JPS5843705B2 - Radio wave pulse repetition frequency precision measurement and interference prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precision measurement of pulse repetition frequency of radio waves and an interference prevention device. The present invention relates to a precision measurement and interference prevention device for the pulse repetition frequency of radio waves, which is used in addition to a radio wave detector to measure the pulse repetition frequency of radio waves etc. with high precision and to eliminate unnecessary external signals.

When measuring the PRF of radar radio waves with a conventional radio wave detector, it was either read from the time axis scale of a pulse analyzer attached to the radio wave detector, or the signals were counted and displayed logically.

By the way, the method of reading from the time axis scale of a pulse analyzer includes errors due to the accuracy of the scale, reading errors, etc.
In addition, in the logic counting method, since all incoming signals including noise are counted as they are, irregular values are always displayed, which is extremely unstable, and it is difficult to obtain an accurate PRF.

On the other hand, if ships, aircraft, etc. are operating in the vicinity of a radio wave detector, they may be subject to interference from radar radio waves that are stronger than these.

However, in the past, radio wave detectors lacked a function to eliminate these unnecessary external signals, which hindered the detection and identification of desired signals.

In view of the above points, the present invention provides a PFtF of a desired received radio wave.
The present invention aims to provide a device for precisely measuring the pulse repetition frequency of radio waves and for preventing interference, which can measure radio waves with high precision and eliminate unnecessary external signals.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a video signal from a radio wave detector receiving section is input to a signal input terminal 1, and a signal amplification circuit 2 amplifies the video signal supplied via the signal input terminal 1 to a predetermined value.

This signal amplification circuit 2 is composed of a general transistor amplification circuit, etc., and its output is applied as a synchronization signal to a frequency adjustment oscillation circuit 4 via a synchronization changeover switch 3.

This frequency adjustment oscillation circuit 4 is constituted by a square wave oscillation circuit such as an unstable multi-vibration radar, and its frequency is variable so that it can be set arbitrarily.

On the other hand, a pedestal marker generation circuit 7 consisting of a waveform shaping circuit 5 and an amplifier circuit 6 is provided, and the inverted output a of the frequency adjustment oscillation circuit 40 is applied to the waveform shaping circuit 5.

This waveform shaping circuit 5 is composed of a monostable multi-bi-break circuit, etc., and outputs an output waveform shaped into a pulse width suitable for a pedestal marker to an amplifier circuit 6.

The amplifier circuit 6 amplifies its output to a predetermined value suitable for the pedestal marker, and is composed of a normal transistor amplifier circuit or the like.

The output C of this amplifier circuit 60 is sent to a marker output terminal 10 as a pedestal (trapezoid) marker via a marker switch 8 and a variable resistor 9.

An analyzer scope attached to the radio wave detector is connected to this marker output terminal 101.

The output C also has a variable resistor 12 connected to the frequency meter output terminal 11 for connecting a frequency meter such as a digital counter.
Sent via .

On the other hand, a blanking trigger generation circuit 16 consisting of a delay oscillation circuit 13, a waveform shaping circuit 14, and an amplifier circuit 15 is provided, and the non-inverted output d of the frequency adjustment oscillation circuit 4 is provided to the delay oscillation circuit 13. can now be added.

The delay oscillation circuit 13 is composed of a monostable multi-by-break circuit, etc., and oscillates only when a signal is input from the oscillation circuit 4 in the previous stage, and is used as an unnecessary external signal PRF whose delay time is to be erased together with the delay caused by the oscillation circuit 4 in the previous stage. In contrast, the delay amount is set so that it is just a little less than one cycle.

The amount of delay can be arbitrarily varied according to the external signal PRF.

The output f of the delay oscillation circuit 13 is transmitted to the waveform shaping circuit 14.
is added to the blanking trigger and shaped into a constant width pulse suitable for blanking triggers.

This waveform shaping circuit 14 is composed of a monostable multi-by-break circuit, etc., and its output g is amplified to a predetermined value suitable for a blanking trigger in an amplifier circuit 15, and then is connected to a variable resistor 17.
Trigger output terminal 18 as a blanking trigger via
is supplied to

This trigger output terminal 18 is connected to an erasure circuit of the radio wave detector.

In the above configuration, the operation when precisely measuring the PRF of a desired external signal will be described with reference to FIG.

When the external signal shown in FIG. 2A is input, first read the approximate value of the PRF of the external signal from the scale of the pulse analyzer, and set the frequency of the frequency adjustment oscillation circuit 4 near the PRF of the external signal. Set.

Next, if the radio wave environment is relatively free of interference, the cycle selector switch 3 is closed.

As a result, the inverted output a of the oscillation circuit 40 is synchronized with the external signal PRF as shown in FIG. 2B, and their frequencies match.

The output a is then shaped by the waveform shaping circuit 5 as a pedestal marker so that it has an appropriate pulse width on the scope of the pulse analyzer.

Therefore, the output of the waveform shaping circuit 5 becomes as shown in FIG. 2C, and is further amplified by the amplifier circuit 6 to a magnitude sufficient to be supplied to and displayed on the scope and frequency meter of an external pulse analyzer.

Then, when the marker switch 8 is closed, the pedestal marker M superimposed on the external signal is displayed on the analyzer scope as shown in the second diagram.

By adjusting the variable resistor 9, the pedestal marker M can be made to a size that is easy to see.

