Acquisition of carrier phase and symbol timing through joint estimation of phase and timing adjustments

摘要

A signal acquisition system rapidly acquires carrier phase and symbol timing of a received PSK-modulated communication signal (24) having a 110-symbol pattern through joint estimation of carrier-phase adjustment and symbol-timing adjustment by processing a common set of sampled data. A reference signal (22) at a local oscillator frequency is mixed with a received communication signal (24) to provide the communication signal (26) at an intermediate frequency. The intermediate-frequency communication signal (26) is converted into a digital communication signal (28), which is formatted into in-phase (I) and quadrature-phase (Q) components. A sampling circuit (18) samples the I components at twice a predetermined symbol rate to provide a first series of I-component samples at the predetermined symbol rate and a second series of I-component samples that are intermediate to the first series of I-component samples and at the predetermined symbol rate, and for sampling the Q components at twice the predetermined symbol rate to provide a first series of Q-component samples at the predetermined symbol rate and a second series of Q-component samples that are intermediate to the first series of Q-component samples and at the predetermined symbol rate. A processor (20) processes the samples to estimate a phase-adjustment value φA and a symbol-timing-adjustment value STA. The phase of the reference signal (22) is adjusted in accordance with the phase-adjustment value φA and the timing of the sampling is adjusted in accordance with the symbol-timing-adjustment value STA.