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GPS

ciechanow.ski

21–30 of 296 posts

Re: GPS

#24
post #11

This person deserves to get filthy rich off of their patreon.

Agreed, amazing content and presentation! The article covers much of what you'd learn in an advanced positioning course.

Re: GPS

#25
However, I do like the role GPS plays as a plot device in all kind of stories, where it's an active device, with GPS-enabled devices giving away position or there's no GPS in the wilderness, as mobile connections fail. So there are two versions of GPS, the popular plot device and the actual navigation device.

(The more sinister version is that this has actually been planted as a cover-up for more realistic electronic intrusions, as this is also a trope in popular media and news.)

Re: GPS

#27
post #3

Auto-upvoted based on domain name. See all submissions from Bartosz: https://news.ycombinator.com/from?site=ciechanow.ski

Yes, great educational content and great interactive animations!

(Also, a constant reminder to learn WebGL. ;-) )

Re: GPS

#28
If all of the teaching materials would be so good... I've encountered first GPS devices back 1997.i remember when my coulegues were explaining them to me. At that time you wouldn't get precise measurements right away. You had to wait for correction factors or something like that. The GPS signal was scrambled at that time.

Re: GPS

#29

There's a lot of really great info in here. One random things I learned from this: > As that angle increases, the signal from a satellite travels more sideways and its larger portion gets affected by the atmosphere. To account for this, GPS receivers ignore ranges measured from satellites at very low elevation angles. ... atmospheric effects are primary source of GPS inaccuracies. (I know GPS has inaccuracies, but I…

Not only that. You can use a ground-based fixed station to listen to GPS signals and work out how much they have been affected by the atmosphere. This then gets fed back into the weather prediction models used by many weather forecasting services.

Re: GPS

#30

> Naturally, large range uncertainty increases the ambiguity of position, but the relative position of the satellites also matters. If they aren’t well spread, the exactness of calculated location also suffers. (see the excellent example in OP) Fun tidbit, the resulting error is known for the system in closed form as Geometric Dilution of Precision, and is a 3x3 (edit: or 4+x4+ if you are estimating bias or quantitie…

The natural expression of the DOP matrix is 4x4, since the receiver is computing a solution in 4D space-time. Its pretty common for the dominant eigenvector to be along the time-vertical axis for a terrestrial receiver.
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