Never pull over for directions again.

For men, who have a genetic coding that precludes actions like, say, pulling over to ask for directions, and encourages behaviors such as, say, playing with electronic gadgets and wandering into the woods, this little device called the Garmin eTrex Legend could be the missing link. However, this unit is fun to play with, useful, and could become indespensible for almost everyone else, as well!

Intro

I was first introduced to the eTrex Legend in July 2001 on a camping trip to my cabin near Lake Tahoe. A friend from work brought his along, and I played with it in the car. However, once we got in the woods and started wandering around and looking at the topo map (with topological elevation and trail information), my brain went into one of its lower modes and commanded me, "must..get..eTrex."

In this review, I'm going to talk about the technical details of the eTrex first, but since the eTrex has so many cool features I'd have to practically write a book to describe them all, I want to also go over the scenarios in which you might use the eTrex, and why it will be beneficial and useful to you.

Handheld GPS

Handheld GPS makers have made tremendous strides in the last couple of years, and if you have not seen GPS lately, or never at all, you will be surprised what powerful features can be packed into a small case. When people see me carrying the Etrex Legend around, they invariably think it's a cell phone, and indeed it's about the same size and weight, though a little bit thicker, than my current phone.

The eTrex Legend is part of a group of second-generation eTrex products that Garmin introduced around this time last year. They update the earlier eTrex models with a higher-resolution display, memory storage for map capbilities, better GPS reception hardware, and other upgrades. If you are to get an eTrex, I highly recommend getting one of these 2nd generation units.

There are alternatives to a handheld GPS which may be more appropriate for certain situations. For example, some people like the convenience of their car telling them to turn right or left at the next intersection (you can have built-in GPS, or Garmin and others make a like of driving directional units), and pilots of airplanes and boats have specialized navigational GPS with very different features.

The beauty of a handheld unit is that it can be used in your car for finding an address, then unplugged and carried out to a boat to map the course you take, then brought to the woods to mark a trail and find your way back. We will talk about these situations more in the How do I use it section.

Your Tax Money at Work

GPS, or Global Positioning System, is a satellite-based navigation system that provides continuous, free, global coverage to an unlimited number of GPS receivers. To a computer engineer like myself, it is a truly fascinating system and I would love to write about exactly how it works. However, for the sake of not boring 90% of our readers, let's just simplify how it works like this:

- Your GPS receiver locks onto signals for each satellite within range, and synchronizes its clock to the clock on the satellite, so they are very, very precisely matched.
- Based on the delay of the signal from the satellite to you, your GPS can calculate the exact distance from where the satellite is in space, to your location.
- When you lock onto 3 or more satellites, your location can be triangulated. Picture 3 satellites at known locations in space, and then draw a sphere around each one (the radius of the sphere being the distance calculated in the previous step). Wherever those three spheres intersect, is voila!, where you are. There are actually 2 intersection points when you have only 3 satellites, but one of them is on (or near) the surface of the earth, and the other is in outer space and can be discarded.

Very roughly, this is how it works. Now let's talk about accuracy. There are naturally errors induced by the signal traveling through the earth's ionosphere and troposphere, and by clouds and other weather. There is even something called a relativistic time delay, since the satellite is in a different gravitational field and traveling at a different speed than you. Like whoah, think Einstein. However, these thigns can be corrected for (in fact, there is a data stream which comes with the GPS data, that includes correction info), and the really nasty errors are actually intentional, and come from Selective Availability.

To understand Selective Availability, or SA, you must first know that the origins of GPS are in the U.S. military. There are actually two signals that are sent from each satellite, the C/A code, and the P code. The C/A code (Coarse Acquisition) used to give you just that, a coarse idea of where you are. Since Uncle Sam decided to be generous, and since you paid for this system with your tax money, the C/A code is widely available and is what your GPS receiver uses. However, the military wanted more accurate information for themselves than civilians (and enemies), so they induced error on the C/A code (which is the Selective Availability), and gave themselves an encrypted p-code (a correction code we won't talk about).

However, due to a number of reasons, some of which having to due with civilian (i.e. Aviation) reliance on GPS for accurate navigation aid, SA was deactivated by a presidential order on May 1st, 2000. Right on! Now, instead of being accurate to a few hundred feet, your handheld GPS can be consistently accurate to LESS THAN 20 FEET, or even better. There is just something so cool about walking a few feet, and having the little triangle on your GPS show you where you just walked on the map.

Well I didn't mean to write a treatise on GPS, so let's talk about the eTrex Legend. Its advanced radio hardware can track up to 12 satellites in parallel, and also is WAAS-capable, meaning it can use data from new FAA satellites to get accuracy down to a couple of feet (there aren't many WAAS satellites flying yet).

The eTrex Legend has a built-in antenna, and gets very good receptions in most urban and rural environments, except in dense downtown skyscapes with sky visibility impeded by skyscrapers. After powering on, it usually takes about 30 seconds to synchronize and begin navigating. I have found it to work fine in fog, clouds, rain, and light snow, but heavy, wet weather can in theory absorb the signals and cancel your chances of using the GPS.

Display

The eTrex Legend has a 4-level grayscale display which shows maps and data on the other screens. It is a great display, and the backlighting is nice for night operation. When showing a lot of map data, the display is sometimes slow to update, but in general it is quite good.

