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Re: [Discuss-gnuradio] PNG's of a neutral hydrogen observation at PARI w
From: |
Marcus Leech |
Subject: |
Re: [Discuss-gnuradio] PNG's of a neutral hydrogen observation at PARI with a USRP. |
Date: |
Mon, 06 Jun 2005 14:14:08 -0400 |
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Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 |
What's the bandwidth of the 10.7Mhz output of the R8500?
Was this a drift-scan, or were you tracking?
Fellow radio astronomers want to know :-)
I have an USRP on the way from Matt along, with a pre-release DBSRX. It
will be interesting
to compare my spectral observations with yours, in the fullness of time.
Lamar Owen wrote:
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!
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