The effect of local oscillator phase noise in low data-ratesatellite receivers

摘要

The origins of phase noise in single-loop synthesisers arenoutlined, and the effects of oscillator phase noise and thermal phasennoise upon data demodulation are identified, together with thenconflicting requirements placed upon the receiver's carrier recoverynloop. Some design criteria and parameters are outlined, and performancenillustration given for the implementation of a VSAT receiver. A typicalnreceiver outline is illustrated. Two or more stages of downconversionnmay be employed, (e.g. from a signal at 14 GHz to IFs at 1 GHz and 70nMHz). Data modulation with BPSK is considered, although the principlesnmay be extended in general to QPSK. The carrier recovery loop (CRL) isntaken to be a squaring loop, or equivalently a Costas loop, employing anphase-locked-loop (PLL)