JPS58178645A - Circuit for alarming fault of antenna - Google Patents

Abstract

PURPOSE:To make it possible to detect a fault even during the operation of a transmitter by using a limitter to protect a transmitting system and detecting the fault of an antenna by using the reflected signal of a transmitting signal. CONSTITUTION:At the time of transmission, reflected electric power from the antenna 1 is applied to the limiter 12 through a directional coupler 2 and circulator 3 to saturate the limiter 12. The recovery time of the limitter 12 is proportional to the reflected electric power. Since the quantity of reflected electric power is large when the antenna 1 is in trouble at the completion of transmission, the recovery time is delayed. Therefore, the fault of the antenna 1 can be detected by discriminating the length of the recovery time in a fault discriminating circuit 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antenna abnormality warning circuit for protecting a transmitter/receiver from abnormalities in the antenna.

As a conventional device of this type, the one shown in FIG. 1 is rare.

In the figure, (1) is an antenna, (2) is a directional coupler,
(3) is a transmitter/receiver switch, which may also be a circulator. (4) is a transmitter, (5) is a frequency amplifier, (6) and (9) are switching circuits, (7) is a detector, (8) is a receiver, (1■ is a pilot signal generator, 01 ) is the antenna (1
) is a control circuit that determines an abnormality.

Next, the operation will be explained.

When detecting an abnormality in the antenna (1), switch the switching circuit (9).
and (61) connect the pilot signal generator aυ and the detector (7).Then, the signal output from the pilot signal generator (1G) passes through the switching circuit (9) and the directional coupler (2). The signal reflected by the antenna (2) passes through a directional coupler (2), a transmitter/receiver switch (3), a high frequency amplifier (5), and a switching circuit (6) before being sent to a detector (7). ) and the control circuit αD.Therefore, in this control circuit (Ill), it is possible to know the magnitude of the reflected power of the antenna [11] based on the magnitude of the detection level of the detector (7), and to detect an abnormality in the antenna I1+.

Since the conventional antenna abnormality warning circuit is constructed as described above, the antenna must be checked before radar operation, and checking during operation is rarely possible. In addition, even if the detector (7) has an abnormality, it cannot be detected and the system is not fail-safe. Depending on the stability of the high-frequency amplifier (5), it may malfunction, and there is also a switching circuit in the receiving system. There were drawbacks such as a worsening of the noise figure due to the inclusion of

This invention was made in order to eliminate the drawbacks of the conventional systems as described above. By using the reflected power of the transmitted signal and detecting abnormalities in the antenna by the receiving system, abnormalities can be detected during continuous radar operation. The purpose of the present invention is to provide a fail-safe antenna abnormality warning circuit.

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

FIG. 2 shows an antenna abnormality alarm circuit according to an embodiment of the present invention. In the figure, (1) is an antenna, (2) is a directional coupler, and (3) is a circulator or transmitter/receiver switch.

(4) is a transmitter that supplies transmission signals to the antenna (1) via a circulator or transmitter/receiver switch (3) and a directional coupler (2), and aυ is a transmitter that supplies a transmission signal to the antenna (1) via a directional coupler (2).
1) a pilot signal generator that supplies a pilot signal to When transmitting, the receiving system I
It is a limiter to protect the Also, in the receiving thread I, 151 is a high frequency amplifier, (7) is a detector, (11 &)
is an abnormality determination circuit that measures the time from immediately after the pilot signal is generated until the limit and ivy 02 recover from the saturated state, and compares this with a set value to determine whether there is an abnormality in the antenna (1).
8) is a receiver that processes the received signal.

Figure 3 shows a timing chart of the above circuit, in which 2 is the transmission timing, b is the pilot signal generation timing, C is the detection output of the detector (7) when the antenna is normal, and d is the detection output when the antenna is abnormal. is the detection output of the detector (7), τ0 is the transmission pulse width, τ1 is the pilot signal pulse width, τ2. τ4 is the recovery time of limiter 02 when the antenna is normal or abnormal, and τ8 is the abnormality judgment circuit (11
This is the determination time set in 11).

Next, the operation will be explained.

