[Qgis-user] Trimble GeoXT 2005 Accuracy

[Springfield Harrison]

Hello All,

Thanks for the comments, I'll reply more fully tomorrow.

The receiver is Trimble mapping grade:

"The GeoExplorer 2005 series consists of:
• The GeoXH™ handheld, providing subfoot (30 cm) accuracy, or even 
8-inch (20 cm) accuracy
with the optional Zephyr™ antenna.
• The GeoXT™ handheld offering submeter accuracy for GIS data collection 
and data
maintenance.
• The GeoXM™ handheld with 1–3 meter GPS accuracy for mobile GIS 
applications."

"Post processed carrier accuracy: 1-30cm".  This receiver was probably 
$5-8000 (?) new.

  * Data collection was stationary, open sky, good satellite coverage,
    several minutes of 5 sec observations, good PDOP
  * SBAS and/or post processed

The concern is not the accuracy as such, but the systematic NW shift.  
This has been observed over several months, consistently. My old Trimble 
ProXR (1994?, $20K new!) is actually better in this regard than the GeoXT!

The Trimble manuals make no mention of the SBAS CRS, implying "turn it 
on and go, the receiver will integrate the SBAS into the rover file."

More tomorrow, thanks . . . . .

-----
Cheers, Spring




On 06/Mar/2021 15:56, kirk wrote:
> A few notes.
>
> sbas which is waas in north America is based on equatorial satellites 
> which will get you in the 1 m range in southern Canada.
>
> you can achieve sub decimeter accuracy consistently using rtk ,either 
> through a ntrip  caster (base station) broadcasting over the intenet 
> or with your own base station and a radio link. there are a few chip 
> sets and break out boards that you acquire and assemble your own 
> system. This is a very inexpensive option.
>
> Another option in Canada is to use precise point positioning (PPP) 
> which requires 6 to 12 hours of observation data using L1, L2 or L1 
> and L2 data and rinex log files. This comes in handy if you need to 
> establish a remote base station.
>
> A proper antennae with a metal ground plane is also critical to 
> getting quality results.
>
> Observing under a forested canopy is difficult especially in summer 
> under leaf on conditions,  after a rain which creates multiparth mayhem.
>
> There is a reason survey grade equipment is relatively expensive. If 
> you require repeatably accurate results in a variety of conditions 
> this is an option.
>
> Kirk Schmidt
>
>
>
>
>
>
>
> Sent from my Galaxy
>
>
> -------- Original message --------
> From: Jorge Gustavo Rocha <jgr at geomaster.pt>
> Date: 2021-03-06 6:41 p.m. (GMT-04:00)
> To: qgis-user at lists.osgeo.org
> Subject: Re: [Qgis-user] Trimble GeoXT 2005 Accuracy
>
> Hi,
>
> I just jump in this thread to say I'm really impressed with 
> Ardusimple. I have a RTK Handheld Surveyor Kit [1] for +- 400 € and it 
> works really well.
>
> I use the national NTRIP service and I have consistently precisions 
> around 10 cm with just one receiver.
>
> I use a free Android application called SW Maps [2]. My survey points, 
> tracks and photos are collect in a geopackage that I can read in QGIS. 
> I use it mostly to collect ground control points for my drone flights.
>
> Regards,
>
> Jorge Gustavo
>
> [1] https://www.ardusimple.com/product/rtk-handheld-surveyor-kit/
>
> [2] https://play.google.com/store/apps/details?id=np.com.softwel.swmaps
>
> Às 20:12 de 06/03/21, Greg Troxel escreveu:
>> Springfield Harrison<stellargps at gmail.com>  writes:
>>
>>> Thanks Dan.  See my relies to Kirk and Greg.  The Emlid sounds
>>> interesting, will have a look.
>> I have an earlier Emlid Reach (not RS or RS2), which has L1 only, and I
>> never got it to work well.
>>
>> Also look at the Ardusimple unit -- but it's more a parts kit than a
>> system.  You need a way to get RTK reference data in, and a good
>> antenna.  One approach is Vespucci (OSM editor for Android) as a
>> datalogger, and the Ardusimple WiFi NTRIP master to get corrections over
>> the phone's hotspot.
>>
>>    https://www.ardusimple.com/product/simplertk2b/
>>
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> -- 
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