After confirming that the PRF of the external signal matches the pedestal marker on the analyzer scope in this way, adjust the variable resistor 12 so that it has a size suitable for the operation of the digital counter type frequency meter, and then After that, if you look at the display on the frequency meter, you will know the PRF of the external signal.

What is added to the frequency meter here is the desired external signal PR
Since this is a pedestal marker replaced with F, it does not contain unnecessary external signals and noise, and the signal strength is stable, the frequency meter can accurately display the external signal PFjF.

Note that in a radio wave environment with a lot of interference, it is difficult to synchronize the frequency adjustment oscillation circuit 4 with an external signal, so with the synchronization changeover switch 3 open, the frequency adjustment oscillation circuit 40 can be adjusted to a desired frequency by manual operation. match the PRF of the external signal.

In this case, the pedestal marker, which is originally asynchronous to the external signal, moves, but if the oscillation circuit 4 is adjusted correctly,
The robot can be kept in a stationary state and there is no problem with measurements.

Furthermore, even if the pedestal marker and the external signal do not overlap on the analyzer scope, if the number of pulses of the pedestal marker M on the scope matches the number of pulses of the external signal as shown in FIG. 2E, It can be determined that both frequencies match.

Next, the operation of erasing unnecessary external signals to prevent interference will be explained with reference to FIG.

Assuming that the unnecessary external signal that you wish to erase is shown in FIG.
The frequency of is set near the external signal PRF.

Then, the synchronization changeover switch 3 is closed to synchronize the frequency of the oscillator 4 with the external signal PRF.

As a result, the non-inverted output d of the oscillation circuit 4 has a waveform as shown in FIG. 3A, and the output f of the delay oscillation circuit 13 triggered by the trailing edge of the pulse of this output d has a waveform as shown in FIG. 3B.

Therefore, the output g of the waveform shaping circuit 140 triggered by the trailing edge of the pulse of the output f has a waveform that is synchronized with the PRF of the unnecessary external signal and delayed by approximately one period, as shown in FIG. 3C.

After this waveform is amplified by the amplifier circuit 15, it is supplied to the erasure circuit of the radio wave detector as a blanking trigger, so on the scope of the analyzer, the blanking gate synchronized with the PRF of the unnecessary signal is delayed by about one cycle. appears near unwanted signals.

Thereafter, the amount of delay of the delay oscillation circuit 13 is adjusted, the blanking gate is moved, and the unnecessary signal is superimposed on the unnecessary signal shown in the third diagram, thereby erasing the unnecessary signal from the scope.

As a result, interference such as radar waves from ships and aircraft operating nearby can be removed, and desired signals can be easily detected and identified.

As explained above, according to the above embodiment, the PRF, which is a signal element such as a radar radio wave, is replaced with an internal signal synchronized with this, and a pedestal marker is generated based on this signal, so that a frequency meter such as a digital counter can be used. By supplying a blanking trigger based on the internal signal to the erasure circuit of the radio wave detector, the following effects can be obtained.

(1) In a real radio environment, PRF can be transmitted via IPPS (pulse per 5e) using simple operations.
It is possible to measure up to the accuracy of (cond).

(2) By having a manual synchronization method, precise measurements can be made even under environmental conditions where multiple radio waves arrive.

(3) Measurement accuracy can be easily confirmed by checking the synchronization status of the pedestal marker, which is a waveform that replaces the external signal, on the pulse analyzer scope.

(4) Measurement results can be stably displayed on the digital counter of the radio wave detector.

(5) By eliminating unnecessary signals from the outside, interference can be prevented and necessary signals can be accurately measured.

(6) Since unnecessary signals are eliminated in rough measurement, precise measurement, direction finding section, and pulse analyzer scope, signal measurement,
Analysis accuracy improves.

As described above, according to the present invention, the PRF of the desired received radio wave
To obtain a radio wave pulse repetition frequency precision measurement and interference prevention device capable of measuring with high precision and erasing unnecessary external signals.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the radio wave pulse repetition frequency precision measurement and interference prevention device according to the present invention, Fig. 2 A to E are waveform diagrams showing the PRF precision measurement operation of the embodiment, and Fig. 3 A to A are waveform diagrams showing interference prevention operation. 1...Signal input terminal, 2...Signal amplification circuit, 3...Synchronization changeover switch, 4...
- Frequency adjustment oscillation circuit, 5, 14... waveform shaping circuit, 6, 15... amplifier circuit, γ...
- Pedestal marker generation circuit, 13...delay oscillation circuit, 16...blanking trigger generation circuit.

Claims (1)

[Scope of Claims] 1. A frequency adjustment oscillation circuit that can be synchronized with the pulse repetition frequency of an external signal, and a marker generation circuit that shapes the waveform of the output of this oscillation circuit and generates a marker signal synchronized with the external signal. and a blanking trigger generation circuit that generates a Plankin trigger in synchronization with the output of the frequency adjustment oscillation circuit. 2. The blanking trigger generation circuit is triggered by the output of the frequency adjustment oscillation circuit, and the delay amount is approximately less than one period of the external signal pulse repetition frequency together with the delay of the frequency adjustment oscillation circuit. The pulse of the radio wave according to claim 1, characterized by comprising a delay oscillation circuit set to , and a waveform shaping circuit that shapes the output of the delay oscillation circuit into a predetermined pulse width. Repetitive frequency precision measurement and interference prevention device.