"real-time" tracking with the NRF9151

[m4rkw]

I want to achieve as close as possible to real-time tracking with the nRF9151. Because of the shared RF path this is somewhat tricky, LTE and GNSS can't run simultaneously. Initially I was running into the carrier-side RRC timeout but figured out how to make RAI work to get around it.

I've now managed to get the GPS read -> send loop down to roughly one event per 2-3 seconds. I suspect this is probably at the limit of what's possible with this SIP because it looks like almost that entire interval is GPS but I thought I'd post here just in case there are some other tricks I've missed.

For reference I'm using my own server on a very fast connection and the traffic is using DTLS. Obviously I can batch the records to eliminate the gaps but I'm aiming for high resolution near-realtime tracking. With an older device that had a GPS chip that was separate from the modem real-time 1Hz was possible, still hoping there might be a way to get near this with the nRF9151.

Thanks,
Mark

[Øyvind]

Hello, have you seen our Developer Academy Cellular IoT Fundamentals course? There is a lesson called nRF91 simple tracker.  Are you looking at using our location services as well?

A separate GPS device will allow you to have true "real-time" tracking. 

Kind regards,
Øyvind

[m4rkw]

Hi Øyvind

Thanks for getting back to me. I already have fully working tracker firmware with a bunch of features, not sure that course is going to help me much.

I know I can use a separate GPS device and have been considering that, I just wanted to see if there’s anything I can do to squeeze more iteration speed out of the 9151 SIP. It’s possible it might fare better in a vehicle as my bench setup antenna is apparently a bit weak.

Since I fixed the RRC timeout LTE now still blocks GPS for around ~1s per cycle which seems like a lot for transmission on an open DTLS connection. I might try reverting to plain UDP for comparison and see if that reduces.

Cheers,

Mark