Homelink GPS Profile Should Include Altitude



The current behavior for Homelink is to program the GPS coordinates to open the menu as you approach your door/gate.  If the door/gate is in a multi-level garage like a condominium the menu pops up as you go up and down the ramps above the door/gate. With at least 4 satellites in view the altitude position can be determined. Saving this to the Homelink profile will remove these false menu popups.


Editor: Accuracy of GPS altitude is only specified as being +/- 75 ft 95% of the time (5% it could be far worse).  It becomes even worse in a garage, where it’s likely the GPS signal will be completely lost.  With a lot of clever programming, such as getting the barometric pressure for the local area via the 3G connection and having a calibrated pressure sensor on board, the altitude could be determined accurately. It would seem this features needs both software and additional hardware to be reasonably accurate.

Perhaps an alternate approach would be to leave the Homelink menu active for a wider distance range than is currently set, so it doesn’t pop up and close in this environment.



Category: Tags: entered 10-Feb-2013


Barometric pressure doesn't help (because of wheather changes). But I'm sure they have all sorts of sensors on board (like a smartphone) with the help of which they can navigate through tunnels and the like - and for sure as well can find out if a car goes up or down a multy story garage.
Perhaps problems similar to that described could be mitigated by having an option to use Bluetooth to sense proximity to the garage, instead of or combined with GPS location.  This would require a Blutooth tag or similar device to be located at the garage door and continously powered.  The car would also need to regularly scan for Bluetooth devices in the vicinity.  However, I am not clear if Bluetooth v4 or v5 is needed for this sort of proximity sensing.
Accelerometers can easily detect car position in 3D space including direction and tilt.  Given a known street elevation at the multi-story condo, it is possible to get reasonable estimates of height and location via what is called "dead reckoning" by measuring tilt, direction and speed.   It won't be extremely accurate and the farther you travel the less accurate is the result; but it can improve the area where Homelink activation is required over short distances which should cover the stacked condo/garage case.