Spread Spectrum Acquisition and Tracking Performance for Shuttle Communication Links

The spread spectrum acquisition and tracking performance for the Shuttle -band and -band communication links are analyzed and compared to test results. The -band link requirements are more severe than those of the -band links, hence, different despreader designs were developed for the two systems. The -band despreader acquires pseudonoise code lock by examining all possible code phases in half chip steps while the -band despreader acquires pseudonoise code lock by continuously sweeping a tau-jitter loop. Both despreaders employ a tau-jitter loop for code tracking. The code tracking performance is computed for the tau-jitter loop and compared to that of the more complex delay lock loop.