The Novation CAT acoustically coupled modem

In telecommunications, the term acoustic coupler has the following meanings: Download high resolution version (1542x1178, 292 KB)This photo of an accousticly coupled modem was taken by user Lorax and dedicated to the Public Domain This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Download high resolution version (1542x1178, 292 KB)This photo of an accousticly coupled modem was taken by user Lorax and dedicated to the Public Domain This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... A modem (from modulate and demodulate) is a device that modulates an analogue carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. ... Copy of the original phone of Alexander Graham Bell at the Musée des Arts et Métiers in Paris Telecommunication is the transmission of signals over a distance for the purpose of communication. ...

1. An interface device for coupling electrical signals by acoustical means--usually into and out of a telephone instrument.
2. A terminal device used to link data terminals and radio sets with the telephone network.

The link is achieved through acoustic (sound) signals rather than through direct electrical connection. In telecommunication and computer communication, the term network interface has the following meanings: The point of interconnection between a user terminal and a private or public network. ... In electronics and telecommunication, coupling is the desirable or undesirable transfer of energy from one medium, such as a metallic wire or an optical fiber, to another medium, including fortuitous transfer. ... The telephone is a telecommunications device which is used to transmit and receive sound (most commonly voice and speech) across distance. ... In the context of telecommunications, a terminal is a device which is capable of communicating over a line. ... In general, data consist of propositions that reflect reality. ... It has been suggested that Office classification be merged into this article or section. ... An electrical connection between discrete points allows the flow of electrons, (current). ...

Prior to the deregulation of telephony in many countries of the world, it was illegal to make an electrical connection to the telephone network. Also, in many households, telephones were hard-wired to wall terminals before connectors like RJ11 and BS 6312 became standardised. With the increased use of computing, acoustic couplers were used to connect modems to the telephone network. In telecommunication, Telephony encompasses the general use of equipment to provide voice communication over distances. ... The telephone is a telecommunications device which is used to transmit and receive sound (most commonly voice and speech) across distance. ... RJ-11 is a physical interface often used for terminating twisted pair type cables. ... British telephone plug with only two pins present, from a modem cable BS6312 is the British Standard governing telephone plugs and sockets. ... A modem (from modulate and demodulate) is a device that modulates an analogue carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. ...

Usually, a standard telephone handset was placed into a cradle that had been engineered to fit closely (by the use of rubber seals) around the microphone and earpiece of the handset. A modem would modulate a loudspeaker in the cup attached to the handset's microphone, and sound from the loudspeaker in the telephone handset's earpiece would be picked up by a microphone in the cup attached to the earpiece. In this way signals could be passed in both directions. A microphone, sometimes referred to as a mike or mic (both IPA pronunciation: ), is an acoustic to electric transducer that converts sound into an electrical signal. ... “Loudspeaker” redirects here. ...

Speeds were typically 300 bits per second, achieved by modulating a carrier at 300 baud. The first such device was the ACOUSTIC DATA COUPLER 300 MODEM from 1968. Image File history File linksMetadata Size of this preview: 800 × 533 pixel Image in higher resolution (3072 × 2048 pixel, file size: 697 KB, MIME type: image/jpeg) Work by Rama File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed... Image File history File linksMetadata Size of this preview: 800 × 533 pixel Image in higher resolution (3072 × 2048 pixel, file size: 697 KB, MIME type: image/jpeg) Work by Rama File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed... This article or section does not adequately cite its references or sources. ... In telecommunications and electronics, baud (pronounced , unit symbol Bd), is a measure of the symbol rate; that is, the number of distinct symbol changes (signalling events) made to the transmission medium per second in a digitally modulated signal. ...

Acoustic couplers were sensitive to external noise and depended on the widespread standardisation of the dimensions of telephone handsets. Once electrical connection to telephone networks became legal, this rapidly became the preferred method of attaching modems, with acoustic couplers becoming rare.

Acoustic couplers are still used by people travelling in areas of the world where electrical connection to the telephone network is illegal or impractical.

See also

• Federal Standard 1037C
• MIL-STD-188

ROFL Federal Standard 1037C entitled Telecommunications: Glossary of Telecommunication Terms is a U.S. Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ... MIL-STD-188 is a series of U.S. military standards relating to telecommunications. ...