Hey Jeff, Thanks for the detailed info. The N310 and the E320 both use the LTE-Lite from Jackson Labs for their GPSDOs, so it's conceivable that the same rework is applicable to both, but I'm not positive - I wasn't directly involved in the hardware investigation. I'll reach out to you off the mailing list and get some of that additional information / screenshots.
Best, Sam Reiter On Wed, Mar 25, 2020 at 4:06 PM Long, Jeffrey P. <[email protected]> wrote: > Sam- > > > > So I am actually using a gps satellite simulator(Labsat). This plays back > previously recorded data and there are a number of test scenarios on there > for me to use. Currently I am using a simple static one recorded in the UK > I think. To protect the output I insert a DC block in. For the GPS rxrs in > the E310, and X310 this has worked great and they lock up pretty quickly > although the X310 does take longer than the E310. That E310 Ublox receiver > is really fast. > > > > I will send my serial numbers to Ettus support but given what you said > about the E320 I decided to go back to basics and see if I could get the > N310 I have to reliably lock and I learned some interesting things about it > and its GPS. After extensive debugging all day using gpsmon I have learned > that the N310 GPS (Jackson Labs LTE Lite) is very finicky it would seem. > > > > I found the following kind of works: > > > > 1)Power up the N310 from a cold start (unplugged at first because it seems > the board gets power even before you hit the switch). > > 2)Run a uhd_usrp_probe –args “time_source=gpsdo,clock_source=gpsdo” to > force it to switch the daughtercards over > > 3)set the system date and time to be close to the signal coming from the > labsat. (Maybe this does not matter but then TOFF is not so out of wack. > > 3)Then run gpsmon and watch it acquire. Almost immediately SNR is good > (45-50) and TPV shows lat and long, quality is 2 and it has 8 sats. Then we > wait. > > 4)Eventually it will acquire(takes 7-8 mins) meaning that the GPS light > will turn on and when I run the sensor query it reports back locked. > > > > While this seems to take forever it is repeatable. Now the fun starts. If > after I have got it to lock up and then one of two things happens, either > the labsat file rolls over or I disconnect the signal from the jack, gpsmon > will show low SNR and eventually it will unlock. This makes sense I > although the rollover thing is weird because ublox does not have an issue > with that. What is really annoying is that when I plug the signal back in > or restart the labsat the GPS never seems to try to re-acquire and there > seems to be no way to restart it. A reboot does not fix it. Only a complete > power down and disconnect from power seems to restart the GPS. It gets in > some messed up state and that’s it. Does that seem normal? My N310s are > fairly old. Did they have some GPS recall at some point? By the way I > noticed in its screwed up state it no longer sends GSV strings and if you > decide to do a N310 bist gpsdo it will totally wipe out the GPS module and > it seems to no longer output pps or the ref too. Probably not intended > behavior? > > > > I have some screenshots of gpsmon if you are interested. I did not want to > blast the list with images. Let me know and I can send them. > > > > I am going to do some experimenting with the E320 and see if it behaves > similarly. I bought my E320s very recently so I would be surprised if they > needed that fix (Serial #31C8CC6). I did notice in the VHDL top for the > E320 that there are some pin controls to the GPS module which I did not see > in the N310 top. This could mean that there is more control over the E320 > GPS?? I was thinking of chipscoping those pins maybe too and see how they > change with UHD startup etc.. > > > > > > Thanks > > Jeff > > > > > > > > > > > > > > > > > > > > *From:* Sam Reiter <[email protected]> > *Sent:* Tuesday, March 24, 2020 9:48 AM > *To:* Long, Jeffrey P. <[email protected]> > *Cc:* [email protected] > *Subject:* [EXT] Re: [USRP-users] E320 GPS staying locked? > > > > Hey Jeff, > > > > What type of GPS antenna are you using? 3.3V or 5V? If it's compatible > with X310 & other USRPs, I would imagine you'll be good to go with the > E320... Do you see the locked / unlocked status change between consecutive > runs of something like gpsmon on the E320? > > > > There were some early-ish runs of the E320 that are eligible for a GPSDO > rework, feel free to send [email protected] a direct email with your > E320's serial number and I can see if yours is one of the affected units. > > > > Sam Reiter > > > > On Mon, Mar 23, 2020 at 4:27 PM Long, Jeffrey P. via USRP-users < > [email protected]> wrote: > > Has anyone had issues with the E320 GPS locking or staying locked? I have > a LabSat GNSS simulator that I am reliably able to get a E310, X310, and > even a N310 to lock to however the E320 I just got will occasionally lock > and then fall out almost immediately. I used mender to up it to 3.15LTS and > everything else works pretty well. I run the e320bist on the gpsdo and it > reports it mostly being unlocked but occasionally it will lock for a minute > or so. When it does lock I can run the query gpsdo immediately after and it > will report locked but again it only lasts for a min or so. > > > > Thanks > > Jeff > > _______________________________________________ > USRP-users mailing list > [email protected] > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >
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