At the time of transmission, the transmission power output from the transmitter (4) reaches the antenna (1) via a circulator or transmitter/receiver switch (3), and a directional coupler (2). The reflected power from this antenna (1) is transmitted to a directional coupler (2) and a circulator (3).
As a result, the limiter (12) is applied to the limiter (12) during transmission, and as a result, the limiter (121) is in a saturated state.This means that if more than a certain amount of power is input to the limiter (121), it becomes saturated and limits its output. This may be because the limiter t13 has a protection function that allows the limiter t13 to recover from such a saturated state when the power input is no more than the above-mentioned amount, and is proportional to the above-mentioned input power.

On the other hand, when a pilot signal is generated from the pilot signal generator tllj at the same time as the transmission is completed, the pilot signal passes through the directional coupler (2) and hits the limiter, but since the limiter 021 is in a saturated state at this time, it is used as an attenuator. Function. Therefore, the pilot signal is limited by a limiter (
During the recovery time of the antenna (1), the recovery time of the limiter (2) is '2+' when the antenna (1) has a small reflected power and is normal.
The above-mentioned antenna with a large reflected power is τ4 at the time of abnormality. Therefore, the waveforms that appear as the output of the detector (7) after passing through the high frequency amplifier (5) are shown in Figure 3c in normal and abnormal conditions.
, d. If τ8 is set as the judgment level in the abnormality detection circuit (11λ), the time τ2 or τ4 until the limiter (12) is recovered and the wholesaler outputs the limiter level V6 can be set as the determination level. By comparing with τ8, the antenna (1
) can detect normality and abnormality. In addition, in the signal C in the figure, the limiter level Vi outputted after the limiter O2 recovers from the saturated state is a value somewhat smaller than the output level ■s of the limiter O2 in the saturated state (during transmission). Furthermore, the broken line in the circular signal d indicates the output waveform of the limiter 02 when the pilot signal continues longer than the pilot signal fl.

As described above, according to the present invention, a limiter is used to protect the receiving line, and the reflected signal of the transmitted signal is used to detect an abnormality in the antenna. Abnormality detection can be performed. Furthermore, since the reception system itself is used to detect an abnormality in a state where the pilot signal cannot be detected, it operates fail-safely even in the event of an abnormality in any circuit from the frequency circuit to the detection circuit.

Furthermore, if the system is already equipped with a test signal circuit, it can be implemented by simply changing the control system and adding an inexpensive detection circuit in one low frequency band, without adding any expensive microwave components. , equipment can be made at low cost,
The effect of improving reliability can be seen.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional aerial w abnormality alarm circuit;
The figure is a block diagram of an antenna overload alarm circuit according to an embodiment of the present invention, and FIG. 3 is a time chart for explaining the operation of the present invention. (1)...Antenna, (4)...Transmitter, (3)...
・Transmission/reception switch, (2)...bidirectional coupler, fiG...
・Pilot signal generator, 03...Pilot signal control circuit, O2...Limiter, (8j...Receiver, (
llj)...Abnormality determination circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Makoto Kuzuno - Figure 1, Figure 2, Figure 3! 11 Government offices 12 Government buildings 1.・11 yen labor special request Sho 57-6214
4 No. 2, Name of the invention Aerial IMi4 Regular Report 3, ? 11i +1: Relationship with the person 'JGf'l Patent applicant 5, Detailed explanation of the invention in the specification subject to amendment 6, Revise the supplementary internal medicine specification as per ゛, Specification - Apply F to J1 pressure as follows.

Claims (1)

[Claims] (1) An antenna, a transmitter that supplies a transmission signal to the antenna via a transmission/reception switch and a directional coupler, and a pilot signal generator that sends a pilot signal to the antenna via the directional coupler. , a pilot signal control circuit that generates the pilot signal immediately after transmitting the transmission signal, a limiter connected between the transmission/reception switch and the reception system to protect the reception system during transmission, and the pilot. An antenna abnormality V characterized by comprising: an abnormality determination circuit that measures the time from immediately after a signal is generated until the limiter recovers from a saturated state and determines whether the antenna is abnormal.
axis circuit.