2 May
2005
2 May
'05
11:11 a.m.
Hi,
Paul Koning said:
Most of the fading is due to phase cancellation between the two sidebands.
The usual technique is to eliminate one sideband and treat the signal
as a single-sideband one, using either the transmitted carrier or a
locally synthesised phase-locked one. My Racal RA1792 has facilities for
an independent sideband system that would allow seperate demodulation
of the two sidebands, but I've not found the relevant hardware yet...
To get back to computers for a while, this Racal receiver has provision
for remote computer control and I'm currently investigating the SCORE
(Serial Control Of Racal Equipment) protocol it uses, with a view to
writing a remote control program so I can control the receiver from
downstairs and stream the audio over the network. It's even more-or-less
on topic - the radio dates from 1987.
--
Cheers,
Stan Barr stanb at dial.pipex.com
The future was never like this!
>>>> "Geoffrey" == Geoffrey Thomas <geoffreythomas at
onetel.com> writes:
> No. Narrow IFs and lack of design attention
due to declining
> worthwhile content on AM (plus novelty of FM in the '60s) and
> other factors all conspired to make it sound crappy.
>
Geoffrey> There was a design - in the late 60's?- which used a
Geoffrey> detector which demodulted both upper and lower am sidebands
Geoffrey> and fed the result to separate speakers. Apparently the
Geoffrey> effect during night time fading was exceptional. Anybody
Geoffrey> recall anything about this - Tony ? Sorry if this is ot.
Don't know about back then, but recently (within the past year) there
was an article about a receiver using that approach. It probably was
in the ham radio publication QEX, and I think that it was by Wes
Hayward -- or at least he was connected in some way.