Multichannel Television Sound - History

History

Multichannel Television Sound was adopted by the Federal Communications Commission as the U.S. standard for stereo television transmission in 1984. 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 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) audio tape 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 FCC rule-making on the BTSC system. 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 around 1990, with the four networks having their entire prime-time schedules in stereo by late 1994 (The WB and UPN, launched the following season with their entire line-ups in stereo). One of the first television receiving systems to include BTSC capability was the RCA Dimensia, released in 1984.

From the mid-1980s to the mid-1990s and also in the 2000s, the networks would display the disclaimer "In stereo " at the beginning of stereo programming;

• NBC would use the image of a television with headphones displaying the NBC Peacock in blue for their "bug" with the above disclaimer to the right of the image.
• CBS displayed a blue or white bar with the words CBS StereoSound (CBS' stereo sound system) emanating from a central position on the screen. This blue bar has been adapted by at least one station, WRAL-TV in Raleigh, NC.
• ABC used a simple In stereo where available disclaimer equivalent to the CBS version until 1989, when it was reduced further to Stereo: Where available. The display was discontinued in 1991 when the network left display of the stereo tag to show producers.
• Fox used white cursive text being "written" on the screen with their stereo bug until fall 1993. Unlike the latter cases however where it was displayed only at a master control level at the time of the program broadcast, the producers of each program inserted the logo within their title sequences directly, and in programs such as Married...with Children, In Living Color, and COPS, the logo is still displayed to this day in syndicated airings of pre-1993 episodes of series carried on Fox, and are also part of TV on DVD prints. The same process was used for NBC's Saturday Night Live due to that program's live production nature excluding attempts to remove the bug for tape airings.
• PBS' stereo tags vary by show producers and member stations.