JPS6040239B2 - Central monitoring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frequency and time division band cancellation type centralized monitoring system, and in particular, a novel centralized monitoring system in which a receiver is installed at the same location as a transmitter and a received signal is determined based on the transmission timing. Regarding the method.

For example, a frequency-time division band elimination method has conventionally been used as a fault monitoring device that systematically and intensively monitors points requiring fault warning, such as railroad crossings scattered on railway tracks, falling rocks, landslides, and the like.

As shown in Fig. 1, this method transmits monitoring signals of different frequencies f, . are the assigned frequency band cancellation filters BEf, , BEf2...B
Em is installed, and when a fault occurs at that location, the fault detection relay Ry is restored and the band cancellation filter at that location is inserted in series into the line, so that the received signal is transmitted to the part of the inserted filter, that is, where the fault occurred. A signal is generated in which only the frequency portion corresponding to the location is deleted, and this is detected by the receiver 2.

Conventionally, as this receiving method, a synchronization signal $ is transmitted together with the above-mentioned signals f and -fn, and this signal is input to the receiver 2 installed at the terminal of the transmission line. Then, as shown in Figure 1, the synchronization signal & It is configured to occur at a timing approximately in the middle of the time of division. The received signal then enters a wideband band-pass filter BPf, ~n that passes each of the frequencies f, ~fn, and the output from the filter BPf, ~n is rectified by a rectifier RF, and then amplified by an amplifier A.
Reception is detected by comparing the rectified output with the sampling pulse. In such conventional methods, it is necessary for the receiving side to determine the synchronization signal indicating the start of the time-division frequency cycle, generate a sampling pulse from that point, and detect the signals at frequencies f, ~fn. be.

That is, the receiving side must independently create timings corresponding to the transmission timings of f, to fn. However, due to transient phenomena in the filter BPfs that passes the synchronization signal and other causes, the rise and fall of the synchronization signal do not become steep, and therefore the synchronization point is not stable, causing the phase of the sampling pulse to fluctuate and malfunction. There is now. This phenomenon becomes more pronounced as the number of types of transmitted frequencies n increases and as the time division switching speed t increases. Therefore, the synchronization point can be detected more accurately than before,
Various improvements have been made to stabilize the phase of the sampling pulse, but in any case, because the timing is created independently on the receiving side, complete stabilization has not been possible. The present invention has been made with attention to the above-mentioned points, and the present invention is made by supplying a time-sharing timing signal generated on the transmitting side to a receiver, and using this timing signal to determine the received signal. It is possible to obtain a sampling pulse that completely matches the timing of Circuit for creating BPfs,S
It is an object of the present invention to provide a centralized monitoring system that eliminates the need for C, simplifies the circuit configuration, and eliminates malfunctions.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The method of the present invention basically consists of a receiver 2 as shown in FIG.
is installed in the same place as the transmitter 1, and the communication cable 4 is installed in a doubly manner with the transmission line 3 to receive the signals of frequencies f, ~fn sent from the transmitter 1 in a time-division manner, and at the same time The received signal is determined based on the switching timing of the time-division signal. If the transmission distance is long, an amplifier 5 may be provided as necessary. An embodiment of the transmitter 1 and receiver 2 is shown in FIG.

