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.

Raspberry Whispers

On the interesting Blog of M0XPD is a very interesting article about WSPR experiments with the RPi.
Read the article: Raspberry Whispers by M0XPD.

I just visited the WSPR data base to collect a list of WSPR spots. And made an Analysis of the WSPR spots that M0XPD made on 30 meter with a power of 200 mW.

The stations that are mentioned in the article Raspberry Whispers have Excellent Ears. (Sensitive receivers)  The lower the Calculated Field strenght  in the better the propagating or the more sensitive the receiving station.

WSPR Analysis
The distance is given in steps of 100 kilometers.
A distance of 250 to 349 km will show up as 300 km.
PI4THT at a distance of 635 km, is placed in the category 600 km.

To compare spots, that are made with a different power (dBm), I calculate the lowest possible power of each spot, using the SNR and the power (dBm) of the transmitting station.

To compare the spots of stations at a different distance, I calculate the Field strength of each spot. This calculation includes the distance in km. In the table, I chose for microVolt/meter, to get nice values.

For one receiving station, the changes in Field strength follow the changes in the propagation to that station.

• The lower the Field strength, the better the propagation.

While comparing two receiving stations:

• The lower the Field strength, the more sensitive the station. 

The RPi is working well.