JPS585384B2 - pulse generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a pulse search radar equipped with frequency switching means that switches the frequency of use without the interference source knowing, as a means of avoiding jamming radio waves intentionally emitted into space. This invention relates to a frequency switching system for pulse search radar that can effectively avoid interference.

In the past, the frequency used was simply switched as a means of avoiding intentionally emitted jamming waves, but with this method, the electronic search device of the jamming source immediately detects that the frequency has been switched. It had the disadvantage that it could be detected, its frequency measured, and then jammed again at a new station wave number.

In addition, since there is a limit to the selection of frequencies used by the search radar, as the frequency switching operation described above is repeated, there is a tendency for the interference source to become aware of the entire frequency switching capability of the radar. .

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional technology, and by making maximum use of the ability to remove interference waves by frequency switching, it is possible to significantly improve the robustness of radars against interference waves. The present invention provides a frequency switching system for pulse search radar that can be used.

Next, an embodiment of the frequency switching system of the pulse search radar of the present invention will be explained based on the drawings. FIG. 1 is a block diagram showing one embodiment, and 1 in the figure indicates the antenna of the pulse radar; 2 is a transmitter/receiver switch, 3
4 is a receiver, 4 is an indicator, 5 is a transmitter, and 6 is an interference wave amplitude detector attached to the receiver 3.

This interference wave amplitude detector 6 is composed of a logarithmic amplifier, a wave detector, etc., and detects the input amplitude of the interference wave by the indicator 4.
PPI (Plane position Indic)
ation) to find the direction with the maximum amplitude and thereby determine the direction of arrival of the interfering radio waves.

On the other hand, a portion indicated by a dotted line 7 is a characteristic feature of the system of the present invention; 8 within this dotted line 7 is a frequency switching circuit, and 9 is a group of transmission frequency oscillators that are input to the transmitter 5.

However, instead of these transmission frequency oscillators 9, one variable frequency oscillator may be used, and the oscillation frequency may be changed by changing the capacitance in the oscillation circuit as necessary.

10 is a frequency selection circuit, and the frequency switching circuit 8
This circuit outputs a switching signal for selecting the desired frequency.

The output sides of matching circuits 11 and 12 are connected to the input side of this frequency switching circuit 10.
, 12 output a signal and send it to the frequency selection circuit 10 when the respective azimuth designating switches 13, 14 and the azimuth signal supplied from inside the radar match.

Next, to explain the operation of the system of this invention, let us assume that the frequency currently used by the radar is fl, and this is set by the indicator 4.
If you draw it based on the concept of the PPI screen, it will look like Figure 2 a,
It operates at fl throughout the entire circumference.

Now, a jamming wave tuned to the currently used frequency f1 has arrived,
If such interference is received, and this is displayed on the PPI using the interference wave amplitude detection circuit 6, it will be in the form shown in Figure 2, where the input amplitude will be maximum in the direction of arrival of the interference wave, and the interference will be caused by the source of the interference. You can know the directional heat that exists.

Therefore, before and after this azimuth θ adjustment, an appropriate azimuth θ1.
θ2 is determined, and the direction designation switches 13 and 14 are set to that value.

As a result, matching circuits 11 and 12 each have θ1. θ2
A signal is output to the frequency selection circuit 10 at an angle of .

In this frequency selection circuit 10, the currently used frequency f
1 and the next new station frequency to be used, for example, f2, and only the currently used frequency f1 is always output.

Here, if the frequency switching on/off signal is turned on, as shown in FIG. 2C, θ1. With θ2 as the boundary, it is possible to transmit at the currently used frequency f1 in the direction of arrival of the interference source as before, and to transmit at the new station wave number f2, which is free from interference, in other directions.

If we look at this situation from the side of the interference source, we cannot detect that the other party's radar has switched frequencies and is operating without any problems, and we cannot even know whether or not the interference radio waves emitted by ourselves were effective. In the method, as described above,
This allows for effective frequency switching.

If the direction of the disturbance source changes, depending on the direction θX,
Azimuth angle θ1. What is necessary is to set θ2 sequentially.

Furthermore, since the antenna pattern on the radar side is accompanied by side ropes and back ropes, the interference source side seems to be able to capture these and detect the new station wave number f2, but the level of these unnecessary ropes is is usually quite small, and is very difficult in practice in a situation where there are scattered radio wave radiation sources such as other radars with a large number of approximate frequencies.

