Using a Garmin GPS
You have just purchased a GPS (Global Positioning System) unit/receiver. As you explore the GPS frontier you will most likely have some questions. Stop by Joe’s and we should be able to answer all your questions. Below we’ve provide quick GPS overview.
The 4 Basic Functions
These are common to virtually any GPS receiver intended for outdoor adventure:
Your location: A GPS unit accurately triangulates your position by receiving data transmissions from multiple orbiting satellites. Your position is given in coordinates: latitude and longitude or Universal Transverse Mercators (UTMs).
Point-to-point navigation: A location, position, or destination is called a "waypoint." This can be a trail head, campsite, or any point of interest. This can be taken using the GPS or from a map, software , and a website. The GPS unit will give you a straight-line, point-to-point bearing and distance to your destination. Since routes are never straight the GPS bearing will change as you travel. The distance to travel will decrease as you approach your goal.
"Route" navigation: By combining multiple waypoints on a trail/route, you can move point-to-point with intermediate bearing and distance guides. Once you reach the first predetermined waypoint, the GPS receiver can automatically point you to the next one.
Keep a "track:" One of the most useful functions of a GPS unit is its ability to lay a virtual trail of where you've been. This is called a track. This differs from a "route," which details where you're going. You can configure a GPS to automatically record "trackpoints" over intervals of either time or distance. To retrace your steps, simply follow the GPS bearings back through the sequence of trackpoints recorded.
A GPS receiver does NOT replace a map and compass or the knowledge of how to use them. Your GPS unit will augment and enhance your navigational abilities with technology. You should still always carry a detailed map of the area and a compass.
A GPS unit is only as good as the map you use with it. The most-useful topographical map available in Ontario is the Backroads Map system available on SD card or DVD. Back Roads Map is licensed Garmin product. This allows the user to zoom into the landscape to a scale of 1:10,000 and 1:20,000
Practice! Practice! Practice! Before using your GPS receiver as a primary navigational tool in unfamiliar territory familiarize yourself with all of the unit's features and controls. Read the manual. Practice in familiar territory until you're comfortable with how everything works. Pop into Joe’s if you have any questions.
To provide accurate navigational information which includes your position, a GPS unit must acquire signals from 4 satellites. To see how many satellites your unit is using turn on your unit and go to the Satellite Screen:
It may take several minutes for the GPS unit to lock in to the satellites, so be patient. The display will list the number of satellites along with the strength of the signals.
If only a few satellites are visible and they display weak signals don't rely on the GPS' directions.
A clear view of the sky is best for an optimal satellite lock. Tree canopy, canyons and tall buildings that obscure the view overhead or of the horizon can at times hamper reception.
Ensure the batteries in the unit are fully charged.
To make map navigation easier, a system of coordinates is used. Coordinates divide the map into a grid and identify a particular location by listing its relative position north/south and east/west. To choose a coordinate system, simply go to the Preferences screen. The most common coordinate systems used in GPS navigation are:
DMS (Degrees/Minutes/Seconds): This is the standard way of listing latitude and longitude:
Example: N47° 37' 12" W122° 19' 45".
In this example, N47° 37' 12" indicates that the north/south position is 47 degrees, 37 minutes and 12 seconds north of the equator; while W122° 19' 45" places the east/west position at 122 degrees, 19 minutes and 45 seconds west of the Prime Meridian (at Greenwich, England).
DDM (Degree Decimal Minutes): A decimal version of DMS, DDM is used by geocachers and other GPS enthusiasts. These coordinates look like this:
Example: N47° 37.216' W122° 19.75'.
The north/south and east/west position remains unchanged. The difference is that the seconds part of the location is converted to a decimal by dividing the seconds by 60.
UTM (Universal Transverse Mercator): This military-derived grid system is not tied to latitude and longitude. It divides the map into a square grid with the grid lines all 1,000 meters apart. Most topo maps have UTM grid lines printed on them. The system is metric-based and requires no conversion of minutes and seconds.
Example: 17T 0550368 5274319.
Here, "17T" identifies the map zone, "0550368" is the east/west or "easting" number, while "5274319" is the north/south or "northing" number.
Your GPS unit can automatically display whichever of these coordinate systems you select. It will convert coordinates from one system to another. This is helpful if you're given coordinates for a location in one system (e.g., UTM), but want to actually navigate in another (e.g., DDM).
Plotting a route with waypoints is easy. Simply press the MARK/man-over-board button (or, on some units, press and hold the ENTER button). If you're marking a waypoint where you stand, you can often do this with the single press of a button. You can also add multiple levels of detail: a name, the coordinates, the elevation and even a short note.
With waypoints in place, your GPS unit can guide you from point to point. Use the FIND or GOTO button to identify a particular waypoint target. Then switch to the Compass screen where the GPS receiver will give you a bearing and estimate the distance and time of travel.
Keeping a Track
If you take a spontaneous side trip from base camp or in any way venture into unknown territory, one of your GPS receiver's most useful features, "tracking," comes into play. When you enable the TRACK RECORDING feature, the GPS unit will automatically set trackpoints as you go, essentially laying a Hansel and Grettle breadcrumb trail to show where you've been.
You can adjust trackpoints to be laid at specified intervals of time or distance. In addition to this essential guiding feature, tracking also allows you to record time and distance travelled.
Getting the Most out of Your GPS
Barometric altimeter: All GPS units provide elevation as part of the information gleaned from the satellites. The advantage of having a barometric altimeter is that it operates without signal from a satellite. So if the signal is too weak to be reliable, the barometric altimeter can still give you an accurate elevation. Since it also measures air pressure, it will give you an idea of approaching weather changes by displaying a chart of barometric trends.
Three-axis compass: The three-axis compass works in a similar manner to a traditional compass. A three-axis compass does not require the GPS user to be constantly moving. With some units, the compass will not work efficiently unless the user is moving.
In addition to having preloaded maps, many GPS units allow you to download more maps using DVD software (available separately). Some GPS units improve flexibility by using removable microSD memory cards. These cards are available preloaded, or you can download maps from your computer to a blank card. If your GPS unit uses memory (SD) cards, it's easy to organize your maps for maximum efficiency and ease.
Batteries: Make sure they're fresh at the start of your trip. And carry spares. Consider turning off nonessential features such as auto-routing and backlighting to conserve battery life.
Tip: Lithium batteries are the best choice for GPS receivers due to their long life. However, when brand-new, these batteries have a brief power spike that adds unwanted horizontal lines across some GPS screens. To solve this, simply use the lithium batteries on another electronic device for a few minutes, and then insert them into your GPS unit.