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Re: GigE (was Re: [Discuss-gnuradio] DSP based SDR)


From: Lamar Owen
Subject: Re: GigE (was Re: [Discuss-gnuradio] DSP based SDR)
Date: Sat, 25 Jun 2005 06:15:56 -0400
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On Friday 24 June 2005 18:31, John Gilmore wrote:
> You've just reinvented the first ten instructions of TCP packet
> processing.

I for one am very familiar with the work of 'address@hidden' and have been in 
awe of your work for some time.  I have not been at this nearly as long as 
you, but I'm glad you remind people that there really is a history here, and 
reinventing already working wheels is counterproductive in a manner.  
Sometimes it can be educational, but that's a different story.

Yet the computing landscape is riddled with wheels that have been reinvented 
dozens of times; simply because it is impossible for any one person to be 
familiar with all the different wheels out there.  But in the age of Google, 
simply searching for what you need is better than going off on your own.  
That is why I waited on the USRP availability; I have needed this 
functionality for at least five years, but the tech wasn't there yet, and, 
quite honestly, the effort is large.  I waited with bated breath for Matt to 
announce that USRP's could be bought, and bought one as soon as I could 
afford to do so.  And am enjoying it immensely!

I think the next logical step is either PCI-e (which could scale to outside 
the box), some form of SATA, or Infiniband or one of its variants.   But 
honestly USB2 is not a bad solution and is great for what the USRP does 
today.

IPv6 with QoS might be able to deal with what hard realtime applications like 
data acquisition and software radio need; but quite honestly it is a lot of 
overhead for the application.  IPv4 is insufficient for hard realtime; 
dropping packets in software radio really isn't an option, otherwise 
out-of-band emissions could result, and our friendly neighborhood EIC at the 
FCC's EB won't like that (and neither will your wallet when you get the NAL 
for $10,000 for unlicensed operation!).  The problem there is the currently 
regulated nature of spectrum usage; maybe one day cognitive radios will be 
able to deal with wide-open spectrum usage; but, even then, the protocols and 
software of the cognitive SDR (and the developers of this software and 
firmware!) are responsible at that point for staying within regulatory 
bounds.

But, back to Ethernet, I'd simply reference what Gibson (as in guitars) is 
doing with Ethernet.  See 
http://www.wired.com/wired/archive/12.01/guitar.html and 
http://www.macworld.com/news/2005/01/24/gibson/index.php and 
http://www.networkworld.com/net.worker/columnists/2003/0602kistner.html for a 
brief introduction.  Or google for 'gibson guitar ethernet' and read the 
hundreds of pages yourself. :-)  Power over Ethernet; in a guitar of all 
things.  Priceless.
-- 
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu




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