[Tilt, TyTN II, MDA Vario III General] LGB:
As far as I understood it, QuickGPS is downloading the satellite almanac from the internet, instead of getting it through the GPS. A GPS which has not been turned on for a while will get this almanac even without internet connection, but it takes about 15 minutes to download it (happens automatically in any GPS unit). Getting it from the internet saves you these 15 minutes, but if you have used your GPS recently for more than a 15 minutes period, QuickGPS should not make any difference.

The almananac for the GPS satellites is like a sun or moon almanac, just for satellites instead. This means that if you have a current almanac, and your GPS knows your rough position, then the almanac will tell the GPS where it should expect to see the satellites. This includes which of the satellites are visible on a given position on the earth (roughly around a third of them), and at what azimuth and elevation. GPS satellites are orbiting the Earth in intervals of just under 12 hours in certain orbits, intercepting the Equator at 55 degree angles (which means that they will cross 55 deg North/South when they are closest to either pole). Since they are more than 20000 km out, this is not a problem if you are actually on or close to either pole, but it means that you will not see satellites right above you at either pole. WAAS satellites are geostationary (which means they can only be somewhere over Equator at about 36000 km orbit), and these satellites do not transmit normal position and time information like the other satellites (SVs) in the GPS system, but precision and integrity information. Put in other words, they tell the GPS receiver 1) Is the signal in your area good or bad and 2) What vector to correct your measured position in whatever area your GPS says you are in. Similar for LAAS units, although they differ in being local area only but on the other hand, more precise. LAAS units are called pseudolites, because they act almost like satellites, though they are really not. For aviation, LAAS enables precision auto-landings in "zero weather" for the same reason, but since the LAAS station is on or close to the surface of the Earth, it only works when in line-of-sight of it.

The problem I am experiencing is if I turn my GPS off and move it a couple of hundred of miles and then turn it on again. This is usually when I am flying, and as we all know, the battery of the Kaiser is not really built for powering the unit for very long! When I turn the GPS on after for intance an hour or so, it still assumes the original position, and it will sometimes get a lock on on or two satellites only, trying desparately to maintain that position. Knowing how the GPS satellites interpolates via a time-shifting technique, I can see why this happens, as it gets a false fix. Aviation grade GPS systems will never lock on to anything less than 3 satellites for a 2D fix, and prefers 5 or 6 satellites minimum for integrity reasons (called RAIM).

What I think is the real problem is that these end user GPS systems for road use have to be more sensitive, so they can be used behind shielded windows and poor reception areas in buildings etc. Trees with many leaves can be an issue also, although clouds are no factor in this equation. Sunspots can blind the system completely if they are strong enough, and that is why eLORAN is an update to the LORAN-C system which is currently being considered for backup purposes mainly.

So, my Kaiser and other end user GPS units will be less restrictive for a good quality fix, and accept second guessing the position, where as aviation and other critical uses of GPS have to have a good position.

We need a GPS utility for the Kaiser GPS to carry out a position reset so it can do a new fix.