Synchronization over LTE/NB-IoT - SNTP time accuracy

Hi,

We are developing an application that requires synchronization between two or more nRF9160-based devices. We have the following requirements and constraints:

  • Required time synchronization accuracy: < 1 ms
  • GNSS is not available — devices are deployed underground without access to an external antenna
  • Both devices connect via LTE-M / NB-IoT

We have the following questions:

  1. What is the expected accuracy of SNTP time synchronization over LTE on the nRF9160?
  2. What is the expected accuracy of LTE network time received via NITZ or SIB16 (configurable via AT%XNETTIME)?
  3. Are either of these solutions capable of meeting our < 1 ms accuracy requirement?
  4. Are there any other Nordic-supported time synchronization solutions that could meet our accuracy requirement given our constraints?

Any guidance or alternative approaches would be greatly appreciated.

Thank you.

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