The BBC broadcasts its classical music station Radio3 on FM and many audiophile enthusiasts believe that Radio 3 broadcasts sound better than "CD quality". These enthusiasts believe that they are listening to a fully analogue audio signal.
Well they are not; ever since the 1970s the BBC has built a digital circuit in the transmission chain to improve the propagation of the audio signal through landlines on their way to the transmitter.
As far as practicality is concerned Radio 3 listeners are listening to a digital radio signal which is broadcast using an analogue carrier wave.
Starting from 1972 The BBC used PCM digital circuits to convert their analogue music signals at a 13 bit/32khz sampling rate. This effectively meant that that Radio 3 audio had a theoretical dynamic range of 78 decibels and an upper frequency limit of 16khz for the music. The frequency limit was further restricted to 15khz because of a bandwidth restriction associated with Frequency Modulated radio broadcasting.
Since the 1980s, The BBC has been using 14 bit/32khz Nicam digital processors.
The Radio 3 FM broadcasts of classical music can sound wonderful and at a bit rate of around 720 kbps they sound just as good to my ears as a CD transcribing around 1400 kbps. The BBC has recently started internet broadcasts of Radio 3 using a 320 kbps AAC codec and this sounds wonderful too.
If you still want to believe that you are listening to a wonderful analogue hi-fi experience when you tune in to R3 FM then think again. There is a difference between believing something to be true and knowing it to be true.
http://www.audiomisc.co.uk/BBC/PCMandNICAM/History.html
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