Based On Software Radio Digital Baseband Signal Processing Technology

With the development of PLDs, FPGAs which has flexible programming characteristics, rich resources and excellent performances have been widly used in field of digital signal processing. In this dissertation, a digital signal processing implementation of software-defined radios (SDRs) has been made on the Xilinx Virtex-4 FPGAs. The signal processing system can be divided into two parts, the transmitter and the receiver. The transmitter has two submodules. One is the channel encoding module, uses the (2,1,7) convolutional coding method, the other is a modulation module, uses the GMSK(Gaussian Minimum Shift Keying) method which will get better spectrum performance than MSK. Prior to modulation, a differential coding module was added which can be demodulated by not only the coherent demodulation method but also the non-coherent method such as 2-bit differential detection. In this way, the applicable range of the modulated signal was extended. The receiver also has two submodules. One is the demodulation module, using the coherent demodulation method which can get lower BER compare with non-coherent demodulator, the other is the channel decoding module, using the Viterbi decoding method which helps to achieve reliable data transfer.In the design, by modeling and simulation in MATLAB, newing modules in ISE development environment use Verilog or use the IP core configuration guide, I built up a baseband digital signal processing system, analyze and verify it through the flow chat and Modelsim simulation waveform.