Doppler Shift Considerations in Naval Satellite Communication Systems Exploying Synchronous Satellites.

摘要

Possible doppler shifts due to motions of existing 'stationary'satellites are shown to be as large as 212Hz/GHz. When the contribution due to ships motion and headway are added,total shifts of 2.5kHz at X band are possible. To avoid a severe penalty in synchronization acquisition time in operating pseudonoise or frequency hop modems now considered for Naval satellite communication,some type of automatic doppler shift compensation is required. Several compensation methods are described that cannot obtain exact correction without undue complexity but can reduce the compensation error to less than 24Hz/kHz of beacon carrier doppler shift with relatively simple techniques. Problems of phase noise due to phase lock loop bandwidths required to track changes in doppler shift and local oscillator spectral purity remain as prime problem areas. (Author)