JPS5999838A - Digital reproducing repeater - Google Patents

Abstract

PURPOSE:To attain the changeover of present use/spare where the deterioration in a transmission circuit is discriminated correctly by controlling the changeover of the transmission circuit by an error rate of a reproduced output. CONSTITUTION:An optical signal separated by an optical separating circuit 9 of the transmission circuit is converted into an electric signal by a photodetector 10, discriminated by a discriminator 11-2 and inputted to one input of a comparator 12. An output of a discriminator 3 is inputted to another input of the comparator 12. If the transmission circuit is not operated normally, since an input digital signal is not reproduced correctly, an output representing dissidence appears at the comparator 12. A counter 12 resets this output for each prescribed period and counts it, and when the result of count exceeds a prescribed number of times, this output is transmitted to a switching circuit 5 to changeover the transmission circuit from the present use line into the spare line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to transmission circuit switching of a digital regenerative repeater equipped with a spare transmission circuit. In particular, the present invention relates to a digital regenerative repeater suitable for optical communication systems.

[Description of prior art]

A digital regenerator is equipped with an identification circuit that identifies an input digital signal, and a transmission circuit that is driven by the digital signal obtained at the output of this circuit and regenerates an output digital signal having the same logic as this digital signal. It is configured to transmit the output digital signal of the transmitting circuit to the digital transmission line of the next section. Since the repeaters are installed on the seabed or buried underground, they are designed to be highly reliable and require little maintenance. The reliability of the components of such a repeater is 81M, h! 1. It can be seen that the parts of the transmitter circuit that dissipate a large amount of power have a significantly shorter lifespan than other parts. Therefore, regarding the transmitting circuit,
A method is known in which a backup circuit is provided in addition to the current circuit, and when the current circuit deteriorates, it is switched to the backup circuit by remote control or automatic control.

In optical communication type digital regenerative repeaters, the lifespan of the laser diode in the transmitting circuit is particularly short, so methods and methods for automatically switching this are being considered for submarine repeaters (References (1) and (2)).

In this conventional method, in order to check the quality of the transmitter circuit at a glance, the power supply current supplied to the transmitter circuit is detected, and when this current exceeds a predetermined range, the working circuit is switched to the backup circuit. It is being

However, the power supply current supplied to the transmitter circuit does not always match the deterioration of the transmitter circuit, and even if the power supply current is within a predetermined range that is considered normal, the elements of the transmitter circuit may deteriorate and the error may occur. There are two cases in which digital reproduction relay is not performed.

[Prior art literature]

(1) Yosogi et al. [Study of submarine optical repeater light source backup switching system] Institute of Electronics and Communication Engineers Communication Systems Study Group Material CS 8l-57 (
2) Wakabayashi et al. [Study on redundant light source configuration for optical submarine repeaters” Institute of Electronics and Communication Engineers Communication Systems Study Group Materials CS 81-61 [
OBJECTS OF THE INVENTION] The present invention is an improvement on this, and an object of the present invention is to provide a digital regenerative repeater that can correctly identify deterioration of a transmitting circuit and switch between working and standby circuits.

[Features of the invention]

The present invention branches part of the output digital signal of the transmitting circuit, identifies the signal obtained at this branched output in the same way as reception identification, and compares the logic of the signal obtained at the identified output with the input signal of the transmitting circuit. The present invention is characterized in that when a logical mismatch is detected in the comparison output exceeding a predetermined ratio, the transmitting circuit is switched to another backup circuit for use.

The present invention is suitable for implementation in an optical communication type digital regenerator.

It is particularly suitable for a device that includes a laser diode as an oscillation element in a transmitting circuit.

The present invention can be implemented in various digital regenerative repeaters in addition to optical communication systems.

[Explanation based on examples]

An embodiment of an optical communication digital regenerative repeater will be described with reference to the drawings.

The figure is a block diagram of 11 units during digital reproduction according to an embodiment of the present invention. The transmission line, not the optical fiber of the previous section, is connected to A on the left end. The next section of optical fiber transmission line is connected to B at the right end. The signal of the transmission line in the previous section is input to the charging converter 1. This output electrical signal is amplified by an amplifier 2 and input to a discriminator 3.

Further, the output of the amplifier 2 is branched and a timing signal is regenerated by a timing circuit 4. The output of the identification 83 is configured to be input to the transmission circuit via the switching circuit 5. Two transmitting circuits are provided, and the input is selectively connected to one of them by a switching circuit 5.

The first transmitting circuit includes a driving circuit 6-1 and a laser diode 7-1 driven by this output, and the second transmitting circuit includes a driving circuit 6-2 and a laser diode 7-2 driven by this output. Equipped with. The outputs of the two transmitting circuits are combined by an optical coupling circuit 8 and transmitted to the next section of transmission line via an optical demultiplexing circuit 9.

