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spudfan

Member Since: 10 Sep 2007
Location: Co Donegal
Posts: 4667

So you have a mobile phone..

Bet this never crossed your mind...

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1992 110 200tdi csw -Zikali
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2011 110 2.4 tdci csw-Masai

13th May 2022 10:46am

Ecco

Member Since: 31 Oct 2015
Location: Kuala Lumpur
Posts: 280

2014 Defender 110 Puma 2.2 DCPU Galway Green

..i have doubts regarding relativity calculations..i did quite a lot of gps designs and firmware related to it, mostly oil and gas (oil platforms) as well as military grade stuff for navy..what exact relativity calculations/corrections, are to be made on CPU side, im not really sure about..what i can confirm is that, in order to attain accuracy levels on the order of 1 to 10 meters, differential correction is essential (unless relativity calculation is new term for differential calculation). Real time DGPS happens when the base station calculates and broadcasts corrections for each satellite as soon as it receives data. Correction is received by the roving receiver via radio signal if the source is land based or via satellite signal if it is satellite based and applied to the position it is currently calculating. Finally, the position displayed and logged to the data file of the roving GPS receiver is a differentially corrected position, which is pretty much standard math, nothing fancy...or im missing something

16th May 2022 6:26am

Honeyman

Member Since: 02 May 2022
Location: Haarlemmermeer
Posts: 58

2011 Defender 130 Puma 2.4 HCPU Sumatra Black

The “relativity calculations” (among many others such at atmospheric corrections) are done by the controlling GNSS network (GPS/Galileo etc) to provide the predicted spacecraft ephemeris data (“where I am going to be at what time”) and time offset corrections to be broadcast to, and applied by, the receivers as part of the “navigation message”. Worked on Galileo until Brexit made me “an agent of a potential hostile power”

2011MY 130 HCPU: daily driver
1979MY RRC 2-door: on the drive, in the garage & in a shed - all at the same time.

16th May 2022 9:14am

Ecco

Member Since: 31 Oct 2015
Location: Kuala Lumpur
Posts: 280

..yes..but that initial article say that 'relativity calculations' has been done on 'computer chips on your cell phone' which im not so sure about, hence my previous post..and those 'relativity calculations' that you have described are literally differential offsets, nothing related to 'relativity'..

16th May 2022 9:23am

Honeyman

Member Since: 02 May 2022
Location: Haarlemmermeer
Posts: 58

Sorry if it didn’t come across well, but I was intending to agree with you! 2011MY 130 HCPU: daily driver
1979MY RRC 2-door: on the drive, in the garage & in a shed - all at the same time.

16th May 2022 9:27am

macfrank

Member Since: 05 Nov 2015
Location: somewhere in the north
Posts: 1076

2015 Defender 110 Puma 2.2 SW Keswick Green

It was a topic at school long before mobile phones were available for "normal people"

The bottom line was, IIRC, that GPS wasn't possible without relativity because the satellite's clocks move at a speed where relativistic effects can't be neglegted.

However, I also think this "wohoo! you're phone caclulates Einstein's equations!" seems to be one of those journalistic simplifications that turn out wrong.
https://en.wikipedia.org/wiki/Error_analys...Relativity

I understand the need to simplify things to get it across to "the public". But, sadly, it often leads to all kinds of misunderstandings of how things really work. And in the end someone suggests to inject disinfectants to get rid of a virus...

18th May 2022 6:14am

Honeyman

Member Since: 02 May 2022
Location: Haarlemmermeer
Posts: 58

Absolutely! It’s a shame, because the navigation chipset in a mobile phone is indeed doing some really cool stuff in order to derive a position fix: the received signals are insanely weak and the amount of real estate available in a modern phone is somewhat limited. 2011MY 130 HCPU: daily driver
1979MY RRC 2-door: on the drive, in the garage & in a shed - all at the same time.

18th May 2022 7:23am

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