What you seem to not realize or understand is that the
GNU Radio software that you can compile and putz around
with is worth significantly more to you than any piece of
hardware that will capture or create EM radiation.
Brian is 100% correct.
Could I make just a small attempt to amplify it?
Once you’ve compiled and putzed around with GNU Radio you
might find that it would be nice to have access to a few live
sample signals. You’ve reached the point where you now simply
must have a USRP. Correct?
No!
Any old radio receiver (or transmitter for that matter) can be
adapted to work with GNU Radio, if you’re willing to do a little
hardware modification (which can be as simple as connecting a wire
from the receiver to your PC’s sound card).
If you happen to be lucky enough to live in a part of the world
where there are “hamfests”, (or mail order etc.) you should be able
to pick up a used scanner and/or HF receiver for next to nothing.
The process of adapting and modifying the receiver and getting it
to talk properly to GNU Radio will, I assure you, teach you many
lessons that you can’t get any other way, nor as well.
Here are two places you might start:
-
Search the net for how to perform a “discriminator tap”
-
See my “very poor man’s USRP” page
A 455 KHz IF Downconverter for Digital Radio Reception
The above link has been out on the nets for a while now and I’ve
gotten a tiny number of emails from interested (mostly) hams. So
far it has not been any problem whatsoever to answer all questions.
The hardware described is certainly not going to threaten Ettus’
business any time soon! It can’t handle much of anything wider than
15 KHz or so! But it can handle several “digital” modes. And you might
learn something along the way.
73
Max
p.s. In case the above isn’t clear, you have my permission, and
blessing, to copy my circuits or whatever. If you want to provide
attribution you may, although the circuitry described is certainly not
original by me. There’s no PCB though 