SPREAD SPECTRUM COMMUNICATION SYSTEMS AND DIGITAL ENCODING OF VIDEO SIGNALS.

摘要

This dissertation covers two distinct areas: (1) spread spectrum communications and, (2) digital encoding of color video signals using ADM.;The PN acquisition research has generated a tight bound to the partial autocorrelation function of a PN sequence. The application of this bound to several PN acquisition methods has made it possible to meaningfully evaluate their performance in terms of the minimum acquisition time required for a given probability of error. In addition, a significant improvement in PN acquisition performance is obtained by applying the concept of recursive estimation. This allows the acquisition process to proceed much faster, as it helps to eliminate most false starting vector choices very rapidly.;The performance of a direct sequence spread spectrum system is evaluated under CW jamming at the carrier frequency. The resulting probability of error is shown to depend on a number of parameters whose effect has not always been well understood. Among others, the results clearly show the effect of the sequence length, L, as well as the effect of the ratio of the processing gain to the length of the sequence, K/L, on the degree of jammer rejection.;The digital encoding of color video signals research attempts to find the limitations of the ADM algorithm in the encoding of NTSC type color video. The approaches taken include composite as well as component coding. The bit rates considered vary from 54MBPS to as low as 8MBPS. All of the above methods and bit rates transmit a good color quality even though there is an increasing general degradation in the picture quality with decreasing bit rates.;In the spread spectrum communications area the research done addresses itself to the question of optimal PN acquisition performance and to the performance of direct sequence spread spectrum systems in the presence of CW jammers at the carrier frequency.;The last part of the research concerns itself with the application of ADM to the transmission of packet video. The research has proven the feasibility of such an approach which has a beneficial side effect in the much reduced data set size (2 bits per pixel).