What’s going on may not be apparent to most users of “GPS-enhanced” ARDF receivers since simply listening to the audio doesn’t provide many clues as to what’s really happening under the hood. But devices that use satellite navigation signals to derive “continuous bearings” and cross track error indications, are making use of a continuous stream of GPS-derived position data that (typically) exhibits a position error of 10 meters or less. That degree of accuracy is easily on par with what expert orienteers can achieve using just a map and compass.
It also might not be obvious that a bearing consists of not just a direction, but also the position at which the direction was read. So accurate position information also enhances the accuracy of bearings.
With the use of GPS, accurate positions are derived and utilized regardless of where a competitor believes himself to be located on the map. GPS accuracy is undiminished when a competitor is tired, confused, or just a lousy orienteer. And because those positions are true and accurate, the bearings and crosstrack error indications provide highly accurate navigation guidance to the actual location of a signal source (fox), even if the competitor erroneously believes that he is headed in a totally different map direction from where his feet are actually taking him.
Most ARDF courses include some very runnable regions with little or no obstacles; though such regions might still be challenging to navigate, they can be traversed easily in a nearly straight line. A GPS device allows one to follow a straight line, accurately, and inerrantly. So on a course with no significant obstacles to movement, a map becomes an unnecessary accessory when GPS is being used. Hundreds of hours spent testing the iPhone app “Map-n-Compass” proved that to be true. The app uses GPS to provide guidance from GPS-derived position data, identical to the technology incorporated into ARDF receivers sporting GPS receivers. The more runnable the terrain, the more effectively GPS replaces the need for a map, and those skills required to read a map and locate one’s location on it.
But GPS also has an impact when courses cover difficult terrain. Consider a course with significant barriers to movement, such as dense forest, steep hills, and swift creeks. Such barriers will pose less of an obstacle to the strongest and fittest competitors, who will be better able to power over the hills, and through deep water, and more closely follow the shortest straight-line route between foxes provided by the GPS-derived crosstrack error. With two equally-skilled navigators, both using GPS, the advantage will swing decidedly in the direction of the one who can best follow the continuous GPS-derived audio-indicated straight-line path. So GPS swings the advantage to those who are most physically fit and powerful, over those with better navigation skills.
It remains true that GPS doesn’t help with pointing an antenna and reading signal strength. It also doesn’t help one recognize reflected signals, and doesn’t make one a good trail runner. And it supplements but doesn’t totally replace observing one’s progress and surroundings to estimate position on a map, and choosing a reasonable route to follow. GPS doesn’t eliminate the need for all skills. But in many situations it greatly reduces the importance of navigation skills.
If you don’t think that satellite position data currently reduces the importance of navigation skills, then just wait. Better algorithms and integration with additional sensor data will bring new features, making it unrealistic for anyone to be competitive without incorporating satellite navigation systems into their receivers.
The latest technology needs to be brought into ARDF equipment. But that doesn’t mean that all technology belongs in the sport. Let’s make the equipment lighter, more integrated, more rugged, less expensive, more available, and simpler to use. But let’s not diminish the fundamental skills required for the sport.
IARU Region I has already set its course toward transforming ARDF into an exercise in geocaching. That doesn’t mean that other regions must follow suit. If “AGPS” proves popular, then it can be added as a separate class of competitor, like the age and gender categories that exist today. But let’s keep traditional classic ARDF as an individual navigation sport: a sport of equal measures brains and brawn.