JPH02142246A - Alarm repercussion preventing system - Google Patents

Abstract

PURPOSE:To prevent the repercussion of an alarm by separately providing an interruption detecting circuit to send an AIS(Alarm Indication Signal) and making an input interruption detecting time enough shorter than an input interruption detecting time for the generation of an input alarm signal. CONSTITUTION:An input interruption detecting circuit 14, a clock source 8 and a selector 12 are provided in respective terminal station repeating devices 1 and 3. The input interruption detecting circuit 14 detects input interruption by the interruption detecting time, which is enough shorter than the interruption detecting time for alarm signal generation, and generates an output. when this output is generated, the selector 12 generates a signal to suppress interruption detection in respective following devices by the clock signal of the clock source 8 and this signal is sent to the following device side. Thus, the alarm generation of the input interruption detection can be surely prevented in the following device.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for preventing alarm spread in a transmission system, there is provided a transmission system including a terminal relay device configured to send an AIS signal to suppress disconnection detection in subsequent devices. The purpose of this is to prevent the spread of alarms due to input loss detection in subsequent devices, from a terminal relay device that sequentially relays transmission signals and a communication processing device that processes the relayed signals. In a transmission system in which each device detects an input disconnection at a predetermined disconnection detection time and generates an alarm signal,
an input disconnection detection circuit that detects an input disconnection and generates an output using a disconnection detection time that is sufficiently shorter than the disconnection detection time; a clock source that generates a clock that is independent of the clock of the transmission signal;
When the detection output of the input disconnection detection circuit does not occur, the received signal is sent to the subsequent device, and when the detection output occurs, a clock source lock signal is used to generate a signal to suppress disconnection detection in each subsequent device. Each terminal relay device is equipped with a selector for transmitting the data to the subsequent device.

[Industrial application field]

The present invention relates to a device for preventing the spread of alarms in a transmission system, and in particular, a phase-locked circuit (PLL) inside the device.
The present invention relates to an alarm spread prevention method for preventing an alarm of input disconnection detection from spreading to the subsequent side in a terminal relay device (inside a cable end) that does not have a cable.

In optical digital transmission lines, etc., one station sends a multiplexed signal through a multiplex converter to the transmission path as an optical signal via an end station relay device, and receives it at the opposite end station relay device. A configuration is adopted in which the signals are separated and sent out via a multiplex converter.

In such a transmission system, when using a terminal relay device that does not have a PLL, it is desired to prevent an alarm for detecting an input disconnection from spreading to subsequent devices.

[Conventional technology]

FIG. 3 shows a schematic configuration of a conventional transmission system and a transmission system to which the present invention is applied. As shown in the figure, a signal multiplexed by a multiplex converter (not shown) inside the station is converted into an optical signal via a terminal repeater 1 and sent out to a transmission path 2, and is sent to the opposite terminal repeater. 3, the signal is received, converted into an electrical signal, input to a multiplex converter 4, demultiplexed, and output.

The terminal relay device 1 has a relay section 5, which relays the input signal of SIN and generates an output signal at 5OUT.

Similarly, the terminal relay device 3 has a relay section 6, which relays the input signal of RIN and generates an output signal to ROUT. The multiplex converter 4 also includes a converter 7, which multiplexes and demultiplexes the RIN input signal to generate an output signal.

In this case, the terminal relay devices 1 and 3 each have an independent clock source 8.9, and when the input is cut off, they send out an alarm signal, and use the clock source 8.9 to generate an A signal with a certain pattern. I S (Alarm Indication
On Signal) By sending out a signal,
Prevent input disconnection detection from being performed in subsequent devices.

This means that when each device generates an input disconnection alarm signal,
This is because it becomes difficult to identify the location of the failure.

FIG. 4 shows the configuration of the alarm signal generation circuit on the receiving side of the terminal relay device, and illustrates the case of the terminal relay device 1 in FIG. 3.

In FIG. 4, the SIN signal is received by the receiving section 11, and in normal conditions is sent to the transmitting side (not shown) via the selector 12. The disconnection detection circuit 13 monitors the input state of the received signal, and generates an alarm signal S INDWN when the disconnection detection time TI has elapsed after an input disconnection occurs.

When the selector 12 receives the alarm signal 5INDWN, it generates an AIS signal using the clock from the clock source 8 instead of the signal from the receiving section 11, and sends it to the transmitting side.

FIG. 5 shows various cases when a conventional device detects an input disconnection.

