Thingy91 Poor GPS with built in antenna

[mikael_ba]

Hello,
We are evaluating the nRF9160 SiP for an asset tracker device. We have both the 9160DK (1.1.0) and the Thingy91 (1.6.0). Both have been upgraded to the latest modem firmware and are loaded with the Asset Tracker V2 application, compiled for the NRF-Cloud.

The Development Kit is able to get GPS fix in a reasonable time however the Thingy is not (with built in antenna). I've carried the Thingy with me on my scooter to work for 2 weeks, evaluating its performance. With a generic external active antenna (LNA disabled), GPS is able to fix on every point on my route home from work, however, with the build in antenna the GPS doesnt get a single fix on my route home. This is using all default values of the Asset Tracker V2 application.

Im wondering, is the performance of the built in antenna really this bad?
What can be done to enhance performance of the built in antenna (combining LTE + GNSS) and what are some recommended antennas (omnidirectional preferably) with vastly better performance?

Thanks in advance

[Kaja]

Hi,

an external active GPS antenna will give you better performance, and the GPS antenna on the DK is larger and has better performance then the one on the Thingy. 

A dedicated GPS antenna will in most cases be better than a shared antenna, as the one on the Thingy, so this is recommended for better GPS performance.  

When you tested the onboard antenna, did you use A-GPS?

Best regards,
Kaja

[mikael_ba]

Hello Kaja,

to say that an external antenna gives better performance than the built-in is a very liberal use of 'better' since we didn't get a single fix with the built in.

Can you recommend any SMD antennas similar to the one Thingy is using but with better performance?
We have ordered a couple of samples but it would be interesting to hear what the testing devision at NS have used and have had success with.

We used the default values when compiling the Asset Tracker V2 (except enabling external antenna in the case where we used that). According to the documentation for the ATV2, A-GPS is enabled by default. The device is provisioned and added to the NRF-Cloud where we inspect the data.

Regards,
Mikael

[Kaja]

Hi Mikael, 

I agree, you should be able to get a fix, do you have a usb cable connected to it when you test it?

We don't have a list of antennas, but you can ask antenna vendors for antennas with better efficiently for the GPS frequency. 

Best regards,
Kaja

[mikael_ba]

Hello Kaja,
I did not have a usb cable connected to the device. It was completely standalone in the outer pocket of my backpack on my way home. We have bought a bunch of external active patch antennas and some PCB antennas to test now.

Thanks

[Kaja]

I see!

Do you have any logs? With and without external antenna? 

If you add: CONFIG_LOCATION_LOG_LEVEL_DBG=y

Then we can see what satellites you connect to and the signal strength.  

My colleague told me that one possibility is to get the log over BLE: run the NUS central example on a  52dk, and have it connect to the Thingy and then save the log from the 52.

We want to see if there is low or high signal strength with the external antenna. 

Best regards,
Kaja