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Re: [Discuss-gnuradio] PNG's of a neutral hydrogen observation at PARI w
From: |
Lamar Owen |
Subject: |
Re: [Discuss-gnuradio] PNG's of a neutral hydrogen observation at PARI with a USRP. |
Date: |
Mon, 6 Jun 2005 15:10:06 -0400 |
User-agent: |
KMail/1.8 |
[forgot to reply-all. Argh]
On Monday 06 June 2005 14:14, Marcus Leech wrote:
> What's the bandwidth of the 10.7Mhz output of the R8500?
It's designed for video capability; our technical director, Charles Osborne
(K4CSO, President of the Society of Amateur Radio Astronomers (SARA)) tells
me it's not real flat, but is probably about 3-4 MHz wide.
> Was this a drift-scan, or were you tracking?
Drift, for testing. The 26m's are outfitted with a DFM Engineering variable
frequency AC motor drive, and will track at sidereal rates. But rather than
power up the two 15 horsepower motors, I just left it at zenith.
> Fellow radio astronomers want to know :-)
Understood.
> 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.
I have a TVRX (and a basic RX/TX pair) on my personal unit; the PARI unit is
outfitted with two basic RX and two basic TX. The TVRX can do 70MHz direct;
I might try that at some point. There's a significant electrical storm here
now, so I have everything disconnected.... :-)
As to the DBSRX, I mentioned to Charles Matt's statement of the 'less than 8dB
noise figure' and Charles wasn't real impressed; need pretty good
amplification ahead of it to get a useful noise temp. We have a few front
ends with less than 3 dB NF here, and we will soon have better. No cryo
here, yet.
--
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC 28772
(828)862-5554
www.pari.edu