Greenwich Time Signal 19:00. By 19:45 the same day the power supply was repaired and the 20:00 pips were broadcast as normal. Many radio broadcasters around the world use the Greenwich Time Signal as a means to mark the start of the hour. The pips are used in both domestic and international commercial and public broadcasting. Many radio stations use six tones similar to those used by the BBC World Service; some shorten it to five, four, or three tones. Greenwich Time Signal The Greenwich Time Signal (GTS), popularly known as the pips, is a series of six short tones broadcast at one-second
BBC Radio 4 7pm its DAB output is usually in mono, even though many of its programmes are made in stereo (including its flagship drama "The Archers"), these can be heard in stereo only on FM, Digital TV on Freeview & Freesat (Ch. 704), Sky, Virgin and on line via BBC iPlayer radio. BBC World Service, which uses BBC Radio 4 FM & DAB frequencies between 01:00am and 05:20am, is in stereo, but only on Radio 4 FM & DAB and not on its own dedicated DAB channel. BBC Radio 4 Extra broadcasts in mono on DAB, but has always been in stereo