Re: LF: Smart noise cancelling?!?

[Andy Talbot <andy.g4jnt@gmail.com>]

Could it just be that it tunes in 9kHz steps? So will jump stright onto frequency

A low cost radio is sure to have a completely digital front end.

'jnt

On 3 November 2016 at 17:14, Alan Melia <alan.melia@btinternet.com> wrote:

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 -----

From: David Hine

To: rsgb_lf_group@blacksheep.org

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.  

---

From: DK7FC <selberdenken@posteo.de>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Sent: Thursday, 3 November 2016, 13:22
Subject: LF: Smart noise cancelling?!?

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