Dorkery Alert! (GPS)

I spent a chunk of yesterday playing with a new toy--I finally had time to walk around with my Garmin GPS 12 global positioning system, making sure I could pick up satellite signal with this unit.

I've always thought the concept of GPS was incredibly cool--a military-run system of navigation satellites that is free for the use of civilians. Also, an interesting read in the Wikipedia article is SA (selective availability): at the origin of GPS, the military intentionally introduced error to the civilian-available (unencoded) signal of ~30 m, so that the enemy couldn't use it during wartime. However, during Gulf War I, the military didn't have enough GPS units, so they had to buy civilian models ("Sergeant! Take two men and do a run to REI! Here's my credit card!"), and the military turned off this feature. Since around 2000, the military has turned off SA permanently, due to pressure from the FAA (i.e., so they could rely on GPS, instead of navigation systems that they have to maintain), and other users.

Another cool tidbit: the GPS system corrects for relativistic effects! Whoah.

Incidentally, this reminds me of a New York Times story I read a while ago. During the response to Katrina, there was a huge clusterfuck because of all of the disparate navigation systems in use. The military used GPS, but some other agency (FEMA? Coast Guard?) used a different navigation system. And to make it more complicated, the 911 dispatchers were purely dependent on street addresses, and couldn't translate to latitude/longitude or UTM (universal transverse mercator--one of the grid systems used by the military).

Anyway, that afternoon, I walked up the Minuteman Trail, while continuously monitoring my speed, bearing (track), position, and altitude:


But wait, it gets even dorkier than that! This walk was a grocery run. So picture me walking back home with a backpack stuffed with groceries (including a box of cereal strapped to the outside); one hand was holding the GPS, and the other carrying a 24-pack of Charmin. Yeah, even going to the grocery store is an adventure with Bats, eh?

It took me a little while to figure out that the default time signal shows Zulu time (Greenwich Mean Time) ("no, it's not 8 PM now"), instead of local. But you can add in your local time zone offset no problem.

Before you beat me up based on my previous post mentioning consumption/buying habits, this is a factory refurbished unit I got for under $100 from REI's Online Outlet Store, and it's been on my list of "stuff I'll get when I have an income" since I started grad school.

And in case you were worried about my using a factory refurbished GPS out in the wild somewhere, I have no plans to use this for life & death applications or anything. My backwoods camping has always been on marked trails.