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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 15:39:23 -0400 |
User-agent: |
KMail/1.8 |
On Monday 06 June 2005 15:28, Matt Ettus wrote:
> Actually, you can do 70 MHz directly into the BasicRX. Just set
> everything like you are using a 6 MHz IF (70-64=6). No need to use the
> ICOM R8500 at all.
Hmm, not sure what the passband of the 70MHz filters is. Shouldn't be too
much aliasing; I'll give it a whirl.
> > 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.
> The DBSRX is not intended to be used for RA applications without an LNA
> in front of it. Besides, even if it had a 0 dB NF, you would still have
> to run the coax from your feed all the way to it, which could be 10+ dB
> of loss.
Well, in our case we were thinking of the USRP potentially in a cabinet with
an embedded PC in each feedbox (they're about 4 feet cubed). Either that or
a frontend with a fiber transmitter in the feed and fiber receivers in the
control room; we have 12 strand singlemode fiber run to the feeds.
You need to come visit after SARA at Greenbank. :-)
> The DBSRX is even has a connector for providing LNA bias over the coax.
This is nice.
--
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC 28772
(828)862-5554
www.pari.edu