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> Small digression: did you know that, until May 2000, GPS satellites (which are owned and operated by the United States Space Force) provided the general publi

by friedgil 11mo ago

> Small digression: did you know that, until May 2000, GPS satellites (which are owned and operated by the United States Space Force) provided the general public a signal with intentional error built into it? What the hell? Why?

Jtsummers 11mo ago
It was to degrade accuracy. Military (and presumably other gov't and allied gov't owned systems) were able to get more accurate signals. The degraded signals meant that someone couldn't use commercial GPS as a guidance system or for similar applications.
godsinhisheaven 11mo ago
Something something Yujio Hanma
guy2345 11mo ago
[dead]
MaulingMonkey 11mo ago
GPS started as a U.S. Department of Defense project, and they had qualms about freely giving the high accuracy positioning information they found so very useful for e.g. targeting bombs and missiles, to every unverified third party in the world. Depending on your preferred flavor of jadedness, one could say it was because of security concerns... or one could say it was because said third parties hadn't paid off the military industrial complex enough!
00N8 11mo ago
They wanted to keep accurate global positioning as a US military exclusive capability. It's definitely useful for guided munitions, & alternative satellite positioning systems didn't exist or were less mature at the time, so US GPS was the only system one could realistically use for that. A missile able to hit a target within a 3 meter radius is vastly more effective than one that can only hit within 100m, for instance. There are still some restrictions around this sort of thing: IIRC a GPS receiver for sale to the public isn't allowed to give accurate data if it's too high up &/or moving too fast, to prevent unauthorized usage in ICBMs & other similar weapons. I think there would be a lot of red tape involved if you wanted to buy an unrestricted GPS device without this limitation.
- 4gotunameagain 11mo ago
  Which is idiotic, because nowadays it is trivial to build your own GPS received compared to the complexity of building a reliable ICBM.
  - DANmode 11mo ago
    But they said 2000.
    - 4gotunameagain 11mo ago
      [] There are still some restrictions around this sort of thing..
0x457 11mo ago
Error was built in to reduce precision and make it harder to use them for targeting. It stopped being useful once there were other constellations available. GPS receivers sold to public also required to not operate at certain altitude/speed to prevent it from being used in ballistic (and probably other kinds?) missiles.
coin 11mo ago
https://www.gps.gov/selective-availability https://www.gps.gov/selective-availability https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Selective_Availability https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_...

Jtsummers 11mo ago

It was to degrade accuracy. Military (and presumably other gov't and allied gov't owned systems) were able to get more accurate signals. The degraded signals meant that someone couldn't use commercial GPS as a guidance system or for similar applications.

godsinhisheaven 11mo ago

Something something Yujio Hanma

guy2345 11mo ago

[dead]

MaulingMonkey 11mo ago

GPS started as a U.S. Department of Defense project, and they had qualms about freely giving the high accuracy positioning information they found so very useful for e.g. targeting bombs and missiles, to every unverified third party in the world. Depending on your preferred flavor of jadedness, one could say it was because of security concerns... or one could say it was because said third parties hadn't paid off the military industrial complex enough!

00N8 11mo ago

They wanted to keep accurate global positioning as a US military exclusive capability. It's definitely useful for guided munitions, & alternative satellite positioning systems didn't exist or were less mature at the time, so US GPS was the only system one could realistically use for that. A missile able to hit a target within a 3 meter radius is vastly more effective than one that can only hit within 100m, for instance. There are still some restrictions around this sort of thing: IIRC a GPS receiver for sale to the public isn't allowed to give accurate data if it's too high up &/or moving too fast, to prevent unauthorized usage in ICBMs & other similar weapons. I think there would be a lot of red tape involved if you wanted to buy an unrestricted GPS device without this limitation.

4gotunameagain 11mo ago
Which is idiotic, because nowadays it is trivial to build your own GPS received compared to the complexity of building a reliable ICBM.
- DANmode 11mo ago
  But they said 2000.
  - 4gotunameagain 11mo ago
    [] There are still some restrictions around this sort of thing..

0x457 11mo ago

Error was built in to reduce precision and make it harder to use them for targeting. It stopped being useful once there were other constellations available. GPS receivers sold to public also required to not operate at certain altitude/speed to prevent it from being used in ballistic (and probably other kinds?) missiles.

coin 11mo ago

https://www.gps.gov/selective-availability https://www.gps.gov/selective-availability https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Selective_Availability https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_...