Second[ary] audio program[ming] (SAP) is an auxiliary audio channel for television that can be broadcast or transmitted both over the air and by cable TV. It is often used for an alternate language (hence giving the facetious "Spanish audio program" expansion to the acronym), or for the Descriptive Video Service (DVS) offered in the U.S. by PBS (the Public Broadcasting Service). Audio can mean: sound that can be heard electronics or other signals of frequencies audible to humans (about 20--20,000 Hz) broadcasting or reception of sound high-fidelity sound reproduction sound recording and reproduction in general I hear in Latin This is a disambiguation page — a navigational aid which... For the geographical meanings of this word, see channel (geography). ... Broadcast could refer to: Broadcast, an electronica musical group broadcasting, the distribution of audio and video signals Broadcast address, an IP address allowing information to be sent to all machines on a given subnet. ... Cable television or Community Antenna Television (CATV) (and often shortened to cable) is a system of providing television, FM radio programming and other services to consumers via radio waves transmitted directly to people’s televisions through fixed coaxial cables as opposed to the over-the-air method used in traditional... A backronym or bacronym is a reverse acronym, that is, the words of the expanded term were chosen to fit the letters of the acronym. ... Acronyms and initialisms are abbreviations formed from the initial letter or letters of words, such as NATO and XHTML, and are pronounced in a way that is distinct from the full pronunciation of what the letters stand for. ... The Descriptive Video Service (DVS), created by WGBH-TV in Boston, is used by the Public Broadcasting Service (PBS) in the U.S. to provide video description for the visually impaired, so they can better understand what is happening on the video portion of the program. ... Wikiquote has quotations relating to: United States Wikinews has news related to this article: United States United States government Official website of the United States government - Gateway to governmental sites White House - Official site of the US President Senate. ... PBS re-directs here; for alternate uses see PBS (disambiguation) PBS logo The Public Broadcasting Service (PBS) is a non-profit public broadcasting television service with 349 member TV stations in the United States. ... PBS re-directs here; for alternate uses see PBS (disambiguation) PBS logo The Public Broadcasting Service (PBS) is a non-profit public broadcasting television service with 349 member TV stations in the United States. ...

SAP is part of MTS, the multichannel television sound standard set by the National Television Systems Committee in the U.S. The NTSC video format and MTS are also used in Canada and Mexico, and in Japan. Multichannel television sound, better known as MTS (often still as BTSC, for the Broadcast Television Systems Committee that created it), is the method of encoding three additional channels of audio into an NTSC-format audio carrier. ... Wikiquote has quotations relating to: United States Wikinews has news related to this article: United States United States government Official website of the United States government - Gateway to governmental sites White House - Official site of the US President Senate. ... NTSC is the analog television system in use in the United States and many other countries, including most of the Americas and some parts of East Asia. ... There are several video formats in use worldwide: Analogue NTSC PAL SECAM Digital ATSC DVB ISDB These are strictly the format of the video itself, and not for the modulation used for transmission. ...

MTS features, including stereo and SAP, travel on subcarriers of the audio carrier, much like stereo information for an FM radio broadcast. The SAP subcarrier is located at 78.670kHz, which is five times the 15.734kHz MTS pilot signal. In turn, the MTS pilot is locked to the horizontal sync frequency of the video carrier for stability. The SAP channel contains mono audio which has been dbx-encoded for noise reduction, to improve the signal-to-noise ratio. Stereo or stereophony generally refers to dual-channel sound recording and sound reproduction – sound that contains data for more than one speaker simultaneously. ... A subcarrier is separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. ... Audio can mean: sound that can be heard electronics or other signals of frequencies audible to humans (about 20--20,000 Hz) broadcasting or reception of sound high-fidelity sound reproduction sound recording and reproduction in general I hear in Latin This is a disambiguation page — a navigational aid which... A carrier wave is a waveform (usually sinusoidal) that is modulated (modified) to represent the information to be transmitted. ... FM radio is a broadcast technology invented by Edwin Howard Armstrong that uses frequency modulation to provide high-fidelity broadcast radio sound. ... A kilohertz (kHz) is a unit of frequency equal to 1,000 hertz (1,000 cycles per second). ... In telecommunication, a pilot is a signal, usually a single frequency, transmitted over a communications system for supervisory, control, equalization, continuity, synchronization, or reference purposes. ... Synchronization is coordination with respect to time. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Monophonic can mean: In music, see: Texture (music). ... Audio can mean: sound that can be heard electronics or other signals of frequencies audible to humans (about 20--20,000 Hz) broadcasting or reception of sound high-fidelity sound reproduction sound recording and reproduction in general I hear in Latin This is a disambiguation page — a navigational aid which... DBX is a noise reduction system for tape recording. ... For other senses of the word code, see code (disambiguation). ... Noise reduction is the process of removing noise from a signal. ... Signal-to-noise ratio (often abbreviated SNR or S/N) is meaningful both in the context of information theory and, informally, for Usenet or other newsgroup-like services. ...

Though not technically a SAP channel, television stations can also broadcast a "PRO" (professional) audio subcarrier which is used to communicate with station personnel. This one-way audio channel allows individuals at the television station to send messages to people located away from the station and is frequently employed during newscasts. This channel is located at 6.5 times the pilot, and is also part of the MTS standard. A professional does something as a profession, or receives payment for some activity. ...

Because of its 250kHz bandwidth, the audio carrier used in the NTSC television system can easily handle multiple audio channels.