Recap on Digital Signal Processing
Gérard Blanchet, Maurice Charbit · 2015
Signal processing consists of handling data in order to extract information considered relevant, or to modify them so as to give them useful properties: extracting, for example, information on a plane's speed or distance from a RADAR signal, making an old and decayed sound recording clearer, synthesizing a sentence on an answering machine, transmitting information through a communication channel, etc. The essential part of the acquisition device is usually the analog-to-digital converter (ADC), which samples the value of the input voltage at regular intervals, every Ts seconds, and provides a coded representation at the output. The digital use of the Discrete Fourier transform (DFT) has acquired an enormous and undisputed practical importance with the discovery of a fast calculation method known as the Fast Fourier Transform (FFT). On a Dual Tone Multi-Frequency (DTMF) phone keyboard, each key is associated with the sending of a signal.