Investigation of phase shift and channel frequency offset recovery in Godard blind equalizer algorithm

Subject Areas : Electronics Engineering

Roozbeh Hamzehyan ¹ (Islamic Azad University Boushehr Branch)

Received: 2021-05-21 Accepted : 2021-05-21 Published : 2017-11-22

Keywords:

Abstract :

An equalizer is used to eliminate the effect of symbolic interference (ISI) in telecommunication channels. One of the equalizer methods that does not require the use of a training sequence is the Godard blind equalizer method. The efficiency of this method decreases significantly in the case of distortion in the phase and frequency of the sent symbols. Therefore, the use of a phase lock loop (PLL) at the output of this equalizer is recommended to eliminate the phase shift and frequency offset added by the channel. In this paper, two types of first and second-order phase lock loops are investigated and confirmed by simulation. The first-order phase lock loop can only remove the fixed phase shift, and the second-order phase lock loop, in addition to the fixed phase shift, can also remove the channel offset frequency.