04-07-2017, 11:14 PM
(04-07-2017, 12:22 PM)ppppenguin Wrote: I wonder how they managed to get the signals from London to "oop north" without mangling them. When they started stereo radio on VHF they couldn't even reliably get a decent quality feed from London to Brum. Hardly surprising that the BBC pioneered digital distribution systems. Their 13 bit PCM system was a revelation.
As far as I know, the BBC used the established GPO landline system for early FM programme distribution, the same as used for its AM network and TV sound. Presumably a link from Newcastle to Pontop Pike was added when that transmitter was built.
There was some criticism of the BBC for not upgrading its landline links for FM. For example, in Germany the programme links were upgraded from 10 to 15 kHz in conjunction with the establishment of its FM network.
Even in 1964, there were still some shortfalls, including in respect of Pontop Pike:
The BBC’s comment that 10 kHz was the internationally accepted bandwidth for music circuits was a bit disingenuous when applied to FM in the 1960s.
It was true, though, in pre-FM days, and was the CCIR standard:
Back then the BBC was working to 8 kHz as its trunk line target:
And so that was the situation when FM arrived.
10 kHz, or preferably 15 kHz landlines were probably acceptable for the distribution of mono programmes, but getting a frequency- and phase-matched pair for stereo over any distance was no doubt a challenge.
Cheers,
Steve
