Getting GPS fix with nRF9160-DK and Thingy:91

[bojan]

Hello guys.

Here with me I have both nRF9160-DK, hardware version 0.8.3 and Thingy:91 boards.
I am on the nRF Connect SDK tag 1.2.0 and have nrf9160 SiP modem firmware updated to 1.1.1 version.
When trying only gps example that I found under samples/nrf9160/gps I was unable to get any GPS fix even when using external antenna (TW4020 from Talysman):

Scanning [-] [1;1H[2JTracking: 0 Using: 0 Unhealthy: 0
Seconds since last fix 1742

Scanning [\] [1;1H[2JTracking: 0 Using: 0 Unhealthy: 0
Seconds since last fix 1743

I know there is some issue with the iBasis SIM roaming cards and local carriers (I am located in France, by the way) that does not allow entering PSM mode. Is this issue occuring in GPS-only example as well? To the best of my understanding, LTE is not active in GPS example.

I don't see any switch on 0.8.3 version of nRF9160-DK board for a selection between on-board/external GPS antenna, am I missing it? Do I need to do something more in addition to connecting external GPS antenna to appropriate connector?

I even tried with some Orange SIM card thinking it is a local card but this card is, to the best of my understanding, registered as a roaming card under other carrier (Bouygues):

Where would be the right place to ask for appropriate SIM cards?

Finally, I was happy to watch your webinar about SDK v1.2 and new exciting GPS solutions (SUPL, A-GPS...). Would that things make our GPS connection easier or we would still need to resolve the issues with local carriers (entering PSM mode...)?

Thanks for your time and efforts.

Sincerely,

Bojan.

[bojan]

Karl Ylvisaker,

I have TW4020 external antenna from Tallysman as well as MXHS83QE1000 adapter cable from Murata. I see the mentions of bias tee for external GPS antennas that are active.

Do I need Bias tee for Thingy:91 board and TW4020 external antenna? If affirmative, how can I mount it on Thingy:91 board?

Regards,

Bojan.

[bojan]

Karl Ylvisaker, TW4020 seems to be an active antenna with Bias Tee needed. In many of your posts (e.g. here or here) you say all we need is an adapter (like the MXHS83QE3000) and external antenna.

Anyway, according to this post, there is a chance we get GPS fix if we use GPS in GPS/GNNS standalone mode with LTE mode turned off. Is it enough to apply 

"AT\%XSYSTEMMODE=0,0,1,0"

 command to select GNSS support only or we need to explicitly turn off LTE mode somehow?

Sincerely,

Bojan.

[Karl Ylvisaker]

Hi Bojan,

bojan said:

Do I need Bias tee for Thingy:91 board and TW4020 external antenna? If affirmative, how can I mount it on Thingy:91 board?

Yes, like you mention in your latest reply - all active antennas need Bias Tee. When connecting the external antenna, the bias tee needs to be connected between the SWF connector and the external antenna cable. The SWF connector is marked "J2" on the hardware illustration on this page.

bojan said:

Anyway, according to this post, there is a chance we get GPS fix if we use GPS in GPS/GNNS standalone mode with LTE mode turned off.

 The post you reference is in regards to having LTE and GPS run concurrently, which requires PSM(but you may do the procedure Sigurd describes, if you need to use both). Unfortunately, activating standalone GPS mode does not improve GPS antenna performance, and the external antenna is still needed.

bojan said:

 command to select GNSS support only or we need to explicitly turn off LTE mode somehow?

By running the AT-command you suggest, you disable LTE and enable only GPS, which is correct. Remember to also use the Set command to activate your GPS module, in addition to enabling it.

Best regards,
Karl

[Karl Ylvisaker]

Hi again Bojan,

I have checked with some of my colleagues about this issue, and it seems that using an active external GPS antenna with the Thingy:91 at times can be very frustrating.
The main reason for this seems to stem from the added loss by the required external components.
Are you currently developing primarily on the nRF9160-DK, or the Thingy:91?

Best regards,
Karl

[bojan]

Hello, Karl Ylvisaker.

We are prototyping with Thingy:91.

I tried with Thingy:91 on-board antenna and GNSS/GPS mode and was able to get the fix in about 110 seconds by putting the Thingy outside my window. The accuracy of the location is quite satisfying. With external antennas, SUPL, A-GPS and the things you announced in your latest webinar about SDK v1.2, I guess this will be a success story!

This about external active antenna and Thingy:91 is quite important information. You are obviously internally aware of that weakness but there is no will from your side to spread that info to the community in a clear way. By reading your posts (e.g. this one), I first though all I need is adapter cable and external antenna. Then, in the meantime, after hours of error and trial, I realized I need a Bias tee as well because the antenna is active. I ordered the Bias tee and now it seems that there is some issue with Thingy:91 and active external GPS antennas. Quite frustrating!

We started with our product development almost two months ago and at that point I convinced the team to go with Nordic solution based on my prior Nordic experiences (mainly around nRF52 BLE modules). During the past 2 months, we spent 90% of the time in setting up the environment and we still feel the pain! There is a nRF52840 module on the Thingy board but it mainly serves as nRF9160 controller and debugger. It is quite difficult to keep that debugging feature inside nRF52840 and add some BLE services on the top of that. I still desperately wait for your feedback on that topic (this thread).

nRF9160-DK boards with some hardware faults (0.8.3 and older) are still on the market. I contacted Mouser, as you suggested, to find out why did they send me the old version and they simply said they are selling from their stocks in a FIFO manner. It is not their fault, they are just selling what you provided them.

I start feeling bad and guilty because I convinced people to go that way. Let me be clear here, I don't have any doubt you are working hard in the background to provide us a high quality development environment. Neither I have doubt your products are great (even the best on the market)! But my managers are not technical people, they just see we are eating time and budget at the moment.

More useful examples, more stable development environment with easy debugging possibilities, more responsive technical support, spreading the info in a clear way... all that is needed if you want to keep your image on the market!

Until the day I begin feeling proud and managers start tapping my shoulders on the corridors, I am sending you my best regards! Let's all grow together!

Cheers!

Bojan.