GPS operating frequency

[rookie1010]

Hello

I did a google search for the operating frequency of GPS and came up with 1575.42 MHz, is that correct?

 

[Born2bwire]

Originally posted by: rookie1010
Hello

I did a google search for the operating frequency of GPS and came up with 1575.42 MHz, is that correct?

Sounds about right. I seem to lean towards 1.9 GHz, but I also know that band is shared by one of the cellular phone frequencies.

 

[Aluvus]

http://en.wikipedia.org/wiki/Gps#Frequencies_used

If you believe Wikipedia, anyway.

 

[rookie1010]

thanks for the replies

i do believe in wikipedia, my mistake, should have googled a wiki for gps 🙂

 

[Cattlegod]

Because of their constant movement with respect to the Earth's reference frame, the clocks on the satellites are affected by both special and general relativity. From the Earth's reference frame, satellite clocks are perceived as running at a slightly faster rate than clocks on the Earth's surface. This amounts to a discrepancy of around 38 microseconds per day, when observed from the Earth. To account for this, the frequency standard on-board the satellites runs slightly slower than its desired speed on Earth, at 10.22999999543 MHz instead of 10.23 MHz?a difference of 0.00457 Hz.[13] This offset is a practical demonstration of the theory of relativity in a real-world system; it is exactly what has been predicted by the theory, within the limits of accuracy of measurement.

That is pretty cool 🙂

 

[Rubycon]

GPS Information here

 

[dkozloski]

Many years ago Hewlett-Packard hauled a cesium beam atomic clock around the countries of the world with a Boeing 707on a demonstration project. It actually came as a surprise to encounter a small timing error later attributed to effects of relativity. Before then it was thought to be so small that it wouldn't be noticed.

 

[Mark R]

Originally posted by: dkozloski
Many years ago Hewlett-Packard hauled a cesium beam atomic clock around the countries of the world with a Boeing 707on a demonstration project. It actually came as a surprise to encounter a small timing error later attributed to effects of relativity. Before then it was thought to be so small that it wouldn't be noticed.

As I understand it, the error was of the 'wrong' sign when compared to the effect predicted by time dilation due to relative movement.

The dominant effect in this case time was because the graviational field at altitude was weaker than at ground level.

 

[f95toli]

Modern atomic clocks (caesium fountains and ion traps) are so accurate thay you have to take general relativity into account. The various clocks that when averaged create UTC (coordinated universal time) are actually already compensated for relativistic effects.
The reason is their respective frame of refrences are located at different distances from the centre of earth meaning the amount of gravitational shift is different .

We are rapidly reaching a point where the uncertainty in the position (and in some applications the speed) of the clock is the limiting factor for the accuracy. Within just a few years we will reach a point where you will need to know the distance at all times with a accurcy of less than 10 cm which is probably not possible.
Hence, if we want to increase accuracy even further we will need to have clocks in space where they are not affected by gravitational shifts (meaning there is no time dilation).