文档介绍：Fundamentals of Measurement Technology(4)
Prof. Wang Boxiong
Digital signal processing, a field which has its roots in 17th and 18th century mathematics, has e an important modern tool in a multitude of diverse fields of science and technology.
Digital signal processing is concerned with the representation of signals by sequences of numbers or symbols and the processing of these sequences.
Digital signal processing
The availability of high speed puters has fostered the development of plex and sophisticated signal processing algorithms, and recent advances in integrated circuit technology promise economical implementations of plex digital processing systems.
The evolution of a new point of view toward digital signal processing was further accelerated by the disclosure in 1965 of an efficient algorithm putation of Fourier transforms: the fast Fourier transform or FFT.
Digital signal processing
The fast Fourier transform algorithm reduced putation time of Fourier transform by orders of magnitude.
The importance of digital signal processing appears to be increasing with no visible sign of saturation.
The impact of digital signal processing techniques will undoubtedly promote revolutionary advances in some fields of application.
Digital signal processing
For a nonperiodic continuous time signal x(t), its Fourier transform must be a continuous spectrum X(f),
The continuous time signals and the continuous spectra must be discretized first and then truncated to get a finite length of sequence before being processed by puter. This forms just the basis for the discrete Fourier transform (DFT).
Discrete Fourier Transform (DFT)
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There are four cases for the Fourier transform of an infinite-length continuous signal (Fig. ).
Discrete Fourier Transform (DFT)
Fig. Types of Fourier transform
Fig. (a): a nonperiodic continuous signal x(t) and its Fourier transform spectrum X(f). The spectrum is continuous.
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