zaterdag 8 februari 2014

DL1SDZ's WSPR spots with 0,5 milliwatt

On his blog Hajo DL1SDZ reports spots made with 200 mW down to 0,5 mW on 30 meters.
He reduced the power from day to day.

Hajo wrote me that the 4 last spots with 1 milliwatt were actually made with 0.5 milliwatt.
In the WSPR data Hajo uploaded the spots of 0,5 mW as 1 milliwatt, since this is the lowest value that can be used. (1 mW is 0 dBm)
Because my excell sheet can not calculate with a power lower than 1 milliwatt, I left the values for 1 milliwatt in the analysis of yesterday .

But today I calculated the lowest possible power for the value of 0.5 mW by hand
and made the next table exclusively for the spots with 0.5 mW.
The calculated lowest possible power is, in some spots, only one step lower.

This table show 4 spots in stead of 3.

The table below that I made yesterday, does include spots of 400 km or more,
so it does not include the spot by HB9JAQ

Click to enlarge
This analysis shows the calculated lowest possible power.
The lowest possible power is calculated from the power sent and the SNR.
The lower the lowest possible power, the better the propagation.

2 opmerkingen:

  1. Bert,

    I didn't want to provoke you to spend extra time by manually calculating the minus power :-)

    But thanks for your effort. As told in another forum, it is not the distance that impressed me. It is still the fact that this kind of flea power makes communication possible over a distance which I could not cover in an afternoons promenade. I compared it with the famous bag of rice, which falls down in China and has effects elsewhere in the world. Fascinating.

    1. Hello Hajo, it is my pleasure. I was curious what the lowest power would be. It did not surprise me that it was about 3 dB lower for each spot.
      The very low power is made possible by the huge changes in propagation. If the propagation changes with 20 dB, the power can 100x smaller. hi 73, Bert