The Method of Reconstructing Optional Spectrum Signal and Digital Quadrature Modulation Based on DDS
MU Chang-qing · Journal of Electron Devices · 2005
Optional spectrum signal reconstruction, digital quadrature modulation and the fast algorithms are discussed.The method of reconstructing optional spectrum signal is converting power spectrum to vector spectrum, operating inverse Fourier transform, windowing and overlapping the series time domain sequence to generate a long time domain sequence, which approximates the infinite sequence of optional spectrum signal, and then performing digital quadrature modulation to reconstruct the optional spectrum signal. The computer simulation indicates that the theoretical reconstruction accuracy of the method is over 80 dB, the actual ratio of signal to noise of the digital quadrature modulator implemented by direct digital frequency synthesis (DDS) is over 65 dB.