Re: Synchronizing 3 USRP-N200

Hi Marcus,

Thanks for replying. I did the following test after your comments:

1- to rule out the scope sink problem, I used a file sink and plotted
the output using octave: Same results observed.

2- I took the outputs of the splitters to the oscilloscope and there are
aligned.

Are there other ways to test Ref/PPS other than the one I mentioned in
my original mesage?

Best/

Zo

Zo,
Have you tried swapping cables between USRP’s? both REF/PPS and signal
(one at a time) to see if the apparent phase differences follow
particular cables/signal paths?

Dear Ian and All,

Although I tried what you have said, the phase is random and
different every time I run the flow graph. I deeply suspect that
synchronization is actually done on the boards.

I use a GPS receiver for synchronization and yesterday I noticed
that the shape of the PPS signal is as the one in the attached image. I
am afraid that the ripple and the overshoot can imitate the behavior of
the PPS in much smaller period than one sec. Do you believe so? Can I
use a usual function generator for the PPS instead of the GPS receiver?
In other words, should the ref/pps signal be sync?

Best regards,

Zo

Subject: Re: [Discuss-gnuradio] Synchronizing 3 USRP-N200
From: [email protected]
Date: Wed, 3 Apr 2013 11:59:20 -0700
CC: [email protected]
To: [email protected]

Zo,Have you tried swapping cables between USRP’s? both REF/PPS and
signal (one at a time) to see if the apparent phase differences follow
particular cables/signal paths?
On Apr 3, 2013, at 2:32 AM, Zooz E. [email protected]
wrote:Hi Marcus,

Thanks for replying. I did the following test after your comments:

1- to rule out the scope sink problem, I used a file sink and plotted
the output using octave: Same results observed.
2- I took the outputs of the splitters to the oscilloscope and there are
aligned.

Are there other ways to test Ref/PPS other than the one I mentioned in
my original mesage?

Best/

Zo_______________________________________________
Discuss-gnuradio mailing list
[email protected]
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio

First you need to ensure that the measurement of your pps signal shows
the
reality, and is not some measuring error. Then you can try to calm down
the
signal with some resistors, in the usual way when a rising edge
overshoots…

Ralph.

From: [email protected]lid
[mailto:[email protected]lid] On Behalf Of
Zooz
Engineer
Sent: Thursday, April 04, 2013 10:37 AM
To: Ian B.
Cc: [email protected]
Subject: Re: [Discuss-gnuradio] Synchronizing 3 USRP-N200

Dear Ian and All,

Although I tried what you have said, the phase is random and different
every
time I run the flow graph. I deeply suspect that synchronization is
actually
done on the boards.
I use a GPS receiver for synchronization and yesterday I noticed that
the
shape of the PPS signal is as the one in the attached image. I am afraid
that the ripple and the overshoot can imitate the behavior of the PPS in
much smaller period than one sec. Do you believe so? Can I use a usual
function generator for the PPS instead of the GPS receiver? In other
words,
should the ref/pps signal be sync?
Best regards,
Zo


Subject: Re: [Discuss-gnuradio] Synchronizing 3 USRP-N200
From: [email protected]
Date: Wed, 3 Apr 2013 11:59:20 -0700
CC: [email protected]
To: [email protected]

Zo,

Have you tried swapping cables between USRP’s? both REF/PPS and signal
(one
at a time) to see if the apparent phase differences follow particular
cables/signal paths?

On Apr 3, 2013, at 2:32 AM, Zooz E. [email protected]
wrote:

Hi Marcus,

Thanks for replying. I did the following test after your comments:

1- to rule out the scope sink problem, I used a file sink and plotted
the
output using octave: Same results observed.
2- I took the outputs of the splitters to the oscilloscope and there are
aligned.

Are there other ways to test Ref/PPS other than the one I mentioned in
my
original mesage?

Best/

Zo