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matb76
Joined: 13 Apr 2007
Posts: 10
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 Posted: Fri Apr 20, 2007 9:39 am Post subject: About Egnos Waas (DGPS) |
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Hi,
i have a SIRF star III gps receiver. I'd like to switch the differential GPS feature on; does anybody knows how is this possible from the phone directly, without PC connection?
I think DGPS gives a great precision advantage over plain GPS; It would be cool to see it implemented in trekbuddy.
I found this thread http://www.trekbuddy.net/forum/viewtopic.php?t=233&highlight=egnos
but i could not make much sense of it.
Any idea? |
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Ranger
Joined: 12 Dec 2006
Posts: 4720
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| Posted: Tue Apr 24, 2007 8:33 am Post subject: |
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You can use TestGPS2 from
http://sweb.cz/happyBOY78/GPSAPI.zip
to set SBAS and DGPS from phone.
No SN unfortunately.
Source code for app is present, maybe some java programmers will add set/reset SN function in future (sorry, but I'm not).
Last edited by Ranger on Tue Apr 24, 2007 8:48 am; edited 3 times in total |
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matb76
Joined: 13 Apr 2007
Posts: 10
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| Posted: Tue Apr 24, 2007 8:39 am Post subject: |
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Thanks for the link.
N00b question: what' do you mean for 'SN'?
Here's the fixed url (typo): http://sweb.cz/happyBOY78/GPSAPI.zip
Thanks again. |
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Ranger
Joined: 12 Dec 2006
Posts: 4720
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| Posted: Tue Apr 24, 2007 8:46 am Post subject: |
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SN means Static Navigation (or car mode if you prefer).
For SirfStarIII receivers this mode prevents position movements for slow speed (<4 km/hour). Should be turned off for hiking/geocaching in many receivers - just look into forum Devices section for started receivers list. |
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matb76
Joined: 13 Apr 2007
Posts: 10
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| Posted: Tue Apr 24, 2007 8:50 am Post subject: |
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| Ranger wrote: |
SN means Static Navigation (or car mode if you prefer).
For SirfStarIII receivers this mode prevents position movements for slow speed (<4 km/hour). Should be turned off for hiking/geocaching in many receivers - just look into forum Devices section for started receivers list. |
Ok i know what you mean. I'm fine with having it off, i'm using GPS mainly for hiking, SN would make things worse.
Thanks! |
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krzysiekz
Joined: 07 Oct 2006
Posts: 168
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| Posted: Tue Apr 24, 2007 9:29 am Post subject: |
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| Is this app work on n6230i? I got nullpointexception when trying to my gps (nemerix based). |
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matb76
Joined: 13 Apr 2007
Posts: 10
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| Posted: Tue Apr 24, 2007 9:52 am Post subject: |
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| krzysiekz wrote: |
| Is this app work on n6230i? I got nullpointexception when trying to my gps (nemerix based). |
AFAIK, it's only for SIRFstart III chipset. |
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krzysiekz
Joined: 07 Oct 2006
Posts: 168
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| Posted: Tue Apr 24, 2007 10:06 am Post subject: |
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| Thx. I read somewhere that nemerix support dgps... Even without it i've got ~4.5m accuracy ;) but tried to enable it. |
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matb76
Joined: 13 Apr 2007
Posts: 10
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| Posted: Tue Apr 24, 2007 10:14 am Post subject: |
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| krzysiekz wrote: |
Thx. I read somewhere that nemerix support dgps... Even without it i've got ~4.5m accuracy  but tried to enable it. |
This tool, as you can read in the included docs, is only for SIRFstar III.
Google for your chipset to see if and how it is possible.
On a side note, i reckon that the precision meter (which i guess is based on the HDOP value) should not change its value with EGNOS. Can anyone confirm this? |
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Ranger
Joined: 12 Dec 2006
Posts: 4720
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| Posted: Wed Apr 25, 2007 10:14 am Post subject: |
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Depends. Position precision in TB is counted from HDOP for external modules, as no other values suitable in NMEA to show precision.
Phones with integrated GPS have precision directly in meters.
So as I understand you, question is how HDOP is DGPS involved in external GPS module.
Who knows ? Docs for GPS modules are rather obsolete  |
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matb76
Joined: 13 Apr 2007
Posts: 10
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| Posted: Wed Apr 25, 2007 4:03 pm Post subject: |
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| Ranger wrote: |
So as I understand you, question is how HDOP is DGPS involved in external GPS module.
Who knows ? Docs for GPS modules are rather obsolete |
I had a more deep look into the issue; HDOP is derived only from geometrical factors (the relative position between the receiver and the SV themselves). Therefore DGPS correction do not affect it. |
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Ranger
Joined: 12 Dec 2006
Posts: 4720
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| Posted: Wed Apr 25, 2007 4:57 pm Post subject: |
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Could be. I don't assume that your question sounds like importance of using SBAS or DGPS in simple hiking navigation.
TB is rather universal (means no too much specialized support for modules chipsets or protocols like sirf mode).
So you can turn on such module modes at least and expect that better coordinates will be shown in TB  |
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