Symbol timing recovery circuit

Abstract

For recovering symbol timing, the instantaneous phase of a received intermediate frequency M-ary PSK signal is sampled at successive phase sampling points of each symbol interval to produce a series of instantaneous phase values so that the phase sampling points divide the interval into first and second half sections. From the instantaneous phase values a phase angle of each half section is derived and a difference between successive phase angles is then detected for each symbol interval. The phase sampling points are controlled with the difference so that it reduces to zero. Data sampling points are determined from the controlled phase sampling points. In a modification, the instantaneous phase of the PSK signal is sampled at successive phase sampling points which are offset on the opposite sides of the data sampling point to produce a pair of instantaneous phase values, which are then converted to corresponding phase deviations with respect to signal points of the PSK signal. A difference between the phase deviations is detected for controlling the phase sampling points.