China Digital Radio (CDR) Receiver Design and Development with FM Interference Cancellation

Abstract

A Chinese Digital Radio (CDR), labelled as GY/T 268-2013 [1], has been made and become effective in 2013 by SGAPPRFT (State General Administration of Press, Publication, Radio, Film and Television), which is an In-Band On-Channel (IBOC) digital audio broadcasting hybrided with analog FM signal in one FM channel. This report investigates the interferences to the CDR digital signals caused by both co-channel and adjacent-channel FM signals, and proposes solutions to combat such influences. Besides an introduction on the CDR and FM broadcasting standard, a literature investigation and a theoretical analysis has been given concerning the FM interference to the CDR digital signal and existing solutions [2]. A new acquisition algorithm is implemented to realize mode detection and synchronization for the hybrid signal. Two FM interference removal methods have been proposed and studied in simulation. An energy detector is introduced to select the best FM interference removal method in run time. The different CDR modes have been added to one existing CDR simulation chain. And the receiver performance in each mode has been studied in the AWGN and TU6 multipath channel conditions. The complete simulation chain will be used for future product development. The proposed solution has reached very good reception performance against co-channel FM interference in commonly used CDR modes. For the adjacent-channel FM interference, if we can detect and select the better removal method in real time, the performance degradation can be controlled to a limited SNR increase under the AWGN channel.