Re: [Discuss-gnuradio] Measure the power using USRP

On 12/07/2015 09:34 PM, w xd wrote:
> Hi,
> I want to measure the power.I'm now transmit the OFDM signal.
>
> I use the usrp to receive data,and I save it to a file.I read all
> the data.Then:
> I use the formula to calculate the power:
> 10*log10(sum(abs(data).^2)/0.001) dbm
> Is it the right way to calculate the power under the ofdm?
> Thanks.
>
> Best Regards,
> z sw
>
Instantaneous signal power is proportional to:

(I**2)+(Q**2)

You can average that to whatever interval you want, and then scale
(perhaps converting into dB, as above). But to determine *absolute*
power at the antenna terminals you'll need a known calibration source
or two, and use that to come up with calibration constants for
your particular setup of frequency/gain/bandwidth/sample-rate.




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