It is a self build device using a 74LS125D as buffer. The level is 3.3V
digital.
As there were no specifications around for the required input levels at
the time we needed the device, we just measured the levels coming from
the 1PPS output and replicated them.
Am 26.09.2019 um 13:51 schrieb Daniel Jepson via USRP-users:
Hi Fabian, Cherif,
What is the external PPS device you are using?
-Daniel
On Thu, Sep 26, 2019 at 9:18 AM Fabian Schwartau via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>> wrote:
Hi,
I have very similar problem with X310. I am running a C++ application,
so I have a bit more flexibility I guess. After I do the
set_time_unknown_pps to sync to the 1PPS signal, I run the function
get_time_last_pps and it sometimes has an offset of 10ns (it was 5ns
for
an old firmware due to a bug, which was fixed a few weeks ago). If that
is the case I just do the sync again until the offset is zero.
I don't know if it is an firmawre problem or if it is because the
signal
integrety of the 1PPS signal is not good enough.
Maybe that is also a solution for you.
Best regards,
Fabian
Am 25.09.2019 um 11:16 schrieb Cherif Diouf via USRP-users:
> Hello,
> I am working with the X310 USRP. I have two identical custom blocks
> feeding the RF frontends.
>
> flowchart
> -----------------
> HW Block1 -> RF0-TX1 |---<
> HW Block2 -> RF1-TX1 |---<
>
> The system is synchronized to an external PPS reference. The
sampling
> rate is 200 MSps and the signal bandwidth is 160 MHz for both
channels.
> The two HW blocks start transmitting at the exactly same time. Time
> resolution is 5ns.
> In most cases the two outgoing RF signals present a 1ns time offset.
> Which can be understood as a phase offset.
>
> But From time to time there is a 6ns delay between the channels. I
> assume this 6ns comprises the 1ns delay due to phase offset + 5
ns delay
> due to misalignment of outgoing samples.
>
> What could be the origin of this one sample misalignement? Is it
a way
> to fix it? Or working close to the limits of the device should such
> behavior be expected?
>
> Thanks in advance
>
> Best Regards
> Cherif
>
>
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--
--------------------------------------------------
M.-Sc. Fabian Schwartau
Technische Universität Braunschweig
Institut für Hochfrequenztechnik
Schleinitzstr. 22
38106 Braunschweig
Germany
Tel.: +49-(0)531-391-2017
Fax: +49-(0)531-391-2045
Email: fabian.schwar...@ihf.tu-bs.de
<mailto:fabian.schwar...@ihf.tu-bs.de>
WWW: http://www.tu-braunschweig.de/ihf
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--
Daniel Jepson
Digital Hardware Engineer
National Instruments
O: +1.512.683.6163
daniel.jep...@ni.com <mailto:daniel.jep...@ni.com>
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--
--------------------------------------------------
M.-Sc. Fabian Schwartau
Technische Universität Braunschweig
Institut für Hochfrequenztechnik
Schleinitzstr. 22
38106 Braunschweig
Germany
Tel.: +49-(0)531-391-2017
Fax: +49-(0)531-391-2045
Email: fabian.schwar...@ihf.tu-bs.de
WWW: http://www.tu-braunschweig.de/ihf
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