[Please! M
On Mon, Jan 10, 2011 at 02:23:47PM +0100, Patrick S. wrote:
He didn’t ask for a simulator, he asked for real hardware.
He did not back his request with some deeper insight why he exactly
needs this thing except for he wants it and has not enough money to buy
it. We do not know what he wants to accomplish, and how he thinks to get
there, what he already did. This would be very valuable information -
If I may add a note here: I agree with Brian and Patrick, and would even
go further to say that developing fun stuff needs no hardware at all.
In fact, whenever I do, say, some kind of receiver, the first thing I do
is record signals to a file, so I don’t have to touch any hardware at
all until I’ve reached a point where I believe my code might work in
real life.
As long as I’m in the software domain, my tools of choice are Matlab (my
dishes out free licences to our students) and scipy. You can get quite
far that way. Pre-recorded signals are available on the net, and a
polite query on this list to obtain such files from other users is not
uncommon. Of course, using Matlab etc. it’s also quite possible to write
transmitters.
As Patrick said, we have no idea what the OP wanted to achieve, but as
was also said before, writing something along the lines of “I’ve just
completed a complete receiver chain for standard XYZ, is there anyone
with a working USRP to help me out” is likely to get a more favourable
response.
Finally, if you’re a student, a university’s probably not far. Here, if
you’re a student and really want to do something with a USRP (and other
hardware), we usually manage to figure something out. The common case is
that we make developing something with GNU Radio and the USRP a topic
for a Bachelor’s thesis. Students get lab access, some tutoring, meet
other GNU Radio developers (unfortunately not too many) and even get a
degree at the end. How about that.
In fact, that’s how most of the guts of the Spectral Estimation Toolbox
got created.
So, I hope this didn’t sound too snobbish – but I think that using GNU
Radio, essentially any budget is enough to get started doing serious SDR
stuff.
Cheers,
MB
–
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)
Dipl.-Ing. Martin B.
Research Associate
Kaiserstraße 12
Building 05.01
76131 Karlsruhe
Phone: +49 721 608-43790
Fax: +49 721 608-46071
www.cel.kit.edu
KIT – University of the State of Baden-Württemberg and
National Laboratory of the Helmholtz Association
Hi there,
Just my 2 cents:
It’s possible to use gnuradio with the soundcard as a receiver /
transmitter.
Most of the people that listens to DRM (Digital Radio Mondiale) in the
shortwaves band just buy small tuners that just downconverts the desired
frequency to 12kHz for soundcard input, like this one:
http://www.pappradio.de
Or you just use your normal AM/FM transmitter and downconverts the FI of
the radio to 12kHz using for example this box:
http://www.electronicspecialtyproducts.com/dm1.html
I’ll be able to use gnuradio to inspect and analyze any narrowband
signal
you want just with a sound card and inexpensive hardware.
Best regards,
Rafael D.
Or you just use your normal AM/FM transmitter and downconverts the FI of
I was supposed to say receiver instead of transmitter.
On 01/10/2011 08:23 AM, Patrick S. wrote:
- Have a look at Digilent [1] Basys and Nexsys boards. You get the same
interface chip as the USRP, which should give a good start for firmware
development, and a FPGA, switches, buttons, displays, connectors
(VGA/PS2 etc.) for about the same or less price. Academics/Students get
it cheaper.
Moreover Digilent offers a number of modules to connect, with examples
and schematics.
If you really want high sampling rates and frequencies, have a look at
the Charleston SDR [2].
Oooh, the Charleston SDR is within about 5-6dB(Msps) of what I’d like in
a cheaper
hardware alternative.
You know, a “reasonable” project for some C++ keener on this list would
be to
write a UHD driver interface for the Charleston SDR system, and
open-source
the results. Might even make a not-bad undergraduate project.
But since we’re on the topic of alternative hardware, I’ll throw in my
PERSONAL* two-cents about this.
I think that there are a couple of different “forks” to this. There
are experimenters who
do Rx-only (I’d say perhaps more than half of the folks on this
list), for whom a less-functional
hardware system (and presumably less costly) would be “reasonable”.
For experimenters who
want to do Tx, they also overwhelmingly-likely want to do Tx/Rx, and
for that, it would be hard
to beat what is already out there (although, I’m willing to be
convinced otherwise).
For an Rx-only “solution”, I’d want:
o Integrated RF down-conversion chain
o It would be hard to get much better than what the WBX uses
here, based on the ADL5387 (quadrature mixer) and
ADF4350 (PLL synthesizer). Such a “line-up” would give
coverage from 68.75MHz to 2.2GHz.
o Ability to use external 10MHz reference both for PLL and
sampling clock.
o One might simplify this to use an external 40MHz
reference that is used directly for the sampling clock, and /4
for the PLL.
o Perhaps a switch-in upconverter that converts HF up to a
convenient IF (70MHz, 100MHz??) for the ADL5387/ADF4350 stage.
o 40Msps ADC
o possibly one with built-in DDC and decimation hardware,
with the proviso that it support
full-rate (no decimation). The one used by the
Charleston SDR has the right overall architecture,
but supports a maximum bandwidth of 2.5Msps complex.
o possibly variable sample rate
o A convenient computer interface
o I'd prefer 1GiGe, so that I could "deliver" the full
40Msps (with reduced sample sizes) to the host computer.
o USB would be acceptable.
Notice that there’s no FPGA shown here. My hope is that there’s
something similar to the TI parts used by the Charleston SDR, but
allowing higher bandwidths (lower decimation).
An alternative (that still doesn’t require an FPGA) is to have
switchable baseband filters on the output of the analog front-end,
covering
various “useful” bandwidths. These would have to be fairly “stiff”,
to allow a lower sample rate to work properly. I wonder if SCFs
(Switched-Capacitor Filters) exist that cover these bandwidths (let’s
say, 2.5MHz to 20MHz). My off-the-cuff proposal for such a scheme
would be four discrete filters:
o 20MHz (40Msps)
o 10MHz (20Msps)
o 5MHz (10Msps)
o 2.5MHz (5Msps)
–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
On 10.01.2011 15:35, Martin B. wrote:
If I may add a note here: I agree with Brian and Patrick, and would even
go further to say that developing fun stuff needs no hardware at all.
So, I hope this didn’t sound too snobbish – but I think that using GNU
Radio, essentially any budget is enough to get started doing serious SDR
stuff.
Yes, it sounds totally snobbish. You let the tax-payer finance your
Gnuradio hardware
and tell other people they don’t need hardware and should live with
simulations.
Hey, why do you think people are interested in Gnuradio?
You know the words “Wasser predigen und Wein saufen?”