Why The US Military Made GPS Free-To-Use

Real Engineering goes into the history of the US GPS system.
siftbotsays...

Promoting this video and sending it back into the queue for one more try; last queued Monday, June 19th, 2017 7:14pm PDT - promote requested by eric3579.

MilkmanDansays...

Interesting and good, but it missed an opportunity to talk about another reason that Clinton removed the scrambling that reduced accuracy to ~100m in 2000:

It was fairly easily circumvented.

Your GPS device isn't sending anything TO the satellites -- just receiving FROM them. So, the scrambling had to be done on a system-wide scale; it couldn't skew your location 37m to the west and your friend a block away 62m northeast. So, every device in a particular area (that can see the same satellites) would be skewed by essentially the same distance and direction.

That means that all you needed to circumvent the scrambling was a GPS device relatively nearby at a known latitude and longitude. Then you took the GPS reported coordinates of that device and compared them to the known coordinates, and badda-bing you've got the skew figured out.

I remember that system being used to overcome the scrambling in the late 90's for robotics / AI competitions where things like early versions of drones or other robots had to autonomously navigate a maze or move towards some particular target coordinates.

Basically, if nerdy robotics enthusiasts could circumvent the scrambling, surely a motivated enemy military or terrorist group could too. So, there wasn't much point in continuing it. Ending the scrambling was a good thing for Clinton to do, but I'm sure that impracticality played just as much if not more of a part in his decision as benevolence towards citizens of the Earth / potential economic rewards for American companies did...

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