Sunday, January 13, 2013

Garmin Personal Navigator GPS 12

Basic GPS unit that you can drop and get wet

A handy and easy to use GPS unit, the Garmin Personal Navigator GPS 12 is an excellent first-time GPS unit for new users and powerful enough for more advanced users who want something that can withstand the rigors of outdoor use.

Designed from the ground up as a GPS receiver for outdoor adventurers who don’t need all the whiz bang features of other models, the Personal Navigator 12 (PN 12) provides all the benefits of a GPS receiver in a rugged package. The PN 12 is based upon the more feature rich GPS 12XL and offers outdoor users the benefits of a 12-channel GPS receiver, no matter the conditions that they are using it.

Unit Details 

The PN 12 is built with a rugged, waterproof plastic case. While I wouldn’t suggest it, the unit is tough enough to survive drops and falls and can be momentarily submerged in water (it is rated to survive up to 30 minutes submerged completely in water). In more benign conditions like rain or snow, the unit performs with no problems.

The PN 12 features a rocker keypad design that facilitates one-handed operation (you can use your thumb to move the keypad) and it is easy enough to use while you are moving. The display is about 2 inches high and 1 ½ inches wide and is made up of a high-contrast LCD screen that also has electro-luminescent backlight for use in all conditions including nighttime. Navigation through the menu system and options on the unit is straightforward and easy to follow.

The unit is about 2 inches wide, 5 ½ inches high and about 1 inch deep and weights in at 9 ½ ounces when fully loaded with its batteries. This is a little larger than some GPS units, but comfortable enough to be handheld and easily packed away when you don’t need it.

The PN 12 features an internal rechargeable lithium battery as a memory backup battery (to save your stored information) and runs on 4 AA batteries. With new batteries the unit should run for continuously for approximately 24 hours. More scattered use should provide significantly more battery time (not really more than 24 hours, it’s just scattered about).

Able to store up to 500 waypoints in memory, the PN 12 also features the ability to store 20 different routes (and reversible) routes each with 30 waypoints. In addition to laying out the routes, the PN 12 is has a “TracBack” function that allows you to automatically reverse your course and go back the same way that you have just traveled (sort of the proverbial line of bread crumbs). Coordinates can be displayed in latitude and longitude, UTM, and MGRS to just name a few of the available coordinate grid systems.

The PN 12 has a positioning averaging feature that helps to reduce the error introduced by the government’s Selective Availability (SA) policy. The unit gives both a figure with the SA and the estimated accuracy of the averaged position. The receiver is also ready to accept a differential GPS receiver that will increase the accuracy of the unit tremendously – but regular users should not need this additional accuracy. Without the differential attachment, the accuracy for the PN 12 however around 15 meters (about 50 feet – though this may increase or decrease depending upon the number of satellites received and the SA policy in the area), and with the differential attachment, this accuracy is increased to between 1 and 5 meters (3 to 15 feet). The PN 12 can receive signals from up to 12 different satellites in the GPS constellation, however it’s unlikely that you’ll ever lock onto all 12 at any one time.

How’s It Work? 

In practice the accuracy of the PN 12 is often greater than the rated 15 meters, even without the differential attachment. This is because while Selective Availability is still in place, throughout most of the country the difference has been reduced to the point that even handheld units have great accuracy. Areas where you may run into problem with the unit’s accuracy are in places where the government has maintained the higher Selective Availability, such as near military bases and other government installations.

We used these units where I worked in Maine to locate roads, house lots and structures on lots. When the points were downloaded and plotted in ArcView, the accuracy was quite good, except again for areas near military installations. Near those areas, you couldn’t rely on the points as accurately representing the location.

The unit holds up as well as it advertises. We dropped them, got them wet, packed them away and let them sit in vehicles and never had a single problem with any one of the units that we had (we had 8 of them).

If you want more information on how the exactly GPS works, or on GPS in general, check out a book like GPS Made Easy, it is a great introduction to GPS navigation in the outdoors and will have you up running with your GPS much faster than trying to figure it out on your own.

The Final Word 

No one needs sub-meter accuracy in a GPS unit unless they are using it for surveying, or detailed research work. For those of us out in the woods navigating or driving and using GPS for navigation, need nothing more than the 15-meter accuracy. Yes, you may probably want better accuracy, but in reality, you don’t need anything better than that.

The Personal Navigator 12 proves to be a worthy GPS workhouse for outdoor users, handling the rough conditions of the outdoors with ease.

While the Personal Navigator 12 may lack some high-end features of newer or more expensive GPS units, the basic level of GPS functionality that it does provide, is more than enough for the average outdoors GPS user.

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