[USRP-users] Broken gpsdo or bad antenna?

John Malsbury john.malsbury at ettus.com
Tue Jun 19 07:14:54 EDT 2012


Dario,

Forgive me if I am not able to see your previous posts as I am answering
from my phone.  Are you saying there is
11 khz of error in the 10 mhz ref, or some frequency set to a daughterboard
LO?

You mention using an external reference.  I don't think you would achieve
lock if this were the issue, but have you ensured the jumper is in the
proper configuration?  Are you selecting default or external as the ref
source in your software?

John

On Tuesday, June 19, 2012, Dario Lombardo <dario.lombardo.ml at gmail.com>
wrote:
> Hi all
> After many tries with my gpsdo, I still can't get a good clock.
> I've written a sw that continuously polls the gps_locked and the
ref_locked sensors. Both of them are always locked, that means that my
antenna is getting a quite "clear" sky view.
> I've connected the front panel connectors of my N210 to a cesium
clock/pps generator, and I get 2 to 0 Hz of error with kal. That should
mean that my usrp works fine and the kal commands are good.hu
> I've left the usrp turned on, with the gps antenna connected, for over 20
hours, but kal still gives me around 11 kHz of error.
> I think that one of these 2 things is happening:
> 1) my gpsdo card is broken. What can I do to ensure that this is not the
case? And if this is the case, what can I do?
> 2) my antenna can't give a signal that is clear enough, so the gpsdo
isn't unable to give me the clock.
> What do you think about the above cases?
> Any help appreciated.
> Dario.
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