Kalman predictor for providing a relatively noise free indication of the phase of a carrier laden with noise

摘要

A receiver responsive to a noise laden phase modulated signal on a carrier hard limits the signal to derive a constant amplitude phase modulated r.f. signal. The constant amplitude phase modulated r.f. signal is supplied to processing circuitry to derive a digital signal having a value representing the phase of the noise laden carrier. A phase locked loop, including a minimum variance Kalman predictor filter, responds to the noise laden carrier to derive a relatively noise free indication of carrier phase. The noise laden indication of phase and the relatively noise free indication of carrier phase are combined to indicate the phase of the phase modulated signal to which the receiver is responsive.