Now, when the SIN signal of the terminal station relay device 1 becomes disconnected, the terminal station relay device 1 detects this and generates an alarm signal 5INDWN. In FIG. 5, T1 indicates the disconnection detection time in this case. The terminal relay device 1 uses the 5INDWN as a trigger to send out the AIS signal as the 5OUT signal. This signal passes through the transmission path 2 and is sent to the multiplex converter 4 via the terminal relay device 3 on the opposite side.

Therefore, if the disconnection detection time of each device is the same, disconnection detection will be blocked by the AIS signal in the subsequent devices, so it is possible to prevent a situation in which each device generates an alarm.

Note that generating the AIS signal using an independent clock source in this way is limited to terminal relay devices (in cable end) that do not have a PLL. This is because a terminal relay device with a PLL can continue to generate a clock due to the free running of the PLL even in the event of an input cutoff, and as a result, the data is scrambled and sent out in an unattended state. However, while the subsequent equipment does not become unmanned, the cable end does not have a PLL and operates using a clock extracted from the input signal, so if the input is cut off, it cannot perform scrambling operation and there is no output. , so the subsequent equipment will be unmanned.

(Problem to be Solved by the Invention) However, in the system shown in Fig. 3, if there are variations in the disconnection detection time of each device, even if the AIS signal is sent out, subsequent devices may detect disconnection and send out an alarm. There is.

In FIG. 5, it is shown that the alarm signal RINDWN is generated during that period due to the variation ΔT in the disconnection detection time of the multiplex converter 4.

In general, the detection time of input disconnection for the same station signal speed is unified, but if the signal speed is different, the disconnection detection time is not necessarily unified.

One possible method for solving this problem is to set the disconnection detection time of the multiplex converter to be sufficiently longer than the disconnection detection time T1 of the terminal relay device.

However, when this method is used, if the RIN signal of the multiplex converter is instantaneously disconnected, disconnection cannot be detected and an alarm signal cannot be issued. In other words, basically, it is not possible to detect an instantaneous interruption within the interruption detection time and generate an alarm signal, but the solution described above will significantly lengthen the interruption detection time. The longer the disconnection detection time is, the greater the risk of not issuing a warning.

The present invention aims to solve the problems of the prior art as described above, and provides a transmission system including a terminal relay device configured to send an AIS signal in order to suppress the detection of a disconnection in a subsequent device when an input disconnection is detected. It is an object of the present invention to provide an alarm spread prevention method that can reliably prevent the generation of an alarm due to input disconnection detection in a subsequent device in a system.

[Means to solve the problem]

The present invention provides terminal relay devices 1 and 3 that sequentially relay transmission signals.
and a multiplex conversion device 4 for processing the relayed signals, and each device detects an input interruption at a predetermined interruption detection time and generates an 11 report signal.
As shown in the embodiment of the figure, an input disconnection detection circuit 14, a clock source 8, and a selector 12 are connected to each terminal relay device 1, 3.
It is prepared for.

The input disconnection detection circuit 14 detects an input disconnection in a disconnection detection time that is sufficiently shorter than the disconnection detection time for generating an alarm signal and generates an output.

The clock source 8 generates a clock independent of the clock of the transmission signal in each device.

The selector 12 transmits the received signal to the subsequent device when the detection output of the input disconnection detection circuit 14 is not generated, and suppresses disconnection detection in each subsequent device using the clock signal of the clock source 8 when the detection output occurs. It generates a signal and sends it to the subsequent device.

[For production]

The terminal relay device 1.3 sequentially relays the transmission signals, and the multiplex conversion device 4 processes the relayed signals. Each device detects an input disconnection at a predetermined disconnection detection time and generates an alarm signal.

In each terminal relay device 1.3 of such a transmission system, an input disconnection detection circuit 14 is provided. Input disconnection detection circuit 14
detects an input disconnection and generates an output using a disconnection detection time that is sufficiently shorter than the disconnection detection time for generating an alarm signal. A clock source 8 is also provided to generate a clock independent of the clock of the signal transmitted by the terminal relay device.

The selector 12 sends the received signal to the succeeding device when the detection output of the input disconnection detection circuit 14 is not generated, and transmits the clock signal of the clock source 8 when the disconnection detection output of the input disconnection detection circuit 14 is generated. The AIS signal is used to generate an AIS signal to suppress disconnection detection in each subsequent device and send it to the subsequent device.

Therefore, detection of an input disconnection is suppressed in devices subsequent to the terminal relay device where the input disconnection has been detected, thereby preventing occurrence of an alarm spread phenomenon in which an alarm is issued in the subsequent devices as well.

