Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A vocoder (pronounced /'vo ko d r/, a combination of the words voice and encoder) is an analysis / synthesis system, mostly used for speech. In the encoder, the input is passed through a multiband filter, each band is passed through an envelope follower, and the control signals from the envelope followers are communicated to the decoder. The decoder applies these (amplitude) control signals to corresponding filters in the (re)synthesizer. It was originally developed as a speech coder for telecommunications applications in the 1930s, the idea being to code speech for transmission. Its primary use in this fashion is for secure radio communication, where voice has to be encrypted and then transmitted. The advantage of this method of "encryption" is that no 'signal' is sent, but rather envelopes of the bandpass filters.

Данное издание не является оригинальным. Книга печатается по технологии принт-он-деманд после получения заказа.