JPS60192434A - Fault detecting circuit - Google Patents

Abstract

PURPOSE:To detect a fault of a circuit through which a burst signal is transmitted easily with simple circuit constitution accurately by detecting whether or not the level of an output signal of the transmission circuit is within a prescribed range and using an exclusive OR with an input signal to detect the fault. CONSTITUTION:An intermediate frequency band directional coupler 10 (same as 5-7), a diode detector 11 and a DC amplifier 12 are fitted to an output/input section (or transmission frequency converter input section) of a fault detection circuit, a comparator 13 is connected to obtain a rectangular wave in response to an input burst signal. On the other hand, a comparator 14 detecting that the level is over L1 and a comparator 15 detecting that the level is below L2 are fitted to a signal detection circuit of the output side of the transmitter. Thus, when both rectangular wave signals are exclusively ORed by exclusive OR circuits 16, 17, 18, a fault of a device (in this case a transmission frequency converter 2 and a power amplifier 3) is detected independently of the presence of the signal.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is based on TDMA (Time Division).
The normality of the transmitter (transmission frequency converter, power amplifier, etc.) that transmits burst signals, such as the transmitter for MultiPle Access.

This invention relates to a circuit for detecting abnormal operation.

[Prior art]

In recent years, in fields such as satellite communications, with the adoption of time division multiple access (TDMA), new technology has been developed for detecting faults in signal transmission equipment such as transmission frequency converters and power amplifiers. is increasingly required. FIG. 1 shows an example of a fault detection circuit in a conventional FDM-FM system. The signal from the modulator (1) in the figure is input to the transmission frequency converter (2), frequency converted, and then passed through the power amplifier (3) to the antenna device (4).
).

In such a device, as shown in the figure, a directional coupler (5) is used for the transmitter output, and a part of the transmitted output is sent to a detector (6) to detect whether the signal is being transmitted correctly. ) or detected using a power sensor, etc.
After passing through the DC amplifier (7), the window comparator (
There is a method of detecting an abnormality in the device based on whether the output level is within a permissible range (above a certain level and below a certain level) using, for example, 8). Tore is the conventional Fl) M
- In the FM method, the output power 1 is always at a constant level, so detection using this method was possible.

If a similar circuit is attached to the output section of the transmitting frequency converter (2), abnormalities in the transmitting frequency converter structure can be detected.

However, with this method, the transmission output is constantly reduced to 0.
In so-called burst mode transmission such as N10FF, the output signal level is not constant, so it cannot function as a failure detection circuit. Moreover, T'D
In a communication system such as MA, the transmission burst length 9 interval etc. are not necessarily constant and many types of burst signals are transmitted, so even if the time constant of the above circuit is set large to detect the average output power. cannot function adequately.

Therefore, in order to determine the output power for each burst, the carrier 0N10FF signal from the terminal station was used as a gate signal.

It is necessary to detect faults using a high-speed sample-and-hold circuit and a comparator circuit that determines the level of its output, but the circuit becomes too complex and the number of interfaces with end station equipment such as gate signal exchange increases, making it difficult to monitor the entire system. The disadvantage is that the reliability of the

[Summary of the invention]

The present invention makes it easy and simple to detect failures in equipment during burst signal transmission by confirming that the output level is within a certain range and by calculating the exclusive OR of the input signal and output signal. This is what we are trying to achieve with a circuit.

The principle will be explained with reference to FIG. Assuming that there is no delay time in the transmission circuit, the times at which input signal A and output signal B exist coincide as shown in (a).

However, if part of one of the signals is missing, (b)
As shown in , an exclusive OR is established between t and t2. Therefore, if the exclusive OR is established, it can be determined that an abnormality has occurred in the transmission circuit.

The above judgment determines an abnormality based on the presence or absence of output signal B, but if it is also confirmed that the level of output signal B is higher than level 1 and lower than level 2, it is possible to detect abnormalities in the transmission circuit. Accuracy is further improved.

In satellite communications, the level of radio waves transmitted from the ground station to the satellite is extremely strictly limited in order to ensure the line quality of the own station and to prevent interference with other stations, so it is necessary to monitor the transmission level of the own station. has become essential.

Even if the input signal A and the output signal B shown in FIG. 2(a) are introduced into a normal exclusive OR circuit, a whisker may appear in the waveform at both ends, making it difficult to judge. Therefore, it is better to delay one signal and determine whether the other signal is present at the rising edge or falling edge of the signal. Since the output signal is usually delayed in time compared to the input signal, there may be cases where it is not necessary to provide a particular delay circuit.

[Embodiments of the invention]

FIG. 8 shows a system diagram of an embodiment of the fault detection circuit according to the present invention. In the figure, (2) to (7) indicate the same functional blocks as in FIG. However, in the present invention, signals (5) to (7) are sent to this output section (or transmission frequency converter input section).
An intermediate frequency band directional coupler θQ similar to .

Install diode detector αV and DC amplifier θ,
A comparator 0■ is connected to this so that a rectangular wave corresponding to the input burst signal can be obtained. On the other hand, a comparator 04) for detecting that the level is 1 or more and a comparator αO for detecting that the level is 2 or less are attached to the signal detection circuit on the output side of the transmitter. In this way, the exclusive OR circuit OQ, 0η, 08
), it is possible to detect an abnormality in the equipment (in this case, the transmission frequency converter (2) and the power amplifier (3)) regardless of the presence or absence of the signal.

