Software Radio Base With The Research And Implementation Of Software Systems

Software Radio (SR) is an active research area world widely at present. The SR technology was first initiated by military SPEAKeasy plan in 1995 and highly promoted by the Joint Tactics Radio System (JTRS), which is planed to be employed in US army by year 2010. The project, on which this thesis is based, is to develop a software transceiver prototype system. The system completes anti-jamming function of Frequency-Hopping (FH) and Direct Sequence Spread Spectrum (DS-SS) by exploiting DSPs+FPGA structure, so it is flexible and modular. The goal of this thesis is to accomplish base-band channel coding /decoding, FH framing/de-framing and FH synchronization, and also to control the modulator and demodulator in the prototype system. All these functions are implemented with a TMS320VC5409 DSP. In the channel coding part of the proposed scheme, each 16-bit are encapsulated into one code block, which is consisted of information bits and parity bits. Then the block is convolved and interleaved. In the channel decoding part, Viterbi algorithm and de-interleaving are realized to decrease bit error rate and increase transmission efficiency. FH synchronization is to obtain initial synchronization, service synchronization and delayed network-joining synchronization when communication is initiated. The thesis analyzes the sync-header synchronization method. In the proposed sync-header coarse synchronization scheme, specific willard sequence is used to identify synchronization capture. The utilization of high speed DSP can highly increase the performance of anti-interference and anti-detection.The modulation mode, data rate and coding mode can be controlled by configuring the registers of modulator Stel-1109. The viewport and NCO frequency control word selection can be accomplished by configuring the demodulator Stel-2105. All these make the initial configuration of modulator and demodulator match the system optimally.