PCM format
Digital audio has a certain age. In 1937 the scientist Alec Reeves invented the PCM (pulse-code modulation) format, however it took some years to commercially use it. It was a Japanese company, known as Denon, in the 60s that began to use it. Until finally the first commercial digital recording came out in 1971.
The BBC was also experimenting with digital audio in the 1960s, developing a 2-channel recorder in the early 1970s. In 1972, it launched an audio transmission system that connected its broadcast center with the remote transmission stations. Later in the US, in 1976, the first 16-bit PCM recorder, manufactured by Thomas Stockham, was launched.
Finally in the 80s, with the help of Sony and Mitsubishi, digital audio recording had become popular among music companies. This led to the introduction of the CD as a physical digital storage format in 1982.
The act of converting analog sound into digital sound is the basis for digital audio. This reproduces the sound through the use of digital signals, which are much easier to work, since they can be corrected without losing quality and in fact they may sound better. Digital audio has been part of the music recording industry since the 1970s despite the existence of experimental recordings from the 1960s. The typical digital audio format is PCM or sound pulse code modulation.
Pulse code modulation
Pulse code modulation (PCM) represents analog signals in digital format. PCM is the standard for audio in computers and is used in the audio CD format, too. The audio CD format is referred to as “red-book” and is owned by Royal Philips Electronics, Inc., known simply as Philips, and must be authorized by them in order to be used. Quantified in numerical code, typically binary, the PCM begins as analog signals sampled for magnitude and then converted.
PCM History
In 1939, the PCM was originally derived as a method for sending digital signals through analog systems. It was subsequently verified that the method worked well in reverse (sending analog signals through digital systems). It was the Canadians who, in 1949, produced the first PCM radio. The first use of the PCM came through the telegraph systems. Today, PCM is used to encode audio bit streams.
PCM sound vocabulary
The vocabulary used in the description of PCM varies according to the quantification techniques used. Here are some of the most common terms: Pulse: they are the electrical transmission pulses; Modulation: it is the process of varying the characteristics of the signals in order to transmit the information; Demodulation: output production, or data, from the modulation process; Sampling: reduction of a continuous signal to a discrete signal that results in a set of values based on a point in time.
PCM quantification
The methods to achieve PCM vary depending on quantization or signal processing. Quantification techniques are based on mathematical processes such as logarithmic, linear and adaptive. Each controls the signal processing according to its own set of rules. In audio, an uncompressed process of a linear signal is used. Sampling rates for audio vary for CDs and for audio programming. Higher bandwidth means higher sampling rates. Telephony has a lower bandwidth rate and uses a non-linear signal process.
New horizons for the PCM
Video formats do not usually use PCM soundtracks due to the need for high bit rates, so you will not see PCM used for formats such as DVD or DVR. However, the blu-ray format will occasionally be able to support a full PCM soundtrack. This will depend on the length and size of the soundtrack.
