JPS58218206A - Trouble detection system applied to device provided with modulating function - Google Patents

Abstract

PURPOSE:To discriminate any abnormal state occuring to a modulating circuit correctly by detecting plural narrow-band signals and monitoring the spectrum state of a modulated signal. CONSTITUTION:A signal from an input terminal 1 is modulated by a modulating circuit 2 and then outputted from an output terminal 3 as a modulated carrier. A part of the modulated carrier is led to three narrow-band-pass filters 11-1- 11-3 having different center frequencies to be band-limited respectively, and then inputted to signal detecting circuits 12-1-12-3. The spectra after the band limitation at the center frequencies f1-f3 are detected by the detecting circuits 12-1-12-3 and sent to a discriminating circuit 13 with levels V1-V3 corresponding to the respective spectra. The circuit 13 compares them to discriminate the occurrence of an abnormal state accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a failure detection method applied to a device having a control function.

This type of conventional fault detection method is based on a modulation circuit 2 having an input terminal 1 and an output terminal 3, as shown in the example of FIG.
The present invention is applied to a signal detection circuit 4, a determination circuit 5, and a display 6. A signal applied to input terminal 1 is modulated by modulation circuit 2 and then output from output terminal 3 as a modulated carrier wave. On the other hand, a part of the modulated carrier wave is guided to the signal detection circuit 4, where it is detected as being proportional to the total power, regardless of the spectrum of the modulated signal. The signal detected by the signal detection circuit 4 is guided to the determination circuit 5, and if the total power decreases, it is determined that an abnormality has occurred in the output of the modulation circuit 2, and this is displayed on the display. 6. According to such a method, the judgment circuit makes a correct judgment regarding the decrease in the total power in the output of the modulation circuit, but the judgment circuit makes a correct judgment regarding the decrease in the total power in the output of the modulation circuit. In this case, the spectrum state changes but the total power does not decrease, so the judgment circuit cannot make a correct judgment.In this way, the conventional method has the disadvantage of not being able to correctly judge all abnormal states of the modulation circuit. was there.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to provide a fault detection method applied to a device having a modulation function that can accurately detect any abnormality in the modulation circuit used. .

According to the present invention, the modulated carrier wave power is band-limited by at least three narrowband filters having different center frequencies, and then each is detected, and the detection levels of these filters are compared to each other by a comparison judge. A fault detection method applied to a device having a modulation function is obtained, which is characterized in that a decrease in the spectral density and level of the carrier wave power is determined by comparing the above.

Next, two failure detection methods according to the present invention will be explained with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment according to the present invention. In the figure, modulation circuit 2. The signal input terminal 1 and the signal output terminal 3 are the same as in the example of FIG. and,
On the output side of the modulation circuit 2, narrowband filters 11-1 to 3° signal detection circuits 12-1 to 31, a determination circuit 13, and a display 14 are connected in order. Each narrow band filter ■l, ■2.
It is expressed as v3. Now, a signal is inputted from an input terminal 1, modulated by a modulation circuit 2, and then outputted from an output terminal 3 as a modulated carrier wave.

On the other hand, a part of the modulated carrier wave is filtered through three narrow band filters 11-1, 11-2 and 11 with different center frequencies.
-3, and after being band limited, enter signal detection circuits 12-1, 12-2 and 12-3, respectively. The band-limited spectrum at each center frequency ft, f2 and f3 is:

The rail v detected by the signal detection circuits 12-1, 12-2 and 12-3 and corresponding to each spectrum
, l, v., and V. are sent to the determination circuit 13. Here, the comparison is made, the presence or absence of an abnormality is determined, and the result of (K) is displayed on the display 14, ':...

FIG. 3 is a graph for comparing and explaining the operation in a normal state and an abnormal state in the above embodiment. In the figure, (a) shows the spectrum state of the modulated signal, and (b) shows the narrowband filter 11-1゜11-
2 and 11-3 are shown.

(c) is the level V 1 + V 2 and ■3 when detected at each center frequency fr, fz and f3
shows. The determination circuit 13 receives the detection level ■I + "2 r v3 in the normal state of the signal detection circuits 12-1 to 12-3 shown in FIG. 3(C), stores the respective values, and then When an abnormality occurs in the modulation circuit 2, the spectrum state of the modulated signal changes, so the detection level Vi at that time.

By comparing the relative levels of V 2 + V 3, the presence or absence of an abnormal state and its contents can be determined. Furthermore, by comparing the absolute levels of the detection levels ■l, v2, and ■3, it is possible to know whether there is a change in the total power, and an abnormal state when the level decreases can be determined.

As is clear from the above description, according to the present invention, the spectrum state of the modulated signal is monitored by detecting and comparing a plurality of narrowband signals. Since any abnormal state can be correctly determined, the present invention has a great effect in that maintenance of the apparatus including not only the modulation circuit but also its front stage is easy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a configuration example of a conventional fault detection method, FIG. 2 is a block diagram showing a configuration of an embodiment according to the present invention, and FIG. 3 shows a normal state and an abnormal state in the embodiment of FIG. It is a graph for explaining the state and operation by comparison. In the figure, 1 is a signal input terminal, and 2 is a modulation circuit. 3 is a signal output terminal, 11-1, 11-2.11-3
12-1.12-2.12°-3 is a signal detection circuit, 13 is a determination circuit, and 14 is a display. Figure 3 Normal state of affairs

Claims (1)

[Claims] 1. After band-limiting the modulated carrier wave power using at least three narrow band filters with different center frequencies, detecting each filter, and comparing the detected levels with each other using a comparison/judgment device. A failure detection method applied to a device having a modulation function, characterized in that a decrease in the spectral density and level of the carrier wave power is determined according to the above.