Close view of the audio tracks of a Sony ICF-36 portable radio, made in 2001. The audio bands of the TV are obsolete and can not be used with digital television channels. Overview of portable radio.
TV radio, TV band radio and TV audio radio are common names for a type of radio receiver that can play the audio portion of a TV channel. The actual device name may comprise a list of all the frequency bands the device can receive (eg AM / FM / Weather / TV radio), one or two of which include the TV channel bands. p> Analog TV analogue audio tuning
For the increasingly rare analog television standard, audio for each television channel is broadcast in a separate frequency band near the frequency band of the video signal (see article NTSC, transmission). This audio signal can be heard separately from the video, using standard analog FM radios equipped with the proper tuning circuits. Design Problems for Digital TV Audio Tuning
After the relatively recent transition of many countries to digital television, no manufacturer of radio receivers has developed an alternative method to reproduce only the audio portion of digital television channels. same).
DTV broadcasters can transmit multiple separate video programs over a channel frequency in a digital subchannel, so it is necessary for a portable radio equipped with a digital audio decoder to do more than simply tune the frequency as with the receivers analogue signals. You also need to provide a way for the listener to choose between these digital subchannels, usually labeled * .1, * .2, * .3, etc., on digital TVs with ATSC tuners. This is possible by using an analogue tuning dial to tune in a digital television broadcast along with a button to select the digital subchannel.
Direct analogue frequency tuning of digital television is further complicated by the fact that digital television broadcasting allows the use of virtual channel numbers that are separate from the actual broadcast frequency channel. Thus, in a fully digital receiver, it may appear that a station is on VHF channel 13, but is actually broadcast on UHF channel 33. This complexity is hidden from users of fully digital receivers, but would be exposed to user of an analogue Tuner with a subchannel selector.
A fully digital tuning system can hide these complexities from the user, but a digital tuner normally has to perform a special channel scan to find available digital broadcasts. For a person traveling long distances with a digital audio radio tuned, it would be necessary to periodically check the available channels to find new stations.
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