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Cellular forums Home > Archive > GPS > October 2005 > Satellites position from lat, long. time?
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Satellites position from lat, long. time?
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| scientia@ipotesi.net 2005-10-14, 11:48 pm |
| Hello,
is there an easy way (such an online form) to calculate
the position of the gps satellites at a given date, time,
in a given place? Altitude, azimuth, and (possibly) distance,
that may be useful to evaluate signal quality.
Thanks
Fabrizio
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| scientia@ipotesi.net 2005-10-16, 5:48 pm |
| Thanks!
Unfortunately I am not able to browse
http://sirius.chinalake.navy.mil/satpred/
(I have been trying for 2 days).
I am in Italy: may this be a problem for reaching that website?
Fabrizio
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| tivc@nep.invalid.nl 2005-10-16, 5:48 pm |
| On 16 Oct 2005 06:14:23 -0700, scientia@ipotesi.net wrote:
>Thanks!
>
>Unfortunately I am not able to browse
>http://sirius.chinalake.navy.mil/satpred/
>(I have been trying for 2 days).
>
>I am in Italy: may this be a problem for reaching that website?
>
>Fabrizio
I -- in Holland -- can't reach this website too.
Ton
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| Sam Wormley 2005-10-16, 5:48 pm |
| scientia@ipotesi.net wrote:
> Thanks!
>
> Unfortunately I am not able to browse
> http://sirius.chinalake.navy.mil/satpred/
> (I have been trying for 2 days).
>
> I am in Italy: may this be a problem for reaching that website?
>
> Fabrizio
>
I have trouble with it too... the domain name is still mapped
to an IP address, but it is seldom reachable.
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| scientia@ipotesi.net wrote:
> Thanks!
>
> Unfortunately I am not able to browse
> http://sirius.chinalake.navy.mil/satpred/
> (I have been trying for 2 days).
>
> I am in Italy: may this be a problem for reaching that website?
>
> Fabrizio
>
I have heard (from the Ham radio network) that the US government has
limited ephemeris data for satellites. I know that for some of the
HamSats, we can no longer get the information openly but have to go to
one website to get it.
Something about someone trying to shoot them down (yes, it is possible
with that data to launch a load of marbles).
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| Sam Wormley 2005-10-17, 2:48 am |
| Ray wrote:
> scientia@ipotesi.net wrote:
>
> I have heard (from the Ham radio network) that the US government has
> limited ephemeris data for satellites. I know that for some of the
> HamSats, we can no longer get the information openly but have to go to
> one website to get it.
>
> Something about someone trying to shoot them down (yes, it is possible
> with that data to launch a load of marbles).
Any GPS receiver will give you the satellite location information.
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| Sam Wormley wrote:
> Ray wrote:
>
>
>
> Any GPS receiver will give you the satellite location information.
>
Unless I misunderstood the original question, he was looking for a way
to predict the location of the satellite in the future? I believe I can
get a general area of the sky the birds are in from my under $400 unit,
but as far as a prediction of where they will be tomorrow, I have not
seen that. For that purpose I am pretty certain you still need the
ephemeris data (which we use to update every 12 hours for navsat because
of little things like gravity and solar wind), and judging from the few
Ham satellites I have attempted to look for recently, is no longer
widely published because of governmental paranoia.
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| Alan White 2005-10-18, 5:48 am |
| On Mon, 17 Oct 2005 20:11:21 -0600, Ray <None@msn.net> wrote:
>...
> I believe I can
>get a general area of the sky the birds are in from my under $400 unit,
>but as far as a prediction of where they will be tomorrow, I have not
>seen that.
>...
The orbital period is 11 hours and 58 minutes, so a satellite will
appear in the same position every 11h 58m - unless I've missed
something.
--
Alan White
Twenty-eight miles NW of Glasgow, overlooking Loch Goil and Loch Long in Argyll, Scotland.
Web cam and weather:- http://www.windycroft.gt-britain.co...ther/kabcam.htm
Some walks and treks:- http://www.windycroft.gt-britain.co.uk/walks/
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| robertharvey@my-deja.com 2005-10-18, 5:48 pm |
| Alan White wrote:
> The orbital period is 11 hours and 58 minutes, so a satellite will
> appear in the same position every 11h 58m - unless I've missed
> something.
But the earth rotates under the satellite's orbit while it is doing it.
The position will appear the same in a frame of refference based on
the satellite's orbit, but based on terrestrial co-ordinates it will be
different...
Not to mention the orbital abberations...
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