[Skimmertalk] CWSL and HPSDR

Thu Jun 20 14:47:24 EDT 2019

I'm not quite sure what you are trying to achieve but the mechanics of CW
Skimmer Server
is all about SNR and very little about absolute signal strength. The
dynamic range of the new
RP 122.88-16 is so large that it really does not matter if you have 10dB
gain or 10db attenuation
before it. It performs really well with any antenna, providing out of band
interferers like
FM broadcast etc. are taken care of and you do not overdrive it.

73

Björn SM7IUN

Den tors 20 juni 2019 kl 19:15 skrev <dd5xx at web.de>:

> Hi Bob,
>
> I already purchased two of those 14:1 transformers from you if you
> remember, so I use them too. I don't think such a approximation is really
> "enough". The old classic Red Pitaya won't show you a real S-value on
> HDSDR, you can try it out. I did test with three different RP. You can
> cross-check at your site. Just be sure to check all (!) band edges when you
> perform this test. The result is not adequate, you will have a match
> somewhere around 30m and a raising drift as you move away from this band in
> either direction. I would be really interested how the new 122.88-16 will
> perform on that test.
>
> 73
> Saki, DD5XX
>
>
> Gesendet: Donnerstag, 20. Juni 2019 um 19:08 Uhr
> Von: "Bob Wilson, N6TV" <n6tv at arrl.net>
> An: "SkimmerTalk Reflector" <skimmertalk at contesting.com>
> Betreff: Re: [Skimmertalk] CWSL and HPSDR
> Most people are using the 14:1 transformer <https://www.kkn.net/~n6tv/XFMR
> >
> plus a 10 dB preamp. to create a "close enough" 50 ohm input to the Classic
> RedPitaya (125-14).
>
> On the new Red Pitaya SDR (122.88-16), none of that is required. I
> produced an S-9 signal by transmitting very low power into dummy load and
> listening on "calibrated" receiver (Elecraft K3, non-SDR, connected to
> Skimmer antenna), then I went through the S-Meter calibration procedure
> with HDSDR using the same signal and antenna and ended up with a correction
> factor of -11.3 dBm. I didn't try doing this on all the bands though. This
> was with the default scaling factor 16 in the Extio_CWSL dialog.
>
> 73,
> Bob, N6TV
>
>
> On Thu, Jun 20, 2019 at 3:25 AM <dd5xx at web.de> wrote:
>
> > Hi Brad,
> >
> > you never will succeed to calibrate your RP with HDSDR/CWSL_Tee and get
> > correct values reported, simply said because you are not using a 50 Ohm
> > input on the classic RedPitaya/StemLab. Even if you try, you would
> realize
> > that your S-meter are not linear 160-10m when you cross-check with a real
> > meter. I don't know how this behaves on the new RedPitaya with the 50 Ohm
> > input, maybe someone tested it already and can give you feedback.
> >
> > 73
> > Saki, DD5XX
> >
> >
> > Gesendet: Donnerstag, 20. Juni 2019 um 03:58 Uhr
> > Von: "Brad Denison" <brad.denison at gmail.com>
> > An: skimmertalk at contesting.com
> > Betreff: [Skimmertalk] CWSL and HPSDR
> > Thanks Bob - perhaps I did not word my question correctly. I am more
> > interested in knowing that if I put in a calibrated signal source (S9
> > for example) to my receivers I get that value reported back correctly.
> > The only way I know how to do this with a QS1R or a RP is by using
> > CWSL TEE & HPSDR, which by default, never returns the value I know I
> > am injecting. MY FDM-S2 for example requires no fiddling with
> > parameters for the software to yield the appropriate S9 on the
> > display.
> >
> > For now I am not worried about the frequency of spots or SNR of spots
> > - just that my receivers are showing S9 when I put in a S9 (or any
> > other value for that matter).
> >
> >
> > Perhaps this clarification will help with an answer.
> >
> >
> > Brad, W1NT
> >
> >
> > >If you can "see" band noise on all bands with scale factor 16 (the
> >
> > >default), you're fine. No need to calibrate the HDSDR S-meter; CW
> Skimmer
> > >doesn't calculate the S/N ratio that way. The scale factor you set in
> > >HDSDR's Extio_CWSL dialog has no effect on the reports generated by CW
> > >Skimmer Server. Better to check that your frequency of your spots
> matches
> > >those reported by calibrated skimmers such as those at KM3T.
> > >
> > >The feature of Aggregator that would compare your frequency calibration
> to
> > >those of all others was disabled a long time ago to improve server
> > >performance, as I understand it.
> >
> > >
> >
> > >73,
> >
> > >
> >
> > >Bob, N6TV
> >
> > >
> >
> > >
> >
> > On Wed, Jun 19, 2019 at 6:04 PM Brad Denison <brad.denison at gmail.com
> > <
> http://lists.contesting.com/mailman/listinfo/skimmertalk[http://lists.contesting.com/mailman/listinfo/skimmertalk]>>
> wrote:
> >
> > >
> >
> > >
> >
> > >* So, it's summer and I figured while not too busy I would do a health
> > check*
> >
> > >* on my skimmers. Using CWSL and HPSDR is not something that I have
> > bothered *>* with too much in detail but I observe that there is an
> s-meter
> > calibration *>* procedure and also that the scale factor parameter
> changes
> > the S-meter when *>* that parameter is adjusted. *> >* So my ask to the
> > experts is when using a calibrated signal source what is *>* the
> > appropriate method to setup HDSDR using CWSL such that I can ensure my
> *>*
> > skimmers are healthy in the levels that they are hearing? *> >* Thanks,
> *>
> > >*
> > Brad, W1NT *>* _______________________________________________ *>*
> > Skimmertalk mailing list *>* Skimmertalk at contesting.com
> > <
> >
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> >
> > *>*
> >
> >
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