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60-413: MTS worked by adding additional audio signals in otherwise empty portions of the television signal. MTS allowed up to a total of four audio channels. Normally two were broadcast to produce the left and right stereo channels. An additional second audio program (SAP), could be used to broadcast other languages or entirely different audio like weather alerts that could be accessed by the user, typically through

120-526: A frequency deviation of ±25 kHz, whereas regular FM broadcasting has a deviation of ±75 kHz. The SAP subcarrier is located at 78.670 kHz , which is five times the 15.734 kHz corresponding to the 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

180-552: A high fidelity range. The second-generation Dimensia audio components were also made for the Digital Command Component System. In 1985, RCA released a fully integrated audio system known as the "RCA Audio System" that used the MSR-140 stereo receiver as its center for control over all the components. This allowed all Dimensia audio components to be controlled and fully functional without the need of

240-498: A woodgrain veneer and a black exterior from 1984 to 1986. These monitors featured BTSC system three-channel audio which had just been adopted by the Federal Communications Commission as the U.S. standard for stereo television transmission in 1984, the same year as the release of Dimensia. In 1985, RCA released a 40-inch projection monitor for the system with the 32 kilobyte microprocessors. This

300-621: A Dimensia television set. The price of this system started at $ 1,500 and included the Digital Command Center remote control. It also used the Colortrak 2000 monitor. The SPK400 and SPK500, released in 1987, were second generation three-way speaker systems. Also released in 1987 for the second generation Dimensia system and for the Digital Command Component System were the MPA-100 and MPA-120 amplifiers; released to replace

360-456: A brick wall elliptical filter in each of the audio channels prior to encoding. The cutoff frequency of this filter was 15 kHz to prevent any horizontal sync interference (15.734 kHz) from being encoded in the audio. Manufacturers of modulators, however, used lower cutoff filters as they saw fit, also reducing the cost of audio filters. Typically, they chose 14 kHz although some used filters as low as 12.5 kHz. The elliptical filter

420-542: A button on the Digital Command Center. The two TV sets that were the center of this system (FKC2600E and FKC2601T) were physically identical to the Colortrak 2000 chassis. These monitors were where the systems 32 kilobyte microprocessors were located. They sat in a dedicated entertainment center that suited all the components of this fully integrated system. The system was available in two color schemes;

480-405: A button on their remote control . The fourth channel, PRO , was only used by the broadcasters. 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

540-449: A completely separate service like a campus radio station or weatheradio . This sub-carrier is at 5x horizontal sync and is also dBx encoded. A third PRO (professional) channel is provided for internal use by the station, and may handle audio or data. The PRO channel is normally used with electronic news gathering during news broadcasts to talk to the remote location (such as a reporter on-location), which can then talk back through

600-454: A similar premise but generally carry totally unrelated programming to the main feed. On digital television systems, selection is done through a menu as with analog television, though some provide easier access rather than having to dig down to find the option. Stations may also choose to transmit audio-only programs by assigning them to separate digital subchannels with an optional screen of title and artist information; however, this prevents

660-497: A small gap between the Main and Stereo signals at 15.734 kHz. This pilot signal is also known as "H", or "1H", and its frequency is selected to be a harmonic of the video's horizontal scan signal so that it can be accurately recreated from the video signal using a phase locked loop . If there is any signal present at the 1H frequency, the television knows a stereo version of the signal is present. The Stereo Subchannel consisted of

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720-641: A time. With the Dimensia remote, just pushing the VCR button will turn on the VCR, turn on the monitor and then play the tape in the VCR, assuming there is one in the VCR. The Dimensia remote was not programmable like most universal remotes today. It was only fully compatible with Dimensia components. These components were referred to as Dimensia Intelligent, hence the name, Dimensia Intelligent Audio Video. Dimensia televisions had many unique features that were state of

780-404: A very large and advanced universal remote , called Dimensia Intelligent Audio Video or Dimensia Digital Control, variations of the Digital Command Center . The capabilities of this remote were far more advanced than many (perhaps any) other remotes at that time. For example, with other universal remotes you can control everything separately by controlling one component at a time; one command at

840-451: 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

900-562: A wide array of high-end features that were novel for its time and are still not common anywhere. The main unique feature of the Dimensia system was the MRT 003, a 32- kilobyte built-in computer module which allowed the monitor to communicate with all Dimensia components and the remote functions. All components were connected via the control bus found on the I/O panel on the back of the TV. The control bus

960-441: Is 19 kHz, not 15.734. SAP, if present, is centered on 5H, but encodes a monaural signal at lower audio fidelity and amplitude. The PRO signal is likewise encoded at 7H. A signal using all four channels extends only to about half of the available bandwidth in the original audio upper sideband. The second audio program (SAP) also is part of the standard, providing another language , a video description service like DVS , or

