Thanks.
What is the deviation between the result calculate by the
formula and the result measured by the calibration source for the USRP
N210? For example,when I ues the formula:10*log10(var(x))+30 to calculate
the power of the receiver data is -20dbm.What is the true range for the
true result?
Thanks.
2015-12-08 10:53 GMT+08:00 Marcus D. Leech <[email protected]>:
> 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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