[Discuss-gnuradio] wrong dB

[feldmaus]

Hi All,

i think i have a misunderstanding, but i don't know where it is.

I tried out an example named <usrp_am_mw_rcv.py> with
a Hardware Signal Generator connected to my USRP.
My Signal Generator generates a sin Signal with 7.0711e-3V effective
at f=1.05e6 Hz.

So my power is,
P = U*I = U^2/R, with I = U/R
P = (7.0711e-3_V)^2/50_Ohm
P = 1e-6 W

Now we convert this into dB,
P_dB = 10 * log10 (P/P_0), with P_0 = 1W
p_dB = -60_dB

But my measured Power is -11,933_dB so what is my Problem ?
Any Hints ?

The example can be found in,
/usr/local/share/gnuradio/examples/usrp/usrp_am_mw_rcv.py

Regards Markus