[Discuss-gnuradio] More sensitivity tests of the USRP2 + Basic_RX

[Marcus D. Leech]

Test setup:

  o A signal generator producing -46dBm at 38.1MHz
  o USRP2 + Basic_RX

  o GRC flowgraph:
      o An FFT filter, reducing the incoming 250KHz bandwidth to 5KHz
      o A power detector:

           (I**2 + Q**2)--->single-pole-iir-filter

      o A strip-chart scope display

Using the scope display, I measured the detector output difference
between nothing connected (which on the BASIC_RX means that
  the A/D is "seeing" the 50-ohm termination across the input-half of
the balun transformer), and my -46dBm signal connected.

That difference amounted to a 65dB difference in detected output power. 
Doing the math, does that mean that a "naked"
  USRP2 + Basic_RX is sensitive down to roughly -111dBm, or should I
factor in root(5KHz), which brings it up to -92dBm.


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