AbstractsEngineering

The purpose of this thesis is to introduce Delta Modulation as an alternative to the more conventional carrier and pulse modulations, Chapter I briefly discusses the carrier and pulse modulations from the standpoint of signal - to - noise ratio, bandwidth occupancy and threshold effects. In this way, the merits of each is brought to the fore and the superiority of FM and PCM can he seen. Chapter II introduces Delta Modulation, a pulse code modulation, giving an extensive review of much of the more prominent literature on the subject. Aspects such as channel capacity, power, spectral densities, overloading, signal - to - noise ratio and bandwidth, are discussed. In Chapter III an experimental Delta-Sigma Modulation System is described in detail, from design to performance. Observations are made which correspond to some made in theory. The system transmits static signals and AC signals up to 20 HZ. The accuracy is good and the circuits simple. In Chapter IV suggestions are made to improve the systemis performance by simple means. Also mentioned are more elaborate means (Continuous Delta Modulation) which enhance the performance considerably but detract from the simplicity. Much of the literature quoted in the bibliography shows and discusses how delta modulation is simple in circuitry yet has all the advantages of PCM. It is upon this theme that the prototype Delta-Sigma Modulator is designed and built. All the circuits are kept as simple as possible. With integrated circuits, delta modulation is fast becoming an economical proposition. Delta modulation, though simple to implement, requires greater bandwidth than the conventional carrier modulations and PCM (for the same performance). At times this would make Delta Modulation uneconomical. However, there is a place for Delta Modulation alongside FM and PCM for some particular applications.