On 07/15/2010 08:51 AM, Jeffrey Lambert wrote:
Hello,
The noise figure will in large part depend upon the receiver front-end
that is attached the USRP or in the daughter board that is used. In that
case that you would like to know the noise figure of the USRP without
any RF front-end then the results may vary whether you are using a
BasicRX board or one of the LFRX boards. For a 50 Ohm system, either of
these should yield accurate results. Mainly, the noise figure of the
USRP will be derived from the AD9862 digitizer. Since this IC contains
an amplifier, the noise figure will vary with the gain of the PGA.
I too am interested in measuring the noise figure of the USRP. If you
are unable to find anything, I will be able to supply measurement data
within the next few weeks for a USRP device and BasicRX daughterboard.
The USRP + BasicRX will have a noise figure of around 35dB, since it has
no amplification. If designing a daughterboard, you can use that number
as the noise figure of the ADC for your calculations of the overall
noise figure.
Matt
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