JPS5979869A - Radar equipment - Google Patents

Abstract

PURPOSE:To excellently and automatically detect a jamming radio wave, by detecting the same on the basis of the ratio of objective radio wave intensity and jamming radio wave intensity. CONSTITUTION:The receiving signal from a preamplifier 1 is applied to a gain control amplifier 3 of an objective radio wave system and the logarithmic amplifier 6 of a jamming radio wave system through a distributor 2 and the signal corresponding to objective radio wave intensity over a wide range is formed in good linearity from a DC amplifier 10a through the gain control circuit 5 and LPF 9a controlled by a detector 4 and a gate generating circuit 14. On the other hand, a DC amplifier 10b similarily generates the signal corresponding to jamming radio wave intensity over a wide range in good linearity through the gate circuit 7, a stretcher 8 and LPF 9b controlled by the circuit 14 while the radio wave intensity ratio of both system is calculated through an adder circuit 11 and, when this ratio reaches a reference value or more, the presence of the jamming radio wave is automatically judged through a comparator 13. By this system based on the correlation of radio wave intensities of both systems, the jamming radio wave is excellently and automatically detected and the alteration and the change-over of an automatic tracking mode are properly performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radar and a device, in which when a pulse radar receives active jamming waves from other radar devices while capturing and tracking a target, it is possible to determine the radio field intensity from the target and the jamming radio waves. We propose a radar device that can automatically detect jamming waves by comparing their intensities and using the magnitude ratio as a variable.

Conventionally, there has been no absolute countermeasure or standard method for detecting jamming radio waves, partly because the nature of the jamming radio waves itself cannot be predicted. however.

Equipping a device that can respond to the characteristics of individual jamming waves in all cases will increase the overall scale of the radar device, especially for radar devices that are required to be small and lightweight, such as aircraft-mounted radar devices. It's not appropriate. Therefore, OW (Continu
ous Wave) Although attention is often paid to interfering radio waves, if detection is performed only based on the absolute radio wave intensity, the receiver may become saturated or there will be no correlation with the target radio wave intensity.

There were many inconveniences, such as the needless determination of the presence of interfering radio waves.

The present invention eliminates these problems with conventional radar devices, and provides a radar device that can automatically detect jamming waves over a wide range of input signal strengths, depending on the ratio of the radio wave intensity from the target to the jamming wave intensity. This is a proposal.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In Figure 1, (1) is a preamplifier, (2) is a divider, C3) is a gain control amplifier, (4) is a detector, (5) is a gain control circuit, (6) is a logarithmic amplifier, ( Power is a gate circuit.

(8) is a stretcher to extend the output pulse width of gate circuit (7), (9a) (9b) is a low-pass filter, (I Da) (10b) is a DC amplifier, and +lυ is an adder circuit.

0 is a reference voltage generation circuit, 0 is a comparator, and (I4 is a gate generation circuit).

FIG. 2 is a characteristic diagram showing an example of the relationship between input signals and output signals in the configuration of FIG. 1. In Figure 2, (
15a) (15b) is the target component and disturbance component of the power input to the preamplifier (1) and the DC amplifier (1).
0a) A characteristic curve showing the relationship between the output amplitudes of (10b),
(1e is a characteristic curve showing the relationship between the output amplitude of the adder circuit 011 and the ratio of the interference radio wave power to the target power.

07) is a characteristic curve showing the output amplitude of the reference voltage generating circuit α power, and a characteristic curve showing the output amplitude of the comparator (1(8)) with respect to the ratio of the interfering radio wave power to the target power.

In FIG. 2, the horizontal axis direction means the strength of input power, or the strength of the input power ratio, and the vertical axis direction means the strength of the output amplitude.

Since this invention is as described above, the preamplifier (
The signal input to 1) is divided into equal parts by a divider (2),
One of them is amplified through a gain control amplifier (3), and then
The wave is amplified and detected by a wave detector (4). Further, from the signal input to the gain control circuit, only the target component is extracted by the tracking gate generated by the gate generation circuit θa, and a gain control signal corresponding to the amplitude intensity is generated. This gain control signal is fed back to the gain control amplifier (3) and works to keep the output of the gain control amplifier (3) constant, so the output of the gain control circuit (5) is the decibel value of the power intensity of the target component of the input signal. is proportional to. What is important here is to select a gain control circuit system that provides sufficient linearity of this gain control characteristic. The output of the gain control circuit (5) is fed back to the gain control circuit amplifier (3) and at the same time passed through the low pass filter (9a).
) and is smoothed, and then input to a DC amplifier (10a) where the input/output characteristics are normalized.

