DPOS vs OPUS Discrepancy

Joe Paulin

Active Member
I have been working on a large route project for a while now here in Ohio. We did static observations on all of our primary control points. The initial plan was to do 2 separate 2.5 hour sessions on each point. Using OPUS to process, on a lot of our points we didn't meet our quality criteria (<0.10' vertical) for the two sessions on the same point. We then switched to 4 hour sessions and that problem went away. Vertical is the weakest link with GNSS, long observations are needed.

Alexey Razumovsky

Well-Known Member
Staff member
We deployed new DPOS yesterday.
SOFTWARE: DPOS(3/26/2019 1:42:02 PM)
It removed last version that has worked since 5/29/2018
SOFTWARE: DPOS(5/29/2018 9:09:56 AM)

@James Suttles: Point #1001 was processed not accurate due to GALILEO data on two CORS (NCEC, NCWA).
GNSS frequency plan was changed in receiver firmware, Justin engine was mismatching this. It leads to a fault. Thank to you we have fixed it.
Now DPOS deals:
Point #1001 N: 161488.898; E: 805123.769; -21.071
Point #31120 N: 161697.500; E: 805389.105;-23.798
Height diff = -21.071 - (-23.798) = 2.727m

@Joe Paulin : I checked how accurate are short observation at Point#1001. I submitted on DPOS original (101 min) file, two halfs of original file, quarters of a file, tenths of a file.
I hope it may clear the issue.


@Jim Frame : I really do not understand why you are always getting 3-4 cm discrepancy in vertical while processing on OPUS and DPOS in CA.
In the meantime I ask my colleague to process last ten jps local base files coming to support with J-field project archives. He submit files to OPUS, DPOS and process files with GrafNav.
Results below (only heights):

Share some files with us for better knowledge to whom we should pointing a finger at.
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New Member
A project I am working on now is showing a discrepancy between OPUS and DPOS of about 0.2’ in the elevations of our base station. This project was located in Bolinas, California.

The base was setup over a point in an open field from a previous job. The coordinates from the previous job were used to start our base for a new job.

The base was setup for about a 4.5 hour session.

Below I have attached the reports for the DPOS and the OPUS files.

Any advice on what could be the cause of the discrepancy would be greatly appreciated. Let me know if more information is needed. I am not sure at this point what would be the more accurate option.


Alexey Razumovsky

Well-Known Member
Staff member
OPUS antenna type specified: JAVTRIUMPH_1M; Antenna height is vertical

DPOS antenna type specified: JAVTRIUMPH_1MR; Antenna height is slant

OPUS : N 658132.113; E 1807012.003; H 22.893 (submited Tyler)
DPOS : N 658132.112; E 1807011.989; H 22.959 (submited Tyler)

Identical antenna parameters deals (JAVTRIUMPH_1MR, vertical)
OPUS : N 658132.112; E 1807012.007; H 22.910 (submited JAVAD)
DPOS : N 658132.112; E 1807011.990; H 22.902 (submited JAVAD)
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