GPS unscrambled

[Brian]

My wife said that she heard (twice) on the radio news that GPS is going to be permenantly unscrambled. Has anyone heard of this or have more info? I searched the Boston Globe today in search of a story but found none. (What a shock)

[Jeff Bredthauer]

It's true! As of midnight last night, the accuracy of the system is 10 times greater than it was yesterday. Everyones GPS units will be that much more precise (even without DGPS). Nice suprise.

My wife said that she heard (twice) on the radio news that GPS is going to be permenantly unscrambled. Has anyone heard of this or have more info? I searched the Boston Globe today in search of a story but found none. (What a shock)

jbredthauer@stez.org

[Peter Baumgartner]

There is an article in today's on-line New York Times.

http://www.nytimes.com/library/tech/yr/ ... 02gps.html

Since I ordered a new fixed GPS yesterday, I feel particularily fortunate.

Peter Baumgartner
CD27 #35 "London"

My wife said that she heard (twice) on the radio news that GPS is going to be permenantly unscrambled. Has anyone heard of this or have more info? I searched the Boston Globe today in search of a story but found none. (What a shock)

pjb@napsys.com

[Jon]

Brian,

I found the GPS story in the Boston Globe. It is right between the article on Republicans stealing small children at night and the one about George Bush smoking crack and worshiping Satan.

Jon

[Scott Ritchey]

In the interest of precision, the GPS program has removed the Selective Availability (SA) dither which added a selectable amount of random error to the locations measured by Clear Acquisition (CA) code GPS receivers ... which includes all commercially-available GPS units. With CA turned on (before), the error was guaranteed to be less than 100 meters 95% of the time. In actuality, it was probably closer to 60 meters. Now, the accuracy should be maybe 20 meters. The error is not zero because atmospheric refraction, which changes the "electrical path legnth" form satellite to receiver is unpredictable and varies with atmospheric conditions in an unpredictable way.

Still, the military signal is encrypted and uses two different frequencies (which allows correction for refraction). A military GPS will do better than 20 meters, although differential techniques are still needed to get in the 2-3 meter range (same as commerial differential).

So long story but nothing was descrambled. The deliberate SA error was set to zero. Non-differential CA accuracy should improve from about 60 meters to, maybe, 20 meters. Differential until will still be more accurate. The media accounts have the right idea but the wrong facts (what else is new).

For the die hards, go to the horses mouth at:
http://gps.laafb.af.mil/



ritcheyvs@aol.com

[John R.]

My wife said that she heard (twice) on the radio news that GPS is going to be permenantly unscrambled. Has anyone heard of this or have more info? I searched the Boston Globe today in search of a story but found none. (What a shock)

Yes, from what I understand you now have about a 50' accuracy compared to the old SA signal accuracy of 300'. But you still don't have the 10'or less accuracy that a DGPS receiver can provide, that will still cost you about $400.

[Lee H. Hodsdon]

Jon,

By the way, i have a used DGPS receiver for sale, cheap.

Lee



lhodsdon@nh.ultranet.com