vrijdag 15 februari 2019

Here is an other analysis of a spot made by Paul PA0K on February 1st 2019. He was spotted by W4HOD over 7200 km with a SNR of -23 dB. This spot reveals, that the propagation, between Paul's station and W4HOD, was not good, at that moment. But never the less, Paul's signal was received, with a bit of luck, as we will see.

Spots sorted by propagation
The table shows all the stations, that were received by W4HOD in Alabama in the time slot of 13:12 UTC. I have sorted the spots by propagation, using the Lowest Possible Power (LPP). The lower the Lowest Possible Power, the better the propagation. The propagation to W4HOD was good, or even very good, for the first 9 stations in the table. This are the stations that have been spotted with a LPP of 50 milliwatt or less.

The propagation from Paul's QTH to W4HOD was poor with a LPP of 500 mW.

W4HOD also received PA1OSF over a distance of  7200 km from The Netherlands. PA1OSF was received with a LPP of 20 mW. The propagation from PA1OSF was 17 dB better than from PA0K. The distance between PA0K and PA1OSF is 71 km (44 mi). The difference can be caused by propagation, antenna direction and the antenna.

Spots received by W4HOD
The propagation between VE3KAE and W4HOD shows the best propagation with a LPP (lowest possible power) of 0.5 mW. Luckely for Paul, VE3KAE used 100 mW. Believe it or not, if VE3KAE had used 5 W, in stead of 100 mW, this signal would have used a large part of the dynamic range of the receiver of W4HOD and Paul's signal would probably not have been spotted.

I noticed that W4HOD received twice the number of spots compared other stations. In an analysis of frequencies that were used, I saw, that W4HOD can receive two signals a few Hz apart. This suggests that there are more than one WSPR receiver or detector at W4HOD.

The dynamic range of the SNR is +1 -(-26) = 27 dB.
The dynamic range in LPP is 1000/0.5 =2000, which is 33 dB.

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