Maps and MapSource

One of the great features about this device is that it comes with 8 Megabytes of memory for storing map data. So, you can purchase a variety of MapSource CDs made by the manufacturer, Garmin, and load map data into the GPS. The CDs I have are:

Roads and Recreations - 1 CD that contains major highways and streets in the US. Think of it as your Road Atlas.

Metroguide U.S.A. - A 3-CD set that contains *detailed* maps of major metropolitan areas, down to street addresses. It contains points of interest such as restaurants, with their exact name, location, and phone number.

U.S. Topographical - This is of interest to those who are in the outdoors, and want trail, altitude, and terrain info.

I use an IBM laptop, which runs the MapSource software. By using the included data cable, I can view a large, color map on the laptop with my current location updated in real time (once per second), and this works anywhere covered by my maps (basically the U.S.).

The MapSource program does not work on my Mac; PCs only. :(

Navigation

When using MapSource on a laptop as described above, I can zoom in and out, change map sets, record waypoints, record the route I travel, and plot a path between two addresses. I can also choose which maps I want to download into the 8MB of memory on the unit, and then use the unit by itself while walking around. Map data is saved in the GPS unit's memory until the next time you overwrite it with something else. When disconnected from the PC, I can do all of the above functions, except plot a path between two addresses -- that has to be done on the PC and downloaded to the GPS. I can, however, just show the address I'm headed to, and figure out how to get there based on the map.

One really cool side effect of all this, which I didn't anticipate when I got it, is that it makes it *really easy* to find your way around, when in a new neighborhood, or even the one you're used to. For instance, just keep the unit plugged into your cigarette lighter for power, and if there is bad traffic or an accident, or you're looking for a street you know is nearby, glance at the map and it shows you your immediate surroundings for 10 or 20 blocks, with street names, etc. Zoom in our out for detail.

One pet peeve about navigation, is navigation of the user interface -- it's easy with one button to switch between screens showing all kinds of info, but if you want to enter an address or go deep into a menu, you have to use this little joystick-like device with onscreen keyboard, which is tedious.

Other Features

Garmin has strong roots in boat navigation and fish finding, so there are some funky features like hunting and fishing calendars, phase of the moon, etc. The unit has more practical screens, such as a fully configurable trip meter display, a track-back system where you can leave "virtual breadcrumbs" and follow your path back to whence you came, a compass, and due to how GPS works (described above), you get a microsecond-accurate time source to boot!


Comparison to other GPS units

I'm not going to go into detail about whether this unit is appropriate for your needs -- it should hopefully be obvious by now whether it would be useful (or cool enough to forget about utility :) for you. However, I highly recommend this web site for further info about all sorts of GPS units:

http://joe.mehaffey.com/

One question is about deciding which eTrex unit to get, since there are many. the Legend is second to the top-of-the-line, and due to the cheap prices nowadays, I would recommend getting the Legend (the unit I am reviewing here), since lower units have at most 1MB of map memory, which is not enough. The top-of-line (but nearly identical) Vista, which I believe is about $75 more expensive, adds these features: a whopping 24MB of map memory, and also includes compass and altimeter instruments, whereas the Legend just estimates those from satellite readings. If these things are important to you or you like its attractive silver case better than the Legend's deep-blue, go for it!

How I use it

I think perhaps I've already given you an idea of how I use it, but here are a few scenarios:

Driving Around
I like to just leave it plugged into the cigarette lighter and sitting next to my gearshift. It's fun while in traffic to look at the map, and even to glance at it while driving to watch which streets I'm passing.

Finding Places
Of course, it's most useful when finding an address - before starting out, just punch in the address and a big arrow will be updated in real time. This works best along with a printout from a map website and preferably directions from whomever you're finding, to give you a general idea of which freeways to take, etc. It is most useful in the last 10 or 20 blocks of hard-to-find places.

Outdoors
We haven't really talked about this much, but the eTrex line is actually designed for the outdoors! It has a durable rubber edging (waterproof!), and an optional neoprene case that makes it float if dropped in water. It can work to specs up to 6 G's, and down to -5 degrees C.

One of the main reasons I got this unit was safety - sometimes I find myself in the backwoods of Northern California in the middle of winter, on skis or snowmobiles. In whiteout storm conditions, my lack of orientation and directional abilities could be my end. With the eTrex and TrackBack, I would probably not have to dig myself a snow tunnel for the night.

How Much?

Of course, we have to end with the cost question. Here is how much I paid for my unit and accessories. I bought from GPS City, but do an online search and you should be able to find equivalent deals elsewhere. This was purchased 7/01.

$220 eTrex Legend
- The little blue wonder
$110 Metroguide CD
- The map CDs are expensive, but at least get a metroguide or the roads & rec; this will GREATLY increase your GPS's usefulness.
$30 Auto Mount
- For mounting to your dash. This is still sitting in the box; I just put the GPS down on the seat next to me.
$14 Carry case
- This is useful for being on the water, but I rarely use it. The GPS is just so durable it's not necessary.
$30 Wolfe PC/cigarette lighter combo cable
- Get this. It lets you use your car's cig power for the GPS, and plug into the laptop's data connector at the same time.