Pulse decoding in stretched pulse laser PMM systems
Abstract
The MAP decoder and a threshold decoder are compared in terms of word error probability (PWE) when using avalanche photodiodes (APD) as photodetectors, with the assumption that the stretched pulse shape is known at the receiver. The MAP decoder is derived based on a discrete Gaussian approximation of the statistics of the APD secondary electrons. The MAP decoder compares the linear combinations of the square of the slot counts at the end of each frame, with the weights being matched to the shape and the possible positions of the received stretched pulse. The threshold decoder continuously compares the number of photoelectrons over the finite duration of the stretched pulse with a specific threshold. The performance of the two decoders in terms of PEW is evaluated, and an approximation to the first crossing time density is presented for the threshold detector.
- Publication:
-
NTC 1981; National Telecommunications Conference, Volume 1
- Pub Date:
- 1981
- Bibcode:
- 1981ntc.....1R..10P
- Keywords:
-
- Decoding;
- Error Analysis;
- Laser Applications;
- Optical Communication;
- Pulse Position Modulation;
- Pulsed Lasers;
- Avalanche Diodes;
- Performance Prediction;
- Photodiodes;
- Probability Theory;
- Signal Processing;
- Thresholds;
- Transmission Efficiency;
- Communications and Radar