GPS Works — Or Does It?
Wonder why I haven’t read more articles like this in US news sources? If I were a conspiracy theorist I’d suspect a cover-up, but as the man said, “never ascribe to malice what is adequately explained by ignorance”. read the Xinhua article on why GPS doesn’t work here and then come back to see my conclusions.
BEIJING, May 18 — A few weeks ago a man turned up at my front door, having been guided there by a GPS satellite navigation system on his dashboard. He was a bit surprised when I told him that the place he was looking for was 10 kilometers away.
I was less surprised because I have been testing these potentially wonderful devices for nearly five years and have yet to come across a single one reliable enough to justify shelling out hundreds of dollars for something that is often less reliable than a map.
One still marvels at a technology able to pinpoint your position and guide you to restaurants and hotels nearby - when it is working properly. I meet people who swear by them, though if you probe further they often encounter bugs such as being directed the wrong way down a one-way street or being given instructions on the motorway seconds after the turnoff has been passed….
In most cases what the writer is commenting on here is the “Urban Canyon” effect and other GPS inaccuracies caused or exacerbated by a poor view of the sky. GPS (or any of its proposed substitutes like China’s own Compass system, the seriously flawed Galileo of the EU, Russia’s GLONASS, etc. must have a good view of the sky in order to produce even their basic specified accuracy.
If you are driving a lot on city streets, depressed highways, in and out of parking garages and under thick forest canopies GPS technology is going to be challenged. To be sure you don’t wind up 10 km in the wrong direction (6 miles for the metrically “hard of thinking”), here are a few tips:
- Use a system with a separate antenna and mount it where it gets the best view of the sky possible.
- Use a system with an active, powered antenna rather than the cheap passive devices most manufacturers try to palm off as “good enough”.
- Use a system that includes WAAS (Wide Area Augmentation System) … WASS is another free US Government service that will increase accuracy astoundingly.
- Test and measure under your actual driving conditions before you invest. A reputable dealer or manufacturer will allow you to test before you buy … if they won’t, you’ll get a better ROI by keeping your money in your pocket.
