JPH02159841A - Receiver fault detector - Google Patents

Abstract

PURPOSE:To simply detect a fault in the reception state such as noise disturbance in a band of a reception signal by discriminating it to be a fault of a receiver when a carrier detection signal reaches a prescribed level or over and a noise detection signal is at a prescribed level or over. CONSTITUTION:When a reception circuit 12 receives a carrier normally, a level of a carrier detection signal is nearly proportional to a reception electric field strength and a nose detection signal ND goes rapidly to a low level when the reception electric field strength reaches a prescribed level or over when the circuit 12 receives a carrier and the signal CD level is a prescribed level or over and the signal ND is at a prescribed level or over (noise is not normally suppressed), a discrimination circuit 13 discriminates the reception state is faulty. Thus, even when the carrier is received and the noise level of the carrier is high, since the reception state is discriminated to be faulty, a fault of the reception state such as noise disturbance in the band of the reception signal is detected simply.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a receiver failure detection device for detecting failures in FfVl receivers and the like used in remote locations and unmanned environments, such as wireless base stations.

BACKGROUND OF THE INVENTION Conventionally, this type of receiver failure detection device monitors the increase or decrease in the current consumption of the receiving circuit 1 using a current monitoring circuit 2, as shown in FIG. is configured to detect receiver failure.

Further, another conventional receiver failure detection device is shown in FIG.
As shown in , the receiving circuit 1 monitors the local oscillation signal of the local oscillator 3 for converting the received high frequency signal into an intermediate frequency signal or a low frequency signal, and when it detects that oscillation has stopped or the output level has decreased, configured to detect machine failures. Note that the receiving circuit 1 mixes the received high frequency signal and a signal at the local oscillation frequency of the local oscillator 3, and sequentially converts the mixed signal into an intermediate frequency signal and a low frequency signal.

In addition, as another conventional receiver failure detection device, the one shown in Fig. 3 (C
As shown in Fig. 1, there is also known a system that monitors the above two states and detects a failure in the receiver when either one of the states is abnormal.

Problems to be Solved by the Invention However, the conventional receiver failure detection device described above monitors the current consumption of the receiving circuit 1 and the oscillation signal of the local oscillator 2, and detects the stoppage of oscillation or a decrease in the output level, thereby preventing the receiver failure from occurring. Therefore, there is a problem in that it is not possible to detect disturbances in the reception condition such as noise interference within the band of the received signal.

In order to detect a failure in the reception state, it is necessary to form a wireless line and perform a loop check after the failure occurs.

SUMMARY OF THE INVENTION In view of the shortcomings of the prior art described above, it is an object of the present invention to provide a receiver failure detection system that can easily detect failures in the reception state such as noise interference within the band of a received signal.

Means for Solving Problems In order to achieve the above-mentioned object, the present invention determines that there is an abnormality in the receiver when the carrier detection signal is above a predetermined level and the noise detection signal is above a predetermined level. According to the present invention, with the above configuration, when the receiver is operating normally and receiving a carrier, the carrier detection signal is above a predetermined level and the noise detection signal is below a predetermined level. If the noise detection signal is not suppressed to a certain level and is not operating normally, the noise detection signal will not be suppressed below a predetermined level, and therefore it is possible to easily detect disturbances in the receiving condition such as noise interference within the band of the received signal. .

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1(a) is a block diagram showing an embodiment of the receiver failure detection device according to the present invention, and FIG. FIG. 2 is a graph showing general characteristics of the main signals of FIG.

In FIG. 1 (al), 11 is a local oscillator that generates a signal of a local oscillation frequency, 12 is a signal that mixes the received high frequency signal and the signal of the local oscillation frequency of the local oscillator 11,
This is a receiving circuit that sequentially converts an intermediate frequency signal and a low frequency signal. When the receiving circuit 12 is operating normally, the carrier is detected by a carrier detection signal CD in which a carrier is detected and a squelch circuit (not shown). A noise detection signal ND with suppressed noise is output.

Reference numeral 13 denotes a circuit that uses the low frequency carrier detection signal CD and noise detection signal ND from the receiving circuit 12 to determine whether there is a problem in the reception state of the receiver, as will be described later.

Next, the operation of the above embodiment will be explained with reference to FIG.

When the receiving circuit 12 is normally receiving the carrier, the level of the carrier detection signal CD is approximately proportional to the received electric field strength as shown in FIG. When it reaches a predetermined level or higher, it drops sharply to a lower level.

Therefore, when the receiving circuit 12 receives a carrier and the level of the carrier detection signal CD is above a predetermined level, and when the noise detection signal ND is above a predetermined level (when noise is not suppressed normally), ), the reception status is determined to be abnormal.

Therefore, according to the above embodiment, even when a carrier is being received, the reception state is determined to be abnormal when the noise level of the carrier is high. Condition failures can be detected.

In the above embodiment, the receiving state is determined to be abnormal only when the noise level of the carrier is high while the carrier is being received.
), when the noise level of the carrier is high while the carrier is being received, when the current consumption abnormally increases or decreases, or when the local oscillator 3 stops oscillating or the output level decreases. It may be configured such that if there is an abnormality, it is determined that there is a failure in the receiver.

As described in detail, the present invention determines that the receiver is abnormal when the carrier detection signal is above a predetermined level and the noise detection signal is above a predetermined level. When the device is not operating normally, the noise detection signal is not suppressed below a predetermined level, and therefore, it is possible to easily detect disturbances in the receiving condition such as noise interference within the band of the received signal.

[Brief explanation of the drawing]

FIG. 1 (a) is a block diagram showing an embodiment of the receiver failure detection device according to the present invention, and FIG.
FIG. 2 is a graph showing general characteristics of the main signal in FIG. 1, and FIG. 3 (al, (bl), (C) are respectively,
It is a block diagram showing a conventional receiver failure detection device.0 12...Reception circuit, 13 - Discrimination circuit, CD...Carrier detection signal, ND...Noise detection signal.

Claims (1)

[Claims] Means for outputting a carrier detection signal and a noise detection signal, and determining that a receiver is abnormal when the carrier detection signal is at a predetermined level or higher and the noise detection signal is at a predetermined level or higher. A receiver failure detection apparatus having means.