Digital terrestrial television

Digital Video Broadcasting (DVB) technology to provide a greater number of channels, and digital quality of sound and picture, through a conventional aerial or antenna instead of a satellite dish or cable connection. Digital terrestrial television is also known as DVB-T.

Transmission

DTTV is transmitted on Radio frequencies that are similar to standard Analogue television, with the primary difference being the use of multiplex transmitters to allow reception of multiple channels on a single frequency range (such as a UHF or VHF channel).

The amount of data that can be transmitted (and therefore the number of channels) is directly affected by the modulation method of the channel. The modulation method is COFDM with either 64 or 16 state QAM (Quadrature Amplitude Modulation). In general a 64QAM; channel is capable of transmitting a greater bitrate, but is more susceptible to interference. The BBC now transmit 16QAM from their multiplexes on the British DTT network, Freeview.

Reception

DTTV is received via a set-top-box, or integrated receiving device, that decodes the signal received via a standard aerial. However, due to frequency planning issues, an aerial upgrade may be required if the DTT multiplexes lie outside the bandwidth of the installed aerial (quite common in the UK).

See also : Digital television