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List:       usrp-users
Subject:    [USRP-users] N200 not syncing to external ref
From:       Liwei via USRP-users <usrp-users () lists ! ettus ! com>
Date:       2016-04-29 4:03:42
Message-ID: CAPE0SYzMakY0+T5v8Q4FwTwUrfES3aWkaDBPOJ-Df8sUQVH78g () mail ! gmail ! com
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Hi list,
    I have 3 N200 (with WBX daughterboards) I'm trying to synchronise for
some phase measurements. Since I have a MIMO cable, two of them are
synchronised to each other via that, and they work well.
    I then feed Ref and PPS signals to the third, and, one of the 2 N200
(which were connected to each other via MIMO). If I understand the
documentation correctly, this should sync up all three N200.
    However, when I feed a single frequency source into all three N200 and
view their time plots, only the two connected via MIMO are synchronised.
The third always show the frequency source at a lower frequency than the
others.
    I've tried disconnecting the Ref signals while the flowgraph is
running, and the frequency/time plots do change, indicating that the USRPs
are synchronising to the Ref signal.
    The Ref and PPS signals are derived from a single timing source and
distributed by 1:2 splitters.

    In addition, the documentation mentions the N200 should use square Ref
signals for best phase performance, but I've been unable to get the N200 to
synchronise when I use a square Ref signal.

    Anyone can shed some light on why the above is happening?

Warm regards,
Liwei

[Attachment #5 (text/html)]

<div dir="ltr"><span style="color:rgb(33,33,33);font-size:13px">Hi list,</span><div \
style="color:rgb(33,33,33);font-size:13px">      I have 3 N200 (with WBX \
daughterboards) I&#39;m trying to synchronise for some phase measurements. Since I \
have a MIMO cable, two of them are synchronised to each other via that, and they work \
well.</div><div style="color:rgb(33,33,33);font-size:13px">      I then feed Ref and \
PPS signals to the third, and, one of the 2 N200 (which were connected to each other \
via MIMO). If I understand the documentation correctly, this should sync up all three \
N200.</div><div style="color:rgb(33,33,33);font-size:13px">      However, when I feed \
a single frequency source into all three N200 and view their time plots, only the two \
connected via MIMO are synchronised. The third always show the frequency source at a \
lower frequency than the others.</div><div \
style="color:rgb(33,33,33);font-size:13px">      I&#39;ve tried disconnecting the Ref \
signals while the flowgraph is running, and the frequency/time plots do change, \
indicating that the USRPs are synchronising to the Ref signal.</div><div \
style="color:rgb(33,33,33);font-size:13px">      The Ref and PPS signals are derived \
from a single timing source and distributed by 1:2 splitters.</div><div \
style="color:rgb(33,33,33);font-size:13px"><br></div><div \
style="color:rgb(33,33,33);font-size:13px">      In addition, the documentation \
mentions the N200 should use square Ref signals for best phase performance, but \
I&#39;ve been unable to get the N200 to synchronise when I use a square Ref \
signal.</div><div style="color:rgb(33,33,33);font-size:13px"><br></div><div \
style="color:rgb(33,33,33);font-size:13px">      Anyone can shed some light on why \
the above is happening?</div><div \
style="color:rgb(33,33,33);font-size:13px"><br></div><div \
style="color:rgb(33,33,33);font-size:13px">Warm regards,</div><div \
style="color:rgb(33,33,33);font-size:13px">Liwei</div></div>



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