ALL-DIGITAL IMPLEMENTATION OF THE CARRIER RECOVERY LOOP IN DIGITAL RADIO SYSTEMS

摘要

For digital microwave radio systems,this Paper describes a fully-digital implementation of the carrier recovery loop currenfly implemented in analog form.The emphasis is placed on carrier recovery loops employing an active filter or a phase lag-and-lead passive filter.It is shown that digiital implementation of the demodulator makes it possible to realize the ideal loop filter which can only be approximated in analog implementation.With such a loop filter and an appropriate phase and frequency detector,it is shown that the acquisition range virtually achieves the maximum possible range for decision-feedback carrier recovery loops based on symbol-rate phase error measurements.