LoRa Basics Modem and LoRa Edge documentation

Scenario - User Loaded Almanac Update


An LR1110 based device can reduce the GNSS scanning time by taking into account coarse orbital parameters for different GNSS constellations (the almanac). In conjunction with a coarse time and position estimate, the LR1110 chip uses this information to optimize the search for, and acquisition of, GNSS signals. Over time, the true satellite positions diverge from those stored in the almanac, as a result the almanac has to be updated regularly.

Maintaining the almanac up-to-date can be done by the application with a full almanac update, where the device application updates all almanac data in the LR1110 chip.


If the LR1110 chip is used with the LoRa Basics™ Modem-E firmware, energy and bandwidth-efficient OTA updates can be used. For more information, see the LoRa Basics Almanac Update scenario.


LoRa Basics™ Modem(s)

LoRa Edge™ LR1110 transceiver



  • The application can download the almanac image from the LoRa Cloud™ Modem & Geolocation Services and transfer said image to the end-device MCU.


Transfer of the almanac image to the device application can be achieved through any communication link, for example, Bluetooth, USB, or LPWAN. It is up to solution developers to implement the almanac image trasfer mechanism best suited for their application.

Prerequisites for LoRa Basics™ Modem:

  • No additional requirements

Prerequisites for LoRa Basics™ Modem-E:

  • No additional requirements

Prerequisites for Transceiver:

  • No additional requirements

Step-by-Step Procedure

The size of the almanac image is 2580 bytes, which is more than the LR1110 chip can handle in one command. As a result, the almanac image must be split into multiple chunks, as described below.

  1. The application downloads a Base64-encoded string containing the almanac image from the LoRa Cloud™ Modem & Geolocation Services.

  2. The Base64-encoded string is decoded to obtain the almanac image.

  3. The application transfers the almanac image to the end-device.

  4. The device application splits the almanac image into chunks. The size of each chunk must be a multiple of 20 bytes and the maximum size depends on the type of device:

  5. The device application transfers the chunks to the LR1110 chip through consecutive calls to the GnssAlmanacFullUpdate() command.


  • The application can split the almanac into chunks before transferring it to the device application.

  • All the chunks must be transferred to the LR1110 chip through consecutive SPI transactions; that is, no other commands can be sent to the LR1110 chip until all of the chunks have been transferred.

The almanac should be updated monthly. At the very least, it must be updated every three months. For LoRa Basics™ Modem-E, after a full almanac update has been performed (assuming the almanac image was obtained from the LoRa Cloud™ Modem & Geolocation Services) the almanac can be kept up-to-date more efficiently using the OTA almanac update procedure as described in LoRa Basics Almanac Update.

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