Synchronization of Spread Spectrum Binary Orthogonal Keyed (BOK) Burst Transmission Systems

Burst transmission systems using spread spectrum waveforms offer interesting possibilities for application in a military environment. However, the high noise immunity achievable can be fully exploited only if precise receiver synchronization is performed. As the bursts in such a burst transmission system can be of very short duration, synchronization becomes indeed a critical task and must be performed afresh for each burst while receiving the burst. This implies a storage of the received signal till at least synchronism has been achieved. After synchronization, the message can be read off. The purpose of this paper is to describe a spread spectrum BOK burst transmission system and present two alternative schemes for receiver synchronization using SAW matched filters for detecting the individual orthogonal data bits and a post-detection correlation circuit. In the first scheme the correlation is performed using an analog tapped delay line and in the second a binary shift register. Synchronization is further improved by staggering the data bits. The performance and the requirements on the components are investigated for both the schemes. The investigations reveal that the simple shift register version is inferior to the analog tapped delay version only by about 1 dB. An experimental set-up for checking the theoretical results is proposed.