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Isn't the proliferation of multiple GNSS constellations actually quite positive thing? The smartphone geolocation chips seem to have no problem receiving signal

Isn't the proliferation of multiple GNSS constellations actually quite positive thing? The smartphone geolocation chips seem to have no problem receiving signals from all constellations. So effectively this competition between the systems allows for denser coverage of location satellites. This in turn should enable more accuracy and faster location acquisition even with limited sky visibility. In security sense, it seems that the situation virtually rules out the possibility of selectively denying some party GNSS access. So if you want to make your adversary location-blind, you'll have to accept losing location data yourself, right?

gandalfian 7y ago
Everyone sharing one system is excellent. Everyone sharing four increasingly redundant systems starts to look like a waste of money. We need a carpooling equivalent gps system. Still better than more bombs I guess.
- kzrdude 7y ago
  What level of redundancy is needed? Having three global systems seems reasonable, if it's an important service.
- ddalex 7y ago
  the problem with just one is that US will insist having a deadswitch on it, just like it did with Galileo. so you must have your own if you don't want US to have a Damocles sword over you
  - vinay427 7y ago
    Newer GPS satellites apparently don't support selective availability, so they would have no way of preventing access to only civilian devices. Of course, any of these systems can be jammed or shot down but that would affect anyone using it. > In September 2007, the U.S. government announced its decision to procure the future generation of GPS satellites, known as GPS III, without the SA feature. Doing this will make the policy decision of 2000 permanent and eliminate a source of uncertainty in GPS performance that had been of concern to civil GPS users worldwide. https://www.gps.gov/systems/gps/modernization/sa/ https://www.gps.gov/systems/gps/modernization/sa/
    - dragonelite 7y ago
      Why would a reformist country like China and Russia trust such a thing. We were also told that mass surveillance was a conspiracy/nutjob story, but the Snowden leaks has shown us a different world.
      - vinay427 7y ago
        They wouldn't, and I can see why. I was just adding some information. As far as anyone in the public has been told, both GPS and Galileo will remain open for anyone to use, but depending on that requires trusting whoever runs it.
    - Spare_account 7y ago
      If I wanted my neighbours to trust my GPS system more, I'd tell them I don't have selective availability.
      - vinay427 7y ago
        Sure. If you wanted GPS to be more widely used and depended on with no ulterior motives, you would also tell them you don't have selective availability. All of these systems require trusting the operators at the end of the day, and I'm not making the claim that one should depend on any single system.
- Barrin92 7y ago
  >Everyone sharing four increasingly redundant systems starts to look like a waste of money straight out of the "having two kidneys is a waste of energy" school of thought
  - gandalfian 7y ago
    You could buy yourself a dialysis machine "just in case" but you will have to give up something else to afford it. There is a trade off.
- gmueckl 7y ago
  It stops looking that redundant when one system goes down because both of its ground based refence clocks go down at the same time. This recently happened to Galileo. Nobody noticed because NavStar and GNSS covered for it.
  - makomk 7y ago
    NavStar GPS can keep on running for quite a while even if the entire ground segment fails. The current generation of satellites even have an Autonav mode that lets them synchronize their clocks and compute corrections to their orbital parameters using cross-links between satellites without any ground assistance. Supposedly it can provide almost full accuracy for six months after a complete failure of the ground segment. Galileo just isn't very robust by comparison.
- not_a_cop75 7y ago
  If everyone is thinking the same thing, then someone isn't thinking. (This time, I wasn't thinking, but I agree with the sentiment.)
londons_explore 7y ago
> selectively denying some party GNSS access. Military depends on an encrypted signal. If you have the encryption key, you can decode it even with a very high level of interference. Disadvantage is the key is shared for all users, and if it leaks to the adversary, then they can jam the signal.
raihansaputra 7y ago
The US is able to block GPS signal to a specific area (I think it was done on the Gulf War) or disable the unencrypted GPS signal (only the US military can decode them). I assume each system has the same capability too. The worst case scenario would be all parties decided to block the unencrypted portion and leaving all civilians to be location-blind, including civilian aircrafts.
- throw0101a 7y ago
  > The US is able to block GPS signal to a specific area ... Anyone can block the signal given how weak it is, and there are news reports of people doing so (and being charged for it). You can supposedly buy jammers online for not a lot of money. > ... (I think it was done on the Gulf War) or disable the unencrypted GPS signal (only the US military can decode them). What you are probably referring to is "Selective Availability" and is the purposeful degrading of the signal to make it less accuracy. The DoD said it will not do so, and has given assurances to the FAA (because planes are now highly dependent on it). The newest GPS III satellites no longer have the S/A hardware: * https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Selective_availability https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_... By 2000 people had figured out to get quite accurate results even with the S/A enabled, so the whole thing not as useful: * https://www.aviationtoday.com/2000/07/01/the-real-reason-selective-availability-was-turned-off/ https://www.aviationtoday.com/2000/07/01/the-real-reason-sel... If there's a war on it's probably cheaper to just jam in the area of operations.
  - tyldum 7y ago
    Jammers are cheap and since a lot of expensive gear has GPS tracking these days, thieves are using simple jammers you plug into the cigarette outlet in cars. This is increasingly becoming a larger problem since they jam a relatively large area.
- jhayward 7y ago
  > The US is able to block GPS signal to a specific area The GPS system does not have any area denial capability. If the US wants to block it in a certain area they have to deploy terrestrial jammers just like anyone else. Allies get decryption keys for the military high-accuracy signal.
dragonelite 7y ago
In a perfect world yeah, but given the geopolitical and geoeconomical changes going on. The tradewar to seperate the Chimerica relationship, you probably want to own your own navigation systems.

