Verfahren und Einrichtung zur Codierung und Decodierung eines analogen NF-Signals in ein PCM-Format, insbesondere zur Uebertragung von Sprachinformation in einer Wechsel- oder Gegen-Lautsprechanlage
A process and a system for encoding and decoding an analog VF signal in PCM format, in particular for the transmission of voice information in a one-way or intercom loudspeaker system. The VF signal is converted into a digital signal by A/D conversion, where each sampling value corresponds to an 8-bit data word. Each data word is transmitted over the PCM multiplex line in a time-slot of a PCM frame. On receipt, the data words are decoded into an analog signal by D/A conversion. To transmit voice signals having a bandwidth between 7 and 8 kHz, the sampling rate of the A/D-D/A converters is twice as fast as the PCM synchronization frequency and during transmission, every second data word is buffered after coding until the next data word is available and the consecutive data words are applied to the PCM multiplex line in such a way that they occupy two adjacent time-slots. On receipt, the data word extracted from the first time-slot is immediately decoded, whereas the data word extracted from the second time-slot is buffered until the decoding of the previous data word has ended.
DE 1991-4107592 A: 19910309