PCM: PCM (abbreviation for Pulse Code Modulation) generally describes a method for digitizing analog signals. With this coding method, continuous amplitude values of an oscillation are assigned to binary values, ie the original signal is sampled at a very specific frequency (usually 8 kHz) and each determined amplitude value is converted into an 8-bit binary word.
The original signal course gives way to a pulse sequence of 0 and 1, which is why one also speaks of a modulation of the signal.
Since this process cannot be performed infinitely precisely, a reverse conversion will never produce exactly the same thing Signal. Despite the resulting noise, the advantage of this method is the interference tolerance of the receiver, since it only has to differentiate between the high and low signals (0 and 1). However, this tolerance is “bought” with a high bandwidth requirement
With the PCM data stream of CD the sampling rate is 44,1 kHz, ie the analog signal is sampled 44.100 times per second and converted into a digital value. At Dolby Digital is the sampling frequency 48KHz, at Dvd audio 96 kHz.