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Sat Jan 12, 2019, 05:48 PM

Planet's erratic magnetic field forces emergency update to global navigation system

Source: The Independent

Planet’s erratic magnetic field forces emergency update to global navigation system

Unprecedented changes required to ensure accuracy of system that guides everything from aircraft to smartphones

Josh Gabbatiss Science Correspondent @josh_gabbatiss
9 hours ago

Earth’s magnetic north pole is veering towards Siberia at an incredibly fast rate, and experts are not sure why.

The erratic movement has forced the scientists tasked with monitoring the planet’s magnetic field to update their system that underlies global navigation, from Google Maps to shipping.

As liquid iron swirls around in the Earth’s core, the magnetic field – and therefore the poles – shift around gradually and often unpredictably.

Scientists must periodically update the World Magnetic Model to map this process, and the most recent version – produced in 2015 – was intended to last until 2020.

However, the magnetic field has been changing so quickly and erratically that while conducting a routine check in early 2018, British and US researchers realised drastic steps were needed.

-snip-

Read more: https://www.independent.co.uk/news/science/magnetic-north-pole-moving-arctic-siberia-canada-earth-navigation-ships-a8724426.html

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Reply Planet's erratic magnetic field forces emergency update to global navigation system (Original post)
Eugene Jan 12 OP
Yonnie3 Jan 12 #1
LakeSuperiorView Jan 12 #2
rickford66 Jan 12 #3
Yonnie3 Jan 12 #4
rickford66 Jan 12 #5

Response to Eugene (Original post)

Sat Jan 12, 2019, 06:31 PM

1. Smartphones use GPS for navigation, not a compass

http://fortune.com/2019/01/11/earth-magnetic-north-pole-shifts-forcing-update/


<snip>
The previous model of the magnetic field was released in 2015 and updates have been slated for 5-year intervals. However, the changes are massive enough for military and civilian navigation—mostly in the Arctic Ocean—that the latest revision had to appear in 2019. A surge in 2016 happened just after the last model was set, making the update more critical four years out.

This update doesn’t affect GPS receivers, which don’t rely on the magnetic north pole. A receiver instead picks up signals from multiple satellites for which the exact position in orbit is known, and use trilateration (the intersection of their signals) to determine a location. However, satellite orbits are optimized for reception in the most-populated parts of the world, and other factors reduce GPS accuracy and reception in the Arctic.
<snip>

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Response to Yonnie3 (Reply #1)

Sat Jan 12, 2019, 06:54 PM

2. My phone has a magnetic compass, in addition to GPS.

 

I assume most smartphones do. But it is correct to say that GPS is used for navigation like with Google Maps.

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Response to Yonnie3 (Reply #1)

Sat Jan 12, 2019, 08:52 PM

3. The GPS satellites can pinpoint your position in space.

The Earth's mapped magnetic field must be used to reference where on Earth your position is.

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Response to rickford66 (Reply #3)

Sat Jan 12, 2019, 09:01 PM

4. I don't think so

It may be used to determine your heading. GPS can determine your position on earth without the magnetometer. If you don't have good satellite line of sight then it may be used to help. My old GPS has no magnetometer and is highly amusing when it gets a bad position fix.

https://www.quora.com/Would-GPS-receivers-fully-work-without-the-Earths-magnetic-field-as-a-reference

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Response to Yonnie3 (Reply #4)

Sat Jan 12, 2019, 09:20 PM

5. Right. But, there has to be some reference to know where the Earth is in it's rotation.

Last edited Sat Jan 12, 2019, 10:51 PM - Edit history (2)

Otherwise all we would know is where you are on a blank sphere. So the ultimate reference must be those cesium atoms running GMT plus your local time. So why the need for the accurate mag var ?

On edit: Since I've only worked on simulated GPS on simulators, I emailed a friend who worked on GPS well before the general public had access to receivers. He was working on a civilian version receiver for tracking vehicles. I hope I don't need to feed him too many beers to get the answer.

Another edit: It's been a long time since I worked on GPS, but from my memory, even the simulated ones had to satisfy the avionics. I think the satellites sent their positions in polar co-ordinates and the satellite would get that position from an INS type of system. But none of this explains the need for the mag var which was the reason for the post in the first place.

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