Study On The π/4-DQPSK In FH/DS Software Radio Data Radio

The aim of this thesis is to implement all digital modem ofπ/4 offset differentially encoded quadrature phase shift keying(π/4-DQPSK), based on some modes, which belongs to a part of the FH/DS software radio data radio.π/4-DQPSK modulation is a linear technology, which possesses features of high spectrum utilization ratio, better spectrum specification, strong anti-jamming ability and good security. The modem method has been employed in mobile communication system and satellite communication system.The paper firstly introduces the rationale of a FPGA-Basedπ/4-DQPSK modem and design & realization of each module, such as pulse shaping filter, despreading and demodulation on IF, bit synchronization. Secondly, author has done algorithm simulation with Matlab. Based on this, under the ISE6.1 of Xilinx company, Very High Speed Integrated Circuit Hardware Description Language (VHDL) has been adopted for designing and implementing every module. Via observing timing simulation, programme can implement right modem, demodulation. This scheme adopts intermediate frequency sampling, digital matched filtering, delay differential demodulation techniques and so on. It directly processes the digital signals on intermediate frequency without down-conversion, and doesn't need pseudo random codes synchronization and carrier wave extraction circuits, compared with classic method. This scheme is characterized by its simplicity, easy implementation, novel ideas and practical value. Thirdly, the scheme has been implemented on the universal soft radio platform to meet the scheduled object. Testing result validates that the program is right, and demonstrates that this scheme is correct and feasible.