Re: GPS Ideas

Abstract Dissonance wrote:
I was reading some stuff today about GPS and had a few ideas. I'm curious as
to if anyone things they have any practicality. I am by no means an expert
on GPS and basically this is my first time even reading about some of the
specs and stuff. I did take several courses in physics several years ago by
I have forgotten most, if not all of what I have learned. These are just
ideas and I am not saying they will work or even make sense... just trying
to get some feed back. (note, everyone is non-relativistic for simplicity)


I was thinking that one could attach to each satellites two frequencies to
transmit on. This might help in solving the problem of the speed of light
changing due to the different mediums that it transmits through.

The data that the satellite transmits would include the distance from itself
to all other satellites and to a reference on the ground.

The idea for the different frequencies is to somehow build up a differential
method of dealing with the change in the speed of light as it passes from
the transmitter to the receiver. I'm not sure if it will work but I was
thinking that, say, if satellite A transmits the signal on frequency X and
frequency Y that one might be able to remove the changes in the speed of
light through the different mediums because it will effect both signals the
same amount. Not sure if this would lead to something worthwhile though.
Basically it would seem that one could compute the dispersion due to the
medium between the transmiter and receiver to "repair" the distance
computed. Maybe there are other ways to do this too by using only one
signal and by using some modulation method.



By including the distances(and maybe positions too) from all the satellites
from each other, which are able to computed in a vacuum(I think, not sure if
it will go through the ionosphere but maybe the method above could work
too). This might not be practical as the satellites would have to send
signals to each other too and some power would be wasted.

It would seem that by knowing the complete geometry of all the satellites
one could use that information to compute a more accurate location of the
GPS receiver. Basically all the information to find the location on earth
would be sent by just one signal. Since the receiver would be getting
atleast three signals(or six) and a series of data that should be identical
except for the computed distances to the reciever from each of the 3
satellites, it could compute errors in the distances and possibly use
statistics to increase the accuracy of the data. One could also calcuate
angles for whatever reason too. By having ground facillaties included, which
would essentially be "fixed" satellites, would could tie everything
together. i.e., angles could be computed from a reference point, say the
north and south poles. One could possibly, say, know how far they are from
the polar axis and such... which at this point I think at this point one has
to reply on "maps" to figure things like that out.

Not sure if that makes sense or would work but just an idea.

Thanks,
Jon

GPS works fine just the way it is.
A $100 receiver will get you 5m general accuracy, a more expensive
survey or military model will get you down to the cm range.
In the US you guys have WAAS which gets you even better accuracy.

I'd suggest taking up Geocaching, the fresh air might do you some good!
:->

Dave :)

.

Relevant Pages

  • Re: Why do relativists ignore the "missing" ticks of traveling clock?
    ... phase relationships between signals. ... used by a single GPS receiver, or are talking about something else. ... I will however assume that we are talking about the positioning ... of the carriers from the same set of satellites, ...
    (sci.physics.relativity)
  • Re: Why do relativists ignore the "missing" ticks of traveling clock?
    ... >> So you don't even know if you are talking about the positioning algorithm ... >> used by a single GPS receiver, or are talking about something else. ... >> of the carriers from the same set of satellites, ... >> solely on the transit time of the signals from four satellites, ...
    (sci.physics.relativity)
  • Re: Galileo
    ... >>>It does depend on the receiver's clock. ... >>>differences between the satellite signals as they arrive. ... > satellites, and is not required at the receiver. ...
    (uk.rec.sailing)
  • Re: GPS Ideas
    ... I was thinking that one could attach to each satellites two frequencies ... The data that the satellite transmits would include the distance from ... the transmitter to the receiver. ... GPS receiver. ...
    (sci.electronics.design)
  • Re: Galileo
    ... The satellites transmit a very>>accurate time signal and the receiver has to measure the time>>differences between the satellite signals as they arrive. ... Each satellite carries an atomic clock; the signals from the satellites are synchronized. ...
    (uk.rec.sailing)
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