- DTV radio
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Digital-television radio, DTV radio, or DTR is an informal term which describes the music channels that are provided with a digital television service. In terms of price and musical variety, DTR falls somewhere between regular AM or FM radio, and satellite radio. However, because it is delivered through a digital signal, the actual sound quality is, in theory, equal to satellite radio.
DTR cannot be purchased as a service on its own. To obtain it, one must subscribe to a digital television service, typically satellite television or digital cable; in some places, digital terrestrial television also carries it. DTR music channels are usually provided as part of the "basic" television subscription service or package.
Number of channels
The number of music channels offered varies with each service provider. In the United States, DirecTV offers up to 84 channels of Sonic Tap, and Dish Network offers 95 channels, 65 provided by Sirius Satellite Radio, and 30 to 60 (depending on type of subscription) from Muzak for residential subscribers.
Music Choice offers nearly 50 channels, which all fit on a single ATSC digital cable TV channel through multiplexing. This includes still TV graphics which are sent at a very low I-frame rate to identify the station and song, and give more info about the artist. This is about four times as many standard-rate SDTV channels as can normally fit on such a channel. It also differs from former cable radio in that it can be watched on the TV, without having to be connected to an FM radio with an external antenna input. CRN Digital Talk Radio Networks offers seven channels, all broadcasting talk radio.
In Canada, Bell TV and Vidéotron offer 45 channels provided by Galaxie, while Shaw Direct, Shaw Digital Cable and Rogers Digital Cable each offer 40 music channels: 20 provided by Max Trax, the other 20 provided by Galaxie. In many markets, Rogers Cable also provides digital cable feeds of most local AM and FM radio stations; Rogers no longer offers the older type of cable FM service formerly required by the Canadian Radio-television and Telecommunications Commission (CRTC). Persona offers 39 channels from Galaxie and Maxtrax.
In the United Kingdom, digital television radio from satellite is received mainly by Sky Television customers, as part of their satellite television service, however other equipment is available to receive many of the non subscription radio and TV channels free. As of June 2004[update], there were approximately 90 radio stations on the Sky Digital service. Around 40 channels are available on the digital terrestrial television service, free of charge using the Freeview service.
In Australia, stations of federal-government-funded television networks ABC and SBS broadcast multiple music channels alongside their digital TV services. These stations are non-commercial, each featuring specific types of music such as jazz, blues or classical, with the SBS channels featuring foreign and ethnic programming, which are not normally played on commercial radio.
Some cable and satellite television providers also simulcast local AM and FM radio stations along with their DTR bundles.
In rare cases, digital TV broadcasters have included the audio of a commonly-owned broadcast radio station among their subchannel offerings (for instance, KCSM-TV in San Mateo, California broadcasts KCSM FM on its DT3 signal). WANN-LD in Atlanta offers six radio stations owned by Clear Channel Communications, in addition to ten TV channels. This type of service is known as DTV radio.
Non-broadcast content, subscription TV channels or datacasting operations unrelated to the main TV programming are also permitted by the DTV standards but are less-commonly used. USDTV was an over-the-air pay TV service that used H.264 compression instead of standard MPEG-2. Mobile DTV now uses MPEG-4 compression, which like H.264 yields a much lower bitrate for the same video quality.
Listening to DTR
One can listen to a DTR channel simply by entering the channel on one's television. However, this requires leaving the television on (which wastes electricity and reduces the lamp life of the backlight), and uses television speakers which are fairly limited in sound quality. Therefore, the recommended setup is to connect the audio outputs of the television set-top box directly to a stereo system. Set-top boxes typically have an extra set of audio outputs to facilitate this. Also, as a song is playing, additional information such as the song title, artist and album typically appear on the television screen. In the case of U.S. direct-broadcast satellite companies, this is text displayed by the box itself, rather than graphics generated at the headend.
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