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DavidW Pocket GPS Moderator
Joined: 17/05/2003 02:26:21 Posts: 3747 Location: Bedfordshire, UK
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Posted: Sun Sep 14, 2003 8:04 am Post subject: 12 satellite fix seen! |
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On Friday 15 August at around 4pm I was driving in the Peterborough area and seeing reports of very high numbers of satellites being used in the fix.
Mainly I was seeing 10 satellites being used, sometimes 9 and sometimes 11, but once I glanced at TomTom Navigator 2 and saw 12 being used!
I suspect this is an unusual case. I couldn't stop to record information using WinFast Navigator, but I suspect this was particularly favourable satellite geometry. Even so, it shows it is possible to get a 12 satellite fix.
Haicom HI-303MMF (SiRFstar IIe/LP based receiver - 231.000.000ES firmware), using the internal antenna.
NMEA mode, SBAS off, using TomTom GPS driver 2.06 in the "Haicom GPS" setting.
David |
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Dave Frequent Visitor
Joined: Sep 10, 2003 Posts: 6460 Location: UK
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Posted: Sun Sep 14, 2003 8:04 am Post subject: 12 satellite fix seen! |
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12 is certainly possible, it really depends the time of day and where the satellites are positioned. I've experienced 12 sat fixes around 6pm. From a frequency point of view I get a 12 sat fix prob one or twice every 6 months. |
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MikeB Frequent Visitor
Joined: 20/08/2002 11:51:57 Posts: 3859 Location: Essex, UK
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Posted: Sun Sep 14, 2003 8:04 am Post subject: 12 satellite fix seen! |
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I often have 10-12 sats in the morning at about 7:00 to 8:45. The first time I took a screen shot nobody believed me!! I was accused of being creative in Photoshop.
It does happen, but not that often. _________________ Mike Barrett |
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Dave Frequent Visitor
Joined: Sep 10, 2003 Posts: 6460 Location: UK
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Posted: Sun Sep 14, 2003 8:04 am Post subject: 12 satellite fix seen! |
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Ah, but you were |
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murphwiz Occasional Visitor
Joined: 31/05/2003 23:32:12 Posts: 25 Location: United Kingdom
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Posted: Sun Sep 14, 2003 8:04 am Post subject: 12 satellite fix seen! |
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I'm using a pharos GPS i180 on a compaq 3630, with TTN 2.24 gps 2.06..
I have difficulty getting a fix, takes ages to fix (10 mins!) and quite often looses it at a crucial moment!
always seems to be 4-5 sats at best..
Anything I can do to improve? |
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DavidW Pocket GPS Moderator
Joined: 17/05/2003 02:26:21 Posts: 3747 Location: Bedfordshire, UK
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Posted: Sun Sep 14, 2003 8:04 am Post subject: 12 satellite fix seen! |
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I worry when someone reports a 13 satellite fix - I don't believe there's any receivers (in the consumer market, at least) with more than 12 channels.
Indeed, I have heard it said that 12 is the maximum number of Navstar satellites that can be overhead with the current orbits used, though I can't find that asserted that strongly. If that's the case, then I think the only chance of a >12 satellite fix is to use one or more SBAS satellites that are putting out ranging information.
murphwiz - is the setup any better with the GPS outside the car? If so, you could have a heat reflecting windscreen.
David |
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MikeB Frequent Visitor
Joined: 20/08/2002 11:51:57 Posts: 3859 Location: Essex, UK
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Posted: Sun Sep 14, 2003 8:04 am Post subject: 12 satellite fix seen! |
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You are indeed correct.
If you are using WAAS/EGNOS/SBAS then you will receive 1 less sat than the maximum.
Unless someone is marketing a receiver with more than 12 channels then more than 12 is impossible.
Potentially you could recieve more than 12 sat fixes as there are a number of spares that may or may not be active, if they are then it is feasible I suppose that more than 12 could be in view at any one time. But what is the point over about 6 sats doesn't seem to improve accuracy at all. _________________ Mike Barrett |
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