Open-loop receiver for MSK with Doppler frequency shift

An open-loop digital receiver performing simultaneous carrier phase/frequency estimation and block (two-bit) detection is proposed for MSK signaling in Gaussian channels affected by Doppler frequency shift. Phase estimation and symbol detection are provided by a parallel bank of matched estimators (each one comprising a phase rotation block and a stochastic nonlinear filter) and by a decision algorithm based on the nonlinear filters' innovations processes. The Doppler frequency shift, estimated by a Kalman-Bucy (1968) filter coupled with a Kay (1989) estimator, is used for fine tuning of the nonlinear filters. The receiver exhibits a, fast phase/frequency acquisition capability and is able to withstand large carrier frequency deviations. These are essential features in LEO satellite burst communications.