1020-650: Is an auxiliary audio channel for analog television that can be broadcast or transmitted both over-the-air and by cable television . Used mostly for audio description or other languages, SAP is part of the multichannel television sound (MTS) standard originally set by the National Television Systems Committee ( NTSC ) in 1984 in the United States. The NTSC video format and MTS are also used in Canada and Mexico . SAP

1080-411: Is any signal present. If there is, the difference signal is extracted by filtering out the signal between 1H and 3H into a separate channel, and the carrier is re-created by adding 2H to this. This signal is then decompressed from its dbx format, and then fed, along with the original Main, to a stereo decoder. FM stereo radio works in the same fashion, differing mainly in that the equivalent to the H signal

1140-598: Is essential to good audio in the decode process. During transmission, the phase of the horizontal sync could vary with picture and chroma levels. ICPM (Incidental Carrier Phase Modulation), a measure of transmitted phase stability, needs to be less than 4.5% for best audio sub channel decoding. This was more of a problem with UHF transmitters of the day. Multi-cavity klystron RF amplifiers of that time typically had an ICPM above 7%. This made UHF transmission of MTS stereo impossible. Later UHF transmitter designs improved ICPM performance and allowed MTS stereo transmission. Because of

1200-479: Is no longer true except for some digital implementations. THAT has created consumer pages on the DTV transition and how it affects MTS. The site describes the situation by stating that most consumers with CECBs will end up with monaural TV sound, since RF-only connections are common and MTS is optional (and rare) for CECBs. The original North American television standards provided a significant amount of bandwidth for

1260-468: Is often used to provide audio tracks in languages other than the native language included in the program. In the United States, this is sometimes used for Spanish-language audio (especially during sports telecasts), often leading to the function being referred to facetiously as the "Spanish audio program". Likewise, some Spanish-language programs may, in rare cases, offer English on SAP. Some stations may relay NOAA Weather Radio services, or, particularly in

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1320-666: Is required from THAT for all analog and some digital implementations of MTS. Several nations outside North America using the NTSC standard adopted the MTS format for their analog systems, including Chile , Colombia , Taiwan and the Philippines . Japan adopted their own EIAJ MTS standard, within their own domestic NTSC variant . Two countries, Brazil and Argentina , used the MTS standard with alternate PAL standards. Second audio program Second audio program ( SAP ), also known as secondary audio programming ,

1380-566: The Digital Command Component System, a fully integrated audio system that permitted the full functionality of Dimensia audio components without a Dimensia monitor. The name "Dimensia" actually dates back to the early 1970s when RCA used the term for an enhanced spatial stereo effect which they called "Dimensia IV". The tagline for the Dimensia was The Next Dimension in Sight and Sound. The RCA Dimensia systems had

1440-521: The remote link to the TV station . Specialized receivers for the PRO channel are generally only sold to broadcast professionals. This sub-carrier is at 6.5x horizontal sync. MTS signals are indicated to the television receiver by adding a 15.734 kHz pilot tone to the signal. The MTS pilot is locked or derived from the horizontal sync signal used to lock the video display. Variations in phase or frequency of

1500-446: The signal-to-noise ratio . The SAP audio has a bandpass from 60 Hz to 12 kHz, which is less than the "regular" audio channel which runs from 50 Hz to 15 kHz. Though not technically an SAP channel, television stations can also broadcast a "PRO" ( professional ) audio subcarrier which is used to communicate with station personnel, particularly those engaged in electronic news gathering . This one-way audio channel allows individuals at

1560-569: The 100 watt MSA-100 amplifier; then later in 1985 the 200 watt MSA-200 amplifier was released which was compatible with the MGE-160 graphic equalizer . The impedance of the SPK-375 was six ohms and their sensitivity was 91 dB/watt/meter. The frequency response of the speakers built into the TV chassis was 50-15000 Hertz, a standard range for mid-range audio components; the external speakers and amplifiers increased this range to 35-20000 Hertz,

1620-402: The 1950s, the upper parts of the color signal pushed into the lower audio sideband . With the audio signal centered within the 0.5 MHz channel, and the lower 0.25 MHz being partially infringed on by leftover video signal, the upper 0.25 MHz was left largely empty. MTS worked by adding new signals to the free portion of this upper 0.25 MHz allocation. The original audio signal

1680-530: The Act to provide dictations on SAP of any "emergency information" displayed in a textual format outside of the Emergency Alert System and newscasts. MTS features, including stereo and SAP, travel on subcarriers of the video carrier , much like color for television. It is not carried on the audio carrier in the manner of stereo sound for an FM radio broadcast, however, as it only has

