GPS article from our local paper (Read 536 times)

The Tennessean Saturday, 06/02/07 Runners say GPS is off-course Distances often disputed by racers By JESSICA HOPP Staff Writer All Jeff Rhoads wanted to do was finish the Country Music Marathon. He had developed T-shaped blisters on the soles of his feet that made every stride a struggle, but he was armed with a Garmin Forerunner 305, a wrist device that logs an athlete's speed, distance and pace through Global Positioning System technology, so he knew exactly how far he needed to go. When the California-native finally saw the digital readout on his wrist tick to 26.2 miles, the large sign posted on the race course offered an unpleasant surprise. It read "Mile 26." "More than a few four-letter words were going off in my head," Rhoads said. Rhoads, who suffered through two-tenths of a mile before the finish, found something many other distance runners are learning: the technology in one of the hottest-selling new running devices isn't perfect. That is causing concern in runners and controversy for the manufacturers and race directors. As more people complain about the inconsistency between course distances and their GPS readouts, the people who measure course distances and the companies who produce GPS devices are pointing fingers at each other. Terry Coker, a 35-year running veteran and co-owner of local athletic store Team Nashville, remains so skeptical of the devices that he won't sell them at his West End store despite the fact that sales for Garmin's fitness and outdoor line were up 20 percent last year nationwide and accounted for $285 million in revenue. "We do not carry them because they are always just a tad off (in distance measurement)," Coker said. "… Until they perfect it, I can't give my endorsement." The device Technology companies, such as Garmin, stand by the exactness of their fitness products. Garmin spokeswoman Jessica Myers said technological advancements in the last several years have improved measurement precision in the newest models — the Forerunner 205 and 305 — to within 3 meters of actual distance traveled. Myers said the 101, 201, 301 Garmin models do not have a "high-sensitivity GPS receiver" so they may be slightly less reliable with accuracy within 15 meters, but that is still not enough to make a significant difference for runners. "GPS is a lot more accurate than people assume it to be," Myers said of the technology, which was developed by the Department of Defense in 1973 and made available to civilians in the late 1980s. In 2003, the government launched the Wide Area Augmentation System, or WAAS, which included ground stations that helped correct the satellite signal and make it more accurate. Still many users say GPS units like Garmin's — which range in price from $160-$377, according to the Garmin Web site — are not without glitches. The main consumer concern is the loss of the satellite signal, which affects the distance measured. "The only thing bad about it is you get under tree lines and the reading can get off," Coker. "I have a friend that runs in Percy Warner Park and he goes ballistic with his. He says, 'I ran 20 miles and the stupid thing tells me I have only run 11 miles.'" Myers conceded occasions when a unit might lose its signal, but she did not believe a few trees could stop the system from working. "GPS is based upon having a clear view of the sky," Myers said. "If you are in a building or a parking garage and you don't have clear view of sky, most likely you will not pick up a signal. "Heavy tree coverage and what we call urban canyons — running under tall buildings in the city — used to cause a hard time picking up signal, but that has improved. High-sensitivity GPS receivers make it much less likely to lose a signal in those environments — not to imply that it won't ever lose the signal." Nashville resident Pamela Hobson, who has owned two Garmin Forerunners, said it does take awhile for the device to find a satellite signal and dense foliage can render it useless. For the most part, however, she is pleased with the advancement the GPS technology. "I think it's great," Hobson said. "It's definitely an advance. It takes something that was a little more guesswork, and now we are able to be a little more accurate and precise with our training." Myers said her company has received e-mails from customers concerned that their GPS measurements don't match those of the race courses. She said reading differentials were not because of the inaccuracy of the GPS device but to the inaccuracy of the race course. "Generally from my understanding of the situation, race coordinators in an attempt to make sure the course meets standards might extend the race slightly," Myers said. And when it comes to large distance differentials like Rhoads? "There is a lot of 'what ifs' in that scenario that makes it hard to know what happens in each individual race," Myers said. The race course When a race course is measured for certification it is done so from the inner most tangent of the course, said Jim Zeigler, a certified course measurer for the Road Running Technical Council, which oversees the certification of courses nationwide. Zeigler said that means runners will log a distance slightly longer than the race itself, which could account for GPS readings with a few extra tenths on long races like marathons. "Runners very seldom run the most direct route, they wander all over the course," said Zeigler, a Nashville resident who was responsible for measuring the Country Music Marathon. "Even the Elite runners swing wide around some corners when the most direct line is a sharp turn. One arc would probably cost them 20 or 30 feet, which is not significant until you do it 100 times. You would be amazed at how much of a difference it makes." Wandering, however, does not account for all the disparity, Zeigler said, adding that much of it is caused by the inaccuracy of the GPS devices. With so many runners questioning the Road Running Technical Council's course measurements, several of the group's members have run in-formal experiments testing the precision of GPS fitness units. Many of the results are logged on the Road Running Technical Council's public message board (http://measure.infopop.cc/eve/ub) and most of them conclude that there is some margin of error in the GPS devices. "GPS just aren't accurate," Road Running Technical Council chairman Gene Newman said. "I am not saying GPS is not a good device to give good indication of where you are, but the only acceptable GPS for accurately measuring a race course costs 30 grand." With continued angst from runners, Newman said the organization would like Garmin to issue a statement to that effect in order to keep runners informed of possible variations. Rhoads, who sent e-mails to Garmin and event organizer Elite Racing after his experience in the Country Music Marathon, is still waiting to hear back from both. "Was Garmin wrong or not? Was the official measurer wrong or not? I don't know," Rhoads said. "I didn't get hurt out of it, and I can still go forward with my races this year, so I am happy."

She said reading differentials were not because of the inaccuracy of the GPS device but to the inaccuracy of the race course. "Generally from my understanding of the situation, race coordinators in an attempt to make sure the course meets standards might extend the race slightly," Myers said. "

WHALESHIT!!!!!!!!!!!!!!!!!!!!!!!!!

I don't have a problem with it being a bit off, personally. I use it for training, and it gets me close enough. I use it as a rough indicator while racing, and it also gets me close enough. I will also say, though, that I have run more than a few races where the course was longer. Not only did the Garmin say it was so, but so did my mapping software on my computer and my car odometer, so there may be some truth to the statement that the courses aren't always accurate, either.