Citation
Abstract
The Pioneer Venus 1978 probe-to-Earth telemetry links will be degraded by fading in the atmosphere of Venus. The severity of this fading is characterized by the variance o?, where the amplitude fading is represented by the lognormal random variable e*. For the convolutionally encoded/sequentially decoded telemetry modes, the link performance depends on o°, the total received signal-to-noise ratio P;/N,, the modulation index 6, and the decoder computational capacity N. _ Using nominal values for anticipated system losses, and assuming a maximum deletion rate requirement of 10-*, the minimum required P;/N, and optimum 6 are profiled as functions of N and o* for the 256-bps large probe telemetry mode. These predictions are based on a recently developed theoretical model for the combined effects of lognormal fading and noisy carrier reference on sequentially decoded phase-shift-keyed telemetry.
Details
- Volume
- 42-24
- Published
- December 15, 1974
- Pages
- 51–59
- File Size
- 653.4 KB