What is GPS Aiding Data?
Written by Matthew Clark-Massera
Updated at February 14th, 2024
Table of Contents
Our latest range of cellular devices make use of GPS Aiding data (or Almanac data for our Edge devices), to dramatically improve the performance of their GPS - speeding up fix times, and increasing battery life.
Only available to devices on Device Manager (OEM)
Our GPS Aiding Data comes through Device Manager. There will be performance implications for clients who wish to use Direct Mode.
For more information, please contact support.
So what is GPS Aiding Data?
Our current line-up of devices (as of June 2023) uses a varied mix of Sony, Nordic, and UBlox receivers. Every 5-7 days, the devices download aiding data over the cellular network. This data contains key information: ephemeris, almanac, accurate time and satellite status. In layman's terms, this basically means the device gets key information such as where the satellites are in the sky and the paths they'll be travelling. This data is around 50kB, and is quick and easy to download.
Without the aiding data downloads, the GPS module would have to download all of this directly from the satellite when it gets a fix. In poor GPS conditions, this could take a long time or fail entirely. With aiding data, the device has all this on hand, so when it tries to get a fix, it only needs to get some signal (even weak signal) from a few satellites, and can still compute a position within seconds!
Benefits
- GPS fix times are significantly reduced. Generally in good signal, we can get a fix in around 10 seconds with the aiding data, without, it takes upwards of 30 seconds.
- The fast fixes mean better GPS performance for our hard-wired trackers - for live location tracking
- For our battery-powered trackers, the impact on battery life is significant. Running the GPS takes energy, the less time we can run it for, the less power it will use - increasing battery life!
- Fixes can be acquired in poor signal conditions - thanks to the Low Noise Amplifiers also fitted to our devices, they will get fixes where other devices simply give up!
Drawbacks
The sole drawback is the tiny 50kB of data use. This is generally not a problem in most applications. But when trying to keep data usage to the absolute minimum - i.e. for NB-IoT - this can eat up the tiny data allowances (100kB for the whole month isn't uncommon). See Data Use. However, we feel the trade-off is well worth it for the improvements in performance and battery life.
Aiding Data Download Errors - Ublox
If the aiding data download is failing - this error will be seen in the device logs (View Device Logs).
Example:
Debug[GSM][Sevr]: HTTP fail online-live1.services.u-blox.com:80 0/4
This means the download has failed, which could be for a few reasons:
- Temporary network issue - the device failed halfway through getting the data. If it's only a couple of logs, it generally isn't much to worry about.
- Issues with DNS on some NB-IoT networks, see DNS Troubleshooting on 4G
- Your SIM provider has a lot of firewalls up, and isn't allowing traffic from this server. The correct servers should be whitelisted - see: OEM - What IP addresses should I allow through my firewall?
- Some other issue (something has changed with the aiding data provider or a FW bug in our devices) - contact DM