Proceedings of the KIEE Conference (대한전기학회:학술대회논문집)

The Korean Institute of Electrical Engineers (대한전기학회)
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RDDAFC Algorithm for QPSK Demodulation at Digital DBS Receiver

디지탈 위성방송 수신기를 위한 QPSK 복조용 RDDAFC 알고리즘

  • Park, K.B. (Dept. of Control and Instrumentation Eng., MyongJi University) ;
  • Hwang, H. (Dept. of Control and Instrumentation Eng., MyongJi University)
  • 박경배 (명지대학교 제어계측 공학과) ;
  • 황유모 (명지대학교 제어계측 공학과)
  • Published : 1996.07.22
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Abstract

A new automatic frequency control(AFC) tracking algorithm, which we call a rotational decision directed AFC(RDDAFC) is proposed for QPSK demodulation at the digital direct broadcasting satellite(DBS). In order to prevent the presence of the residual phase difference between symbols received at k and k-l by the CPAFC[1] as well as the AFC based on $tan^{-1}$ circuit[2], the RDDAFC rotates the decision boundary for the kth received symbol by the frequency detector output of the (k-1)th received symbol before passing through the cross product discriminator. Test results show that the total pull-in time of the RDDAFC and PLL was 0.13msec under a carrier frequency offset of 2.4MHz when S/N equals 2dB.

Keywords