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Crazy Druid Member
Joined: 25 Mar 2006 Posts: 188 Location: Edinburgh, Scotland
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Posted: Fri May 05, 2006 7:26 am Post subject: WAAS |
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Probably just me being stupid,
if I have WAAS on what numbers should I see? 33 + 51 ?
I keep getting 37 + 49, I get a Grey bar on 37, but never get any D's
Oh I am just south of Edinburgh....
Should I be able to get D's?
John |
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Wildlifewriter Founder member
Joined: 04 Aug 2005 Posts: 948 Location: Norn Iron
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Posted: Fri May 05, 2006 9:45 am Post subject: Re: WAAS |
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Crazy Druid wrote: | Should I be able to get D's?
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It depends on what make and type of GPSr you have.
More recent Garmin units will "see" and use the signals from PRN120 (#33) but will not take corrections from #37 because it carries the "Do not use" signal. (#33 is a testbed vehicle, so it doesn't say "Do not use".)
The reasons for all these shenanigans with operational flags, test systems, etc, etc, are so tedious that I can't be bothered going into them all. Suffice it to say that the the EGNOS system is now almost FOUR years behind schedule, and still doesn't work properly.
TRy to position your unit so that it can receive signals from satellite #33 - and leave it there for at least 20-30 minutes. This will allow the full WAAS/EGNOS almanac to be downloaded (it's not the same as the ordinary GPS orbital data), at which time your unit may be able to apply corrections.... er, correctly.
Hth,
-Wlw |
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Crazy Druid Member
Joined: 25 Mar 2006 Posts: 188 Location: Edinburgh, Scotland
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Posted: Fri May 05, 2006 10:29 am Post subject: |
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Thanks Wlw,
I will try to find it, I use the Legend
Whats the best way to get it to see #33?
I was just thinking...
As soon as I turn my Legend on #37 and #49 are always displayed, will #37 be replaced by #33 if it finds it? or do I need to reset the Sat's in the memory?
John |
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Wildlifewriter Founder member
Joined: 04 Aug 2005 Posts: 948 Location: Norn Iron
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Posted: Fri May 05, 2006 12:27 pm Post subject: |
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Crazy Druid wrote: | As soon as I turn my Legend on #37 and #49 are always displayed, will #37 be replaced by #33 if it finds it? or do I need to reset the Sat's in the memory? |
This is a tricky one.
Satellite #33 (the ESTB testbed) is not an "official" WAAS station - though it IS in the almanac.
If you can operate your Legend in such a location that it has a good view of the sky to the SSW (where 33 is) but is obscured to the SSE (where the other two are), it may switch over. Before this happens, the existing data in the unit has to "decay"* and then it will look for other satellites. This could take several hours to work through.**
-Wlw.
* That isn't actually what happens. It's very complicated.
** The time is variable, and depends on a whole host of factors which are so complicated that even I don't fully understand them. |
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Haggis Hunter Founder member
Joined: 29 Aug 2005 Posts: 2487 Location: The building site formally known as Edinburgh!
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Posted: Fri May 05, 2006 6:51 pm Post subject: |
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Wildlifewriter wrote: | * That isn't actually what happens. It's very complicated.
** The time is variable, and depends on a whole host of factors which are so complicated that even I don't fully understand them. |
Ah ha! I know someone who can answer the complicated questions!! You still won't have a clue after reading it though, but apparently he can answer it? _________________ Let me know if I say anything that offends you
I might want to offend you again later |
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Crazy Druid Member
Joined: 25 Mar 2006 Posts: 188 Location: Edinburgh, Scotland
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Posted: Fri May 05, 2006 7:06 pm Post subject: |
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Don't know if I would want to read it now, it would just give me a headache
i will just stick to blocking out the ones I don't want and try to get the ones I do... |
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Wildlifewriter Founder member
Joined: 04 Aug 2005 Posts: 948 Location: Norn Iron
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Posted: Fri May 05, 2006 7:47 pm Post subject: |
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Haggis Hunter wrote: | Ah ha! I know someone who can answer the complicated questions!! |
Not this question, he couldn't.
Some people think that their Garmin GPSrs are not handling the thing correctly, but this is not so...
... the GPS receivers behave according to industry standards AND the published specifications. It's the EGNOS system itself which is not running exactly within those specifications.
At the moment.
Perhaps it will, one day - but I stopped holding my breath about two years ago.
-Wlw |
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HighlandNick Founder member
Joined: 30 Aug 2005 Posts: 635 Location: Highlands, Scotland
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Posted: Fri May 05, 2006 9:23 pm Post subject: |
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Wildlifewriter wrote: | I stopped holding my breath about two years ago.
-Wlw |
Are you there Mother?? |
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