Noise level reading

[Patrick73]

Hi there !

I'm tuned to the 2m band and my SDRuno reads abt -125 dBm on a 'clear' frequency (using a 4 elts Yagi, FM mode, 9 kHz filter).
Could someone explain in simple words why, in the spectro, the noise floor shows abt 145-150 dBm ? What is measured there ?

Thanks.

[glovisol]

PSE read thread on low noise operation.
Glovisol

[Patrick73]

That's not the kind of reply I was expecting, but thank you

[Tech_Support]

Hello Patrick,
The noise floor on the spectrum display is the noise power per bin of the FFT, or put another way, it is the total noise power in the resolution bandwidth of the FFT. I cannot see the RBW value in your picture, but it will be shown in the lower right hand corner of your SP1 display. The Power meter on the other hand shows the total power within the demodulation bandwidth, which in your case is 9 kHz. The difference between the two values will be 10*Log (9 kHz/RBW)

Sincerely

SDRplay Tech_Support

[Patrick73]

Thanks for the detailed reply and the formula.