| Frequency-Hopping (FH) is a kind of Spread-frequency communication. With high ability of anti-jamming, anti-fading, low probability of interception, the multiple access network capacity, it becomes popular in modern military communication and mobile communication. FH sequence synchronization is the key of FH communication which determines the operation of syetem. In order to solve the difficulty in accurate synchronization of pseudo-sequence in FH system, the author proposes a new method using dynamic double frequency to realize the synchronization. This is the first time to bring the safe of FH sequence into code category, the scheme is implemented on the base of Kerckhoff assumption in code theory, so the synchronization dependes on initial value of chaotic sequence (the key), which has no relation with arithmetic and system framework. In addition, this method produces continuous frequency. These are different from traditional methods in essence. By using MATLAB/SIMULINK as simulation tools, it founds the platform of dynamic double frequency synchronization based on single-user. In the scheme of the system, according to Tangent-Delay Ellipse Reflecting Cavity map System (TD-ERCS), cosine mapping method is adopted to produce the TD-ERCS chaotic sequences and wide frequency interval is realized by a so-called means of symmetrical channel; DDS and VCO are chosen as the frequency synthesizer, then all these realize the synchronization simulation in dynamic double frequency method. Compared with the traditional method of m sequence phase searching acquisition, the paper draws a conclusion that dynamic double frequency method makes synchronization time very short and bit error rate near zero. Generally speaking, this method is better than traditional methods in some capability. |
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