Re: [Discuss-gnuradio] how to get dBm value from usrp_spectrum_sense.py

[John Orlando]

2010/6/17 lishan_wh <address@hidden>:
> Hi,
>
> I wonder how can I get the dBm value by using usrp_spectrum_sense.py.
>
> should I do it as follows?
>
> fft = gr.fft_vcc()
>
> c2mag = gr.complex_to_mag_squared()   (or without squared?)
>
> log = gr.nlog10_ff()
>
> stats = gr.bin_statistics_f()
>
> self.connect(self.u,s2v,fft,c2mag,log,stats)
>
> in main function, I defined
>
> m = parse_msg(tb.msgq.delete_head())
>
> Is mean(m.data) the dBm value? If it isn't, how can I get the it?

The easiest way is to simply use an RF signal generator with a known
output power level, feeding it directly into the USRP.  Then, you can
measure the value of the signal you are receiving (either manually in
your application or by viewing the samples with a graphical tool such
as using usrp_fft.py) and calibrate against this.

-- 
John Orlando
CEO/System Architect
Epiq Solutions
www.epiq-solutions.com