A serious problem in the design of a high-speed multi-tone modem for use with an HF radio link is symbol synchronisation. The difficulty is caused by the combination of severe multipath propagation and fading introduced by the HF radio link.Generally, symbol synchronisation is performed in two parts: acquisition and tracking. In this paper, symbol synchronisation acquisition is only discussed.The conventional symbol synchronisation acquisition technique used in multi-tone modem is usually PN synchronisation series method. In this paper, a new design of symbol synchronisation acquisition scheme in the high-speed multi-tonc HF modem is proposed.We have derived the theoretical formula of the design and proved with computer simulation that the protested property is better than that of PN synchronisation series.The applying of TMS320C25 Assembly language to the dcsign has shown that this scheme is easier to implement.It has proved that the new design of symbol synchronisation acquisition can operate at low signal-to-noise ratios in the presence of time-varying multipath profiles typical of HF channels by the practical live trials.
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