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Re: [linrad] RE: Linrad and the microwaves



Strange story,
But I suppose you will tell us that the noise level=antenna temperature, is
lower when looking up to the moon, than when looking at the horiziont. In
the latter case your antenna temperature will not be lower than 145 K ( half
of the antenna aperture sees the 290 K earth) and in practice your stations
noise temperature will be in the order of 290 K, implying an S-meter
deviation of S2 in 2,5 kHz bandwidth. Elevating the antenna, the noise
temperature will be much lower and your S-meter will deviate less. That
probably gives you the indication of weaker copyable signals. But in both
cases you deal with the same thermal noise, so still S/S+N determines your
reception.
73
Arie Dogterom, PA0EZ



-- Original Message -----
From: Koellner Guenter <guenter.koellner@xxxxxxxxxxx>
To: <linrad@xxxxxxxxxxxxxxxxxxxxxx>
Sent: Monday, January 27, 2003 12:55 PM
Subject: AW: [linrad] RE: Linrad and the microwaves


> Hello Leif,
>
> I do not know which kind of noise it is, I just mean that noise on EME is
quiter than on terrestrial. Maybe, or surely, it is more constant. Another
comparison: I did SSB QSO on the moon with signal strengthes that never
would have allowed a SSB QSO on terrestrial pathes. Just when I remeber my
only 23cm SSB with G4CCH, that signal on terrestrial would not even have
been noticed.
>
> 73, GŁnter
>
> > -----UrsprŁngliche Nachricht-----
> > Von: Leif Ňsbrink [SMTP:leif.asbrink@xxxxxxxxxxxxxxxxxx]
> > Gesendet am: Montag, 27. Januar 2003 13:05
> > An: linrad@xxxxxxxxxxxxxxxxxxxxxx
> > Betreff: [linrad] RE: Linrad and the microwaves
> >
> > Hi Guenter and all,
> >
> > > My experience with DSP processing on terrestrial pathes is, just
> > > in a few words, that I think that there is much more background
> > > noise, which cannot be handled by those narrow filters. If you
> > > want to use narrow filters, you must have low background noise,
> > > and this is the case at EME. I got this experience with Spectran
> > > as well as with the 25Hz filter of my FT847.
> >
> > Interesting.
> >
> > Do you mean the "background noise" is of QRN type so it is smeared
> > out by a narrow filter? I thought microwaves provided a nice
> > white noise floor without impulse noise. Is there something else?
> >
> > 73
> >
> > Leif  /  SM5BSZ
>

LINRADDARNIL