σ9 is a delay circuit that delays the input signal A so that it can be determined whether the output signal B exists at the rising edge of the input signal A. Comparators αY and αG can be easily configured using operational amplifiers.

The OQ and α forces are normal edge-trigger type D flip-flop circuits, and if the D terminal is at H level when the input to the T terminal rises, the output terminal also goes to H level. It is constructed using data such as data. 08) is an OR circuit, and when the exclusive OR is established, an alarm signal is output from this OR circuit.

FIG. 4 is a waveform explanatory diagram of each part of FIG. 8, and the operation of the circuit of FIG. 8 will be explained using this diagram.

The input signal A shown in FIG. 4(a) is converted into a rectangular wave by the comparator 03 and delayed by the delay circuit 00, resulting in the waveform shown in FIG. 4(b). Regarding the output signal B shown in FIG. 4(c), the transmission between t and t2 is normal as shown in the diagram, but due to transmission abnormality, the level decreases between 1314 and t.
It is assumed that the level becomes too high between 5t6.

In such a case, the output signal B is at the level L1 shown in (a).
The comparator αΦ outputs when the level is 2 or higher, and the comparator outputs when the level is 2 or higher (1G converts the waveforms as shown in (e) and '(f), respectively. Judgment of the presence or absence of transmission abnormality at times t and t2 is delayed. At the rising edge of the input signal t12
In D flip-flop circuit Qf19. It is judged by whether or not there is an output in α force. The Q output of the D flip-flop α force is shown in (g), and the 4 outputs of 00 are shown in (h).

Time t1. At t2, the comparator αa is outputting, so the Q output of the D flip-flop αQ becomes L level,
Comparator αO is not outputting, so D flip-flop α
The Q output of the power becomes L level, and the output of the OR circuit (G) becomes L level.

At time t3t4, comparator Q41. Since Qυ is not output, at t34 when the input signal rises, the Q output of D flip-flop 0 becomes H level, the output of D flip-flop <171 becomes L level, and an alarm signal is output from the OR circuit (G). . Between t and t6, comparators Q4) and Q5) both output, so at t56 when the input signal rises, the Q output of the D flip-flop 0Q becomes L level, and the output of the D flip-flop α becomes H level. An alarm signal is output from the OR circuit (c).

In the above example, an OR circuit (G) is used to generate an alarm output, but if the outputs of the flip-flop circuits αQ and αF are used as they are, an alarm output can be output by distinguishing between levels Hgh and LowW.

As explained above, if this circuit is used, the burst length (pulse width) of the input signal can be used to determine whether the level of the output signal is within a certain range after a certain period of time after the rise of the input signal. It has the advantage that it is possible to very easily determine whether it is normal or abnormal without being affected by the distance between the two, and there is no need for the normally used carrier 0N10FF signal (gate signal) from the outside.

In addition, although the above explanation has mainly been made using TDMA signals as an example, it is also possible to use a system such as 5CPC where the carrier is disconnected/connected depending on the presence or absence of voice, or the carrier 0N10 of the modulator.
It is also effective for detecting FF circuits.

〔Effect of the invention〕

This invention detects whether the level of the output signal of the transmission circuit is within a certain range and then performs an exclusive OR with the input signal □ to detect a fault, so that burst signals are not transmitted. This has the effect that failures in circuits can be easily detected with high accuracy using a simple circuit configuration.

Furthermore, if an exclusive OR is formed depending on whether the other signal is 1 or not depending on the rising edge of the input signal, there will be no erroneous judgment.

[Brief explanation of the drawing]

Fig. 1 is an example of a conventional signal detection circuit, Fig. 2 is a waveform explanatory diagram showing the principle of the present invention, Fig. 8 is an embodiment of the signal detection circuit according to the present invention, and Fig. 4 is the waveform of Fig. 8. It is an explanatory diagram. In the figure, (2) is a frequency converter, (3) is a power amplifier, (5), αQ is a directional coupler, (6), (11
) is the detector, Q-sen. 04), Qυ is a comparator, 0, α is a D flip-flop circuit, 2) is an OR circuit, and θ is a delay circuit. The same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 Figure 2 Figure 4 Draft procedure amendment (voluntary) 1. Indication of case Japanese Patent Application No. 59-49788 3. Person making the amendment Representative Hitoshi Katayama 5. Subject of amendment (1) ) Drawing 6, contents of amendment (]) Figure 8 of the drawings is corrected as shown in the attached sheet. 7. List of attached documents (1) Drawings 1 or more 101-

Claims (2)

[Claims] (1) A first comparator that detects that an output signal of a wireless communication device that transmits a burst signal wave is higher than a first level L1, and a first comparator that detects that the output signal is higher than a first level L2 (
a second comparator that detects that the input signal of the wireless communication device is larger than L2>Lt); and a circuit for determining the outputs of the first and second comparators. (2) The fault detection circuit according to claim 1, wherein the wireless communication device includes a frequency converter or an amplifier.