[Discuss-gnuradio] Peak hold spectral plot, TVRX, at 322 MHz, +/- 4MHz.

[Lamar Owen]

Thought the group would be interested in the attached plots.  This is with the 
current CVS usrp and gnuradio code, along with the latest distributed fpga 
code for the half-band filtering.  The plots were generated with an HP 8657B 
lab generator, set to -30dBm and stepped in 10kHz increments through the 
passband.  

One plot is of the TVRX.  Also, for comparison, the passband of the 10.7MHz IF 
of an Icom R8500 fed into a USRP BasicRX is presented.  Note the 'saddle' 
shape in the R8500 plot, which is inverted in frequency (making the labels on 
the plot misleading, although the center frequency is 322MHz).  The TVRX is 
about -8dB at +3MHz, and -3dB at -3MHz; the R8500 (a much more expensive 
front-end) is a little better, at -5dB +3MHz (remember, the spectrum here is 
inverted) and +1dB at -3MHz.

All in all the TVRX fares pretty good here.
-- 
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu

usrp-tvrx-bandpass-322-8MS-20051105.png
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usrp-r8500-bandpass-200511051325.png
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