〔Example〕

FIG. 1 shows an embodiment of the method of the present invention,
The configuration of the input disconnection detection circuit provided on the receiving side in the terminal relay device l is illustrated, and the same parts as in FIG. 4 are indicated by the same numbers. 14 is a second disconnection detection circuit.

Further, FIG. 2 is a time chart showing signals of various parts at the time of input disconnection detection in the method of the present invention, and is based on the present invention.

In FIG. 1, the SIN signal is received by a receiving section 11, and in normal conditions is sent to a transmitting side (not shown) via a selector 12. The disconnection detection circuit 13 monitors the input state of the received signal, and generates an alarm signal S INDWN when the disconnection detection time TI has elapsed after an input disconnection occurs.

The disconnection detection circuit 14 also monitors the input state of the received signal, and generates an AIS sending trigger signal when the disconnection detection time T2 has elapsed after the input disconnection occurs. When the selector 12 receives this signal, it generates an AIS signal using the clock from the clock source 8 instead of the signal from the receiving section 11, and sends it to the transmitting side.

FIG. 2 is a time chart showing signals of various parts when an input disconnection is detected in the method of the present invention, and shows a case where a disconnection occurs in the input of the terminal relay device W1.

Now, when the SIN signal of the terminal station relay device 1 is disconnected, the terminal station relay device 1 detects the disconnection according to the disconnection detection time Tl and generates the alarm signal 5INDWN.
2, the disconnection is detected and an AIs signal is generated. AI
The S signal passes through the transmission path 2 and is sent to the multiplex converter 4 via the terminal relay device 3 on the opposite side. Like other devices, the multiplex converter 4 has a disconnection detection time T1 for generating an alarm signal, and since the AIS signal arrives before that time elapses, disconnection detection is not performed, and the alarm signal is not detected. RIND
WN does not occur.

In this case, the disconnection detection time T2 is set to be sufficiently shorter than the disconnection detection time T1. Therefore, when the AIS signal is being sent, even if there are variations in the disconnection detection time T1 of each device, disconnection detection will not be performed in the subsequent devices, and therefore it is possible to prevent the alarm from spreading.

〔Effect of the invention〕

As explained above, according to the present invention, in a transmission system including a terminal relay device configured to generate an AIS signal in order to suppress a failure detection of a subsequent device when an input failure is detected, A separate disconnection detection circuit is provided, and the input disconnection detection time is made sufficiently shorter than the input disconnection detection time for generating the input disconnection alarm signal, so subsequent devices do not detect input disconnection before the AIS signal arrives, and the alarm is generated. This makes it possible to prevent the spread of

Fig. 1 is a diagram showing an embodiment of the present invention method, Fig. 2 is a time chart showing various signals at the time of input disconnection detection in the present invention method, and Fig. 3 is a conventional transmission system and a transmission system to which the present invention is applicable. Figure 4 is a diagram showing the configuration of an alarm signal generation circuit on the receiving side of a conventional terminal relay device, and Figure 5 is a time chart showing the signals of various parts when input interruption is detected in the conventional system. be.

1.3・One end station relay device 2 ~ Transmission line 4-Multiple converter 5.6 -- Relay section 7-Converter 8.9-m-clock source 11-Receiving section 12-Selector 13, 14 ~ disconnection detection circuit

[Brief explanation of the drawing]

Diagram showing an example of this RBy4 thread figure Input disconnection detection using the method of the present invention Time nayat showing each part signal bit W, 2 Diagram 5.6...middle part 7...Mugihanja 8.9...Kuro Noah M 9 showing the j11 schematic configuration of the transmission system Figure 3 Figure 4 shows the connection of the conventional i-report signal generation outlet route.

Claims (1)

[Claims] Consisting of terminal relay devices (1, 3) that sequentially relay transmission signals, and a communication processing device (4) that processes the relayed signals, each device detects a signal at a predetermined disconnection detection time. In a transmission system that detects an input disconnection and generates an alarm signal, the input disconnection detection circuit (14) detects an input disconnection and generates an output with a disconnection detection time sufficiently shorter than the disconnection detection time, and a transmission signal clock; A clock source (8) that generates an independent clock, and a clock source (8) that sends the received signal to the subsequent device when the detection output of the input disconnection detection circuit (14) is not generated, and a clock source (8) that generates an independent clock. Each terminal relay device (1, 3) is equipped with a selector (12) that generates a signal for suppressing disconnection detection in each subsequent device based on the clock signal of the device and sends it to the subsequent device. Warning spill prevention method.