Enable Fine Timestamp on RAK gateways to capture nanosecond-level data for accurate LoRaWAN geolocation using TDoA positioning.
This advanced timing feature enhances the accuracy of uplink timestamps by recording time at the RF front end instead of relying solely on the concentrator’s internal counter. When multiple GPS-synchronized gateways are deployed, the Fine Timestamp metadata allows geolocation services to determine a device’s position through Time Difference of Arrival (TDoA) analysis.
The Fine Timestamp feature is only available on certain RAK gateway models due to hardware differences.
Key Concepts
- Standard Timestamp: A basic time marker attached to uplink packets, generated by the concentrator’s internal counter with microsecond-level precision. It can be synchronized with GPS to ensure alignment across multiple gateways.
- Fine Timestamp: A higher-precision timestamp (nanosecond-level) captured at the gateway’s RF front-end, significantly improves time synchronization.
- TDoA (Time Difference of Arrival): A geolocation method that calculates a device’s position by comparing the fine timestamps of uplinks received by multiple gateways.
How It Works
- When the feature is enabled, the gateway records a Fine Timestamp for every uplink packet it receives.
- The Fine Timestamp is embedded in the uplink metadata and forwarded to the LoRa Network Server (LNS).
- The LNS collects uplink metadata from multiple GPS-synchronized gateways and forwards the Fine Timestamp information to a Geolocation Service.
- Using Time Difference of Arrival (TDoA) algorithms, the Geolocation Service compares the Fine Timestamps from different gateways to estimate the device’s location with significantly higher accuracy than standard timestamping.
For geolocation use cases, gateways must be synchronized through
GPS:
- GPS provides a unified absolute time reference (UTC + PPS signal).
- This synchronization ensures that the standard timestamps across multiple gateways are aligned.
Enable Fine Timestamp
Fine Timestamp can only be enabled when the gateway is running in Packet Forwarder mode. Ensure the gateway is operating in this mode before proceeding.
- Log in to the gateway's web user interface (UI).
- Navigate to LoRa Configuration > Fine Timestamp.
- Enable the Fine Timestamp feature by toggling the switch.
- Click Save changes to apply the configuration.
The Fine Timestamp is included in the uplink metadata and can be used by Geolocation Services (e.g., Actility) for TDoA-based positioning.
FAQs
- How many gateways are required for TDoA positioning?
At least three GPS-synchronized gateways are necessary; having four or more enhances reliability and accuracy. - Does enabling Fine Timestamp affect uplink performance or latency?
No, it only adds additional metadata to the uplink report. Payload transmission remains unaffected. - Can a gateway without GPS use Fine Timestamp?
Yes. It can record Fine Timestamp locally, but without GPS synchronization, it cannot contribute to multi-gateway TDoA positioning. - Can the LNS itself calculate location using Fine Timestamp?
No. The LNS typically forwards this information to an external Geolocation Service for processing.
Glossary
TERM | DEFINITION | NOTES | |
|---|---|---|---|
| Fine Timestamp | A nanosecond-level timestamp captured at the RF front end, enabling precise time measurement for geolocation. | Required for TDoA-based geolocation. | |
| Standard Timestamp | A microsecond-level timestamp generated by the concentrator’s internal counter, which can optionally be synchronized via GPS. | Provides baseline timing and can be GPS-aligned for consistency across multiple gateways. | |
| TDoA (Time Difference of Arrival) | A geolocation technique that estimates device position by comparing the differences in arrival times of an uplink signal across multiple gateways. | Accuracy depends on gateway density and GPS synchronization. |
Changelog
-
Version 1 - Enable Fine Timestamp for Precise LoRaWAN Geolocation on
RAK Gateways
- Date Published: 10/31/2025
Updated