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Re: [Discuss-gnuradio] Welcome and brief update

From: Chris Albertson
Subject: Re: [Discuss-gnuradio] Welcome and brief update
Date: Fri, 10 Jan 2003 15:13:56 -0800 (PST)

If you want ideas...

I think you need to look at your (potential) users and why they are
attracted to GNU Radio.  I think very few of them will just say
"wow a _software_ radio! Cool."  No, if GNU Radio is to be a hit
outside of a very rarified group of true geeks it will have to do
something.  Either something that nothing else can do or do it
cheaper or "free-er".

The weak link in any software radio is the ADC.  With present
technology there are two ways to go, Lots of bits or lots of samples.
You can have 24-bits or 100M sample per second but not 100M 24-bit
samples.   I think this means you either go for wideband or for weak
signals.  Ignore the middle ground.  You don't need a 
3 Ghz Pentuim IV to pick up an AM broadcast station.
You can't get HDTV bandwidth down a sound card and you
can't get 100db noise floor (required for weak signal work.) with a
12-bit ADC.  So you have to choose one at a time.

One other thing you can do with present technology is to use two
ADC chips and do the conversion in quadrature.  Once you have
coherent radios you can do interresting things like combine signals
from multiple radios in phase.  Synthentic phased arrays ans so
on.  Radio astronamers do this kind of stuff.  Once you have a
Synthentic phased array then someone will start thinksing
"software radar"
In the wide band area, it seem there is a lot you can do that is
not done:  You could in theory recieve the entire amature 2 meter band
at once.  There is another opensource software radio project "linrad"
that is going the weak signal route.  Already it seems to work better
then most off the self radios for it's purpose.  They are using
high-end sound cards for ther 106db dynamic range.

--- Eric Blossom <address@hidden> wrote:
> I'd like to extend a welcome to all the new subscribers.
> Although the list has been relatively quiet, there's been a lot going
> on behind the scenes.  Matt and I and the others who've been working
> on GNU Radio have agreed to move the bulk of our discussions to the
> list, so everybody is more included.
> We're putting together a Wiki (user editable web site) for
> discussion,
> FAQs, ideas, brain storming and project coordination that should make
> it easier for folks to contribute and see what others are up to. 
> Look
> for that in a week or so.
> As far as I can tell we've got folks with a wide variety of
> backgrounds on the list.  We've got radio folks without much
> experience in software, we've got software folks who are interested,
> but don't know much about radio, we've got industry lurkers, students
> as well as generalists.
> Here are a few areas where we can use help:
> (1) RF Hardware design: to make GNU radio more accessable for those
> without high speed A/D hardware, we'd like one of you RF guys to
> design a simple RF front end that could be directly hooked to one of
> the "HiFi" 96 KHz sampling rate sound cards.  Please make it simple
> and buildable out of things that anybody can order from
> mini-circuits,
> digikey, etc.  The idea is not to build the greatest piece of RF
> hardware ever, but to build something minimalist that actually works.
> Perhaps a basic 2M or 70cm downconverter.
> (2) CORBA expert: We're currently investigating what's the right
> remote control paradigm for GNU Radio.  I'd like to talk to somebody
> who's got deep knowledge and experience with CORBA (or some better
> idea) who can help me evaluate our options for glueing CORBA into a
> real time runnning system.
> (3) ATSC Equalizer expert: If you happen to be one, or are good on
> comms theory and practice, we'd love to talk to you or have your
> direct involvement.  We can provide gigabytes of off the air samples,
> so you won't need any RF hardware.
> (4) Examples and "HOWTOs": We could use some simple applications,
> perhaps some that are complete simulations (no hardware required),
> and
> instructions on how to use them.  "Getting Started with GNU Radio"
> (Yes, I understand that we're a bit of moving target...)
> If you've got other ideas, please jump in.
> Again, welcome to all.  With the ground work that's been laid, we
> have
> a great opportunity to expand the GNU Radio community of users and
> developers this coming year.
> Eric
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> http://mail.gnu.org/mailman/listinfo/discuss-gnuradio

Chris Albertson
  Home:   310-376-1029  address@hidden
  Cell:   310-990-7550
  Office: 310-336-5189  address@hidden

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