Measured Noise Performance of a Direct-Sequence Spread-Spectrum System and a Comparison of Single- Vice Dual-Channel Delay-Lock Loops

摘要

A direct-sequence (DS) spread spectrum system which could be used by a conventional amplitude modulated (AM) radio system was designed, built and tested. A delay-lock loop was used to provide code synchronization in the receiver. The noise performance of single-channel delay-lock loop (DCDLL) with no data being transmitted. When data was transmitted a DCDLL was used and the noise performance (probability of bit error) of the DS spread spectrum system was measured. Test results indicate that SCDLL performs as well as or better than the DCDLL. The measured noise performance advantage relative to the DCDLL and that this DS spread spectrum can be used to transmit low rate digital data reliably at values of SNR much than unity. It is recommended that this DS spread spectrum system be considered by the Department of Defense to be implemented in AM radio system to provide low data rate-anti-jam-interference rejection capability.