Which one of the following Telephonic Conferencing with a radio link is very…

Concept — Teleconferencing is a live meeting between people sitting at different places, held over a telecommunication link such as a telephone circuit, a terrestrial radio-relay hop or a satellite hop. Its forms are named by the media that link carries: speech alone (audio conferencing), speech with still graphics (audio-graphic conferencing), and speech together with live moving pictures (video conferencing). Classifying any named service therefore means asking two things — which channels its link carries, and in which direction.

Application — The stem asks for the conferencing form that runs over a telephone or radio link and is in common use everywhere. Video conference carries two-way speech together with live moving pictures over ordinary telephone, ISDN, IP, radio-relay or satellite circuits, so a meeting room, a classroom or a hospital anywhere can hold one on standard equipment. That is the form the stem describes, so the answer is Video conference.

Cross-check — Test each of the other named values against the same two questions, which media and which direction:

• TPS, the Telephone Participation System, carries speech only over telephone circuits and has no moving-image channel, so it is not the picture-bearing conference the stem points to.

• Telepresence is a studio-based implementation of video conferencing that needs dedicated rooms, life-size displays and reserved bandwidth; it is a specialised and costly subset, not the ordinary form available worldwide.

• Video teletext is a one-way broadcast videotex service that carries pages of text and block graphics inside the television signal; it displays information and does not conference at all.

Result — Video conference.