The optical signal branched by the optical separation circuit 9 is converted into an electrical signal by the photodetector IO, and is input to the equalization conversion circuit 11. This equalization conversion path 11 includes a filter circuit 11-1 whose frequency characteristics approximate the loss characteristics of one section of the transmission path;
A discriminator 112 having substantially the same characteristics as the input discriminator 3 is provided. The amount of loss in the signal path leading to the discriminator 11-2 via the optical separation circuit 9 is approximated to the amount of loss in the transmission path in the next section. A timing signal is supplied from the timing circuit 4 to the discriminator 11-2. This equalization conversion circuit 11
The output of is connected to the input of comparator 12 -)j. The output of the discriminator 3 as well as the input signal of the transmitting circuit are connected to the input of this comparator 12. The output of the comparator 12 is input to a counter 13, and the switching circuit 5 is controlled by the output of the counter 13. This counter 13 is configured to be reset at regular intervals.

To explain the operation of the device configured in this way, the optical signal input from the previous section is converted into an electrical signal by the photoelectric converter l, amplified by the amplifier 2, and the digital signal is reproduced by the discriminator 3. . The digital signal is sent from the switching circuit 5 (and is applied to the 8 circuits, the laser diode is driven, the optical digital signal is regenerated, and the optical digital signal is transmitted to the transmission line of the next section.

Here, one of the transmitting circuits of 2(11ii) is currently in use,
The other side is for backup, and the optical signal separated by the optical separation circuit 9 is converted into an electrical signal by the photodetector lO, attenuated, further identified by the discriminator 11-2, and sent to one input of the comparator 12. appear.

If the transmitting circuit is operating normally, the digital signal reproduced at the output of the discriminator 3 and the optical digital signal transmitted from the optical coupler 8 should have the same logic. Thus, as long as the transmit circuit is operating normally, the two inputs of comparator 12 are equal and no signal is delivered to its output. However, if the transmitting circuit ceases to operate normally, the transmitting circuit will no longer correctly reproduce the input digital signal, and an output indicating a mismatch will appear at the comparator 13. The counter 13 resets and counts this output at regular intervals, and when the count exceeds a predetermined number of times, the output is sent to the switching circuit 5 and the transmitting circuit is switched from the active circuit to the backup circuit.

The output of the transmitting circuit is branched off by an optical separation circuit 9 and then passed to a discriminator 11.
The amount of attenuation of the path leading to the input No. 2 is 1 minute if the loss characteristics of the transmission line in the next section are attenuated to such an extent that the discriminator 11-2 operates normally.

[Explanation of effects]

As explained in Section 1-7 above, according to the present invention, the switching of the transmitting circuit is controlled by the error rate of the reproduced output, so it is more accurate than when it is identified by an indirect quantity such as the power supply current. It has certain excellent characteristics.

[Brief explanation of the drawing]

The figure is a block diagram of a digital regenerative repeater according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Photoelectric converter, 2... Amplifier, 3... Discriminator, 4... Timing circuit, 5... Switching circuit, 6...
- Drive circuit, 7... Laser diode, 8... Optical coupler, 9... Optical separation circuit, 10... Photo detection circuit, 1
1... Waveform shaping circuit, 12... Comparator, 13...
counter. □',! l ″

Claims (5)

[Claims] (1) A first identification means for identifying an input digital signal; and a transmission circuit that is driven by a digital signal obtained as an output of this means and reproduces an output digital signal having the same logic as this digital signal, and the transmission circuit includes: In a digital regenerative repeater that is equipped with a plurality of circuits and is configured to selectively switch and use one of the circuits, there is provided a branching means for branching the output digital signal of the transmitting circuit described in 2; a second identification means for identifying a signal obtained as an output; and a comparison means for comparing the logic of the signal obtained as an output of the second identification means and the signal obtained as an output of the first identification means. . A digital regenerative repeater, characterized in that, when a logical mismatch is detected in the output of the comparing means exceeding a predetermined ratio, the transmitting circuit is switched to another one for use. (2) The digital regenerative repeater according to claim fl), wherein the digital regenerative repeater is an optical repeater. (3) The digital regenerative repeater according to claim (2), wherein the transmitting circuit includes a laser diode oscillation circuit. (4) A digital regenerative repeater according to claim 11, wherein the transmitting circuit includes a power amplification circuit. (5) The attenuation of the signal path from the output of the transmitting circuit to the input of the second identification means via the branching means is configured to approximate the attenuation of the transmission line in the next section of this digital regenerative repeater. A digital regenerative repeater as claimed in claim number +1j.