Correlative phase modulation for fixed satellite service-s. Volume 2: Supplementary report

Performance under fixed satellite service conditions of a binary correlative phase modulation (CPM) scheme with simple implementation, and more complex quaternary CPM schemes was simulated. Compared to QPSK the CMP schemes have an important power advantage in the uplink as a saturated Earth station power amplifier can be used without any rf filtering; the power efficiency in the downlink is comparable to QPSK for the binary scheme and 2 dB higher for the quaternary schemes. The spectrum efficiency is 1.25 to 1.40 bits/sec/Hz for the binary scheme and 1.10 to 1.25 bits/sec/Hz for the quaternary scheme, the precise figure depending on interference conditions. Carrier regeneration is shown to benefit significantly from sampling with the symbol clock; channel distorsions have no serious effect. Though no general design concept is offered, the combination of coding with general CPM is shown to be promising.