Re: [Discuss-gnuradio] Are microtune 4707's worth having?

[Tom Huppi]

On Wed, 10 Nov 2004, Eric Blossom wrote:

> On Wed, Nov 10, 2004 at 02:41:38AM -0500, Tom Huppi wrote:
> >
> > There are a box of 108pc on e-bay w/ no bids for $50.
> >
> > I'm sorry for my lack of knowledge.  I see more IF info related to
> > the 49xx pieces (on microtune's websiite), but one of the USRP
> > modules seems to have a 4702.
>
> I sent a message to the seller asking for a data sheet.
> I'll let you know what I find out.

I should have mentioned that even if the items are usefull, I
don't need to be the one who gets them, though I would like to see
them go to good homes (i.e., feeding into CPU's executing GnuRadio
code.)  Put another way, don't hesitate to bid on them, but maybe
we can avoid a bidding war.  I'm happy to try to get them and
divide them amoungst interested parties (lacking the 'haxpertise'
to do much more at this point), but I don't want to waste my
time/money on useless items.


> > Also I have not learned enough to understand
> > the relationship between signal transmission frequencies (and
> > various modulation types) and the AD sampling rate needed to do
> > something usefull with them.
>
> The Nyquist criterion specifies that your sampling rate needs to be at
> least 2 times the bandwidth of interest.  In reality, a number closer
> to 2.5 works better.
>
>
> If you haven't already, take at look at 
> http://comsec.com/wiki?SuggestedReading
> Lots of good sources of information there.

I've been dividing my time between reading the site (including
starting on some of these links), hardware research, and FreeBSD
build issues.

Intuitively, it seems to me that downmixing could be no more
effective than alchemy or perpetual motion.  If every wave of a
siganal of interest were important, I could see downmixing it
effective, but only if the resulting wave were sampled at higher
frequencies than Nyquist scpecifies as a minimum.  Clearly, every
wave is _not_ critical in a lot of instances.  While I continue to
learn more about this I tossed the question out, and I do
appreciate the answer.  In fact, SSB (and non-vocal data carried
on the lower bands) was my initial interest, and what lead me to
become aware of GnuRadio.

Thanks,

 - Tom