Teletext
Information service broadcast together with a TV programme, can only be displayed if the TV set is equipped to receive this type of data. The information is limited to a maximum of 999 pages. A suitably equipped TV set can call up each page individually. Some TV sets are capable of storing a number of pages, thus enabling direct access to these.

Terrestrial
"related to the earth's surface", this term is used for all broadcast services with the exception of space (satellite) and astronomic broadcasts. A "normal" or terrestrial domestic antenna is used to receive standard conventional TV and radio programmes.

Throughput damper
Reduction of the signal level at all outputs, eg among distributors within a receiving structure.

Transponder
Every satellite is equipped with a certain number of transponders. Every transponder can transmit at least one TV channel (ASTRA) or in some cases two channels (EUTELSAT, Intelsat). Where a digital transmission format is used, each transponder is capable of transmitting several TV and radio channels. The transponder receives a signal from earth and transmits it back to earth at a different frequency.