Multiple Channel USRP Confusion

GNU Radio
1

Hi all,

I am looking to simultaneously record two real signals (not with IQ)
using a single LFRX daughtercard.

How can I do this with GNURadio companion? I have spent a while looking
at the USRP Source and Dual USRP Source blocks and could not figure out.

I am looking to record from Side A with RXA and RXB. I tried setting
the RX Antenna setting to RXAB and used the complex to real block to
extract channel RXA, and complex to imaginary block to extract RXB. I
don’t think this worked properly.

I also tried using two separate USRP source blocks, each on side A but
one for RXA and the other for RXB. When I did this I got an error
related to already having one USRP side A block running.

Any help would be greatly appreciated

Thanks,
Dan

2

You can only get side A signals on output A and side B signals on output
B for the usrp dual source. Until now…

I have a branch were I added the option to change the A and B sources to
select for different sides.
http://gnuradio.org/cgit/jblum.git/log/?h=grc/dualusrp

Please try it out and let me know.
Thanks, -Josh

3

Dan,

I have a solution that I have been using for a while. I have attached
the
relevant files and a working example. You will need to put all the files
except the .grc file into your .grc_gnuradio directory and restart grc.
Not
sure if this is a good way to do it, but it works for me.

the helper blocks are the core, the dual_a, dual_b are heir blocks that
add
on top of this one. I also included a quad source block for real inputs
using 2 LFRX in case you are interested. I have changed the fusb
parameters
such that I can records data at high sampling rates (4MSps) without
getting
overruns.

Hope that helps.

Regards,
Karthik

4

Dan

I haven’t used GNURadio companion before, but what you need to do is the
following:

Set the mux to (0xf1f0f1f0). This will connect ADC0 (which is the first
ADC
on side A) to the I input of the first DDC in the USRP. ADC1 (which is
also
on side A) will be connected to the I input of the second ADC. Then you
just wire up your two chains in your GNURadio apps and use a
deinterleaver
to connect the appropriate channel to the right blocks in your app.
There
is an example app somewhere in the Gnuradio installation directory that
shows how to receive 4 real channels with 2 LFRX boards.

Sebastiaan

5

Thanks Karthik!

I will take a look at the attachment. That is great, I want to
eventually sample 4 real channels, and want to avoid the
overrun/underrun problems.

Thanks for your help!!

-Dan

— On Wed, 3/10/10, Karthik [email protected] wrote:

From: Karthik [email protected]
Subject: Re: [Discuss-gnuradio] Multiple Channel USRP Confusion
To: “dan s” [email protected]
Cc: [email protected]
Date: Wednesday, March 10, 2010, 12:52 PM

Dan,

I have a solution that I have been using for a while. I have attached
the relevant files and a working example. You will need to put all the
files except the .grc file into your .grc_gnuradio directory and restart
grc. Not sure if this is a good way to do it, but it works for me.

the helper blocks are the core, the dual_a, dual_b are heir blocks that
add on top of this one. I also included a quad source block for real
inputs using 2 LFRX in case you are interested. I have changed the fusb
parameters such that I can records data at high sampling rates (4MSps)
without getting overruns.

Hope that helps.

Regards,
Karthik

On Tue, Mar 9, 2010 at 10:33 PM, dan s [email protected] wrote:

Hi all,

I am looking to simultaneously record two real signals (not with IQ)
using a single LFRX daughtercard.

How can I do this with GNURadio companion? I have spent a while looking
at the USRP Source and Dual USRP Source blocks and could not figure out.

I am looking to record from Side A with RXA and RXB. I tried setting
the RX Antenna setting to RXAB and used the complex to real block to
extract channel RXA, and complex to imaginary block to extract RXB. I
don’t think this worked properly.

I also tried using two separate USRP source blocks, each on side A but
one for RXA and the other for RXB. When I did this I got an error
related to already having one USRP side A block running.

Any help would be greatly appreciated

Thanks,
Dan

Discuss-gnuradio mailing list

[email protected]

http://lists.gnu.org/mailman/listinfo/discuss-gnuradio

6

Thanks so much, this is exactly what I am eventually trying to
accomplish.
Sampling 4 real signals using two LFRX daughtercards

Thanks,
Dan

— On Wed, 3/10/10, Sebastiaan H. [email protected] wrote:

From: Sebastiaan H. [email protected]
Subject: Re: [Discuss-gnuradio] Multiple Channel USRP Confusion
To: “Karthik” [email protected]
Cc: “dan s” [email protected], [email protected]
Date: Wednesday, March 10, 2010, 1:13 PM

Dan

I haven’t used GNURadio companion before, but what you need to do is the
following:

Set the mux to (0xf1f0f1f0). This will connect ADC0 (which is the first
ADC on side A) to the I input of the first DDC in the USRP. ADC1 (which
is also on side A) will be connected to the I input of the second ADC.Â
Then you just wire up your two chains in your GNURadio apps and use a
deinterleaver to connect the appropriate channel to the right blocks in
your app. There is an example app somewhere in the Gnuradio
installation directory that shows how to receive 4 real channels with 2
LFRX boards.

Sebastiaan

Â
On Tue, Mar 9, 2010 at 10:33 PM, dan s [email protected] wrote:

Hi all,

I am looking to simultaneously record two real signals (not with IQ)
using a single LFRX daughtercard.

How can I do this with GNURadio companion? I have spent a while looking
at the USRP Source and Dual USRP Source blocks and could not figure out.

I am looking to record from Side A with RXA and RXB. I tried setting
the RX Antenna setting to RXAB and used the complex to real block to
extract channel RXA, and complex to imaginary block to extract RXB. I
don’t think this worked properly.

I also tried using two separate USRP source blocks, each on side A but
one for RXA and the other for RXB. When I did this I got an error
related to already having one USRP side A block running.

Any help would be greatly appreciated

Thanks,
Dan