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A new GPS made for commercial, certified use (eg. for use in aviation) will cost way more that $5K. Just a software update to it might cost as much. Technology

by snom380 13y ago

A new GPS made for commercial, certified use (eg. for use in aviation) will cost way more that $5K. Just a software update to it might cost as much. Technology is getting cheaper, certifying it isn't. In don't know about ships, but I assume there is some form of certification for nav equipment there as well.

D9u 13y ago
I don't know about presently, but in the past the GPS transmitters had an introduced error known as "Selective Availability," the purpose of which was to deny pin-point accuracy to unauthorized devices. For a price, one could acquire the necessary hardware/software to mitigate Selective Availability in order to increase the accuracy of GPS readings, although I forget what those prices were/are.
- joosters 13y ago
  GPS used to be that way to give the military access to accurate positioning and provide lower accuracy to others. They can still do this selectively to whole areas of the world should they want to.
  - bigiain 13y ago
    This probably still mostly true. The US claim that since 2008 they've been launching GPS satellites without selective availability capabilities. That means 27 of the current working GPS satellites are older ones which do have SA which could be switched back on at any time, and 12 are newer allegedly non-SA equipped satellites.
- mikestew 13y ago
  Selective Availability hasn't been used for over a decade: http://www.gps.gov/systems/gps/modernization/sa/ http://www.gps.gov/systems/gps/modernization/sa/
  - bigiain 13y ago
    I remember reading a fascinating article (which seems to elude me on Google right now) about the competitors in the 1990 BOC single handed Around the World yacht race noticing the CEP (circular error probable) on their GPS devices drop from ~100m down to ~10m or better in late July – a week or so before the Gulf War officially started. They didn't permanently switch off Selective Availability til mid 2000, but they could and did temporarily switch it off when it suited them (and, no doubt, could easily switch it back on today if they thought it worthwhile… They claim any satellites launched since 2008 haven't had SA capability, but I suspect that's only a small-ish percentage of the GPS constellation today…)
- jevinskie 13y ago
  SA has been turned off, at least for now and at least in the US.

by snom380 13y ago

D9u 13y ago

I don't know about presently, but in the past the GPS transmitters had an introduced error known as "Selective Availability," the purpose of which was to deny pin-point accuracy to unauthorized devices. For a price, one could acquire the necessary hardware/software to mitigate Selective Availability in order to increase the accuracy of GPS readings, although I forget what those prices were/are.

joosters 13y ago
GPS used to be that way to give the military access to accurate positioning and provide lower accuracy to others. They can still do this selectively to whole areas of the world should they want to.
- bigiain 13y ago
  This probably still mostly true. The US claim that since 2008 they've been launching GPS satellites without selective availability capabilities. That means 27 of the current working GPS satellites are older ones which do have SA which could be switched back on at any time, and 12 are newer allegedly non-SA equipped satellites.
mikestew 13y ago
Selective Availability hasn't been used for over a decade: http://www.gps.gov/systems/gps/modernization/sa/ http://www.gps.gov/systems/gps/modernization/sa/
- bigiain 13y ago
  I remember reading a fascinating article (which seems to elude me on Google right now) about the competitors in the 1990 BOC single handed Around the World yacht race noticing the CEP (circular error probable) on their GPS devices drop from ~100m down to ~10m or better in late July – a week or so before the Gulf War officially started. They didn't permanently switch off Selective Availability til mid 2000, but they could and did temporarily switch it off when it suited them (and, no doubt, could easily switch it back on today if they thought it worthwhile… They claim any satellites launched since 2008 haven't had SA capability, but I suspect that's only a small-ish percentage of the GPS constellation today…)
jevinskie 13y ago
SA has been turned off, at least for now and at least in the US.