JPS61196634A - Fault detecting circuit for optical fiber transmitting device - Google Patents

Abstract

PURPOSE:To investigate and initialize fault causes at the trouble recovering work of the optical fiber transmitting device and to shorten the work recovery by being provided with a pulse oscillator at the transmitting side, monitoring the output waveform condition from the pulse oscillator in the receiving side, and constituting the circuit so as to be able to decide automatically to turn off the transmitting signal input which occurs at the opponent station transmitting side. CONSTITUTION:An opponent station receiving side converts the light signal received from a light transmitting line 4b to an electric signal by a light and electric converting circuit 5 and decodes it by a decoding circuit 6. At such a time, for example, as part of a trouble detecting alarming circuit 7, a 1/2 frequency dividing circuit 71 and the circuit of a retriggerble one-shot multi 72 are serially connected, the circuit is constituted so as to stipulate the detecting protecting time at the time constant of the above-mentioned multi 72, and then, a regular clock signal to extracted by the light and electric converting circuit 5 is divided by 1/2 by the 1/2 frequency dividing circuit 71, identified and reproduced as alternating data of 1 or 0, the output signal of the multi 72 is held permanently in the stable condition of 1 or 0. For this reason, it can be identified by the output waveform of the retriggerble one-shot multi 72, whether the regular data are obtained and the transmitting pulse oscillating device signal is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fault detection circuit for a nine-way fiber transmission device that detects a transmission signal disconnection in a digital/l/optical transmission device that optically transmits digital signals. It is something.

[Conventional technology]

A conventional device of this type is shown in FIG. In the figure, 1 is a transmission signal input terminal, 2 is an encoding circuit that converts the code of the digital signal input to the transmission signal input terminal 1, 3 is an electrical/optical conversion circuit that converts an electrical signal into an optical signal, 4a, 4b are optical transmission lines for transmitting and receiving original signals, 5 is an optical-to-electrical conversion circuit that converts optical signals into electrical signals, 6 is a decoding circuit that decodes encoded electrical signals, and 7 is a fault that has occurred. 8 is a received signal output terminal.

Next, the operation will be explained. First, the digital signal for transmission inputted from the transmission signal input terminal 1 is sent to the encoding circuit 2.
After being converted into a code convenient for transmission by
The optical conversion circuit 3 converts the electric signal into an original signal and sends it out to the optical transmission line 4aK. Further, the optical signal received from the optical transmission line 4b is converted from an optical signal to an electrical signal in the original/electrical conversion circuit 5, and then decoded into a digital signal before being encoded in the decoding circuit 6 and then received. The signal is output to the signal output terminal 8. The fault detection/alarm circuit T is an optical transmission line 4a.

This system detects a failure occurring in the 4b'ffi or digital source transmission device, and outputs an alarm depending on the presence or absence of a pulse signal.

[Problem that the invention seeks to solve]

Conventional digital source transmission equipment is configured as described above, so if a failure occurs in the optical transmission line or the transmission signal output is cut off at the transmitting side of the other station, signal regeneration will not be possible on the receiving side of the local station. This made it possible to detect failures, but there were problems such as the inability to clearly distinguish and detect whether the cause of the failure was in the optical transmission path or on the sending side of the other station. Rarely.

The present invention has been made in order to solve the above-mentioned technical problems, and when there is no abnormality in the optical transmission line and a transmission signal input cutoff occurs on the transmitting side of the other station, the transmitting side of the other station An object of the present invention is to obtain a digital source transmission device capable of detecting a disconnection of a transmission signal input.

[Means for solving problems]

The digital source transmission device according to the present invention provides a pulse with a frequency equal to 1/2 of the signal transmission speed on the transmitting side so that when a transmission signal input disconnection occurs, the receiving side of the other station can detect the transmission signal input disconnection. It is equipped with an oscillator, and the output of this pulse oscillator is transmitted to the receiving side of the other station.

[Effect]

In this invention, when a transmission signal input interruption occurs,
The output of a pulse oscillator with a frequency equal to the signal transmission speed IA provided on the transmitting side is transmitted.

By detecting the above-mentioned pulse output signal, the receiving side of the partner station can easily determine whether the transmission signal input has been interrupted based on the content of the signal while maintaining the transmission system in normal operation by utilizing the periodicity of the pulse signal.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as in FIG. 3 are indicated by the same reference numerals. In FIG.
10 is a transmission signal input disconnection detection circuit.

