Garmin 196: Anyone else dissapointed in the actual ability to capture sats

Mike,

I have found the III Plus and III Pilot to sometimes be a little better on
reception. However, the 196 is pretty good.

What I think might be happening is that your 196 does not have a current
almanac and your II+ does.

To use a satellite for navigation, the GPS must have ephemeris data. This
is the fine orbital data. The data is only current for about 30 minutes and
is broadcast every 30 seconds. It takes 18 seconds to download. Every
satellite broadcasts its own ephemeris data.

The almanac is more like rough data from which the GPS can calculate roughly
the location of all the satellites. The GPS uses its last known position,
its internal time, and the almanac to know which satellites to try to
receive when it is turned on. If the internal clock is off, the GPS has
been moved more than 500 miles from its last location, or it does not have a
good almanac, the GPS will be slow to locate a fix. The almanac data takes
12.5 minutes to download, every satellite broadcasts the almanac, and it is
current for something along the order of a month.

It would be possible for the 196 to randomly get enough satellites to fix a
position even without the almanac-- this would be slow as you found out. If
you shut the GPS off before the almanac was loaded, it would be slow to
re-acquire a fix. This sounds like how your 196 is behaving.

Try to let your 196 get a fix and then leave it on. I suppose 30 minutes
would probably be enough, by I would try a little more to be on the safe
side. This should allow it to download a current almanac. It should work
much better after this.

You might also look at:
http://www.gpsinformation.org/dale/gpsfix.htm
http://www.geotips.com/geotip/geotip4.0.htm

As far as the logbook. I forget whether the 196 uses speed or altitude for
starting the time on a flight. However, hold the PAGE button and select
LAND mode when you use it in your car.

Overall, I think the 196 is a very capable piece of hardware. You might
also take a look at my site, www.cockpitgps.com for some more info on using
it.

John Bell