Unlike the full featured GPS receivers in most devices, the LR1110 module in the Yabby Edge lowers the total fix energy by relying on cloud based post-processing for the position calculation. This allows it to skip the power-hungry ephemeris download portion of the GPS fix process. However, not having the ephemeris makes it harder to locate the GPS signals in the first place, as their transmitter frequencies vary with their positions in the sky. As such, the LR1110 requires aiding data from the cloud and an estimated position to deliver its best performance.
Three forms of aiding are required:
- The coarse time, in seconds, with errors in the order of 20 seconds
- The coarse position, in meters, with errors in the order of 150 km
- The predicted satellite orbits (almanac), with age < 3 months
To handle almanac file downloads and sending a position estimate to the device (required for proper GNSS performance), the Location Engine (LE) must send this information down to the device. It does this via the LoRaWAN network server, whereby API credentials must be configured via the OEM Server UI to allow for the LE to send downlinks via the Network server.
LoRaWAN is not the ideal solution for sending large files, therefore multiple downlinks (between 4 and 100 downlinks – region specific) are required to complete the Almanac file download. For example, the Yabby Edge LoRaWAN in Europe will take about one week to complete the almanac download, if configured to heartbeat twice daily. It is recommended that the Almanac files are updated every 4 weeks for optimum GNSS performance.
The Yabby Edge LoRaWAN sends and receives multiple messages (uplinks and downlinks), on multiple ports, which includes messages for device management. For the full integration guide, please see Yabby Edge LoRaWAN Integration.
Additionally, the Yabby Edge LoRaWAN sends device management and Almanac Downloads on the below ports:
Port 89 – connection
Port 202 – Time Aiding
Port 100 – Position Aiding
Port 90 – MTU
Port 91 & 92-99 – Almanac Aiding
Port 101-116 – Uplink Fragments
GNSS Aiding Mode may be disabled if your Yabby Edge LoRaWAN device is using Wi-Fi scans only. This decreases the device’s time on air, allowing for more frequent uplinks if required.