Preface to Working with Garmin Receivers

"Working with Garmin receivers" is intended to be a practical operation manual for the entire line of Garmin handheld receivers. While Garmin has many features that are the same across their entire product line they also have many differences. In an attempt to isolate the major user interface differences to one section this manual uses fairly generic step by step instructions throughout the document. Please read the section on user interface early in your reading. This will help you understand the philosophy of the interface design and will hopefully allow you to understand generic instructions and relate them to the exact key sequences that you will need to use.

This manual covers both older "multiplex receivers" and the newer 12 channel parallel units. Older units are primarily the G-45 family of products. The 45 family consists of the 45 and its successor the 45XL as well as its brothers the G-40 and the baby of the family the G-38. For automobile use many chose the G-II as their preferred unit. At one time these were the premier handhelds but technology has made them obsolete but still useful for a great many people.

The newer parallel units fall into several families. The G-12 family looks similar to the older multiplex units and includes the G-12 at the bottom (shown on the left) and the G-12XL as the vanguard product. The G-48 rounds out the family at the top as a replacement for the older G-45XL. To maintain the automotive market the G-II was replaced with the G-II+, still a favorite for users wanting a unit that can switch itself from automotive (horizontal orientation) to handheld (vertical orientation). A new family was introduced with the G-III (shown on the right). It uses the case design of the II+ and added internal maps to the suite of other information available for the user. The G-III family includes the G-III, the G-III+ with uploadable detailed street maps, and the G-III Pilot, with a Jeppesen database and special features for flying use. The G-III family has a different interface from the G-12 family in that it is much more menu oriented.

In addition to these families there are several individual products that are covered in the manual. The 12CX is a latest generation handheld with color display, 1000 waypoints, a 2000 point track log, audible alarms and dedicated zoom keys. Otherwise it is similar to the 12XL. The 12MAP uses the 12CX hardware design with its audible alarm and patch antenna. It is then loaded with III+ software and high-res grey scale screen so it has built in maps, customizable display features and III family user interface.

Garmin introduced a pluggable memory cartridge in it Street Pilot vehicle units and later developed the emap as a portable unit that can use these same cartridges (shown to the left). It differs from other Garmin units in may ways and is focused on providing and electronic map display with gps functionality. Garmin took a new tack in the etrex (shown on the right). This began as a small entry level hiking unit weighing only 5.3 oz. Its success led to the introduction of a whole new family of smaller handhelds including the Summit, Garmin's first unit with an integrated fluxgate compass and barometric altimeter; the Venture, a full featured replacement for the G-12 series for hiking use; and two new small mapping units, the Legend and the Vista. The Vista combines a mapping unit with an integrated compass and altimeter. To provide for marine users Garmin has introduced the 76 and the Map76 line of handhelds with specific marine features.

Thus Garmin handhelds have progressed from the original multiplex receivers to the second generation of receivers featuring 12 channel receivers to the latest even lighter units that all run off of 3 Volts power while supporting the same or improved functions of their 6 volt predecessors.

This manual does not explicitly cover non-handhelds like the StreetPilot family or the new aviation/automotive unit, the 295. Nor does it cover the dedicated marine units. There is a chapter briefly highlighting these units so that these users can determine which areas of the manual are likely to apply to their models. The StreetPilot units have a distinct user interface and different capabilities that primarily feature detailed moving map support with secondary support for traditional gps functions. They are most like the emap unit which is covered in this manual. Users of the aviation or larger marine products are similar in many ways to the handheld units and thus these user may still find this manual useful in describing features and capabilities as generally applied to the Garmin philosophy and theory of gps design.

I would like to offer my special thanks to the sci.geo.satellite-nav newsgroup whose members have provided me with the education I needed to to this manual. Note that information provided in this manual is based on my own knowledge and, in some cases, conjecture. Garmin considers much of its internal algorithms to be proprietary so a user must look at the results and try and guess as to how they were computed. Garmin have every right to maintain this position but it means that there are some subtle performance information that is undocumented by them. I have attempted to provide one reasonable explanation for these kinds of behaviors but it may not be the correct one. It should, at least, help you in understanding how is could work! Please let me know of anything you find that is incorrect or that could be worded better.

