[Discuss-gnuradio] PNG's of a neutral hydrogen observation at PARI with a USRP.

[Lamar Owen]

Attached are a couple of PNG's made at PARI with one of our two 26 meter 
parabolics, 60dB of gain/downconversion from 1420MHz to 70MHz, and connected 
to the 10.7MHz IF output of an ICOM R8500 tuned to 70MHz.  I set 
average_alpha to the ridiculous value of 0.005 to get the smoothness.  Just 
wish I could get a flat passband and 0.1dB per division. :-)  The 0.1dB per 
division won't be too difficult, but the flat passband I understand will have 
to wait.

The version of usrp_fft.py I used I renamed spectro, and set the frequency 
scale appropriately, as you will see in the images.

Images are named with date and UTC time, telescope was at zenith and 
collecting data close to the galactic plane.

I do have a question:  I tried to set the fft size to 4096, and got an error 
when I did that.  I need fft's with 65536 or more points, doable?

Progress!
-- 
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu

h1-20050606173942-26w-z.png
Description: PNG image

h1-20050606174210-26w-z.png
Description: PNG image