Almost every time I connect my unit to the Home app. it has an update for QuickGPSfix and a notice that the update will cause my unit to find locations more quickly. Can someone tell me how this works? What does QuickGPSfix actually DO to make things work better?
There are two ways that your unit can get information about which satellites will be available at any given time - either by waiting to gather that data from one of the satellites, or from the QuickGPSfix files that you receive from TomTom. When you turn your unit on, if it had no idea what satellites were likely to be within "view", it would have to search the entire constellation to see who was home. The information from the satellites is called "almanac" data. Your QuickGPSfix files supply the same kind of information. Although TomTom calls what it sends "ephemeris" data, ephemeris info is really only good for about four hours. What you're getting from TomTom is the almanac data without having to wait for it.
From our friends at about.com:
If you've ever wondered why your GPS receiver sometimes takes longer to become ready to navigate after it's turned on, it is because it must acquire some basic information in addition to capturing GPS satellite signals.
You may encounter a slow start if your GPS has been unused for days or weeks, or has been transported a significant distance while turned off. In these cases, the GPS must update its
almanac and
ephemeris data and store it in memory.
The GPS almanac is a set of data that every GPS satellite transmits, and it includes information about the state (health) of the entire GPS satellite constellation, and coarse data on every satellite's orbit. When a GPS receiver has
current almanac data in memory, it can acquire satellite signals and determine initial position more quickly.
