Many Thanks to Bert, PA1B, who made the figure more readable! Bert is a QRP and QRPp enthusiast, experimenting with very low power transmissions, even with 3.6 milliwatts.
This is the link to his interesting blog: Blog
(you can find QRP and QRPp activity, attenuators, his Monster Can antennas, and more).
Use of the figure.
In this figure you can see that if you use 1.000 W and your signal is 9+40 dB, if you use (under the same conditions) 1 watt, then your signal is 9+10 dB; so, if the QRM is under 9+20 dB, the QSO is possible.
If you use 100 watt, and your signal is 9+20dB, then, with 1 watt the signal is 9, with 5 watt the signal is 9+7dB, and with 100 mW the signal is 7+2dB.
If you use 100 watt, and your signal is 9, with 1 watt the signal is 5+4dB. Again, if the QRM is under 5+5dB, you can make QSO also with only 1 watt.
Hello Fabio, Thank you for you excellent entry in your Blog.
RispondiEliminaThe table clearly shows that QRP is working. FB. 73, Bert