Learn me this on GPS please

Don't GPS receivers on Earth use some kind of time-shift measurement calculation to determine your position?
Yes, and as tcope may be referring to, the software compensates for all kinds of things including the Einstein's general theory of relativity. My colleagues at the office were having a discussion about this a couple of weeks ago, in the context of accurate timekeeping and how the nuts and bolts of our broadcast studios all stay in sync. The following pages were brought up as being excellent resources:

Gravity's Effect on Spacetime — NOVA | PBS

GPS and Relativity
 
GPS signals need to compensate for things like gravity and the speed of the satellite as these things slow down time. GPS sats are 12,000 miles from the Earth and almost 9000mph. Basically 45,900ns slower each day. This amounts to GPS being off miles.

So as far as GPS is concerned, it is more the effect of speed and gravity on time then the speed of the signal.

Does this mean the world isn't flat???

SB
 
How Fast Does Light Travel? | The Speed of Light (Speed of light)


Radio waves in vacuum travel at the speed of light.[7][8] When passing through a material medium, they are slowed according to that object's permeability and permittivity. Air is thin enough that in the Earth's atmosphere radio waves travel very close to the speed of light.

The wavelength is the distance from one peak of the wave's electric field (wave's peak/crest) to the next, and is inversely proportional to the frequency of the wave. The distance a radio wave travels in one second, in a vacuum, is 299,792,458 meters (983,571,056 ft) which is the wavelength of a 1 hertz radio signal. A 1 megahertz radio signal has a wavelength of 299.8 meters (984 ft). (Speed of RF) from Wikipedia
 
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My original comment should have included that radio and light speed is the same in a given medium.

Comparing a vacuum to an atmosphere or other medium should have been included to indicate the difference.
 
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Being that RF travels at only about 200 miles per second less than the speed of light (186,000,200 )miles per second, there would be negligible lag time.


Radio waves are a form of electromagnetic radiation – the same phenomenon as light, X-rays and various other types of radiation, but with much longer wavelengths. As such, they travel at the speed of light (ie 300,000 kilometres/186,000 miles per second)
 
Given that the home point is mark by a gps position could it be argued that in a RTH Situation the satellites are controlling the bird
 
Given that the home point is mark by a gps position could it be argued that in a RTH Situation the satellites are controlling the bird
Not really.
The home point was stored in memory and the GPS receiver in the Phantom listens to signals from several satellites and calculates its position from those and works out for itself how to get to where t wants to be.
 
Not really.
The home point was stored in memory and the GPS receiver in the Phantom listens to signals from several satellites and calculates its position from those and works out for itself how to get to where t wants to be.
We've managed to break the thread of Lightspeed posts I think my job is done here. :)
 

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