Successive Approaching Phase Rotation Algorithm for Amplitude & Phase Computation in Demodulation

A successive approximation phase rotation algorithm (SAPR), based on Data Table, was presented to calculate amplitude and phase from In-phase and Quadrature-phase data as to avoid complicated calculation using square root and arctangent transcendental functions in digital demodulation. Multiplication is only needed in the algorithm by using data table stored in large capacity memory, the procedure is simple and fast. The algorithm can be realized by the use of CPU, Field Programmable Gate Array-FPGA and Synchronous Dynamic Random Access Memory-SDRAM. The sinuous values of certain bits are stored in the SDRAM after being quantized. And FPGA reads the sine values in the SDRAM to calculate the amplitude and phase according to I/Q data in demodulation. The algorithm has the characteristic of convenient^ high speed and high accurate.