I bet you are tired of getting lost trying to find a
locality that you know is just over there. Or, have you been on a field trip
where the leader takes you through so many twists and road changes that you
will never find the place again? Or, do you want to plan your trips in advance
and go right to the spot? There is help. It will cost you, but there is really
good help, and you have already paid for the most expensive part.
Global Positioning System or GPS is an amazing scheme where
24 orbiting satellites broadcast a precise and unique time signal which allows
a receiver to triangulate you position to within 20 feet or so. The Department
of Defense paid for it and for a long time, they deliberately broadcast signals
that could not be decoded to better than 200 feet, but they gave that up and
now everyone (I really mean everyone) can know where they are. During Desert Storm, there were not enough
$10,000 military models to go around, so they started broadcasting the signals
straight and issuing $100 Delorme civilian systems. This was the first war
where our guys knew where they were.
But wait, there is more!. These early models would just tell
you the latitude and longitude and that was that. What you really need is a map
with a “you are here X” and maybe a voice readout saying “you passed the point
marked Trilobites”. Talking models
installed in a car cost $1000+ and models with a map cost $300.
Remember, the receiver is entirely passive, they have no
idea where you are, and do not care. Have you seen those car commercials where
you press a button and someone knows where you are? You might as well carry a
cell phone because that is what the car uses when you want help.
So maybe you want a better location. The FAA has put up a
satellite that sends a correction signal that improves the location to within
10 feet, most new systems receive this automatically. They want to route planes to airport runways. If you really want
better, you need to tap into a local radio correction signal like the ones
broadcast by the coastal service, airports, bus companies but you need a GPS
with a radio receiver. This is the scheme that allows bus companies to know
exactly where the buses are stalled and the FAA to consider letting computers land
aircraft in total fog.
These signals are good to better than 3 feet. Suppose you
want to measure how fast southern California is moving toward Canada, you just
need to read every satellite for 3 months and do lots of processing and you
will find out that it is 3 cm a year.
Ok, lets get specific. You really want a system with a map
and at least 12 meg of internal memory. My Garmin Etrex Vista has a 120x240
pixel display and 24 meg of memory and it is very functional. I wish is had
more pixels and a color screen and got 24 hours of battery life, but ….. A great shopping site with lots of info on
all the systems is:
Remember that I mentioned memory? You can download specific
areas of the country in great detail. Half of Texas fits into 24 meg of memory.
You need the dedicated program associated with each unit. Garmin has “MapSource
Roads and Recreation” for about $90.
Garmin also makes accessories like a dual cable system to power the unit
from the car and connect it to the computer, but their connectors are terrible.
Go to www.gpsgeek.com and buy their cables.
You would think that after you bought the computer, the
software, the GPS receiver, and the cables that you would be done. No. It is
like buying a new car, everything seems to be an accessory and cost extra. The
problem is that the maps are a little out of date. Maybe the cities are better,
but rural Oklahoma has not had an update since the Chickasaw turnpike was put
in.
So, who has better maps? Microsoft Streets and Trips are
excellent and I use them a lot. Too bad they do not communicate with the GPS,
so I frequently have both systems up at the same time. Are we done? No, because
what we really want is a USGS topo sheet with quarries and such things. And you
can have it: Maptech will sell you
scanned topo maps copied from the USGS for anywhere in the US.
This is a lot of CDs, particularly for Texas, cost about
$100. The topo maps are terribly out of
date (1955 is a common survey date) but do have quarries and topology (but not
recent ones). You can transfer picked points from Maptech to and from Garmin,
but not maps. Do you see where you are headed? You need 3 mapping systems up at
once. I hope you have a lot of memory on your computer. Two screens would be
nice.
All the items listed above are on the ESSENTIAL list, so
lets list an optional. Garmin does not trust you and requires that you keep
your map CD in the drive while you are using it. That is slow and prevents me
from using a CD of topo information from Maptech. There is a way around this
with www.farstone.com .
Create a virtual drive with Farstone and load the Mapsource
disk into it and Garmin thinks that you have the CD in place, and it is 100%
legal. I have been using it on my laptop for more than a year and it always
works. This uses about 700 meg of disk space.
So, what does it cost to be a GPS enabled field trip leader?
About 3 grand covers the computer, receiver, and the software.
So what is the downside? Garmin has miserable customer
support. Gps4fun has no customer
support. If you are in the HGMS, I will help you.