Spread-Spectrum CDMA Synchronization for a Voice Conference Modem

A direct-sequence spread-spectrum modem utilizing intra-network code-division multiple access (CDMA) was designed to provide jam resistance, conferencing, and security for tactical voice communications among aircraft and ground controllers. The approach used for PN code acquisition is described. An approximate analysis is developed which accounts for the interdependence of the signal and noise estimates. Techniques used to mitigate the effects of narrowband interference upon the noise estimation accuracy are described and analyzed.