Experimental Evaluation of MSK and Offset Keyed QPSK Through Satellite Channels

Abstract

Laboratory test measurements show nearly equivalent error rate performance of MSK and OKQPSK modulation formats for channels having bandwidths approximately equal to the bit rate bandwidth and typical associated phase delay characteristics. High quality MSK and OKQPSK transmitters and a versatile modular receiver have been designed and constructed to eliminate differences associated with varying degrees of hardware quality when the performance of the various modulation formats is compared. The selection of a modulation format should, therefore, be strongly directed by considerations other than error rate, such as complexity, sensitivity to alignment, and compatibility with differential coding.