[Skimmertalk] Elad S2 vs Duo issue

[Bob Wilson, N6TV]

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
>