Getting Started

The first step in working with your new Garmin is getting power for the unit. Most of the time this means installing a set of 4 AA batteries (2 AA's on the latest generation units). To install the batteries look on the bottom of the unit and turn the D ring 90 degrees counterclockwise. (The emap door just slides off.) This will release the door and permit the installation of the batteries. Notice that there is a + and a - indicated near the battery tubes. Make sure the new batteries a placed in the unit with the + side of the battery showing at the + end and the - side of the battery showing on the minus end. Once installed you can close the case using the D ring to lock it down. All Garmin handhelds also support an external interface connector that can also be used to power the unit. This use is covered in a later chapter.

Now turn the unit on by holding the red button down long enough for the opening screen to appear on the display. (The power button is on the side on etrex and emap.) The unit will perform some internal tests and start acquiring satellites so that it can compute a position. Mapping units will normally require you to acknowledge a disclaimer screen by pressing the enter key. If you wait long enough this screen will time out. If this is the first time you have used the unit you will normally have to provide it with a general idea of your current location. This is an optional step, and is not available on the etrex, since if you are willing to wait a little longer to find your first position you can skip this. This can be done on some units by scrolling through a list of states and countries,using the arrow keys or pad, or on units with maps you can scroll on the map itself to select your approximate location. (For more information on obtaining a fix see the chapter on this subject.) Once the unit has acquired 3 satellites it will compute a fix and switch from the opening satellite status screen to the position screen. (The emap does not switch screens nor does it have a page key.) You can now use the unit to read your current location and other data. Pressing the page key multiple times will switch you through most of the available screen displays.

To turn the unit off, press and hold the red button (the same button you used to turn it on) for 3 seconds until the unit turns off. While the unit is on pressing the this button will toggle the backlight on and off. (Emap has a separate button for this.) On some units you can press this button multiple times to increase the lamp brightness. There is a small icon that looks like a light bulb on the opening status screen (The etrex and emap have this on the global menu screen.) that indicates when the lamp is on. Generally this lamp is set to timeout after a period of time. If it goes out, depressing any key will turn it back on. You will have to depress the key a second time to perform whatever function it was supposed to do.

While any AA cells can be used in your unit it will work best with AA alkaline batteries. Four fresh batteries will generally produce slightly more than 6 volts of output and register full on the battery gauge that appears on the status screen. (Two batteries for 3 volts on the etrex and emap) The empty mark on the gauge corresponds to 4 volts (2 volts on the etrex and emap) from the batteries and the unit will shut down when the battery voltage drops below about 3.8 volts on a G-III family or about 3.7 volts on a G-12 family or one of the older multiplex units. Battery life varies from one unit to another with newer units getting the best battery life. On older units the battery life can be as low as 8 hours while on the latest units using a battery save feature can reach a claimed life of 35 hours from a 4 cell unit and nearly 20 hours on a 2 cell unit. Actual life varies a lot depending on conditions.

Many users prefer to use rechargeable batteries in their units. While they need to be replaced more often the total life of the batteries is much longer. The low battery warning level works for all battery types but the full charge on ni-cad and NiMH batteries will show only 3/4 full. This is normal behavior but the G-III family has a special setting for ni-cad batteries to give a better battery display if you want to use it. For best battery performance you should replace rechargeables as soon as you receive the low warning indication. You will have to recharge any batteries external to the unit as there is no provision for recharging them while inserted in the case. In cold climates lithium batteries may offer the best performance.

Battery manufacturers are not very consistent in the diameter of the AA batteries. In particular the batteries with the gauges builtin tend to be slightly larger in diameter than the normal batteries. This has been known to cause problems of premature shutdowns in some units in high vibration environments, such as on motorcycles or off road vehicles. The best solution, if you experience this problem, is to add a ring of tape to the outside two batteries so that they are fairly snug in the tube. Don't add too much or you may have problems removing the batteries. Garmin retrofitted some G-II+ units and G-III units with a capacitor to minimize the impact of this problem but you may still experience it in a few cases. Using external power is also a good way to prevent this problem. For more information on batteries look in the User Interface chapter.

99/6/22 initial release
99/8/10 added section on getting started
99/9/9 revised preface for more model numbers.
00/2/10 added etrex data.
00/6/1 added emap data
00/7/5 moved some battery data to user interface chapter.
01/7/13 made some minor updates.

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by: Dale DePriest - all rights reserved.