1740-742: 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

1800-526: 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

1860-682: 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

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1920-489: The ambient light in the room; at night or with the lights off it would lower its brightness. Retailed at over $ 5,000 USD upon its release in October 1984, it came with all the matching Dimensia-intelligent components, including the VCR, CED player (canceled just before release, with the Digital Command Center remote's "DISC" button being relabeled "VID2", though some of the manuals for Dimensia components continued to show

1980-447: The art at the time and some that are still rare today, including: There are different models of the Dimensia, and there were two "generations" of the console and full Dimensia systems. This variation of the Dimensia featured just the TV monitor mounted in a heavy wood grain veneer with a large input/output panel. It was on a swivel mount. It was not as commercial as the monitor for the full component-based Dimensia system; however, it

2040-511: The audio portion of NTSC Channel 6 at 87.75 MHz, but only in monaural . Because the pilot tone frequency at 15.734 kHz is different from that of the ordinary FM band (19 kHz), such radios cannot decode MTS. In ideal circumstances, MTS Stereo is better in performance than standard VHF FM stereo. In both FM Stereo and MTS the L-R subchannel is AM double-sideband modulated. AM is known to be susceptible to interference and noise reduction to

2100-426: The audio signal, 0.5 MHz, although the audio signal itself was defined to extend from 50 Hz to 15,000 Hz. This was centered on the audio carrier signal 4.5 MHz above the video signal, and given 25 kHz on either side of the carrier, using only 15 kHz of it. This meant the lower and upper 0.2475 MHz of the audio channel was unused. Due to the nature of the NTSC color signals added in

2160-564: 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. 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

2220-741: The case of PBS stations, a local National Public Radio (NPR) sister station, on the audio channel when SAP is not being used. In Canada, parliamentary and public affairs channel CPAC similarly uses SAP to carry both English and French-language audio. SAP is also a means of distribution for audio description of programs for the visually impaired . Under the Twenty-First Century Communications and Video Accessibility Act of 2010 , top U.S. television networks and cable networks have been gradually required to broadcast quotas of audio described programming per-quarter, Since May 26, 2015, broadcasters have been required under

2280-504: The console Dimensia monitor was intended to stand alone (the full system had a 100 or 200 watt amplifier and 3-way tower speakers), but was still a high-end system, it featured a more complete built-in audio system than most monitors of the time. It had both woofers and tweeters in the TV cabinet, whereas almost all standard CRT television sets featured just one (mono) or two (stereo) low fidelity mid-range speaker drivers. It also had selectable external speaker connectors to be powered by

2340-453: The control bus data link via the same piggy-back style RCA connectors . All Dimensia-Intelligent components could interact with the monitor's built-in computer. The first generation console Dimensia I/O panel shown to the left also has a SCART interface, an early multiport A/V interface which was popular in Europe (called EIA Multiport-Stereo Connector by RCA). The Dimensia system came with

2400-462: The horizontal sync are therefore transferred to the audio. UHF transmitters in use in 1984 generally had significant phase errors introduced in this signal making the transmission of stereo audio on UHF stations of that time nearly impossible. Later refinements in UHF transmitters minimized these effects and allowed stereo transmission for those stations. Most FM broadcast receivers are capable of receiving

2460-624: The internal amp. The commercial models featured a 20-foot-long (6.1 m) grounded power cord and BNC high-end commercial coaxial inputs. These models were around before the Dimensia system and were called the RCA Lyceum TV . These units were often used in educational facilities or other institutions and had the same chassis as the Colortrak 2000 and Dimensia tabletop model (the primary one). The commercial models had many extensive features such as automatic color balance and an automatic screen brightness adjuster which varied according to

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2520-486: The main features of the Dimensia's was the large input/output panel on the back. This included several RCA composite video terminals as well as multiple unbalanced and balanced RF antenna/cable inputs. This enabled easy connection of all Dimensia system components, each on their own channel. Additionally, the RCA cables were able to be connected piggy-back, resulting in daisy-chain wiring. The components were also connected to

2580-407: The original "DISC" button; some CED players released before the Dimensia system hit the market have the special control jack and can be used with the system), amplifier , equalizer, speakers, tuner, cassette recorder, CD player and turntable. This was the most remarkable system, as all the components were compatible with the TV's computer and almost any operation could be executed with just the push of

2640-502: The same two audio signals, L and R, but mixed out of phase to produce the "L–R" signal, or "difference". This signal is sent at a higher amplitude and encoded using dbx compression to reduce high-frequency noise. To lower total average power, the carrier is not sent (which means there is no always-on signal at that frequency). On reception, the receiver uses the video signal to create the Pilot, and then examines that frequency to see if there

