JPS60240233A - Receiving alarm system - Google Patents

Abstract

PURPOSE:To obtain a digital multiplex radio receiving system which can identify a faulty part by combining the detecting output of an input wave which has passed through a receiving filter, and the detecting output of an input wave which has passed through the filter of a narrower band than said filter. CONSTITUTION:Plural receiving waves received by an antenna 1 are made to branch by a branching filter 2, supplied to a receiver 3, brought to frequency conversion and amplified, and sent out to the outside from a terminal 14 through an AGC amplifier 4 and 5. On the other hand, part of an output of the AGC amplifier 4 is made to branch into two, one of them remains as it is, and as for the other, the output of the vicinity of the center frequency is extracted by a narrow band pass filter 6, they are detected by detectors 7, 8, respectively, and thereafter, outputs compared with a reference level by comparators 9, 10 are provided to terminals 15, 16 of a logical circuit 11. In such a case, for instance, in case of a transmitting place to a system 1, a wave of an adjacent channel is received in advance, therefore, the terminal 15 and the terminal 16 go to ''0'' and ''1'', respectively. In such a way, a faulty part can be identified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in a receiving alarm system for a digital multiplex radio system using microwaves.

Generally, the frequency of radio communications in the same area and in the same direction is shifted little by little to prevent waves other than the desired wave from mixing in.

However, since each frequency band used for wireless communication is determined depending on the purpose of communication, it is necessary to make the most effective use of the allocated frequency band to carry out the maximum number of communications.

In particular, a digital radio system that transmits information using on/off digital signals is more resistant to interference than an FM radio system that transmits analog information as it is, so the frequency interval between adjacent channels is narrower.

Therefore, in addition to the desired wave, part of the wave of the adjacent channel is also received.

On the other hand, even in the above-mentioned receiving system, it is necessary to constantly monitor whether the local station is operating normally, and if a failure occurs, it is necessary to identify the failure location so that prompt measures can be taken. It is desirable to be able to generate warnings.

(bl Conventional technology FIG. 2 shows an example of a conventional receiving alarm system.

In the figure, 1 is an antenna, 2 is a reception branching filter, 3 is a receiver, 4 and 5 are automatic gain control (hereinafter abbreviated as AGC) amplifiers, 7 is a first detector, and 9 is a receiver. Comparator, 20 is system-1, 21 is system-2, 14, 15 and 1
7.18 indicates the terminals, respectively.

Note that system-1, system-2, etc. have the same configuration.

The operation of the reception alarm system shown in FIG. ...
etc. can be added to

For example, the received wave applied to system-1 is amplified and frequency-converted by receiver 3 and converted into an intermediate frequency signal, and then
to terminal 1, which is amplified to a predetermined level by GC amplifiers 4 and 5.
It is sent to the outside from 4.

Note that a part of the output of the AGC amplifier 4 (corresponding to the reception level) detected by the first detector 7 is checked by a comparator 9 to see if it is above a reference level, and if it is below the reference level, it is not received. A level-off alarm is sent to the outside from terminal 15.

(C1 Problem to be Solved by the Invention The receiving alarm system shown in FIG. 2(a) constantly receives waves from adjacent channels as well as desired waves, as shown below.

That is, the spectrum of the received wave received by the antenna 1 in FIG. 2+al is arranged as shown in FIG. 2(b).

Note that f,, fo + f+ (... are the center frequencies, respectively.

In order to extract the spectrum of the desired wave from the spectrum of the received waves arranged in this way, the combined band of the reception demultiplexer 2 and the reception filter (not shown) included in the receiver 3 shown in FIG. This is separated using filtering characteristics.

This band filter characteristic must be designed to minimize the distortion imparted to the digital signal passing through it, and to remove as much adjacent channel waves as possible, but as the operating frequency increases, the band filter has a steep cutoff characteristic. (Figure 2 (the dotted line in bl shows the frequency characteristics of the bandpass filter of System-1).

Therefore, in the case of a digital radio system in which the frequency interval between adjacent channels is narrow, a part of the system-2 wave (shaded area) is also received in addition to the system-1 wave, which is the desired wave.

For this reason, the following problems occur.

(1) Even if the reception level of the desired wave is cut off, as long as the system-2 wave that is higher than the reference level is received, a reception cut-off alarm will not be sent due to the reception of this wave, so what should be done to deal with this? I can't.

(2) When the reception of System-1 and System-2 is interrupted due to fading, a reception interruption alarm is sent out, but each system does not have the function to identify the cause of the failure and issue an alarm. It takes time to identify
Disaster recovery takes time.

That is, since it does not have a function to identify and issue an alarm when a fault occurs, there is a problem in that it is difficult to quickly respond to the fault.

