mountain goat wrote:
... the basic question is how much map can one store in 8Mb. I am trying to buy a first GPS unit and have it narrowed between two units...garmin's etrex legend, and magellian's meridian gold.
MG:
The answer is: It depends on the maps.
Only Garmin maps can be downloaded to Garmin GPSRs (GPS receivers) and only Magellan maps can be downloaded to Magellan GPSRs so look at the Garmin maps (you do it online at their website
http://www.garmin.com/cartography/ ) and the Magellan maps (you can do so at Wide World of Maps) and see which you like better. Any GPSR compatible mapping program can upload/download waypoints/routes/etc.
I belong to a couple of online GPS groups and this question comes up a lot. The general consensus is the Garmin maps are better than Magellan's but each has it's supporters so you should make your own decision so you get what fits your needs.
Street maps contain much more information per unit of area and therefor consume much more GPSR memory than topo maps for that area.
To put some hard number to all this: I've got a Garmin Legend and GPS V which are loaded with topo maps for hiking and the V also is loaded with Phoenix Street maps.
The Garmin topo maps which cover the area from Phoenix north to Paulden, East to Holbrook, south to Bylas, west to Coolidge, north to Apache Junction, west to Phoenix consume 6.32 MB. This easily fits into the Legend's 8MB memory. They are 1:100K scale. IIRC they are based on USGS maps. The Magellan topo maps are based on the same maps.
The Garmin street maps for the Phoenix metro area consume 9.05 MB. This area is bounded by Gila Bend, north to Wickenburg, west to Sunflower, south to Florence, and west back to Gila Bend.
Other things to consider:
-ergonomics, hold both GPSRs in your hand and play with them, work the buttons. Can you do everything with one hand? Or do you have to hold the unit in one hand and work the buttons with the other?
-How many batteries does it hold? More batteries = longer the unit will run before draining the batteries (all other things being equal). The Garmin website shows how long their units will run on a set of alkalines and how many each unit holds.
I've shopped around for Garmin and got the best deal from
http://www.tvnav.com/ . I've also done business with
http://www.gpsnow.com . Both were courteous, had the stuff in stock and it arrived when they said it would.
Two things I consider must-have accessories are rechargeable NIMH (nickel metal hydride) batteries and a smart battery charger. Stay away from NiCad batts because of the memory problems. You want a smart charger because it senses the state of charge of the battery and stops charging as soon as it reaches full-power. Over-charging shortens the battery's life. Stay away from so-called "automatic" battery chargers that just run for a period of time and then just shut-off. These don't check how much power is already in the battery and can cook them.
More info at
http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM
Excellent battery charger:
http://www.imaging-resource.com/ACCS/C401FS/C401A.HTM
Bill