FCC chair says we’re too dependent on GPS and wants to explore ‘alternatives’.
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three sats determine your accurate position. the fourth is for clock correction only.
No.
Satellites project a sphere, you need 4 in order to get to a singular point. I've outlined each step. Fourth isn't for clock correction only. And even outlined why sometimes 3 is okay, but that requires additional logic that many gps devices sometimes can't compute, and even outlined that the vast majority of devices will use way more than 4.
https://gisgeography.com/trilateration-triangulation-gps/
https://www.gps.gov/multimedia/tutorials/trilateration/ -
Isn't GPS a US project?
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You know what's a great backup? The ability to read a map or use a compass. This is set up to get Starlink or another billionaire to own GPS.
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Lat/Long is only valid if elevation is valid. You can't reference a lat/long that is miles into space... or beneath the crust of the earth.
It's like you're making my point for me.
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Reject modernity, return to sextant.
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It's like you're making my point for me.
A watch... or other simple gps device doesn't know what the elevation is.
Only one of the 2 selected points in a 3 satellite setup will be valid. And your device would have no idea which one is valid without elevation knowledge or a 4th satellite. Some devices can figure it out with just 3 satellites. Many/most won't. But ultimately it's the same thing. You need 4 pieces of input. Either 3 satellites AND elevation. Or 4 satellites.
So no. I've not made a point "for" you. You're just ignorant or specifically being obtuse on something you clearly don't understand.
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A watch... or other simple gps device doesn't know what the elevation is.
Only one of the 2 selected points in a 3 satellite setup will be valid. And your device would have no idea which one is valid without elevation knowledge or a 4th satellite. Some devices can figure it out with just 3 satellites. Many/most won't. But ultimately it's the same thing. You need 4 pieces of input. Either 3 satellites AND elevation. Or 4 satellites.
So no. I've not made a point "for" you. You're just ignorant or specifically being obtuse on something you clearly don't understand.
A watch... or other simple gps device doesn't know what the elevation is.
My point, exactly
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A watch... or other simple gps device doesn't know what the elevation is.
My point, exactly
Which is why they'd need 4 satellites. Read the whole post. Read the given sources. Stop being stupid.
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Nah the idea is sound. As someone else said, GPS is incredibly fragile. Also very terrestrial...it doesn't work once you leave the atmosphere.
This will probably be another SpaceX grift, but there are alternative technologies that are more resilient to attack. From military/defense perspective (the original reason for GPS), that's pretty important.
it doesn't work once you leave the atmosphere.
Fun fact: just this past week an experiment on a lunar lander confirmed that GPS signals can be detected from the surface of the moon. I don't know if those signals can give any kind of location precision, but it is an interesting finding.
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Which is why they'd need 4 satellites. Read the whole post. Read the given sources. Stop being stupid.
I did read the whole post. Stop being an asshole.
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GPS depends on a friendly spectrum. I suspect the FCC is preparing for a war where GPS will be jammed, faked, or destroyed.
How's the FCC going to prepare for anything when it's being gutted?
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I did read the whole post. Stop being an asshole.
Clearly you didn't... You keep asserting false statements that have already been disproven with sources.
But ultimately it’s the same thing. You need 4 pieces of input. Either 3 satellites AND elevation. Or 4 satellites.
If a watch doesn't "know" elevation (barometer or other sensor providing such information) as the fourth data point... Then it NEEDS 4 satellites to make the data points whole. Making your statements yet again wrong. I've covered the cases... but you keep pushing false statements like "gps is triangulation" (completely incorrect) or "GPS uses 3 satellites" which is also only correct in one very specific case... Where it's largely 4 or more, with reality being more like as many satellites as the device can read the pulses for. Often being a dozen or even more...
I am making accurate and complete statements. You are the one peddling misinformation.
Hell to prove the point... my time server grabs GPS as it's primary source. It grabs up to 12 satellites to sync time. It shows me my sync status for lat/long as well... At 3 satellites it CANNOT get a lock for location OR time. At 4 it gets a weak lock.
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Clearly you didn't... You keep asserting false statements that have already been disproven with sources.
But ultimately it’s the same thing. You need 4 pieces of input. Either 3 satellites AND elevation. Or 4 satellites.