The transmitter 1 transmits multi-frequency monitoring signals of f, f2, . It's a signal. The receiver 2 is a broadband band/gas filter BP that passes all frequencies f, ~fn.
f, ~n, amplifier A, Schmitt circuit SC, rectifier RF
, an AND gate 10, a shift register 11, a memory 2, etc., which are also well known. The method of the present invention is characterized in that a timing signal for time division, that is, an output signal of the counter 8, is also supplied to the receiver, and a sampling pulse is generated using this timing signal and compared with the received signal. That is, as shown in FIG.
A monitoring signal with a frequency of is transmitted from a transmitter 1, passes through a transmission circuit 3 and a relay Ry at each information site, and is received by a receiver 2 via a communication cable 4. In the receiver 2, the received signal passes through band pass filters BPf, -n to remove noise, is amplified, has a level determined, is further rectified, and is taken out from the rectifier RF as a DC signal as shown in FIG. 4b. On the other hand, the output of the counter 8 is given to a sampling pulse generator 9, which generates a sampling pulse approximately at the middle of the time t of the time division (FIG. 4c). The received signal is determined by comparing this sampling pulse with the DC output using the band gate 10. For example, when a failure occurs at the information site D' and the relay Ry at that location is restored, the obijo cancellation filter BEf2 is inserted into the line, so the received signal becomes a signal with missing frequencies, and the output of the rectifier RF is as shown in Figure 4. b as shown by the dotted line. Therefore, since there is no received signal at these transmission timings, the output of the band gate 10 becomes a signal in which the timing portions are cut off, as shown by the dotted line in FIG. Since the circuits BP and SC for creating the circuits are no longer necessary and stable sampling pulses can be obtained with the simple circuit 9, stable reception signals can be discriminated. The output information of the AND gate 10 is input to a shift register 1, for example, and is shifted using a sampling pulse, and the output information is written from the shift register to the memory 2 in parallel. Information for each cycle of the time division step is written in the memory 12, and the memory 2 can also be controlled using the timing signal for time division. shift register 1
The following circuit is an example of a circuit for extracting verification results and displaying information on the information site, and any known circuit may be used for this. FIG. 5 shows another embodiment of the system of the present invention, in which the communication cable 4 of the first embodiment is not used and only the transmission line 3 is used. That is, hybrid coils 13 and 14 are provided at both ends of the line 3, a frequency converter 15 is connected to the hybrid coil 14 at the terminal, and a receiver 2 is connected to the hybrid coil 13 at the transmitter side. The frequency converter 15 converts the frequency L to fn (
For example, a slightly higher frequency (for example, 3 to 2) than 1 to 2)
Shoes HZ) and convert it into a hybrid coil 13,1
4, in the same manner as in the first embodiment. In this case, it goes without saying that the broadband filters BPf, to n of the receiver 2 are filters that allow the frequency converted by the frequency converter 15 to pass. As described above, according to the present invention, the receiver is installed at the same location as the transmitter, and the time-sharing timing signal generated by the transmitter is directly supplied to the receiver without going through the information site. , the receiver generates a sampling pulse using the timing signal, and the received signal input via the information site is determined by the sampling pulse, so there is no synchronization point for creating independent timing in the receiver. There is no need to detect the timing, and there is no need to send a synchronization signal to the receiver via the information site to create an independent timing. Therefore, the generation of sampling pulses and the circuit configuration of the receiver for comparison Not only is this simplified, but the time-division timing signal is directly used as the sampling pulse generation timing, which has the great effect of eliminating any errors caused by synchronization point fluctuations.

[Brief explanation of the drawing]

Fig. 1A and 1B are system diagrams showing a conventional general frequency-time-division band-cast elimination centralized monitoring system, Fig. 2 is a system diagram showing an embodiment of the inventive system, and Fig. 3 is a system diagram showing the inventive system. FIG. 4 is a time chart showing the operation of the method of the present invention, and FIG. 5 is a system diagram showing another embodiment of the method of the present invention. 1...Transmitter, 2...Receiver, 3...
...Transmission circuit, 4...Communication cable, 9...
...Sampling pulse generator, 1 to N...
Information site, BEf, ~BEf2. …．・Obijo erasure filter evening. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1 Frequency-time-division band-elimination type concentration that transmits monitoring signals of frequencies corresponding to the rejection frequencies of band-elimination filters installed at multiple information sites in a time-division manner, and receives and detects information from each information site at the receiver. In the monitoring system, the receiver is installed at the same location as the transmitter, and the transmitter generates a timing signal, and the timing signal converts the monitoring signal into a time-division signal, and the timing signal is directly supplied to the receiver. The centralized monitoring method is characterized in that the receiver generates a sampling pulse using the timing signal input from the transmitter, and compares and checks the sampling pulse with the received signal input via each information site.