22-05-2011, 07:12 PM
(22-05-2011, 05:27 PM)Aerodyne Wrote: This is a facinating topic. Sadly I can't think of much to add except to say that in the early 1960s I built a 'high fidelity' AM tuner, based upon a design in Practical Wireless. This thing used an EF50 and, I believe, an EF80. THe sound when played through my homebuilt stereo outfit was mono, of course - but quite remarkably detailed and pure from the BBC's stations, both medium and long wave. Fair enough, AM cannot have the dynamic range of FM but apart from that slight drawback, the thing sounded fantastic. This leads me to realise that AM truly has been 'nobbled'.
Well, AM is just about OK for television :P
The only problem with using AM for audio is AGC, which of course means you have a compressor in your radio. Of course, with video, you can derive the AGC from the sync pulses...
I'm looking forward to eventually reinstating my workshop, and one of my first projects will be an AM transmitter
And digital delivery certainly does screw up simulcasting. Not surprising, given that it seems to be hard enough to keep an audio stream in sync with the pictures with a TV service!
Joe, you're right about Classic FM. A while back I found an interesting document about their broadcast infrastructure: http://www.ibs.org.uk/files/04_Clasic_FM_Relocates.pdf
Mark