If a watch doesn't "know" elevation (barometer or other sensor providing such information) as the fourth data point... Then it NEEDS 4 satellites to make the data points whole. Making your statements yet again wrong. I've covered the cases... but you keep pushing false statements like "gps is triangulation" (completely incorrect) or "GPS uses 3 satellites" which is also only correct in one very specific case... Where it's largely 4 or more, with reality being more like as many satellites as the device can read the pulses for. Often being a dozen or even more...
I am making accurate and complete statements. You are the one peddling misinformation.
Hell to prove the point... my time server grabs GPS as it's primary source. It grabs up to 12 satellites to sync time. It shows me my sync status for lat/long as well... At 3 satellites it CANNOT get a lock for location OR time. At 4 it gets a weak lock.
You keep asserting false statements that have already been disproven with sources.
I don't. You just aren't paying attention to what I'm saying. You keep arguing up a strawman.
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You know what's a great backup? The ability to read a map or use a compass. This is set up to get Starlink or another billionaire to own GPS.
Ding ding ding. This is just a talking point so they’ll be able to pivot into “we should give Musk a trillion dollar contract to run GPS on his Starlink satellites”
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Is that the difference between when something like Google Maps has your general location and when it has your specific location?
A-GPS works faster than GPS on its own.
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You keep asserting false statements that have already been disproven with sources.
I don't. You just aren't paying attention to what I'm saying. You keep arguing up a strawman.
You are not getting a 3 dimensional location. That’s why GPS coordinates only exist on 2 planes. You don’t know what you’re talking about.
Proven wrong, as it's a "2d" map that only exists on a 3d plane. It's a slice of space that represents the moving target of "ground level". The point that this is a problem to take it as just a "2d map" is that you can't take 3 point readings from on top of a 1000 ft cliff and 3 feet away at the bottom of a cliff and expect 3 point measurements to actually give you accurate measurements since it's just "2d" right? Elevation matters as it needs to be accounted for during the calculations.
So which coordinate accounts for elevation? Latitude or Longitude?
Where elevation = ground. As stated...
Then you assert.
It’s like you’re making my point for me.
Which was in response to a post stating that the watch would need a 4th satellite or "elevation" in order to get a valid GPS value.
And after I further clarified for you how it works... again... and that I was NOT making your point. I assumed you simply didn't understand the point I was actually making.
My point, exactly
No... It wasn't your point at all because you asserted that GPS is 3 point triangulation. When it's 4 point Trilateration which only has the option of 3 point when the fourth value of elevation is already known, which the vast majority of devices that use GPS don't know.
What have I straw-manned? Can you point to it? What part of GPS needs 4 nodes/data points is vague?
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Reject modernity, return to sextant.
Dont need a sextant if you dont leave your house
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They're already are multiple alternatives to GPS. GPS is the American navigation system, but there's also GNSS which is mostly used in Europe and Scandinavia. There are other systems for other parts of the world, even the North and South pole now.
Everyone just uses GPS universally though.
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You know what's a great backup? The ability to read a map or use a compass. This is set up to get Starlink or another billionaire to own GPS.
Subscription based navigation? Want to use your car's navigation system, there's a fee for that? Want to fly a drone, that'll be 9.99/month. Hopefully there will be a carve out for emergency systems.
This will also allow Tesla to up their traffic game. If everyone is using the Starlink GPS for navigation they'll have all the data.
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They're already are multiple alternatives to GPS. GPS is the American navigation system, but there's also GNSS which is mostly used in Europe and Scandinavia. There are other systems for other parts of the world, even the North and South pole now.
Everyone just uses GPS universally though.
there's also GNSS which is mostly used in Europe and Scandinavia
GNSS is the generic term that covers all satellite navigation systems (GPS included).
Galileo is the EU/ESA system you're thinking of.
GLONASS (Russian) and BeiDou (Chinese) are the other two major constellations with global coverage. The only other full system I know of is NavIC, which is Indian and has only regional coverage.
Most devices actually connect to all of them. I've just checked my phone, and it's connected to all of GPS, Galileo, GLONASS and BeiDou. People just say "GPS" because it's catchier than "GNSS".
