| As hybrid spread spectrum technology has the advantages of DS and FH with high anti-interference ability, this thesis researches its key technologies. Based on the existing M-ary orthogonal spread spectrum technology, a low complexity dual M-ary orthogonal spread spectrum scheme with DQPSK(DMorth-DQPSK) is proposed. Then frequency hopping sequences and its synchronization methods are researched using TOD information, and an improved algorithms are presented. Some meaningful results are given through the study of the various subsystems. Finally FPGA codes of the composite system have been completed.This thesis mainly includes the following:1. Based on the principle analysis of dual M-ary orthogonal spread spectrum, this thesis presents DMorth-DQPSK ansd gives the structures and theoretical BER analysis. Then build a simulation model, and complete simulation verification work.2. Based on the analysis of the Bluetooth frequency hopping sequence generation algorithm which based on the clock and address(key), an improved algorithm is proposed, and the simulation of the algorithm is researched in this chapter.3. An integrated synchronization scheme is proposed using TOD. In the capture stage, high bits of the TOD are used to calculate the synchronization frequencies, and maintaining the synchronization state with service hopping inserted in the data hopping in the data transmission stage.4. Implement the hybrid spread spectrum communication system on FPGA.First of all,the architecture of the system,the software interface and the transmission data frame format are designed in this chapter.According to the above scheme, the encoding implementation on FPGA is completed, and the software is simulated,debugged and tested on the software and hardware platform that has been selected. The test results show that the system designed in this thesis realized the function of the hybrid spread spectrum communication system,and all the performance indexes are able to meet the requirements. |
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