Re: [Discuss-gnuradio] unexpected LookupError using gpsdo

[mleech]

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!).