Frequency tracking for communication signals using the M-ary orthogonal Walsh modulation scheme

摘要

A frequency tracking loop is provided for a communication system using an off-the-shelf Walsh modulation scheme. The frequency tracking loop is fast, and includes a correlator 120, such as a mud transformer, and a discriminator 130. The correlator 120 generates a correlation vector 122 that indicates the result of correlating the input signal with each set of Walsh functions, along with corresponding index values. The discriminator 130 receives the frequency error signal (e. G., The output of the correlator 120 having the highest energy level) and the frequency error signal RTI ID = 0.0 ). The frequency error signal () Is generated by generating an outcome between the output having the highest energy and one or more other correlated correlator outputs. In addition, the filter 140 generates the resulting error signal () And adds the frequency offset estimation signal (). /RTI