[Skimmertalk] Elad S2 vs Duo issue

[Don Moman VE6JY]

I believe that I have eliminated those issues... the Elad software lets me
see the entire band and the spectrum is identical.  I ran them on their own
Elad software and (thankfully!) both are equal and sensitive.  But
something? in SkimSrv is really reducing the S2's performance.  The
difference is more than just the ATT on, typically 25 on average.  I have
reversed the ant cables just in case.  Both are fed from the same ant thru
a multicoupler.  These tests should rule out, I think, everything except
something in the way the S2 interacts with SkimSrv....

I was temporarily reporting on the same band with the same call to hilite
the differences and try to figure this out.

On Thu, Nov 29, 2018 at 12:36 PM Bob Wilson, N6TV <n6tv at arrl.net> wrote:

> Don,
>
> Remember that the "noise" component of the S/N ratio is averaged across the
> *entire* monitored segment, so if one receiver is picking up some local
> broadband noise (perhaps from a switching power supply) in the upper half
> of the band, but the other is not, they could report wildly different S/N
> ratios for the same absolute signal strength of a CW station.  As
> suggested, try to use a full band scope program like HDSDR to "see" the
> noise floor.
>
> As an aside, are your skimmers monitoring the same band segments with two
> different SDRs, but reporting all spots to the RBN under the same callsign,
> VE6JY?  That practice is strongly discouraged, as it makes using the data
> on the RBN website much more difficult for those who are trying to do
> signal or data analysis.
>
> For example, just now I see:
>
> VE6JY <http://reversebeacon.net/qrz/VE6JY>  NB6GC
> <http://reversebeacon.net/qrz/NB6GC> 14035.0 CW CQ [LoTW] 19 dB 22 wpm
> 1907z
> 29 Nov
> VE6JY <http://reversebeacon.net/qrz/VE6JY>  NB6GC
> <http://reversebeacon.net/qrz/NB6GC> 14035.0 CW CQ [LoTW] 44 dB 22 wpm
> 1907z
> 29 Nov
>
> How can a user trying to measure front to back ratios or average signal
> strength using your node interpret such dissimilar readings?
>
> As a reminder to everyone using multiple SDR or antennas, if they are
> covering the same band segments with two different instances of skimmer
> server, *please* use a *different callsign* on each instance, e.g. VE6JY-1
> and VE6JY-2, so that the raw data files and web site can make best use the
> S/N numbers being reported.
>
> To change the skimmer callsign, edit the .ini files used to start each
> skimmer using a text editor such as Notepad, and change the User section,
> like this:
>
> *Skimmer 1 ini file*:
> [User]
> Call=VE6JY-1
>
> *Skimmer 2 ini file*:
> [User]
> Call=VE6JY-2
>
> Thank you.
>
> 73,
> Bob, N6TV
>
> On Thu, Nov 29, 2018 at 9:59 AM Don Moman VE6JY <ve6jy.1 at gmail.com> wrote:
>
> > I've been noticing for some time that the S2 is not catching nearly as
> many
> > CW spots than the Duo, with both on identical antennas (fed from the same
> > multicoupler) and on identical bands.  On virtually identical W7 laptops.
> > Signal reports are like in the 20-30 range for the Duo and maybe in the
> > 5-10 range for the S2. S a lot weaker.  I'm looking at the traffic in the
> > Aggregator 5.2 window.
> >
> > I have reversed the antenna feeds - no change.  I have checked a weak
> > signal in the native Elad software, both are identical there. I have
> tried
> > different bands, from 630m to 20m and difference remains.  The difference
> > is significant and more than just what the antennuator being on would do.
> > I am using this .ini file from the Elad website...
> >
> >
> http://sdr.eladit.com/FDM-S2%20Sampler/ExtIO%20Dlls%20for%20use%20with%20%20third%20party%20software/Skimmer_Server_Dll_1_00/ELAD_FDMS2_SkimSRV.ini
> >   I have tried changing the ATT and LP values but they don't seem to make
> > any difference.
> >
> > Any assistance or insight would be appreciated, thanks
> >
> > Don
> >
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