20726RE: [perseus_SDR] Re: Fierce competition
- Jul 9, 2013Hello Bjarne,Very interesting story. Could it be that it sounds like the attached file. I'm calling it the corkscrew qrm. I noticed it already several times during our mid winter DX-peditions in Walsoorden, Zeeland, The Netherlands. I always thought it had something to do with snow or rain but was never really confirmed by other DXers.73,Guido.
Van: perseus_SDR@yahoogroups.com [mailto:perseus_SDR@yahoogroups.com] Namens bjarnemjelde
Verzonden: dinsdag 9 juli 2013 20:08
Onderwerp: [perseus_SDR] Re: Fierce competition
To Leif and Jürgen:
The blowing snow noise is somewhat different to the falling snow/rain noise. Mostly, falling snow or rain is not a problem. Sometimes in combination with wind it is. Blowing snow is quite a different matter: It can best be described as a Formula One car cranking the RPM up to 18000.
I use insulated wires. However I have tested uninsulated steel and aluminium wires and there is no noticeable difference in noise pickup.
I can't say much about other antenna types. The only other antenna type I have up is the Mini-Whip and to my memory I haven't tested the blowing snow conditions with the M-W.
I have yet to find a noise blanker which can eliminate, or even slightly reduce blowing snow noise. It has the capacity to cover all but the strongest signals. The good thing is that when the wind calms down, the noise disappears...
The wind needs to be around 12 m/s, and of course there must be quite a bit of snow around, as percipitation or dry, light new-fallen snow on the ground.
Jürgen, no I have no recordings. SDR recordings with this kind of noise are deleted :-)
--- In perseus_SDR@yahoogroups.com, Leif Asbrink <leif@...> wrote:
> Hi Bjarne,
> > Leif, somewhat off-topic but on the web page
> > you referred to, you asked: Is there a similar
> > phenomenon static snow?
> Very interesting:-)
> I just wonder if/how the discharges differ. A snow-flake
> presumably has a much smaller mass than a typical
> static rain droplet. Even so it might have a fairly
> large surface area so its capacitance might not differ
> too much from that of a nearly spherical water ball(??)
> > Indeed there is. Both falling snow, and blowing snow.
> > I have lots of experience with both... With blowing
> > snow, the audio frequency of the interference vary
> > with the wind speed.
> What is your experience with different antenna types?
> I guess a magnetic loop would not be very sensitive
> while a small whip antenna might be very sensitive
> even though the number of hits would be small because
> of the size.
> > As for the bandwidth discussion: As a MW DX-er I don't
> > need more than the Perseus 1600 kHz span. I own a G33DDC
> > which can record 4 MHz, but I almost always use its
> > 1250 kHz setting.
> What about blanking static snow? Did you find a noise
> blanker that helps or is static snow fatal for the
> reception of weak signals?
> Leif / SM5BSZ
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