[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
> 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
> 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
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.
Shirleys Bay Radio Astronomy Consortium
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