[USRP-users] Regarding noise power calculation using SBX board

Matt Ettus matt at ettus.com
Mon Feb 18 15:22:19 EST 2013


There are no units on those samples.  You need an absolute amplitude
reference in order to determine the volts to number conversion.

Matt


On Mon, Feb 18, 2013 at 5:33 AM, senthil murugan
<amrita.senthil at gmail.com>wrote:

> hi,
>
> I am trying to estimate noise power without injecting any signal in SBX
> board with USRP N210.
>
> 1. Carrier frequency is 2.452GHz with BW of 10MHZ.
> 2. Gain = 0dB and using Tx/Rx port.
>
> noise power = (sum of 64 samples of amplitude squared)/64.
>
> I am getting around -78 dB. If I try to evaluate dBm/Hz, I am getting
>  -78 - 70 = -148 dB/Hz.  Hence , it will be -118 dBm/Hz.
>
> Its not matching with theoretical value of -174 dBm/Hz + 5 dB = -169
> dBm/Hz.
>
> Where am I going wrong with my calculations?
>
> Thanks
> sencen
>
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