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Comment by ok_dad | Hacker News Reader

Could the USA still turn on Selective Availability for GPS? I am not up to date with the newest satellites, but to me this is more of a threat than anything else. I know there are alternative systems, can most GPS devices use GLONASS or Galileo signals as well?

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At the very least iPhone is GLONASS and Galileo capable, I would imagine Android devices have been as well

I care more about airplanes, ships, trucks, and things of that nature. People will be able to get along fine with no GPS, a large ship transiting the Panama Canal will NOT be fine without GPS.

They can't turn it off completely without hurting themselves, the US needs high precision GPS around the world, so I doubt they'd do that.

GPS has two modes of operation, one low precision and one high precision one, which can optionally be encrypted. It would still be usable for military, but not for others. The low-precision mode might still be available publicly.

You're confusing selective availability, which is on the civilian side, with bands.

There are four civilian bands, with a fifth in the works for critical uses. There are two military bands, and they are encrypted.

The military bands (two) have always been encrypted and being on different bands, cannot be received at all by civilian receivers, though I imagine it's mostly a firmware change with some minor hardware changes.

Don't talk about things you wildly do not understand or know anything about.

> Don't talk about things you wildly do not understand or know anything about.

Can't see why I wouldn't on a tech forum. Certainly not because some rando on said forum instructs me so. Good day.

I would have thought the USA government wouldn’t shoot itself in the face, but look at the current stuff going on. I’m not sure they wouldn’t fuck over all the users of GPS at this point, including themselves.

From Wikipedia:

> United States President Bill Clinton signed a bill ordering that Selective Availability be disabled on May 1, 2000; and, in 2007, the US government announced that the next generation of GPS satellites would not include the feature at all.

Also, SA just meant you couldnt resolve with an accuracy less than 100 meters. It didn't mean "turn off GPS in a part of a world".

I believe they could select the level of degradation with SA, you could even turn the non encrypted channel off IIRC. Luckily, it seems they stopped including the feature in newer satellites, so that’s good at least.

Can SA even be toggled on/off by geo location? You wouldn't want to degrade service in the US.

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