| 摘要 |
PCT No. PCT/GB90/01607 Sec. 371 Date May 26, 1993 Sec. 102(e) Date May 26, 1993 PCT Filed Oct. 18, 1990 PCT Pub. No. WO91/06157 PCT Pub. Date May 2, 1991.A network head-end station (1) is arranged to receive an upstream TDMA frame comprising interleaved optical signals from a plurality of terminations (2) connected to the head-end station (1) by a fibre network (3). The upstream TDMA frame includes a quiet phase during which none of the terminations transmit. The station (1) includes an opto-electronic receiver (4), a DC clamping circuit (10) for the opto-electronic receiver (4) and a clamping pulse generator. The clamping pulse generator is arranged to generate a pulse at a predetermined time falling within the quiet phase to operate the DC clamping circuit to clamp signals received during the remainder of the TDMA frame to a DC reference level received during the quiet phase. |
