iDTV - Integrated Digital Television. A television with a built in digital tuner which can receive DTT.

IMPULSIVE NOISE  - The term which describes the clicks from central heating boilers in the home, washing machines and light dimmers, which can cause a flash on analogue televisions in marginal reception conditions and, with digital reception, may cause blocking, freezes, and high pitched clicks on sound. In many cases, the equipment causing the interference is illegal and should be replaced. However, it is not usually tactful for an installer to suggest that. The alternative is to improve the aerial installation by: better earthing of the installation external rather than loft aerial quality twin screened downlead and especially the interconnecting lead from the wall One particular form of impulsive noise is ignition interference from passing vehicles, which can be 'the straw that breaks the camels back' in marginal reception conditions. The improvements above will help but, in addition, try moving the aerial to the back of the house such that the roof provides screening from the road. Also, tilting the aerial upwards by perhaps 5 deg is also helpful. The problem can be made worse if the analogue signal levels are close to overload so the usual advice about minimum gain of pre-amps applies. Many first generation set-top boxes employ MPEG decoder chips which are not very robust in this respect. It is likely that improvements will be made in this area in second generation equipments.

INTEROPERABILITY - Interoperability is the holy grail of all multiplex operators. Digital set-top boxes are fearsomely complicated; specification and testing to ensure different types perform the same way is a big and expensive overhead at best and a potential nightmare in an open market situation. In a closed system, the multiplex operator would expect to have a contract with its suppliers to provide comprehensive conformance testing. In DTT, responsibilities are not so clear-cut. The DTG could have a role to play.

I.R.D. - Integrated Receiver/Decoder. A satellite receiver with a built in decoder for unscrambling subscription channels such as Sky Movies.

I.S.T. - Information Society Technologies. The European funding part of the 5th and 6th (et al) frameworks for research and technology development, which took over from earlier programs such as ESPRIT and ACTS.

I.T.C. - Independent Television Commission, the governing body of television broadcasters (except the BBC who are self-regulated).