Next, the operation of the embodiment will be explained below. That is, multiple digital signals input to the transmission signal input terminal 1 are converted into codes advantageous for transmission by the encoding circuit 2.
The electrical/optical conversion circuit 3 converts the electrical signal into an original signal and sends it to the optical transmission line 4a. Further, the original signal received from the optical transmission line 4b is converted from the original signal to an electrical signal in the original/electrical conversion circuit 5&C, and then decoded by the decoding circuit 6 into a pre-encoded digital signal (destination station). The received signal is output to the output terminal 8. When the fault detection/alarm circuit T detects a disconnection of the signal input from the transmission signal input terminal 1 in such an operating state, the encoding circuit 2 activates the pulse oscillator 9.
The output of is encoded as a transmission signal. At this time, all the transmitted data is sent along with this clock signal! Fix it to 1).

This operation allows 9RZ conversion or CM I (comp
tev managedinstruction) The encoded electrical signal is transmitted at 1) 1, l of the original transmission rate.
□I is converted into an original signal by the electric/optical conversion circuit 3 as an alternating signal and sent to the optical transmission line 4a. The receiving side of the other station is
The original signal received from the optical transmission line 4b is converted into an original signal and an electrical conversion circuit 5.
The signal is converted into an electrical signal and decoded by the decoding circuit 6. On this occasion.

For example, as part of the fault detection/alarm circuit T, a 1/2 frequency divider circuit T1 and a retriggerable one-shot multi circuit T2 as shown in FIG. If the circuit is configured so as to be determined by the time constant of
The output signal of the retriggerable one-shot multi 72 is permanently maintained in the stabilized state of 1) 1 or ij l o @. For this reason, by setting the time constant of the retriggerable one-shot multi 72 in advance, it becomes possible to identify whether it is normal data or a transmission pulse oscillator signal from the output waveform of the retriggerable one-shot multi 72. As a result, the fault detection and alarm circuit T can transmit a fault alarm indicating that the transmission signal input to the transmitting side of the other station has been cut off. Further, when the transmission signal input disconnection detection circuit 10 detects the transmission signal disconnection of the other station, the result is transmitted to the failure detection/alarm circuit 7, and outputs to the other station that a failure has occurred.

In addition, in the above embodiment, an example was shown in which the output of a pulse oscillator with a frequency equal to the transmission speed provided on the transmitting side is transmitted when the transmitting signal input is cut off. In such a case, even if a slam signal with a predetermined value corresponding to the cause of the failure is transmitted, the receiving side can detect the failure occurring on the transmitting side of the other station and the cause.

〔Effect of the invention〕

As described above, according to the present invention, a pulse oscillator is provided on the transmitting side, and the state of the output waveform from the pulse oscillator is monitored on the receiving side, and it is possible to automatically determine whether or not the transmission signal input has occurred on the transmitting side of the other station. Since the circuit is configured in a manner similar to the above, it is possible to investigate the cause of a failure at an early stage during failure recovery work of an optical fiber transmission device, and there is an effect that the recovery time for one work can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a digital source transmission device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a part of a fault detection/alarm circuit, and FIG. 3 is a block configuration diagram of a conventional digital source transmission device. Illustrated. In the figure, 1 is a transmission signal input terminal, 2 is an encoding circuit, 3 is an electrical/optical conversion circuit, 4 is an optical transmission line, 5 is an optical/electrical conversion circuit, 6 is a decoding circuit, and T is a fault detection/alarm. 8 is a reception signal output terminal, 9 is a pulse oscillator, and 10 is a transmission signal input disconnection detection circuit.

Claims (2)

[Claims] (1) An encoding circuit that encodes a digital signal, an electrical/optical conversion circuit that converts the encoded electrical signal into an optical signal and optically transmits it, and an electrical/optical conversion circuit that converts the encoded electrical signal into an optical signal and transmits it optically. Consists of an optical-to-electrical conversion circuit that converts optical signals into electrical signals, a decoding circuit that decodes the converted electrical signals into digital signals before transmission, and a fault detection/alarm circuit for transmitted and received signals. A pulse oscillator with a frequency equal to 1/2 of the signal transmission speed, which starts pulse oscillation by the output signal from the fault detection/alarm circuit, and uses the output pulse as an input signal to the encoding circuit. When a transmission signal input interruption occurs, the output of the pulse oscillator is transmitted through an encoding circuit and detected on the reception side, thereby making it possible to detect a transmission signal interruption on the reception side. Fault detection circuit for optical fiber transmission equipment. (2) A 1/2 frequency divider circuit and a retriggerable one-shot multi circuit with a predetermined time constant are connected in series as part of the fault detection/alarm circuit, and the output is extracted from the optical/electrical conversion circuit. Depending on the waveform, when the clock signal is normal, it is 1/
The output pulse waveform whose frequency is divided by 2 is output from the retriggerable one-shot multi, and when a signal other than the normal signal, such as an output signal from a pulse oscillator, the output of the retriggerable one-shot multi becomes "1" or "0". 2. A failure detection circuit for an optical fiber transmission device according to claim 1, characterized in that the circuit is configured to identify when the continuous stability has been achieved.