2700-417: The same way as the discrete left and right main audio channels, and ATIS station ID , which is heard as Morse code . On FM radio, radio reading services and other audio programs can be heard on subcarriers through subsidiary communications authority ; however, these are generally prohibited from public listening without special equipment. HD Radio subchannels, somewhat more widely available, operate on

2760-418: The sub-channel aids in the improvement of SNR over standard FM broadcast. The sub-channel information is dbx - encoded to improve the audio with typical SNR greater than 50 dB. By adding noise reduction to the sub-channel only, complete mono compatibility was maintained. Viewers who owned mono TV sets would hear normal audio, only limited to 15 kHz bandwidth. The original specifications called for

2820-563: The television station to send messages to people located away from the station, and is frequently employed during on-location newscasts as the foldback channel to reporters and cameramen . This channel is located at 6.5 times the pilot (102.271 kHz), and is also part of the MTS standard. Second audio programs are also available in other media. On analog television receive-only satellite television systems, audio programs are manually tuned by their subcarrier frequency, commonly around 6 MHz, often as low as 5.8 or as high as 7.2. These travel

2880-460: 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,

2940-558: The use of dbx companding , every TV device that decoded MTS originally required the payment of royalties —first to dbx, Inc. , then to THAT Corporation which was spun off from dbx in 1989 and acquired its MTS patents in 1994; however, those patents expired worldwide in 2004. Though THAT now owns some patents related to digital implementations of MTS, a letter from THAT to the National Telecommunications and Information Administration in 2007 confirms that no license

3000-485: The viewer from watching the main video in the case of television stations. RCA Dimensia Dimensia ( / d ɪ ˈ m ɛ n s i ə / dih- MEN -see-uh ) was RCA 's brand name for their high-end models of television systems and their components ( tuner , VCR , CD player , etc.) produced from 1984 to 1989, with variations continuing into the early 1990s, superseded by the ProScan model line. After RCA

3060-516: Was a unique RCA connector which was colored black. All Dimensia branded components had this control jack and they all interconnected by using RCA plugs that could piggy-back, resulting in a daisy chain which simplified wiring. This was known as the SystemLink, a communication system that had 16 kilobytes of computer memory (after the discontinuation of the Dimensia product line, RCA reused the SystemLink term for their universal remotes). One of

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3120-418: Was acquired by General Electric in 1986, GE sold the RCA consumer electronics line to Thomson SA which continued the Dimensia line. They are significant for their wide array of advanced features and for being the first television receiver systems to feature a built in computer, somewhat of an early incarnation of a smart TV , but without internet access (see Technological convergence ). In 1985, RCA released

3180-576: 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

3240-422: Was chosen for having the greatest bandwidth with the lowest phase distortion at the cutoff frequency. In comparison, standard FM modulators filter the audio at slightly higher frequencies but still must protect the 19 kHz pilot signal. The filter used during EIA/FCC testing had a characteristic that was −60 dB at 15.5 kHz. As transformer audio coupling was common at that time, the lower frequency limit

3300-594: Was left alone and broadcast as it always had been. Under MTS, this is the Main Channel. The actual signal in this channel is constructed by adding together the two stereo channels to produce a signal largely identical to the original monoaural signals and can be received on any NTSC television even without stereo circuitry. A second channel is then added, the Stereo Subchannel, centered at 31.468 kHz and extending 15 kHz on either side. This left

3360-465: Was otherwise identical to the 26 inch displays that were initially released. The initial 1984 Dimensia system came with one of several three-way stereo loudspeaker systems. The first one was the SPK375 which were made to go on optional speaker stands. They were rated at 60 watts RMS and 120 watts maximum and were in a 36-pound acoustic suspension enclosure . These were initially meant to be used with

3420-401: Was set to 50 Hz although modulators without transformer inputs were flat down to at least 20 Hz. Typical separation was better than 35 dB. However, level matching between channels was essential to achieve this specification. Left and Right audio levels needed to be matched within less than 0.1 dB to achieve the separation stated. Maintaining the phase stability of the horizontal sync

3480-426: Was still considered high-end and had the control bus. In other words, the console Dimensia system was intended to be more stand-alone television set than the full Dimensia system. The second generation console version of the Dimensia had the speakers located on the sides rather than underneath the screen (e.g. Model GPR2750P). It had three coaxial cable/antenna posts for separate RF inputs and one output. Audio : Since

3540-484: 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 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 1985 to 2000, the networks would display the disclaimer "in stereo (where available)" at

3600-488: 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

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