[Tracking the process reconstructing original signal with sampled data by spectroscopy].

With spectroscopy, the principle and process of sampling and reconstructing a continuous-time signal are discussed. A symmetrical frequency-finite spectrum function F (omega) is constructed with three modified rise-cosine pulses. Its corresponding time-domain signal f(t) is worked out theoretically. f(t) is sampled with a comb function deltaT (t). By modifying the value of T, Shannon sampling signal is obtained. With Fast Fourier Transform (FFT), the frequency spectrum F(d) (omega) of the sampling signal is figured out. The calculated F(d) (omega) is compared with the constructed F(omega). The processes to reconstruct f(t) with the sampling signal and its digital frequency spectrum F(d) (omega) are discussed. As the result, there is little difference between the calculated F(d) (omega) and the constructed F (omega). The original signal can accurately be reconstructed with the sampling data in time domain, so can with the frequency spectrum F(d) (omega) by FFT. As soon as signal storage is concerned, we can store the sampling data or its digital frequency spectrum.