Implementation of correlation in the DVB-S standard

摘要

The Direct-Video-Broadcast Satellite (DVB-S) standard is used to provide video and radio to millions of users worldwide. It is designed to provide quasi-error free satellite communications. This paper discusses some of the limitations of the DVB-S standard, describes some attempts in related work to address these concerns, and presents a new modification to enhance the performance and reliability of the Direct-Video-Broadcast Satellite (DVB-S) standard by using a correlator in a DVB-S receiver. In many existing receive chains, synchronization speed is slightly delayed because phase ambiguity cannot be determined and corrected until after Viterbi decoding. Using correlation against known symbols before demodulation, the phase ambiguity can be corrected prior to Viterbi decoding, thus reducing the amount of time required to synchronize the received signal. To enhance the correlator's ability to detect the DVB-S synchronization bytes, a two byte, rather than single byte, known sync word is proposed as a modification to the standard. The motivation behind a longer sync word is to improve the standard in high noise environments. A two byte sync word provides more known information for correlation. The resulting correlation peaks are double that of when a single byte is used; this corresponds to about a 3 dB increase to provide fast signal acquisition and signal tracking in a noisy environment.