Low data rate digital space communications

Abstract

The low available transmitter power and the large frequency uncertainty constrain the data rate to be low. An all-digital communication receiver is proposed, and its feasibility is established. Although coherent systems should be used whenever practical, the noncoherent MFSK system is more suitable for very low data rates. The effect of Rician fading on the performance of MFSK receiver is studied. Fading characteristics of the Venus channel are examined based on the exponential model and available experimental data on the Venus atmosphere. Because of the requirement of high communication efficiency, three codes are evaluated and compared. The rapidly varying phase error at low data rate has great effects on the tracking loop behaviors which are examined by extensive computer study of the phase plane trajectories.