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Hi David, what describe (jump to frequency as you
tune a station in) sounds like a little bit of sophisticated radio electronics.
It suggests that the unit employs synchronous detection, somtimes called
enhanced sideband detection I think. I dont have details to hand but it
would allow a clear signal to be received in a much narrower receiver bandwidth
than the 18kHz of the bog standard diode detector usually used on cheapies.
It also has the advantage that it greatly reduces the effects of fading
(apparent over-modulation) on the audio quality.
It may sound unlikely at first sight at
that price But sophisicated MSF synching clocks are available for about the same
price.
Alan
G3NYK
----- Original Message -----
Sent: Thursday, November 03, 2016 4:32
PM
Subject: Re: LF: Smart noise
cancelling?!?
Hi Stefan,
Although this is a bit different, but also to do with noise, I bought a
very cheap kitchen broadcast radio from Tesco for £9. It has Long
Wave on it, and I am amazed it is the only LW radio I have that can
receive all the stations that still are on LW without any background
noise once a station is tuned in. It can be mains powered and next to a
computer or TV, and still no local noise!! The model number of this Tesco
kitchen radio is RAD - 113B. On tuning to a station, it suddenly
'locks on' to it with a small 'jump'. Then the local noise totally
disappears, leaving only the required LW programme interference free!!
Why is this? -could it be the way this very cheap radio detects the signal? If
so, the detection method used in this cheap radio would be very
useful for LF work, in which local mains noise is always a big problem.
Perhaps someone here also owns this Tesco radio, and can answer why
it is so quiet indoors where all my other Long Wave (and much more
expensive) receivers are all swamped by local noise when used
indoors?? I hope this is useful. Regards, David.
Hi
all,
Last night i thought a bit about noise cancelling on LF/VLF.
Depending
on the band and distance and strength of the QRN, different
settings for
a noise blanker are used, or optimal. Different rise times,
treshold
levels and so on.
I thought about propagation changes and
different shapes of QRN bursts
in the time domain, requiring different
blanker settings.
Is it possible to program an 'intelligent' noise
blanking system that is
evaluating the input spectrum, looking at the
shape/type of a sferic and
automatically sets individual dynamic noise
blanker parameters for each
burst?
Or do i miss something
here?
Just a thought. I guess i'm not the first one who has this idea
:-)
73,
Stefan
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