Unexpected LookupError using gpsdo

GNU Radio
1

Hi,
I have bought two gpsdos and install them to my usrp n210. Then I
congfiured them step by step according to the following link provided by
ettus LLC http://files.ettus.com/uhd_docs/manual/html/gpsdo.html.
After all the things had done, I tried to retrieve
the current GPS time by the “gps_time” sensor using the codes : "
usrp->get_mboard_sensor(“gps_time”) ". The

compilation is ok and I executived the program. Then an unexpected
LookupError occured :

Error: LookupError: Path not found in tree: /mboards/0/sensors/gps_time

I printed all sensor list and there are only two sensor “mimo_locked”,
“ref_locked”. So I thought that means The gpsdo was not properly set so
that the usrp didn’t find any “gps_time” sensors. But when I executived
the program “test_pps_input” at /usr/local/share/uhd/example. The pps
seens all right. That means the gpsdo is ok. What’s more, when I used
the reference sources provided by an external GPSDO by the code :
usrp->set_clock_source(“external”);

usrp->set_time_source(“external”);

It work well too.

Now I am confused . why is that happen? Was my gpsdo broken? All the two
gpsdos have the same LookupError.

Thanks for your help.

2

On Wed, 21 Mar 2012 21:23:39 +0800 (CST), Fengzhu FengzhuYe wrote:

Hi,
I have bought two gpsdos and install them to my usrp n210.
Then I congfiured them step by step according to the following link
provided by ettus LLC
http://files.ettus.com/uhd_docs/manual/html/gpsdo.html.
After all the
things had done, I tried to retrieve the current GPS time by the
“gps_time” sensor using the codes : "
usrp->get_mboard_sensor(“gps_time”) ". The
compilation is ok and I
executived the program. Then an unexpected LookupError occured :

Error: LookupError: Path not found in tree: /mboards/0/sensors/gps_time

I printed all sensor list and there are only two sensor
“mimo_locked”, “ref_locked”. So I thought that means The gpsdo was not
properly set so that the usrp didn’t find any “gps_time” sensors. But
when I executived the program “test_pps_input” at
/usr/local/share/uhd/example. The pps seens all right. That means the
gpsdo is ok. What’s more, when I used the reference sources provided by
an external GPSDO by the code :
usrp->set_clock_source(“external”);

usrp->set_time_source(“external”);
It work well too.

Now I
am confused . why is that happen? Was my gpsdo broken? All the two
gpsdos have the same LookupError.

Thanks for your help.

Did you
do the post-installation task:

http://files.ettus.com/uhd_docs/manual/html/gpsdo.html#post-installation-task-n-series-only

Also, the “gps_time” is only available once the GPSDO is locked to a
GPS satellite constellation–that’s where it gets the time from (and the
phase reference!).