Phase Noise Effects on Space Shuttle Communications Link Performance

The purpose of this paper is to present a theory which can be used to determine the effects which phase noise sources produce on the bit error probability performance of phase coherent links. The paper begins by presenting typical math models for phase noise sources known to exist in frequency generators. These phase and frequency instability models are then incorporated into equivalent loop models known to characterize the performance of CW and Costas loops. From these equivalent loop models a general analysis is presented which can be used to: (1) determine optimum tracking performance (minimum phase-error jitter) and (2) evaluate bit error probability degradations due to combined phase noise sources. This paper concludes with an example which applies the theory presented to assess the impact on link performance due to phase noise sources generated in the Shuttle
S
-band payload interrogator. By careful design and control of the power spectral densities of the phase noise sources one can design a system so that the phase noise has a small effect on bit error probability performance.