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Capture algorithm of GMSK signal in digital trunking communication |
1. School of Electronic and Information Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China; 2. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China |
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Abstract To solve the problem that the noncohernet demodulation with better performance than differential demodulation couldn′t correctly estimate carrier frequency error in domestic digital trunking system, a capture algorithm was designed. The algorithm was made up of frequency estimation and symbol synchronization. Depending on the characters of wireless signal and signal frame, the noncohernet demodulation algorithms was adopted in frequency estimation. The results were given through analyzing the pilot signal in the frequency estimation algorithm. Performances of some estimation algorithms were compared, and the relevant simulation results were obtained. According to the requirement of the noncoherent demodulation in symbol synchronization, the optimal sampling site was searched through the training symbols to ensure the detection success rate of optimum sampling site. The results show that the performances of frequency estimation and symbol synchronization are ensured in the proposed capture algorithm, and the demodulation performance of system is improved.
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Received: 04 January 2013
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