SDR platform other than usrp with gnuradio

Hello,

I am currently working on a custom made SDR platform and trying to use
gnu
radio to program it. I understand that I need to write seperate source
and
sink blocks to receive and send I/Q samples from and to the device. I
was
wondering if anybody in the list could help me in understanding how to
write these block. I suspect I would need to write something similar to
the usrp code. Can you please let me know a starting point on how to
write
these blocks? The device I am currently using interfaces with the host
using ethernet and sends/receives base band I/Q samples.

Are there documentations on interfacing gnuradio to SDR platforms other
than usrp. It would be very helpful if you could give some pointers.

-Anand

============================================
Anand Prabhu Subramanian
Wireless Networking and Simulation Lab (WINGS)
State University of New York, Stony Brook
http://www.wings.cs.sunysb.edu/~anandps

On Fri, Jul 18, 2008 at 04:52:13PM -0400, Anand Prabhu Subramanian
wrote:

Hello,

I am currently working on a custom made SDR platform and trying to use gnu
radio to program it. I understand that I need to write seperate source and
sink blocks to receive and send I/Q samples from and to the device. I was
wondering if anybody in the list could help me in understanding how to
write these block. I suspect I would need to write something similar to
the usrp code. Can you please let me know a starting point on how to write
these blocks? The device I am currently using interfaces with the host
using ethernet and sends/receives base band I/Q samples.

TCP, UDP, or raw ethernet? If TCP, it ought to be very easy to talk to.

Are there documentations on interfacing gnuradio to SDR platforms other
than usrp. It would be very helpful if you could give some pointers.

-Anand

Anand, the USRP is one of the more flexible devices, and thus all of
the code around it is fairly flexible and complicated by all the
things that can be tweaked. In general, the code doesn’t have to be
that complicated.

To get an idea about a couple of basic but useful sources and sinks,
take a look at

gnuradio-core/src/lib/io/gr_file_{source,sink}.{h,cc,i}

Eric

Dear Eric,

Thanks for the pointer. I get raw IP packets. I have written a C program
to
read these packets and plot the spectrum in matlab. I wanted to use
gnuradio
to do different signal processing functions. Also I plan use the OFDM
module
in gnuradio. I am trying to understand the usrp_spectrum_sense.py file
in
the example and see what are the functions/classes related to USRP are
used.

I will go through the pointers you have given and get back with specific
questions.

One question regarding the samples that come out of USRP. Are they
baseband
I/Q samples?

Thanks,
Anand

Look at gr-msdd6000 and you will see how an IP based device was
interfaced
to gr. You device will need different controls of course but it should
definitely give you a helping start. UDP is the chosen transfer
mechanism
but TCP is also supported.

Bob

ARRL SDR Working Group Chair
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
“Trample the slow … Hurdle the dead”

Thanks Bob.

-Anand

On Fri, Jul 18, 2008 at 05:55:21PM -0400, Anand Prabhu Subramanian
wrote:

Dear Eric,

Thanks for the pointer. I get raw IP packets.

Intersting choice. What are you using for the protocol field?
Why not go for UDP? It’s only 8 bytes longer, and easy to deal with
in user mode on any OS.

I have written a C program to read these packets and plot the
spectrum in matlab. I wanted to use gnuradio to do different signal
processing functions. Also I plan use the OFDM module in gnuradio.

OK.

I am trying to understand the usrp_spectrum_sense.py file in
the example and see what are the functions/classes related to USRP are
used.

Besides what it takes to initially get the usrp setup, the only thing
it expects is that the gadget it’s talking to has a way to set the
frequency.

I will go through the pointers you have given and get back with specific
questions.

Very good.

One question regarding the samples that come out of USRP. Are they baseband
I/Q samples?

Yes. We send 16-bit I & Q.

Eric

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