifier and the output of the local oscillator, an intermediate frequency amplifier that amplifies the output of this mixer, and an output of this intermediate frequency amplifier. a detector that detects the signal and outputs a received video signal, and a sensitivity time control circuit that switches several types of fixed sensitivity time control signals by external switching control and applies them as a gain control signal to at least one of the high frequency amplifier and the intermediate frequency amplifier. A pulse radar receiver characterized by: