Efficiency and reciprocity in pulse-amplitude modulation. Part 2: Testing and applications

The paper is the second of two papers on efficiency and reciprocity in pulse-amplitude modulation, and experimental and practical aspects are discussed. Transmission with an overall loss of about 2 dB is achievable in practice and should be capable of improvement. Response is level up to about 4 kc/s using 10kc/s sampling, depending on the choice of filter. Subjective speech tests show that satisfactory transmission can be obtained with an economical filter network. Advantage is taken of the `transparency¿ of the system to provide voice-frequency signalling. The potential applications for the technique of efficient and reciprocal pulse-amplitude modulation are reviewed briefly.