Research on Waveform Table Compression Algorithm Based on Direct Digital Frequency Synthesizer (DDS)

Direct digital frequency synthesizer (DDS) requires configuration of waveform data tables of hundreds of thousand or even a few million words. Integrating such a large amount of high-speed ROM with current integrated circuit technology is difficult and uneconomical. In order to reduce hardware resources, this paper proposes an improved parabolic interpolation algorithm, which is a low-power direct digital frequency synthesizer structure, using a smaller lookup table to find the sine function. The algorithm performs interpolation calculation according to four waveform data points near the interpolation interval, and can automatically identify the singularity of waveform and select three different parabolic interpolation algorithms, so as to reduce the interpolation error to the lowest level. The algorithm can obviously reduce the maximum interpolation error for different waveforms containing singularities. The experimental results show that the improved parabolic interpolation algorithm has smaller interpolation error than other algorithms when compressing the same waveform under the same compression conditions.