Anyone that has used a GPS device for any length of time knows that battery life is a huge concern. The process by which a device obtains a location fix is quite complex and uses a great deal of power. In order to determine its location, a GPS device must make contact with at least three satellites and obtain their Ephemeris and almanac data. Ephemeris data gives the satellite’s current position in its orbit, and almanac data gives the satellite’s current course information. The device then uses this data to perform complex calculations to determine its own location. All of these calculations drain a lot of battery power from the device.
A recent development may address this problem. In November, Microsoft Research issued a paper introducing the concept of a special kind of GPS sensor called CLEO. CLEO has the ability to take the unprocessed Ephemeris and almanac data and send it to a remote server (often referred to as the cloud). All the calculations to determine the location fix of the GPS device are then performed in the cloud and sent back to the device, thus significantly decreasing the amount of battery power used by the device.
In addition, the National Geospatial-Intelligence Agency (NGA) is working to make it even easier for the GPS device to more quickly pick the best satellites. For some time, the NGA has used a ground station network to gather information on the satellite orbits, referred to as Precise Ephemeris (PE). A GPS sensor can use this PE data to find the best satellites for its location. The most accurate PE data is obtained by using the widest possible range of stations. Instead of using resources to build more stations, the NGA is now appealing to other government and research organizations to share the reference data from their own ground stations. This “crowd-sourcing” will increase the range of stations and data available, thus enabling GPS devices to find satellites even more quickly and to swiftly choose the best satellites for their location.
These innovations have the potential to greatly increase the usefulness of GPS devices. Rather than taking only periodic location fixes to save battery life, as is common with many tracking devices, this technology would enable continuous GPS monitoring with significantly decreased battery usage.