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

The origins of phase noise in single-loop synthesisers are outlined, and the effects of oscillator phase noise and thermal phase noise upon data demodulation are identified, together with the conflicting requirements placed upon the receiver´s carrier recovery loop. Some design criteria and parameters are outlined, and performance illustration given for the implementation of a VSAT receiver. A typical receiver outline is illustrated. Two or more stages of downconversion may be employed, (e.g. from a signal at 14 GHz to IFs at 1 GHz and 70 MHz). Data modulation with BPSK is considered, although the principles may be extended in general to QPSK. The carrier recovery loop (CRL) is taken to be a squaring loop, or equivalently a Costas loop, employing a phase-locked-loop (PLL)