[inquisitive]

Pete, I have no idea where you got an accuracy of 500m-1km from

Personal observation and experimentation, of course. That's why I encouraged others to do the same.

As this is an argument about the existence of GPS, and not accuracy

Sorry, I'm not gonna let you change the subject of this conversation.

I have a number of GPS receivers and car satnavs show their location accurately on roads, not 1km out.

[StinkyOne]

My apologies - I forgot that you guys will jump at even the smallest error in phrasing.

This made me laugh. You literally DMed me once because I misspelled a word. Turnabout is fair play and all that.

Thanks. Geez, that took a struggle for you to concede.

What did I concede? I never argued that cell phones didn't supplement their GPS data. That can be pretty important if you don't have line of sight to the sky. I said let's take them out of the mix because you're trying to use them as a straw man of sorts. You're arguing a losing position. We all know GPS works very well. You can try to cast doubt on that, but it isn't reality. Then again, neither is a flat Earth and you're still trying to defend that so maybe you're just a contrarian?

[HorstFue]

...., some ships even use it as a back up to a compass. The position of the bow and the position of the bridge are taken with different antennas and the bearing between them is calculated, giving the heading. They are permitted under international maritime Organisation rules. And they work!

That's interesting. It was in my early GPS days, also some 20+ years ago, when I thought, GPS derives speed and heading from two consecutive measures of position. Meanwhile I learned, GPS not only calculates the position with one measure, using doppler shift it also calculates speed and heading, very accurate. The measure of doppler shift is integral part of the position calculation, as the receiver(s) have to be tuned for the variance in frequency of the incoming signal, due to high speed of the satellites.
Maybe this "two GPS device setup" has something to do with redundancy and the measure of the bearing between those two antennas is a plausibility check.
Thinking about it again (I've only sailed yachts), now I got it: One GPS alone will only show course/track over ground not the direction of the keel (true course).

[Treep Ravisarras]

you keep using and misattributing to GPS - your iPhone 7 is a poor choice of equipment for this discussion

Thank you for allowing me to clarify my point. It helps me think more clearer and I will incorporate your thoughts as follows:
(p.s. mobile phone was in Aeroplane Mode the whole time, so not communicating with networks. Do you know what means Aeroplane mode?)

Flat Earth or not I think we can all agree that, there is no device that will tell us our position more accurate than a gps device. Even a poor choice of gps device gets position within 2.4m of random government sign. Now how it works...? Round Earth says satellites. Flat Earth says I don't know.

Your schtick is extremely transparent, as always. Nobody is questioning that GPS works in certain areas, and that it can, on occasion, be accurate.

Who says schtick? You are clever enough to dig through metadata of my picture to uncover it was taken by an iPhone 7, but dumb enough to not know that gps is:
- accurate to be approved primary means of navigation in aviation world wide.  Four billion air passengers (4,000,000,000) with zero deaths in commercial passenger jets last year, with planes descending at night, in between mountains using only GPS every day.
- used in millions of ships as primary means of navigation as we have just found out thanks to Tontogary
- working well in each of the billions of mobile phones world wide.

I suspect another case of not following real flat earth principles. Pity, because that is not how our knowledge gets increased. Seeing, observing, continually gaining knowledge.

I never argued that cell phones didn't supplement their GPS data.

This why I put my device in Aeroplane mode, so it would just get position with gps, not communicate with any networks to get more data.

[AATW]

I don't know why there is so much argument about how accurate GPS is.
Isn't the point that it does demonstrably work.
The only debate relevant to the FES is whether it could work without satellites and, if it could, why this is another big conspiracy to pretend that it does work with satellites.

[Treep Ravisarras]

I don't know why there is so much argument about how accurate GPS is.

Uber is certainly leaving this debate in their wake.

They say they know where satellites are at any given time. Then they use newly gathered 3D maps of cities to figure out which satellites the device can see directly, which are blocked. This results in improved positioning, which is important for them in their business model.





By way everyone can find out position of satellites now because it is sent out every gps radio signal. Called the "Almanac".

Simple copy of current Almanac here.

You can also buy a cheap raspberry and read NMEA-0183 data that it continually outputs on RS-232. $60 dollars here. I have done this many times not raspberry but.

Now how it works...? Round Earth says satellites. Flat Earth says I don't know.

why this is another big conspiracy to pretend that it does work with satellites.

Yes tried to find out how big conspiracy was in other thread but got shut down.

[HorstFue]

Another strong hint, that only satellites can build a GPS system:
GPS receivers, even "consumer level" will additionally calculate speed and heading for each position measurement.
Long ago I though, heading and speed are calculated from two consecutive measures, but as I learned that imposes great errors.
The better way is to use Doppler Shift, and this can be done within the same measure.
Due to the high speed of the sender/satellites, the signal sent has a frequency shift. Receivers continuously adjust for this frequency shift and so measure the Doppler Shift.

Actually this Doppler Shift could also be used to calculate a position of the receiver.
History, Sputnik I:
When the Soviet Union launched the first artificial satellite (Sputnik 1) in 1957, two American physicists, William Guier and George Weiffenbach, at Johns Hopkins University's Applied Physics Laboratory (APL) decided to monitor its radio transmissions. Within hours they realized that, because of the Doppler effect, they could pinpoint where the satellite was along its orbit.
Vice versa, if position of Sputnik is known, hints for the position of the receiver can be obtained.
Indeed, the first satellite based navigation systems TRANSIT was based on Doppler Shift.

[Westprog]

I don't know why there is so much argument about how accurate GPS is.

Uber is certainly leaving this debate in their wake.

They say they know where satellites are at any given time. Then they use newly gathered 3D maps of cities to figure out which satellites the device can see directly, which are blocked. This results in improved positioning, which is important for them in their business model.





By way everyone can find out position of satellites now because it is sent out every gps radio signal. Called the "Almanac".

Simple copy of current Almanac here.

You can also buy a cheap raspberry and read NMEA-0183 data that it continually outputs on RS-232. $60 dollars here. I have done this many times not raspberry but.

Now how it works...? Round Earth says satellites. Flat Earth says I don't know.

why this is another big conspiracy to pretend that it does work with satellites.

Yes tried to find out how big conspiracy was in other thread but got shut down.

I find this fascinating. It's literally possible to point a receiver up into the sky, at a known, predicted position, and to pick up a signal. I can't think of anything that would explain this apart from there being something up in the sky. However, if there's something up in the sky, then we are dragged into the worldview of satellites and spacecraft and orbiting the Earth. So we have to say that we don't know.

If the Flat Earth is a fact, then there can't be a satellite up there. When someone points a satellite receiver up into the sky, and gets a signal, there must be some other explanation. The alternative would be that FE theory is wrong, which is impossible.

[TomInAustin]

Nice rationalization there, but those explanations have not been demonstrated to be true. All we know is that GPS is wrong when attempting to determine distance.

You didn't even read your own link.  Please explain "Survey Class GPS".

Nice try.  Your fear of admitting we know anything about distance is quite obvious.