JPH03255731A - Equipment fault detecting system for intermediate frequency band equalizer - Google Patents

Abstract

PURPOSE:To hold the transmission quality of a line satisfactorily by periodically inserting a notch circuit just before an intermediate frequency(IF) equalizer, and confirming the presence/absence of a fault in the IF equalizer itself. CONSTITUTION:A notch circuit 1 is formed by using an amplitude equalizer 11 to change the frequency characteristic of the amplitude of an output signal and an attenuator 12 to attenuate the amplitude over all frequency bands, and set just before an IF equalizer 10. By inserting this notch circuit 1, when the amplitude frequency characteristic outputted from the IF equalizer 10 takes a form 111 remaining the amplitude frequency characteristic of the amplitude equalizer 11 in the notch circuit 1, it is decided that the fault is generated in an amplitude equalizing part 10 of the IF equalizer 10, and when the amplitude of the characteristic for the attenuator 12 of the notch circuit 1 takes a form 112 being attenuated over all the frequency bands, it is decided that the fault is generated in an AGC amplifier 102 of the IF equalizer 10. Therefore, the fault of the IF equalizer 10 itself can be detected while being distinguished from the abnormality caused by the phasing of a radio line.

Description

[Detailed Description of the Invention] [Summary] Amplitude equalization and reception output level that are inserted into an intermediate frequency signal circuit before a demodulator of a microwave radio receiving device to correct changes in amplitude frequency characteristics due to fading. Regarding a detection method for equipment failure in an equalizer that performs AGC control to maintain a constant value, the purpose of this invention is to provide a detection method that can distinguish and detect failures of intermediate frequency equalizers themselves from abnormalities due to fading of radio channels. Immediately before the equalizer, there is a notch circuit that pseudo-attenuates the amplitude of the output signal and changes the frequency characteristics, a switch that turns the notch circuit on and off in the intermediate frequency signal circuit, and a switch that connects the notch circuit to the intermediate frequency signal circuit. A comparator is provided that compares the output IF of the equalizer when inserted into the frequency signal circuit and the output IP of the equalizer when not inserted into the circuit, and the output of the comparator is the output of the switch. The equalizer is configured to be determined to be normal if there is no change and substantially the same between on/off, and to be determined to be malfunctioning if there is a change.

[Industrial Field of Application] The present invention relates to a digital microwave radio device, and more particularly to a method for detecting a failure in a device provided in an intermediate frequency circuit before demodulation of a receiving device.

In a digital microwave radio device, as the capacity of a transmission signal increases, transmission distortion of a received signal increases. Therefore, a vase that equalizes the transmission distortion of the received signal has become important.

[Conventional technology]

A conventional device for equalizing transmission distortion of a received signal is inserted into the intermediate frequency signal IF circuit at the front stage of the demodulation board 20 of the receiving device, as shown in FIG. Amplitude equalization was performed to correct this, and AGC control was performed to keep the received output level constant.

[Problems to be Solved by the Invention] However, the abnormality in the output of the intermediate frequency equalizer 10 (abbreviated as IF band equalizer) inserted into the intermediate frequency IF circuit is caused by a failure of the equalizer 10 itself. There is a problem in that it is difficult to find out whether this is due to fading of the radio line in front of the equalizer 10 or the like.

An object of the present invention is to provide a detection method that can detect only a failure of the intermediate frequency equalizer itself, distinguishing it from abnormalities due to fading in the wireless line.

[Means for Solving the Problem] As shown in FIG. 1, this problem involves creating a notch that creates fading that pseudo-attenuates the amplitude of the output signal and changes the frequency characteristics of the amplitude immediately before the IF band isoflower 10. Circuit 1 and
A switch 2 turns the notch circuit into/off a circuit with an intermediate frequency IP, and a switch 2 turns the notch circuit 1 into a circuit with an intermediate frequency I.
A comparator 3 is provided to compare the output IF of the flower vase 10 when it is inserted into the circuit of F with the output IF2 of the flower vase 10 when it is not inserted into the circuit, and the output of the comparator 3 is connected to the switch 2. This problem is solved by the present invention, which determines that the flower vase 10 is normal if there is no change and is substantially the same between turning on and off, and that the flower vase 10 is malfunctioning if there is a change.

In the principle diagram of FIG. 1 showing the basic configuration of the intermediate frequency band device fault detection system of the present invention, 1 is provided immediately before the intermediate frequency band device failure detection system 10 of the receiving device, and is provided with a pseudo-output signal. This is a notch circuit that creates fading that attenuates the amplitude of the signal from a specified value and changes the frequency characteristics of the amplitude.

