This is again something for Arne, the developer of the great Grafana page wspr.live

The following may be a possible bug-report - I just want to notice:

The grafana page offers the possibility to compare the performance of two different reporting antennas, if wsprdaemon is used. I like to use it, when experimenting with antennas to find advantages of disadvantage of various antennas.
In the following example, I compare my kiwi3 antenna with my kiwi 6 antenna towards North-America:
So on the wspr.live page, I use the "receiver SNR Comparison' chart under WSPR Daemon Graphs bullet point;

The upper part of that Grafana page then looks like this:



At the right side we see the map with a lot of points - these are the spots, which have been reported from both, kiwi3 and kiwi6
As one can see, I have clicked on one spot at the east coast of USA, which appears the station WY1U
According to the data of this spot, the difference of SNR between both antennas is 0  - so both antenna copy this station in same 'quality'....

However the reality is totally different !!



According to the data on my spotting PC, the real difference is 11db !
Kiwi6 antenna receives WY1U with 11db higher SNR !

Why is the Grafana page showing no difference ? The Grafana page is called: Receiver SNR comparison - so if the map is talking about Diff - this should be the comparison of SNR data ?!?
I now believe that the DIFF number in this map is a comparison of some other data, but which is irrelevant for this grafana page

Could this been changed ?

It is very useful to compare the SNR results of the spots per each antenna when using wsprdaemon data. Unfortunately it doesn't work at this moment...

Many thanks for the great work already done with wspr.live Arne!

regards,
Ulli, ON5KQ

P.S.: I don't know, if Arne is following this group regularly. May be someone can forward my message to him by e-mail ?!

Hello,
I created that map when trying to implement a request by Clint. It does show the difference of spot count not the difference of SNR. I clarified the title and info text to prevent future confusion. From your request I notice that there is need for a map to directly compare the per station SNR values. I will implement that there the next time I work on it.

Regards
Arne

Hi Arne,
yes, I misunderstood the current reading in the map - though it would be great to use Grafana as a dashboard, on per station SNR values. With wsprdaemon-data we have the advantage that although the call of the spotting station is the same, we can see the snr per kiwi-rx hardware (receivers) - in my case kiwi3 or kiwi 6 in above example...

regards,
Ulli, ON5KQ

Hi Arne,
excellent - I realized, that you are already working on implement a map with real SNR difference numbers!

However we must be careful, when calculating!
A special case, which makes problems:
- What if first receiver don't hear a station at all and the reference receiver's mean receive SNR of that station is -20dbm.
In that case there should be no difference calculated, because the 'difference' then is 100%....hi

However if we follow the calculation as it is implemented now, we get a lot of false reports - let's take the example of above
receiver 1 don't hear the station at all.....---> Does it mean this field is 0  (zero?!)
Then reference receiver hears this station with -20dbm  --->   0dbm minus (-20dBm) = +20dBm

So:  An orange point is shown and receiver 1 as if the receiver 1 would hear the station 20db better - instead it don't hear it at all !

We can indeed see lots of high numbers - when we compare totally different  receive locations, where the chance is high, that one station don't hear the same stations as the reference receiver... could you check it please ?!

But this map will be great, once you have found the time for some tuning.... (as with the case mentioned above)

Many thanks for the great work !

Ulli, ON5KQ