Abstract:

To reduce the influence of spectrum leakage of spectrum analysis, the method and operation of traditional DFT(Discrete Fourier Transform) are expanded from classical one-dimension spectrum to a time-frequency spectrum of two-dimension, and the relationship between a frequency component's amplitude in energy leakage spectrum and truncating length of a time-domain signal is examined in terms of time-spectrum. The result indicates that the amplitude fluctuation of any frequency component along with the truncating length of the time-domain signal complies with sinc function, so that a expression of signal can be presented in time-spectrum with a sinc function. The spectrum from any appointed signal length is constructed and zero error of amplitude spectrum is implemented. The index law that the relationship between DFT spectrum amplitude error under un-period truncation and signal cycles is obtained. When the signal cycle length is 10 times, DFT spectrum produced by the standard deviation is about 0. 001.

Key words: spectrum leakage, time spectrum, sinc function, spectrum structure