A direct-sequence spread-spectrum multiple-access (DS SSMA) system was examined, realized (hardware), and tested. Essentially, two transmitters were built: one had voice capability, whereas the other transmitted only binary data. Gold codes were used for the spreading sequence. The PN synchronization used a serial search technique for acquisition, and a tau-dither loop for tracking. A squaring loop and a differential encoding scheme (for carrier phase ambiguity) was used in the demodulation process, which was followed by conversion to a voice output when desired. The system was found to perform quite well under both single and multiple-access conditions. As a demonstration of the feasibility of implementing the system on chips, a few small blocks were put on ICs using CMOS technology. These performed as expected, and clearly demonstrated both the feasibility and attractiveness of a VLSI implementation. >
['Donald C. Kemdirim', 'J.S. Wight']
DS SSMA with some IC realizations