engineering

Multichannel Television Sound

Multichannel Television Sound is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Multichannel Television Sound rather than just read about it. In short: Multichannel Television Sound (MTS) is the method of encoding three additional audio channels into analog 4.5 MHz audio carriers on System M and System N. The system was developed by an industry group known as the Broadcast Television Systems Committee (BTSC), a parallel to color television's National Television System Committee, which developed the NTSC television standard.

Key takeaways

Multichannel Television Sound belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Multichannel Television Sound to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Multichannel Television Sound from memory before moving on to harder problems.

Reference excerpt

Multichannel Television Sound (MTS) is the method of encoding three additional audio channels into analog 4.5 MHz audio carriers on System M and System N. The system was developed by an industry group known as the Broadcast Television Systems Committee (BTSC), a parallel to color television's National Television System Committee, which developed the NTSC television standard. It was approved in 1984 and was widely deployed in the next two years. MTS works by adding additional audio signals in otherwise empty portions of the television signal, and allows up to a total of four audio channels, with two producing the left and right stereo channels. An additional second audio program (SAP) is used to broadcast other languages or radio services, including weather radio that could be accessed by the user, typically through a button on their remote control. The fourth channel was a professional audio channel used for internal purposes by broadcasters and is indecipherable with a common consumer receiver. MTS was considered a major advance in television broadcasting. In 1986, two years after MTS broadcasts began, the Academy of Television Arts & Sciences awarded five Technical and Engineering Emmy Awards to the inventors of the technology and to the two networks, NBC and ABC, that aggressively introduced it. For years, television shows would display a badge during the opening of a program that was "Presented in Stereo". MTS, an analog standard, has not been used since the 2009 switch to digital television.

History Initial work on design and testing of a stereophonic audio system began in 1975 when Telesonics approached Chicago public television station WTTW. WTTW was producing a music show titled Soundstage at that time, and was simulcasting the stereo audio mix on local FM stations. Telesonics offered a way to send the same stereo audio over the existing television signals, thereby removing the need for the FM simulcast. Telesonics and WTTW formed a working relationship and began developing the system which was similar to FM stereo modulation. Twelve WTTW studio and transmitter engineers added the needed broadcast experience to the relationship. The Telesonics system was tested and refined using the WTTW transmitter facilities on the Sears Tower. In 1979, WTTW had installed a stereo Grass Valley master control switcher and had added a second audio channel to the microwave STL (Studio Transmitter Link). By that time, WTTW engineers had further developed stereo audio on videotape recorders in their plant, using split audio track heads manufactured to their specifications, outboard record electronics, and Dolby noise reduction that allowed Soundstage to be recorded and electronically edited. In addition, an Ampex MM1100, 24-track audio recorder was also used for music production and mixing. PBS member stations who wished to deliver Soundstage in stereo were provided with a four-track (left, right, vertical drive, and time code) audiotape that could be synced with the video machines in those cities. During the FCC approval process, several manufacturers applied to the FCC for consideration. Most notably the Electronic Industries Alliance (EIA) and Japanese EIA asked to be included in order to represent their members in the testing and specification phases of the approval process. WTTW engineers helped set standards for frequency response, separation, and other uses of the spectrum. They also provided program source material used for the testing and maintained the broadcast chain. A 3M 24-track audio recorder was used to allow the selection of 12 different stereo programs for testing. The Matsushita Quasar TV manufacturing plant and laboratory, just west of Chicago, was used as the source for all testing of the competing systems. Following the testing, several questions were raised about the validity of some of the tests, and a second round of testing began. WTTW installed a Broadcast Electronics prototype stereo modulator in October 1983 and began full-time broadcasting in stereo at that time using the Telesonics system prior to Federal Communications Commission (FCC) rule-making on the BTSC system. MTS was officially adopted by the FCC on 23 April 1984. Following EIA and FCC recommendations, the BE modulator was modified to meet BTSC specifications, and by August 1984 was in full-time use on WTTW. Sporadic network transmission of stereo audio began on NBC on July 26, 1984, with The Tonight Show Starring Johnny Carson, although at the time only the network's New York City flagship station, WNBC, had stereo broadcast capability; regular stereo transmission of NBC programs began during early 1985. ABC and CBS followed suit in 1986 and 1987, respectively. FOX was the last network to join in 1987, with the four networks having their entire prime-time schedules in stereo by late 1994 The WB and UPN networks launched the following season with their entire line-ups in stereo from the start. One of the first television receiving systems to include BTSC capability was the RCA Dimensia, released in 1984. From 1985 to 2000, the networks would display the disclaimer "in stereo (where available)" at the beginning of stereo programming, sometimes using marketing tags such as CBS's "StereoSound" to describe their institution of stereo service. Networks in Canada and Mexico, which also used the NTSC video standard, utilized MTS sound when made available.

DTV transition in the United States As a component of the NTSC standard, MTS is no longer being used in U.S. full-power television broadcasting after the June 12, 2009 DTV transition in the United States. It remains in use in LPTV and in analogue cable television. All coupon-eligible converter boxes (CECBs) are required to output stereo sound via RCA connectors, but MTS is merely optional for the RF modulator that every CECB contains. NTIA has stated that MTS was made optional for cost reasons; this may have been due to a belief that MTS still required royalty payments to THAT Corporation, which is no longer true except for some digital implementations. THAT created consumer pages on the DTV transition and how it affected MTS by the choice of CECB, as some only receive stereo-incompatible RF signals and only output mono sound.

Specification

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Multichannel Television Sound

Start with the simplest possible case. Write down what Multichannel Television Sound claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Multichannel Television Sound before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Multichannel Television Sound ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Multichannel Television Sound

In research: Multichannel Television Sound appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Multichannel Television Sound in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Multichannel Television Sound is common in secondary-school and first-year university syllabi. It links to neighbouring topics Broadcast engineering, Sound, Television technology, so understanding it makes those chapters shorter.
In everyday life: Look for Multichannel Television Sound outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Multichannel Television Sound in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Multichannel Television Sound means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Multichannel Television Sound out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Multichannel Television Sound in simple terms?

Why does Multichannel Television Sound matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Multichannel Television Sound?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Multichannel Television Sound.