2 is a switch that turns the notch circuit on/off to the intermediate frequency IP circuit.

3 is the output ■F of the IF band equalizer 10 when the notch circuit 1 is inserted into the intermediate frequency IP circuit using the switch 2, and the output IF2 of the IF band equalizer 10 when it is not inserted into the circuit. It is a comparator for comparison.

[Operation] In the present invention, if the output of the comparator 3 does not change and is substantially the same when the switch 2 is turned on or off, the equalizer 10 is normal, and if there is a change, the IP band equalizer 10 is malfunctioning. It is determined that

Therefore, distinguishing it from an abnormality due to wireless line fading,
The problem is solved because failures in the intermediate frequency band equalizer itself can be detected.

〔Example〕

The principle diagram shown in FIG. 1 shows the configuration of a method for detecting equipment failure in an intermediate frequency band according to an embodiment of the present invention, and has already been described in detail. FIG. 2 is a characteristic diagram for explaining the operation of the embodiment of the present invention, and (1) in the figure shows the amplitude equalization section 10. In the case of a failure, (2) in the figure is
This is a case where the AGC amplifier 10□ of the IP equalizer is out of order.

The notch circuit 1 according to the embodiment of the present invention includes an amplitude equalizer 1.0 that changes the frequency characteristics of the amplitude of an output signal. and.

This is a simple circuit made using an attenuator 1□ that attenuates the amplitude in all frequency bands, and is placed immediately before the IF equalizer 10. Turning on/off the notch circuit 1 to the intermediate frequency circuit is as follows:
This is done with a switch 2 having a switching contact, but soldering can be easily done by attaching with a similar method. By inserting this notch circuit 1, the amplitude frequency characteristic 1 of the output of the IF equalizer 10 is
1 is a form 11.1 in which the amplitude frequency characteristics of the amplitude equalizer 1 of the notch circuit 1 remain, as shown in (1) in FIG. If,
Amplitude equalization section 10 of IP equalizer 1o. It is determined that the attenuator 1 of the notch circuit 1 is broken, as shown in (2) in Fig.
If the amplitude of the characteristic □ is of the form 11□ which is attenuated in all frequency bands, it is determined that the AGC amplifier 10□ of the IP equalizer 10 is malfunctioning.

Therefore, in the embodiment of the present invention shown in FIG. 2, there is no problem because the failure of the intermediate frequency band equalizer itself is detected separately from the abnormality due to fading of the wireless line.

In actual use, although not shown in the figure, after switching the main working line to the protection line, the working line's IF
It is sufficient to confirm whether or not the equalizer is malfunctioning.

[Effects of the Invention] As explained above, the notch circuit of the present invention is periodically
By inserting the IF equalizer immediately before the equalizer and checking whether the IF equalizer itself is malfunctioning, it is possible to easily maintain good line transmission quality.

[Brief explanation of drawings]

Fig. 1 is a principle diagram showing the basic configuration of the equipment fault detection method of the intermediate frequency band equalization section of the present invention, Fig. 2 is a characteristic diagram for explaining the operation of the embodiment of the present invention, and Fig. 3 is a FIG. 2 is a block diagram of a conventional intermediate frequency band equalizer. In the figure, 1 is a notch circuit, 2 is a switch, 3 is a comparator, 10 is an equalizer, and 20 is a demodulator.

Claims (1)

[Claims] It is inserted into a circuit for an intermediate frequency signal before demodulation of a radio receiving device, and performs amplitude equalization to correct changes in amplitude frequency characteristics due to fading, AGC control to keep the level of received output constant, etc. In the equipment failure detection method of the equalizer (10), a notch circuit (1) that artificially attenuates the amplitude of the output signal and changes the frequency characteristics is provided immediately before the equalizer, and the notch circuit is connected to the intermediate frequency signal. Switch to turn on/off the circuit (2)
and a comparator (IF_1) that compares the output of the equalizer when the notch circuit is inserted into the intermediate frequency signal circuit with a switch (IF_1) and the output of the equalizer (IF_2) when the notch circuit is not inserted into the circuit. 3), and if the output of the comparator does not change and is substantially the same when the switch is turned on or off, the equalizer is normal;
A device failure detection method for an equalizer in an intermediate frequency band, characterized in that if there is a change, it is determined that the equalizer is in failure.