DVB-T is a technical standard developed by the DVB Project that specifies the framing structure, channel coding and modulation for digital terrestrial television (DTT) Broadcasting .
DVB-T, in common with almost all modern terrestrial transmission systems, uses OFDM (orthogonal frequency division multiplex) modulation. This type of modulation, which uses a large number of sub-carriers, delivers a robust signal that has the ability to deal with very severe channel conditions.
Using different combinations of the above parameters a DVB-T network can be designed to match the requirements of the network operator, finding the right balance between robustness and capacity. Networks can be designed to deliver a whole range of services: SDTV, radio, interactive services, HDTV and, using multi-protocol encapsulation, even IP datacasting.
One final technical aspect of DVB-T worth mentioning is its capacity for Hierarchical Modulation. Using this technique,two completely separate data streams are modulated onto a single DVB-T signal. A “High Priority” (HP) stream is embedded within a “Low Priority” (LP) stream.Broadcasters can thus target two different types of receiver with two completely different services. For example, DVB-H mobile TV services optimized for more difficult reception conditions could be placed in the HP stream, with HDTV services targeted to fixed antennas delivered in the LP stream.
DVB-T has technical characteristics that make it a very flexible system: