GB2179518A - Optical fibre transmission systems - Google Patents

Abstract

In an optical fibre transmission system, semiconductor function transceivers at either end of a single optical fibre path are used to effect bidirectional transmission in burst mode. As described data for transmission is stored in buffer register 6 for application to semiconductor junction transceiver 1 linked to fibre 2 and data received from the fibre is stored in buffer register 9. <IMAGE>

Description

SPECIFICATION Optical fibre transmission systems The present invention relates to optical fibre transmission systems.

According to the present invention an optical fibre transmission system comprises a single-fibre transmission path, an optoelectronic device at one end of said path which is capable both of emitting and responding to light signals, first electric circuit means to apply electric input signals to said device for transmission as light signals over said path, second electric circuit means to provide electric output signals in response to light signals received by said device over said path, first and second electric signal storage means, and control means to enable said first and second electric circuit means alternately to effect the transmission and reception over said path in burst mode of signals from and to said first and second electric signal storage means respectively.

Preferably said first electric signal storage means is arranged to accept electric input signals in a substan tially continuous stream and to release said signals in bursts of predetermined length for transmission over said path, and said second electric signal storage means is arranged to receive signals in bursts of a predetermined length from said path andto release said signals in a substantially continuous stream.

An optical transmission system in accordance with the present invention will now be described by way of example with reference to the accompanying drawing, which shows schematically a transmitter/receiver station of the system.

Referring to the drawing the transmission system utilises an optoelectronic device 1, which is capable of both emitting and responding to light signals, to effect bi-directional transmission of light signals over a single optical fibre path 2 in burst mode. By burst mode is meant the transmission of bursts of information signals in opposite direCtions alternatively in each of a succession of time intervals, with a gap between transmissions in the opposite directions to allow for propagation of the first burstto be completed before the return burst is transmitted. In the present system this gap also has to take into accountthe "turn round" time of the device 1 from detectorto emitter.

The biassuppliedto the device 1, which may beof the kind known as a semi-conductor junction transceiver (SJT), is provided by a power supply 3. Under the control of a unit4this bias is arranged to be switched between a forward bias for the transmitting mode and either a zero or a reversebiasforthe receiving mode.

A substantially continuous stream ofinput signals in binary coded form at a rate of, say, 80 Kbit/sec, representing for example coded speech, signalling and control or data, on an input path 5 are entered into atransmit buffer register orstore 6. The signals in the register 6 are transferred in groups of, say, 10 bit values, every 125 microseconds to a transmitter circuit 7 for transmission as a burst by the device 1 at a "line" rate of, say, 256 Kbitlsec.

Within each 125 microsecond interval a return burst of 10 bit values at the line rate of 256 Kbitisec is received by way of the device 1 and a receiver circuit 8, from which each such received burst is transferred to a receive buffer register or store 9. The received bit values may then be read from the register 9 at a rate of 80 Kbitisec as a continuous stream ofoutputsignals on a path 10.

As shown in the drawing a circuit 11 may be provided to derive or extract clock and synchronising signals from received bursts. The control and synchronisation unit4 may comprise a microprocessor (not shown).

1. An optical fibre transmission system comprising a single-fibretransmission path, an optoelectronic device atone end of said path which is capable both of emitting and responding to light signals, first electric circuit means to apply electric input signals to said device fortransmission as light signals over said path, second electric circuit means to provide electric output signals in response to light signals received by said device over said path, first and second electric signal storage means, and control means to enable said first and second electric circuit means alternately to effectthetransmission and reception over said path in burst mode of signals from andto said first and second electric storage means respectively.

2. An optical fibre transmission system in accordance with Claim 1 wherein said first electric signal storage means is arranged to accept electric input signals in a substantially continuous stream and to release said signals in bursts of predetermined length for transmission over said path,and said second electric signal storage means is arranged to receive signals in bursts of a predetermined length from said path and to release said signals in a substantially continuous stream.

3. An optical fibre transmission system substantially as herein before described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Optical fibre transmission systems The present invention relates to optical fibre transmission systems. According to the present invention an optical fibre transmission system comprises a single-fibre transmission path, an optoelectronic device at one end of said path which is capable both of emitting and responding to light signals, first electric circuit means to apply electric input signals to said device for transmission as light signals over said path, second electric circuit means to provide electric output signals in response to light signals received by said device over said path, first and second electric signal storage means, and control means to enable said first and second electric circuit means alternately to effect the transmission and reception over said path in burst mode of signals from and to said first and second electric signal storage means respectively. Preferably said first electric signal storage means is arranged to accept electric input signals in a substan tially continuous stream and to release said signals in bursts of predetermined length for transmission over said path, and said second electric signal storage means is arranged to receive signals in bursts of a predetermined length from said path andto release said signals in a substantially continuous stream. An optical transmission system in accordance with the present invention will now be described by way of example with reference to the accompanying drawing, which shows schematically a transmitter/receiver station of the system. Referring to the drawing the transmission system utilises an optoelectronic device 1, which is capable of both emitting and responding to light signals, to effect bi-directional transmission of light signals over a single optical fibre path 2 in burst mode. By burst mode is meant the transmission of bursts of information signals in opposite direCtions alternatively in each of a succession of time intervals, with a gap between transmissions in the opposite directions to allow for propagation of the first burstto be completed before the return burst is transmitted. In the present system this gap also has to take into accountthe "turn round" time of the device 1 from detectorto emitter. The biassuppliedto the device 1, which may beof the kind known as a semi-conductor junction transceiver (SJT), is provided by a power supply 3. Under the control of a unit4this bias is arranged to be switched between a forward bias for the transmitting mode and either a zero or a reversebiasforthe receiving mode. A substantially continuous stream ofinput signals in binary coded form at a rate of, say, 80 Kbit/sec, representing for example coded speech, signalling and control or data, on an input path 5 are entered into atransmit buffer register orstore 6. The signals in the register 6 are transferred in groups of, say, 10 bit values, every 125 microseconds to a transmitter circuit 7 for transmission as a burst by the device 1 at a "line" rate of, say, 256 Kbitlsec. Within each 125 microsecond interval a return burst of 10 bit values at the line rate of 256 Kbitisec is received by way of the device 1 and a receiver circuit 8, from which each such received burst is transferred to a receive buffer register or store 9. The received bit values may then be read from the register 9 at a rate of 80 Kbitisec as a continuous stream ofoutputsignals on a path 10. As shown in the drawing a circuit 11 may be provided to derive or extract clock and synchronising signals from received bursts. The control and synchronisation unit4 may comprise a microprocessor (not shown). CLAIMS

1. An optical fibre transmission system comprising a single-fibretransmission path, an optoelectronic device atone end of said path which is capable both of emitting and responding to light signals, first electric circuit means to apply electric input signals to said device fortransmission as light signals over said path, second electric circuit means to provide electric output signals in response to light signals received by said device over said path, first and second electric signal storage means, and control means to enable said first and second electric circuit means alternately to effectthetransmission and reception over said path in burst mode of signals from andto said first and second electric storage means respectively.

2. An optical fibre transmission system in accordance with Claim 1 wherein said first electric signal storage means is arranged to accept electric input signals in a substantially continuous stream and to release said signals in bursts of predetermined length for transmission over said path,and said second electric signal storage means is arranged to receive signals in bursts of a predetermined length from said path and to release said signals in a substantially continuous stream.

3. An optical fibre transmission system substantially as herein before described with reference to the accompanying drawing.