[USRP-users] Noise Measurement of USRP N210

Marcus D. Leech mleech at ripnet.com
Tue Sep 16 11:50:05 EDT 2014


On 09/16/2014 11:44 AM, FIXED-TERM Ghobrial Antoun (CR/AEH4) via 
USRP-users wrote:
> Hello ,
> I am using USRP N210 with daughter boards LFTX and LFRX (operating 
> frequency range is 30 Mhz) using Simulink model with Sampling rate 500 
> Khz.
> I checked the date sheet for the USRP and it is written that there are 
> two  noise:
>
>     * Phase Noise for different frequency (10 KHz, 100 KHz, 1 MHz).
>     * Receive Noise Figure.
>
> What are these noise ? I need to know how can I model the noise coming 
> out from the USRP ..
> Any suggestions Please !!
> Mit freundlichen Grüßen / Best regards
> *Antoun Ghobrial *
>
>
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
The phase noise in that situation is dependent entirely on the master 
clock on the N210, since the LFRX/LFTX have no downconversion at all.

If you require very-low phase-noise, use an external 10Mhz clock.

The noise figure is somewhat irrelevant for the LFRX, since it has no 
gain at all, the noise figure is utterly-dominated by the ADC, and ADC
   equivalent noise figures are not very good--usually 15 to 20dB or 
worse.  If you care about noise figure, use a lower-noise amplifier in front
   of the LFRX, although for "on the air" applications at low 
frequencies, noise is *dominated* by Galactic background noise, which is
   anywhere from 3000K to 100000K, depending on frequency.



-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

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