ChatterBank0 min ago
Time signal
If you have fm BBC4 and hear the "Pips", and in another room you have satellite BBC 4, the "Pips" on each system are slightly out of sync with each other. I understand the satellite signal has further to travel.......but this does not alter the fact that as a precise time signal one of them is wrong.
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The time lag caused by the distance of the satellite from the Earth's surface is roughly a quarter of a second. Any additional delay is due to signal processing times, which are inherent with digital technologies. Radio 4 time signals received through terrestrial digital TV (Freeview) and DAB radio also exhibit a time lag when compared to conventional analogue radio signals.
When the current FM radio transmitters are finally turned off, and wholly replaced by digital broadcasting, it would seem sensible for the BBC to arrange for the pips to be transmitted fractionally ahead of the true time, in order that they're received at the correct time on DAB (and just � second behind on satellite services).
However the Digital Radio Working Group (which was set up by the UK Government to plan the future of digital radio) currently has an (extremely optimistic) 'switch-off date', for FM transmitters, of 2020. Given that the original switch-off date for analogue TV was 2001, it would seem likely that FM radio will probably be around well after 2020.
Of course, the BBC could simply correct the current errors by asking the National Physical Laboratory to supply several sets of 'advanced pips', to use with satellite, DAB and Freeview transmissions. Most people though, would probably argue that the BBC could find better ways to spend licence-payers' money.
Chris
When the current FM radio transmitters are finally turned off, and wholly replaced by digital broadcasting, it would seem sensible for the BBC to arrange for the pips to be transmitted fractionally ahead of the true time, in order that they're received at the correct time on DAB (and just � second behind on satellite services).
However the Digital Radio Working Group (which was set up by the UK Government to plan the future of digital radio) currently has an (extremely optimistic) 'switch-off date', for FM transmitters, of 2020. Given that the original switch-off date for analogue TV was 2001, it would seem likely that FM radio will probably be around well after 2020.
Of course, the BBC could simply correct the current errors by asking the National Physical Laboratory to supply several sets of 'advanced pips', to use with satellite, DAB and Freeview transmissions. Most people though, would probably argue that the BBC could find better ways to spend licence-payers' money.
Chris
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