[Qgis-user] Trimble GeoXT 2005 Accuracy

[Kirk Schmidt]

Hi Springfield:

PPP requires long observation times in the order of hours and therefore 
a new field survey.  I would try post processing from a high precision 
site with your existing data.

Another issue may be the aviation antennae you mentioned.  These are 
usually mounted on the top of a fuselage and therefore the aluminum acts 
as a ground plane to effectively filter out multipath.  If you use a 
metal disk or plate and a ground plane on your antennae and mount it on 
a tripod, you may find you end up with better results.  You will notice 
survey grade antennae's have a large diameter plastic case since the 
contain an internal 10 cm metal disk.

Kirk Schmidt

On 3/9/2021 1:36 PM, Springfield Harrison wrote:
> Hello Garth,
>
> Thanks very much for that reference.  I have used the service in the 
> past.
>
> I'm in the middle of other work but may try to re-process some Map A 
> files using PPP to see what changes.
>
> Your work sounds more like surveying than mapping, interesting.
>
> I do use the GPS reception planning tools but SV availability is 
> certainly better than in the early days.
>
> Thanks again . . . .
>
> -----
> Cheers, Spring
>
>
>
> On 09/Mar/2021 09:01, Garth Fletcher wrote:
>> Nicolas Cadieux wrote:
>>> Kirk could be on the right track.  You could try PPP using this 
>>> site.  You will need to create a user name and password.  Then, you 
>>> upload the Rinex file.   I am 99% sure you can process point from 
>>> outside of Canada. 
>>
>> I routinely use CSRS PPP to post process RINEX files from Southern New
>> Hampshire (43°N, 72°W).
>>
>> Using an iGage iG3s (L1/L2 dual frequency, GPS + GLONASS) recording at
>> 5 second epochs in forested areas, from post processing I get
>>  30 minute recordings, 95% error ellipses < 1 meter
>>  10 hour recordings,   95% error ellipses < 2 cm
>>
>> CSRS-PPP site is
>> <https://webapp.geod.nrcan.gc.ca/geod/tools-outils/ppp.php?locale=en>
>> enter your email address
>> select Static and which NAD 83 epoch you want, or ITRF
>> Submit a RINEX file (.zip compressing the file is encouraged)
>> they will email back a detailed report
>>
>> You can submit for 1 of 3 levels of post processing
>>  ultra-rapid : submit > 90 minutes after end of recording
>>  rapid: submit > 24 hours after end of recording
>>  final:  submit ~ 3 weeks after end of recording
>>
>> Major part of corrections are in ultra-rapid, the higher levels provide
>> further refinements.
>>
>>
>> FYI: Trimble provides occupation planning aids at
>> <https://www.gnssplanning.com/#/charts>
>> just enter your location and date and it shows you the DOP as
>> a function of the hour of day.
>>
>> Cordially,
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-- 
Kirk Schmidt, MScF, BScF, RPF
General Manager
Nortek Resource Solutions Inc.
RR # 1
Thorburn, NS
B0K 1W0
Tel (902) 922.3607
Email: kirk at nortekresources.com
Web: www.nortekresources.com