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TV on Cellphones

December 23rd, 2004 · No Comments

New Scientist writes:

With cellphone bandwidth so expensive, operators need another way [than GPRS or 3G] to transmit their pictures. Which is why the cellphone industry has been working on a number of ways to deliver live TV to phones via digital signals broadcast from existing TV transmitters.

The most promising scheme, called Digital Video Broadcast-Handheld (DVB-H), was last week chosen by the European Telecommunications Standards Institute as the standard for Europe. DVB-H is based on the successful digital terrestrial TV system that delivers the UKs 30-channel Freeview digital TV service.

Its strength is its method of transmission, which is highly resistant to the kind of interference that has bedevilled analogue pocket TVs till now. The data is split into packets that are transmitted in thousands of parallel digital streams spread across a range of frequencies. When they reach the receiver, the packets are joined up to reconstruct the video stream.

Using MPEG-4, Windows Media or Real Video compression, watchable live TV can be squashed into a 240 kilobit-per-second data stream. In addition, DVB-H banishes the problem of on-screen ghosting caused by signals reflected from buildings, mountains and aircraft. The digital receivers software recognises the reflected packets as duplicates and discards them.

Tags: Telecom

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