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| GeoCommunity Mailing List |
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| Subject: | Re: [gislist] GPS systems (2nd time) |
| Date: |
06/08/2005 08:55:01 AM |
| From: |
Brian Russo |
|
|
Neil Havermale wrote:
> Bader -
>
> There are two aspects of your accuracy quest: the GPS receiver and its level
> of smarts and second, your source of differential corrections. Differential
> corrections are a supplement to the GPS system and while not a GPS timing
> signal itself, the RTCM-105 standard correction passes fine-tuning aspects
> for each satellite in view. The differential corrections remain key to
> accuracies under 10 meters these days. If you can get the "free"
> differentials from the WAAS (North America) or SBAS (Europe) satellites,
> under $300 handhelds like Garmins (http://www.garmin.com) will deliver 1.5
> meter accuracy 67 percent of the time. These free corrections are not
> available everywhere.
>
> For just about anywhere on the planet your can replace free with commercial
> differential corrections like Omnistar (http://www.omnistar.com receiver
> with annual subscription $800+yr1) and you might get 1.2 meters out of the
> same Garmin - but this integration is not really a handheld solution any
> more. Put the most accurate Omnistar correction on a high-end Trimble or
> Thales handheld/PDA ($3500+) who's' built-in GPS engines know how to deal
> with "carrier surfing" or "carrier smoothing", you'll gain 0.5 meters say 95
> percent of the time when in good conditions.
Do you know if they simply implement Kalman filters or similar?
Strongly agree with everything else, more emphasis that you'll need
someone who actually knows how to use this (technique > equipment).
- bri
>
> http://www.trimble.com/pathfinderproxh.shtml
>
> http://www.thalesnavigation.com/en/index_flash.asp
>
> Thales, Garmin and Trimble represent high accuracy integrated GPS, hardened
> WinCE forms with daylight readable screens, a CPU and memory to handle PDA
> GIS tools like ArcPAD, EzMAP, and MapX Mobile.
>
> To achieve a one meter accuracy say 50 percent of the time you'll need to
> consider a professional GPS system investment. Gaining accuracy to within a
> meter essentially all of the time will require a professional and well tuned
> system.
>
> FWIW
> MidNight Mapper
> Aka neil
>
> -----Original Message-----
> From: bader nader [mailto:gis_man2002@yahoo.com]
> Sent: Tuesday, May 31, 2005 7:23 AM
> To: gislist@lists.geocomm.com: arcgis@lists.directionsmag.com:
> esri-l@esri.com
> Subject: [gislist] GPS systems (2nd time)
>
>
> Hi all
>
> I have posted before that I'm planning to buy a GPS system , really I'm
> confused ...
>
> When I do a search I found a lot of GPS...
>
> really I need some one who has a good experience in that and he used it .
> Since when I buy it no way to bring it back or to buy another.
>
> we are looking for handy one with one meter or less accuracy (in the middle
> east), handy (IPAQ, tablet PC), something like build in or Card.
>
> another Question whether the existence of the external antenna will make big
> effect.
>
> Hope that some will help me...
>
> Regards,
>
>
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--
Brian Russo <brian@russo-associates.com>
Russo & Associates: Geospatial Services & Solutions
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