Therefore, the relationship between the input power and the output amplitude of the DC amplifier (10a) is as shown by the characteristic curve (15a).

The other output of the other two-way divider (2) is connected to the logarithmic amplifier (6).
) whose output amplitude is proportional to the decibel value of the input power over a wide range of input power. The output of the logarithmic amplifier (6) is input to the gate circuit (7), which passes only a certain time period outside the target by the gate generated by the gate generator circuit α, and is sent to the stretcher (8) and the low-pass filter (9b). It is then replaced by DC voltage.

Furthermore, the signal normalized by the DC amplifier (1ob) has a characteristic &! The input/output characteristics shown in (15b) are shown.

Here, the gains of the DC amplifiers (10a) and (10b) are determined so that the slopes of the characteristic curves (15a) and (15b) are equal.

Furthermore, by inverting the polarity of the output amplitude of the DC amplifier (10a) and inputting it to the adder circuit aυ, the output amplitude of the adder circuit αD becomes the decibel value of the power ratio of the interfering radio wave and the target, as shown in the characteristic curve 0e. Proportional. Reference voltage generation circuit α
If the output is defined as the characteristic curve α, then the comparator (IJ
Now, the output amplitudes of both the adder circuit α1) and the reference voltage generating circuit Oz are compared, and the circuit operates according to the characteristic shown in the characteristic curve 0.

In other words, regardless of the absolute value of the jamming signal power, it is determined that the signal strength is jamming only when the ratio to the target power exceeds a certain threshold. When the tracking performance of the entire device hardly deteriorates, this invention is useful because it does not affect the operation of the radar device.

Furthermore, when there is no target and the output amplitude of the DC amplifier (10a) is zero, the input to the comparator Q31 changes only according to the jamming signal strength, so the jamming signal can be detected relatively early. .

As mentioned above, the feature of this invention is that it has two signal systems: a gain control amplifier combined with a gain control circuit with excellent linearity, and a logarithmic amplifier. The point is that it is possible to automatically detect jamming signals over a wide range based on the ratio of the jamming signal strength to the signal strength from the target. This depends on the presence or absence of jamming signals.

Assuming a radar device that changes the operating mode, if there is only a small amount of interfering radio waves and it does not cause a significant drop in target tracking performance, the mode may be changed unnecessarily, even without operator intervention. This is extremely useful for improving the stability of the overall system operation.

In addition, since the basic configuration of this invention is the same as that of conventional radar equipment, it goes without saying that it will not affect the basic performance of radar equipment, and it is possible to improve It is possible to add the functions that characterize the present invention to the radar device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a characteristic diagram showing an example of the relationship between the input signal and the output signal in the above block diagram; (1) is a preamplifier;
(2) is a divider, (3) is a gain control amplifier, (4) is a detector, (5) is a gain control circuit, (6) is a logarithmic amplifier, (
7) is the gate circuit, (8) is the stretcher, (9
a) (9b) is a low pass filter, (1oa)
(1ob) is a DC amplifier. 01) is an adder circuit, (1 side is a reference voltage generation circuit, (1 row is a comparator, and α→ is a gate generation circuit.

Claims (1)

[Claims] A preamplifier that amplifies a received signal, a divider that evenly distributes the output of the preamplifier, a gain control amplifier that amplifies one output of the divider, and an output of the gain control amplifier. a gain control circuit that generates a gain control signal for the gain control amplifier according to the magnitude of the output of the upper We detector; and a gain control circuit that amplifies and detects the other output of the divider according to logarithmic characteristics. A logarithmic amplifier, a gate circuit that passes only a part of the output of the logarithmic amplifier, a stretcher that stretches the output pulse width of the gate circuit, and smoothes the two signals of the gain control circuit output and the stretcher output, respectively. two low-pass filters,
and two DC amplifiers that amplify the outputs of the two low-pass filters, respectively. and an adder circuit that adds the outputs of the two amplifiers mentioned above. A reference voltage generation circuit that generates a reference voltage, a comparator that compares the output of the adder circuit and the output of the reference voltage generation circuit and outputs a judgment signal, and a target tracking gate and an interference for the gain control circuit and the gate circuit, respectively. A radar device comprising a gate generation circuit that outputs a wave extraction gate.