Only recently has our technology advanced to the point that commercial application of spread-spectrum signaling is economically feasible. This has motivated a number of companies and individuals to seek new ways to benefit from spread-spectrum techniques in commercial systems and products. In this paper, we give a very brief overview of spread spectrum signaling. We then consider applications to satellite mobile applications as well as indoor wireless applications. An overview is presented of several proposals to provide worldwide personal communications through satellite-based spread-spectrum systems, the tradeoffs to be considered, and the controversies involved. A description of a high-capacity wireless office telephone system serves to illustrate how spread-spectrum signaling may be useful in this environment. Finally, we describe a number of digital processing algorithms and devices that implement spread spectrum signaling in a cost-effective manner.>

This paper presents a derivation of the noise performance of the cross-product AFC with decision feedback (CPAFCDF). This is an AFC loop configured for use with differentially phase-shift-keyed (DPSK) signals and gives excellent performance in noise.

The automatic frequency control (AFC) loop is beginning to play an important role in digital data links. There is very little published literature which deals with AFC loop implementations and performance in noise (in contrast to the large body of literature dealing with phase-locked loops). This paper presents a brief discussion of eight different AFC loop implementations, including the block diagram, discriminator characteristic, and loop tracking error in the presence of gaussian noise. Tracking performance of the various loops is compared in the presence of noise for CW, DPSK, and MFSK signaling.