Design of a algorithm of mapping from phase to sine amplitude in DDS of a GPS signal simulator system

Based on trigonometric identities, Sunderland technique is a effective compression algorithm for mapping from phase to sine amplitude in ROM-based direct digital frequency synthesizers (DDS) design. A modification based on Taylor-series linear interpolation method was proposed to provide additional improvements in compression efficiency. Their effect on distortion and trade-offs were investigated, and spurious were identified by using fast Fourier transform algorithm (FFT). A computer program was created to simulate and optimize the effects of the memory compression and algorithmic techniques on the output spectrum of the DDS with the help of matlab computing tool. The subjected multiplierless architecture was then implemented in a Xilinx's field programmable gate array (FPGA). Simulation results show that the proposed techniques is effective, and the digital output of the designed DDS which using this compression technique has the worst case spurious about -90 dB. A 80 MHz DDS was developed and used successfully in a actual projects of a GPS signal simulator system.