Evaluation of a poisson windowed test signal for pcm codecs

Abstract

This project deals with the critical evaluation of a Poisson windowed test signal which was proposed for in-service and production testing of filtered pulse code modulation systems. The Poisson windowed test signal has various advantages over the existing two test methods specified by the International Consultive Committee for Telephone and Telegraph (CCITT). The main goals of the new test signal are to minimise the test time and to accommodate the send- and reel eve filters normally found in communication systems. The evaluation process included the compilation of performance curves of signal ,to noise ratio vs. signal level and gain variation vs. signal level. These curves were compiled by simulating the codec and filters on a digital computer and processing the output data. Three sets of programs were The results obtained revealed some fundamental limitations of the proposed test signal. Using the basic properties of the Poisson windowed signal, an alternative test signal was proposed. It was the single sided exponentially windowed sinusoidal which proved to be suitable for the testing of filtered pulse code modulation stems.