Optimal filtering of digital PPM transmitted over optical fibrechannels

The abundance in bandwidth available in the best monomode fibres may be exchanged for improved receiver sensitivity by employing digital PPM. In this paper the authors derive an optimal filter for a digital PPM coding scheme operating over a fibre channel employing a PIN-BJT receiver. Experimental results obtained at a data rate of 8 Mbit/s show that the digital PPM system offers an improvement of 4.2 dB over an equivalent binary PCM system