I have included a couple of pictures taken this afternoon as I tested Phil's nRF24 lockdown project with a calibrated laboratory Spectrum Analyzer.
In the code only channels between 1-80 have ben used
/************* Radio config - make it unique! **********************************/
const byte pipeOut[] = "xxxxx"; // last 5 digits of your phone number is sufficiently unique in our small group
const byte mychannels[] = {5, 80, 10, 75, 15, 70, 20, 65, 25, 60, 30, 55, 35, 50, 40, 1}; // choose 16 FHSS hopping channels
/*******************************************************************************/
which should put the system within the legal limits for most countries, 2,400 GHz - 2,483 GHz, but not all so if you go for the project you have to look up the limits for your region.
You will notice from this pictures looking at the marker 1 & 2 that the system is clearly within the limits.
You will also see the output is 19,74 dBm which is slightly less then 100mW
- Marker 2 shows a frequency of 2,401 GHz, channel 1