Until recently, the civilian Global Positioning System (GPS) was a good tool for navigating global terrain. However, as of May 2, 2000, GPS users have experienced dramatic accuracy improvements with their old and new GPS units, making them a great navigational tool. President Clinton decided to throw the switch on the Selective Availability (SA), which reduced accuracy of up to 100 meters, or more. Clinton believes “this increase in accuracy will enhance the lives of people around the world.”
For the past ten years hunters and anglers have used the GPS as a guide for navigating all types of terrain and water sources. This device was made possible by the Department Of Defense (DOD), as a way of allowing the general public to enjoy the comfort and safety of knowing exactly where they are at any given day and time. The GPS works by transmitting radio signals to outer space, which thereby locate receiver satellites, called Space Vehicles (SV). A typical GPS unit requires a lock on to at least three SV’s to display accurate locations and time readings. However, as many as four to eight SV’s will improve the accuracy of a particular unit.
Many outdoor enthusiasts have used these units for years, and noticed slight inaccuracies with pinpointing their exact location. This inaccuracy (SA) was a DOD mandated degradation, limiting accuracy for non-military and government users. Though SA limited the potential accuracy of GPS units, these devices have remained an indispensable tool for navigation; whether hiking, hunting, boating, or merely exploring.
Good News Has Arrived
Good news my fellow enthusiasts! Now that SA is no longer, the doors to the future are wide open, and everyone using their old or new GPS units should now experience accuracy of 10 to 20 meters. I have tested this theory and have been completely amazed by the results. Now, my GPS shows me exactly where I am on any given USGS topographical map, to within 20 meters.
How This Helps You
Hunters will now be able to safely leave their camps or kill sites with reassurance that their GPS units will bring them back to the same location (within 10 to 20 meters); whereas before they had to respect the >100-meter inaccuracy and take a chance on never relocating their possessions. A 100-meter, or more, inaccuracy in Alaska could find you pushing your way a through dense spruce forest or wondering aimlessly over sedge tussocks and clone-like hills of tundra, searching for your intended point of aim.
Today users should be completely happy with the accuracy of their units. The DOD states they have no plans to ever reapply the SA mode to the space-orbiting satellites, therefore, global users should experience satisfactory results with navigation.
FAQ’s
- Should I replace my old model? No, older models should be getting the higher accuracy right now, without modifications.
- Since Alaska is not a direct part of the contiguous 48, will we still get more accuracy? Yes, the Standard Positioning Service (SPS) signal is updated to reflect the new accuracy available without SA. This means a global update has occurred.
- Will GPS units improve in the future? Absolutely, consumers should start seeing lighter-weight, more compact models by next year. Companies are sure to begin marketing this wave of technological advance.
- Will Selective Availability be turned on again? The DOD has stated they have no plans to ever use SA again, but national security will determine their future decision.
- Which brand should I buy? It depends on your budget and preferences. Units are available from $99 to $350. From my research, Garmin tops the reliable units. Megellan and Eagle also rank among the best manufacturers.
Remember to always use your GPS in conjunction with USGS topographical maps. This way you can use terrain association along with geodetic information, ensuring that mistakes in navigation are limited and that you may refer to your map in case of GPS failure. A back-up compass is also a good idea. For general map reading, refer to Cliff Jacobson’s book Basic Essentials of Map and Compass. To learn more about the practical hunting uses of the GPS, refer to my book, A Complete Guide To Float Hunting Alaska. Check it out in book stores or online in our store.
-Larry Bartlett
Author / Wilderness Guide