JPS63309033A - Hot stand-by line switching system - Google Patents

Abstract

PURPOSE:To accurately switch a hot stand-by line even in case of line trouble wherein no alarm signal is generated by sending by sending out a forcible switching signal to a line in the opposite direction from a line which sends an abnormal signal due to a silent failure and switching an in-use/stand-by state forcibly. CONSTITUTION:A terminal station A detects a signal received from an up line by a silent failure detection part 7 because the signal is abnormal although no alarm signal is sent, and the silent failure detection part 7 sends out the forcible switching signal to a down line through a down line transmitters 6a or 6b. This forcible switching signal is received and detected by a transmitter receiver 15a or 15b of a repeating station B first, and sent out to a switch 9 through a time constant circuit 18, so that an in-use transmitter receiver 10a is switched to a stand-by transmitter receiver 10b. Then a transmitter receiver 26a or 26b of a next-stage repeating station C receives the forcible switching signal and sends it out to a switch 20 through a time constant circuit 29, so that an in-use transmitter receiver 21a is switched to a stand-by transmitter receiver 21b.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a hot standby line switching system, and particularly to a so-called silent failure system in which an abnormal signal is transmitted as it is to a terminal station without generating an alarm signal indicating an abnormality. ) Concerns the hot standby line switching method in the state.

Conventional technology Conventionally, in communication lines using the hot standby system, switching of the hot standby line was performed by switching the output of the transmitter in response to an alarm signal generated from each device of the own station or other stations in the event of an abnormality. It is being said.

However, there are some Isodei devices that do not have a built-in device that generates an alarm signal in the event of a failure.
, an abnormality occurs in the line, but since no alarm signal is generated, the transmission output cannot be switched successfully, and the abnormal signal caused by the first line change continues to be transmitted to the terminal station via the relay station on the way. .

OBJECT OF THE INVENTION Therefore, the present invention provides a method for switching the hot standby line even in such a so-called silent failure state.
The purpose is to provide a hot standby line switching method that allows for

1.According to the present invention, when a device in a line fails, a silent failure system is provided that transmits the abnormal signal as it is to the terminal station via a relay station on the way, without generating an alarm signal indicating an abnormality. In this hot standby line switching method, the terminal station detects the siren-hift-1-irnia condition and sends a forced switching signal using a line in the opposite direction to the line where the abnormality has occurred. Accordingly, a standby line switching system is obtained, which is characterized in that the standby transceiver is switched to the active one.

Example Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram of an embodiment of the invention.

In the figure, terminal station A has an uplink antenna 1° coupler 2 and a pair of receiving I! 13a and 3b.

Terminal A also has a downlink antenna 4. It has a switch 5 and active and backup transmitters 6a and 6b.

Furthermore, a silent failure detection section 7 is provided, which detects whether the received signal from the uplink is abnormal or not, and in response to this detection, generates a forced switching signal and sends it to the downlink. The first ability to do so is right.

Relay station B has uplink antennas 8.12. Switcher 9.
Working and backup transceivers 10a and 10b, coupler 11
has. In addition, relay station B has antenna 13 for downlink.
．． 17. Switcher 14. It has working and backup transceivers 15a and 15b, and a coupler 16. Furthermore, the time constant circuit 18
is provided to delay the switching signal from the switch 9 for a certain period of time.

Relay station C has uplink antenna 19, 23° cut IJ 20. It has active and backup transmitting/receiving units 121a and 21b, and a coupler 22. Relay station C also has downlink antennas 24, 28 . Coupler 25゜Working and standby transceiver 2
6a and 26b, and a switch 27. Furthermore, a time constant circuit 29 is provided, which delays the switching signal of the switch 20 by a certain period of time.

In such a configuration, transmitting/receiving 1 is performed at relay stations B and C.
For example, when floa and 21a are operated as active systems, for example, sending and receiving! Assume that an abnormality occurs in the frequency of a local oscillator (not shown) that does not have an alarm signal generation function in the fi 21a.

In this case, the output level of the transmitted signal does not decrease and is normal, so the transmitter/receiver of relay station B cannot detect the abnormality, and therefore, although the signal is abnormal, it is transmitted as it is to terminal station A. That will happen.

At the terminal station Δ, although the alarm signal is not transmitted, the signal received from the uplink is abnormal, and this is detected by the siren l-failure near detection unit 7. Detection of this siren 1-fail is possible by performing a parity check on the received digital data. In the case of a failure due to silent failure, the received digital data will permanently contain errors! Furthermore, if a parity check is performed using the parity code, silent failures can be detected. Since parity errors caused by line conditions, noise, etc. are not fixed but temporary, data errors caused by these phenomena can be clearly distinguished from data errors caused by the above-mentioned silent failure. Further, by sending certain digital pattern data at a certain timing and checking for abnormalities in this pattern data, it is possible to detect 5. silent failure, and various detection methods can be applied.

In response to this silent failure detection, the silent failure detection unit 7 sends a forced switching signal to the downlink via the downlink transmission m 6 a or 6b. This forced switching signal is first transmitted by relay station B's transmitter/receiver n15a or 1.
5b receives and detects the reception, and sends it to the switch 9 via the time constant circuit 18.

Therefore, from the active transmitter/receiver [10a to the standby transmitter/receiver 10b]
It will be switched to.

Next, the forced switching signal is received by the transceiver 26a or 26b of the next-stage relay station C, and sent to the switching device 20 via the time constant circuit 29. Therefore, the active transmitter/receiver 1f121a
The transmission is then switched to the standby transceiver 21b. At this time, the silent failure state is canceled for the first time, so the terminal station Δ side monitors the timing of release of this silent failure state, and the relay station C
You can learn about obstacles.

When it is confirmed that the transmitter/receiver 21a operates normally through maintenance of the relay station C, the transmission of the forced switching signal from the likely fail-your detecting section 7 is stopped. Therefore, each relay station returns to the state immediately before the occurrence of Siren 1-Fail Near.

The time constant circuits 18 and 29 are designed to have a time constant of several seconds for switching the transmitter/receiver from active to standby mode, and several minutes for switching the transmitter/receiver to the reverse state. By doing so, it becomes possible to determine whether a forced switching signal is actually generated when switching from active to standby, and it is possible to suppress noise and the like. Additionally, when switching from standby to active, if the downlink that is transmitting the forced switching signal is disconnected due to a failure such as fading, the forced switching signal will be disconnected, and it will appear as though things have returned to normal. It is possible to prevent this.

As described above, according to the present invention, [Nolent Fail]
I sent a forced switching signal to the line in the opposite direction to the line that transmitted the abnormal signal by A, and forcibly opened the active/standby state. This has the effect of making it possible to use a hot standby line.

It also has the effect of being able to identify the relay station that caused the failure.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the invention. Explanation of symbols of main parts 7...Silent failure detection section 9.20...Switcher

Claims (1)

[Claims] A hot standby line switching method in a silent failure state that transmits an abnormal signal as it is to a terminal station via a relay station on the way without generating an alarm signal indicating an abnormality when equipment in the line fails, The terminal station detects the silent failure state and sends out a forced switching signal using a line in the opposite direction to the line where the abnormality has occurred, and uses this forced switching signal to switch the standby transceiver to the active one. A hot standby line switching method characterized by: