Adaptive multiharmonic phase jitter compensation

A multiharmonic adaptive phase jitter compensator for a high speed modem is provided. The compensator includes an IIR filter for each harmonic of phase jitter for which compensation is desired. The coefficent update of each IIR filter as well as the input to the primary jitter frequency IIR receives identical information from a phase detector which compares an equalized phase corrected signal entering a decision means with the ideal point determined by the decision means. However, the IIRs for the higher harmonics are trained with different information. Thus, the primary jitter frequency as adaptively determined by the first IIR is fed to harmonic computation circuitry. The harmonic computation circuitry then provides an adapted second harmonic to the second harmonic IIR, and adapted third harmonic to the third harmonic IIR, etc. The outputs of all the IIRs are summed, and the cosine and sine of the sum are provided to phase correct the equalized signal before it enters the decision circuitry.