Now, one embodiment of the frequency selection switching circuit 10, which is the center of the system of the present invention, will be described with reference to FIG. 3. 31 is a selection signal generation circuit, and θ1. This is a circuit that receives the direction matching signal of θ2 as input and generates an output signal, and outputs the signal only when the frequency switching on/off signal is on.

This output is sent to the read selection circuit 34, and the outputs of the current frequency register 32 and the new station wave number register 33 are also introduced into the read selection circuit 34.

The current frequency register 32 is used to store the designation code of the currently used frequency, and the new station wave number register 33 is used to store the designation code of the frequency to be used next. The wave number register 33 stores a designation code for the next frequency to be used.

The read selection circuit 34 normally reads the contents of the current frequency register 32, but when a signal from the selection signal generation circuit 31 is introduced, the read selection circuit 34 reads out the contents of the current frequency register 32 or the new station wave number according to the signal. The frequency designation code in the register 33 is read out.

This read selection circuit 34 is configured such that the frequency designation code read from the current frequency register 32 or the new station wave number register 33 is sent as a frequency switching signal to the frequency switching circuit 8 shown in FIG.

Note that any frequency designation code can be selected within the given frequency selection range.

Here, the orientation matching signal θ is sent to the selection signal generation circuit 31.
1. When not only θ2 but also multiple pairs of signals are input, for example, 2 pairs, as shown in FIG. 4a, θX1. θ
The same thing can be done for the interference sources in the two directions of X2.

Furthermore, another embodiment of the present invention can be achieved by providing a plurality of new station wave number registers and updating the readout at regular intervals.

An example in which the above-mentioned "fixed time" is shorter than the time for one scan is shown in FIG.

Furthermore, in the case of a radar combined with the above-mentioned disturbance amplitude detector 6, if a circuit is configured to automatically set the azimuth designation switch 13, 14 according to the azimuth θ detected by this,
This invention can be fully automated.

As described above, according to the present invention, the direction of arrival of the jamming radio waves is known by displaying the input amplitude of the jamming radio waves on the indicator and finding the direction with the maximum amplitude, and the predetermined directions before and after this direction of arrival are determined. setting, and when switching the frequency used when receiving the above-mentioned jamming radio waves, the currently used frequency is maintained as is within the set angle of the above-mentioned direction that includes the direction of arrival of the above-mentioned jamming radio waves, and the interference is switched off at other azimuths. Since we avoided interference by switching to another frequency that is not affected, each time the frequency used is changed, the frequency used is measured by the electronic search device on the side of the interference source, and the new station frequency is not interfered with. Furthermore, there is no risk that the entire frequency switching ability of the radar side will be known to the jamming side, and jamming waves can be reliably and effectively avoided, and the robustness of the radar against jamming waves can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the frequency switching method of the pulse search radar of the present invention, and FIGS. 2a to 2C are diagrams for explaining the operation of the frequency switching method of the pulse radar, respectively, FIG. 3 is a block diagram showing the configuration of one embodiment of the frequency selection circuit in the frequency switching method of the above pulse radar, and FIGS. 4 a and b show frequency switching in another embodiment of the frequency switching method of the above pulse radar, respectively. FIG. 1...Pulse radar antenna, 2...
・Transmission/reception switch, 3...Receiver, 4...
Indicator, 5...Transmitter, 6...Interference wave amplitude detector, 8...Frequency switching circuit, 9...
... Transmission frequency oscillator group, 10 ... Frequency selection circuit, 11, 12 ... Matching circuit, 13゜14
... Direction designation switch, 31 ... Selection signal generation circuit, 32 ... Current frequency register, 3
3... New station wave number register, 34... Read selection circuit.

Claims (1)

[Claims] 1. In a pulse search radar that has a frequency switching function as a means of avoiding jamming radio waves that are intentionally emitted into space, the input amplitude of the jamming radio waves is displayed on an indicator and the direction with the maximum amplitude is found to detect the jamming radio waves. Know the direction of arrival, set a predetermined direction before and after this direction of arrival, and when switching the frequency to be used when receiving the above-mentioned jamming radio waves, the current frequency will be set within the set angle of the above-mentioned direction that includes the direction of arrival of the above-mentioned jamming radio waves. A frequency switching method for a pulse search radar, characterized in that the frequency is maintained as it is, and in other azimuths, the frequency is switched to another frequency that is not interfered with to avoid interfering radio waves.