synchronous detector by using fast fonrier transformFFT and inverse fast fourier transform IFFT

摘要

PURPOSE: A device for detecting synchronization of a transmitter and a receiver using an FFT(Fast Fourier Transform) and an IFFT(Inverse FFT) is provided to detect a signal part from a frequency-analyzed noise signal, and to predict noise of the signal part on the basis of past noise information, then to remove the predicted noise from the signal, thereby generating a noise-removed signal. CONSTITUTION: An A/D converter(2) converts an analog voice signal mixed with noise into a digital signal. An FFT unit(3) analyzes the noise-mixed voice signal by frequency band, and performs an FFT process. An m channel noise predictor(4) inputs the noise-mixed signal, and predicts noise of the signal on the basis of past noise information. A remover(5) removes the predicted noise from the noise-mixed voice signal, and outputs a pure voice signal(S). An IFFT unit(6) performs an IFFT process for the noise-removed voice signal. A D/A converter(7) converts the digital signal into an analog signal. A voice recognition device(8) recognizes which word is produced for the noise-removed voice signal.