According to JUPEM circular 1/2008-Appendix A1, there are two methods to carry out GNSS calibration. We can either use tribrach or mount the GNSS gadget onto the pillar screw. I did discuss with District Surveyor on this issue because initially we understand that the antenna height should measure from the GNSS gadget’s marker to the survey station. Thus, we also applied the same concept measured the antenna height from the marker to the pillar and subsequently to the top of the screw. However, we still unable to get the acceptable result when compare with JUPEM reference.
The kindness of the District Surveyor has explained to me the content of this circular. The antenna height should measure according the below diagram.
Please take note that antenna height will be negative which equal to the height of the screw.
The second clarification is regarding the comparison of coordinate especially the ellipsoid height. I did 3 pillar on yesterday (minimum requirement) and result showed the differences in latitude and longitude were within 3cm and JUPEM circular 1/2008 under "Ujian cerapan statik berkala" 4.3.9 stated that the tolerance must less than 3cm in North/east and 6cm in height difference.
The three (3) pillars observation on yesterday showed that the difference ellipsoidal height more that 6cm. District Surveyor emphasized that the statement is on comparison between coordinate of epoch and not to the reference JUPEM coordinate. If we need actual height then we need to refer to geodesy department to get the geoid height "N" correction. It sounds positive to me but my friend measure from the marker to the top of screw and able to get tolerance result. I do not how to describe it!
3 comments:
I'm sure we need to compare to JUPEM coordinates!
Dear CK,
Our GNSS observation is compulsory to compare with JUPEM pillar reference which available in SPAK.
The district surveyor was emphasized that our cadastral involved of x and Y coordinate or Lat/long in GDM2000. In term of value of Z is not the main issue because our present NDCDB system has not applied the height in our cadstral coordinate system.
In my GNSS calibration, my ellipsoid height more than 6cm and caused to seek district surveyor advise.
I will tell you more info when I submit my CRM data.
Dear CK,
Our GNSS observation is compulsory to compare with JUPEM pillar reference which available in SPAK.
The district surveyor was emphasized that our cadastral involved of x and Y coordinate or Lat/long in GDM2000. In term of value of Z is not the main issue because our present NDCDB system has not applied the height in our cadstral coordinate system.
In my GNSS calibration, my ellipsoid height more than 6cm and caused to seek district surveyor advise.
I will tell you more info when I submit my CRM data.
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