gandalfian 7y ago

Everyone sharing one system is excellent. Everyone sharing four increasingly redundant systems starts to look like a waste of money. We need a carpooling equivalent gps system. Still better than more bombs I guess.

kzrdude 7y ago
What level of redundancy is needed? Having three global systems seems reasonable, if it's an important service.
ddalex 7y ago
the problem with just one is that US will insist having a deadswitch on it, just like it did with Galileo. so you must have your own if you don't want US to have a Damocles sword over you
- vinay427 7y ago
  Newer GPS satellites apparently don't support selective availability, so they would have no way of preventing access to only civilian devices. Of course, any of these systems can be jammed or shot down but that would affect anyone using it. > In September 2007, the U.S. government announced its decision to procure the future generation of GPS satellites, known as GPS III, without the SA feature. Doing this will make the policy decision of 2000 permanent and eliminate a source of uncertainty in GPS performance that had been of concern to civil GPS users worldwide. https://www.gps.gov/systems/gps/modernization/sa/ https://www.gps.gov/systems/gps/modernization/sa/
  - dragonelite 7y ago
    Why would a reformist country like China and Russia trust such a thing. We were also told that mass surveillance was a conspiracy/nutjob story, but the Snowden leaks has shown us a different world.
    - vinay427 7y ago
      They wouldn't, and I can see why. I was just adding some information. As far as anyone in the public has been told, both GPS and Galileo will remain open for anyone to use, but depending on that requires trusting whoever runs it.
  - Spare_account 7y ago
    If I wanted my neighbours to trust my GPS system more, I'd tell them I don't have selective availability.
    - vinay427 7y ago
      Sure. If you wanted GPS to be more widely used and depended on with no ulterior motives, you would also tell them you don't have selective availability. All of these systems require trusting the operators at the end of the day, and I'm not making the claim that one should depend on any single system.
Barrin92 7y ago
>Everyone sharing four increasingly redundant systems starts to look like a waste of money straight out of the "having two kidneys is a waste of energy" school of thought
- gandalfian 7y ago
  You could buy yourself a dialysis machine "just in case" but you will have to give up something else to afford it. There is a trade off.
gmueckl 7y ago
It stops looking that redundant when one system goes down because both of its ground based refence clocks go down at the same time. This recently happened to Galileo. Nobody noticed because NavStar and GNSS covered for it.
- makomk 7y ago
  NavStar GPS can keep on running for quite a while even if the entire ground segment fails. The current generation of satellites even have an Autonav mode that lets them synchronize their clocks and compute corrections to their orbital parameters using cross-links between satellites without any ground assistance. Supposedly it can provide almost full accuracy for six months after a complete failure of the ground segment. Galileo just isn't very robust by comparison.
not_a_cop75 7y ago
If everyone is thinking the same thing, then someone isn't thinking. (This time, I wasn't thinking, but I agree with the sentiment.)

londons_explore 7y ago

> selectively denying some party GNSS access. Military depends on an encrypted signal. If you have the encryption key, you can decode it even with a very high level of interference. Disadvantage is the key is shared for all users, and if it leaks to the adversary, then they can jam the signal.

raihansaputra 7y ago

The US is able to block GPS signal to a specific area (I think it was done on the Gulf War) or disable the unencrypted GPS signal (only the US military can decode them). I assume each system has the same capability too. The worst case scenario would be all parties decided to block the unencrypted portion and leaving all civilians to be location-blind, including civilian aircrafts.

throw0101a 7y ago
> The US is able to block GPS signal to a specific area ... Anyone can block the signal given how weak it is, and there are news reports of people doing so (and being charged for it). You can supposedly buy jammers online for not a lot of money. > ... (I think it was done on the Gulf War) or disable the unencrypted GPS signal (only the US military can decode them). What you are probably referring to is "Selective Availability" and is the purposeful degrading of the signal to make it less accuracy. The DoD said it will not do so, and has given assurances to the FAA (because planes are now highly dependent on it). The newest GPS III satellites no longer have the S/A hardware: * https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Selective_availability https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_... By 2000 people had figured out to get quite accurate results even with the S/A enabled, so the whole thing not as useful: * https://www.aviationtoday.com/2000/07/01/the-real-reason-selective-availability-was-turned-off/ https://www.aviationtoday.com/2000/07/01/the-real-reason-sel... If there's a war on it's probably cheaper to just jam in the area of operations.
- tyldum 7y ago
  Jammers are cheap and since a lot of expensive gear has GPS tracking these days, thieves are using simple jammers you plug into the cigarette outlet in cars. This is increasingly becoming a larger problem since they jam a relatively large area.
jhayward 7y ago
> The US is able to block GPS signal to a specific area The GPS system does not have any area denial capability. If the US wants to block it in a certain area they have to deploy terrestrial jammers just like anyone else. Allies get decryption keys for the military high-accuracy signal.

dragonelite 7y ago

In a perfect world yeah, but given the geopolitical and geoeconomical changes going on. The tradewar to seperate the Chimerica relationship, you probably want to own your own navigation systems.