(dl Means for solving the problem) The problem described above is that the first detection output obtained by detecting the reception input wave that has passed through the reception filter, and the This problem can be solved by the receiving alarm system of the present invention, which sends out alarms for each fault by combining the received input wave that has passed through the wave detector with the second detection output obtained by detecting the received input wave.

(114) Function The function of this means is that instead of transmitting a reception alarm by using only the detection output obtained by detecting the reception signal that has passed through the conventional broadband reception filter with the first detector. , the above-mentioned detection output and the detection output obtained by detecting the received signal from which interference waves have been removed through a wave filter having a narrower band than the reception filter with a second wave detector are outputted from an AND circuit. It is possible to send alarms for each fault by combining them using different logic circuits.

As a result, troubleshooting measures can now be taken quickly.

(f) Embodiment FIG. 1(a) shows an example for implementing the method of the present invention.

In the figure, ■ indicates the antenna, 2 indicates the reception branching filter, 3 indicates the receiver, 4 and 5 indicate the AGC amplifier, 6 indicates the narrowband filter, and 7
．． 8 is the first. The second detector, 9°10, the comparator, 1
1 is a logic circuit, 12 is a system-1, 13 is a system-2, and 15 to 24 are terminals.

In the figure, a plurality of received waves received by an antenna 1 are demultiplexed by a demultiplexer 2. Then, for example, the received wave applied to the receiver 3 is frequency-converted and amplified, and is sent out from the terminal 14 through the AGC amplifiers 4 and 5.

On the other hand, a part of the output of the AGC amplifier 4 is branched into two parts.
One is left as is, and the rest are narrowband filters 6 with center frequency fo.
Nearby outputs are extracted (interfering waves are removed), and the first... After being detected by the second detectors 7 and 8, the comparator 9.10 compares the output with the reference level and outputs the output to the logic circuit 11.
are applied to terminals 15 and 16, respectively.

In system-2, the output of a comparator (not shown) is applied to terminals 18 and 19 of logic circuit 11 through similar processing.

Therefore, the comparator output applied to the logic circuit 11 is as follows depending on the type of fault.

15 16 18 19 Transmission is interrupted for system-1 ○ System-1 failure ○ ○ Transmission is interrupted for system-2 ○ System-2 failure ○ ○ Disconnection due to fading ○ ○ ○ Here, 15.16.18.19 is the terminal number , O indicates that there is an output from the comparator.

Furthermore, when a failure occurs in the propagation path due to fading, the reception levels of systems -1 and -2 drop simultaneously, so the outputs of comparators 9 and 10 are applied to all terminals.

FIG. 1 (bl shows an example of a logic circuit for realizing the above operation).

In the figure, 15 to 19 are detection signal input terminals, 20 to 24 are alarm sending terminals, 25, 26 and 34 are negative circuits, and 2
7 to 33 indicate logical product circuits (hereinafter referred to as AND circuits), respectively, and show the configuration of the logic circuits in the case of system-1 and system-2.

The operation of FIG. 1(b) is as follows.

For example, in the case of a transmission failure for system-1, the output of the detector 9 becomes 0 because the wave of the adjacent channel is being received, and the output of the terminal 15 is O, but since no desired wave is detected, the output of the detector 9 is 0, and the output of the detector 9 is O because the desired wave is not detected.
The output of will be 1.

On the other hand, since system-2 is operating normally, terminal 1
8 and 19 are O.

Therefore, 1 is output from the AND circuit 27 to the terminal 20,
Since the outputs of the other AND circuits 28 to 33 become 0, the terminals 21 to 24 become 0, and only a transmission interruption alarm is issued to the system-1.

Hereafter, the fault location can be identified in the same manner.

(g) As described in detail, the present invention enables the receiving side to identify which of the other station's transmission failures, the propagation path failures, and the own station's reception failures, and to prevent the occurrence of failures. The response will be swift.

[Brief explanation of drawings]

FIG. 1(a) is a block diagram showing an example for implementing the present invention, FIG. 1(bl is a logic circuit block diagram of the present invention, FIG.
a+ is a block diagram showing a conventional example, and FIG. 2 (bl is a diagram explaining the influence of adjacent channels). 4.5 is an automatic gain control amplifier, 6 is a narrowband filter, 7.8 is a first and second detector, 9.10 is a comparator, 11 is a logic circuit, 12 is a system-1, 12 is a System-2, 15 to 24 indicate the terminals, respectively.

Claims (1)

[Claims] The first signal obtained by detecting the received input wave that has passed through the receiving filter
By combining the detection output of 1 and the second detection output obtained by detecting the reception input wave that has passed through a filter with a narrower band than the reception filter, an alarm on the fault side is sent out. A receiving alarm system characterized by: