DGPS VerificationPrimary DGPS and s

DGPS Verification
Primary DGPS and secondary DGPS comparison/ checks shall be performed in
accordance with the SOP-004 GPS Procedure.
The DGPS will be verified by comparing the observed antenna positions to known
control points on the wharf. This activity may be conducted while the offshore vessel
mobilizes in Loyang Offshore Supply Base, Singapore (HILONG 106). A survey total
station will be set up over a known point at the wharf and the vessel DGPS antenna
position observed. Observations will be subsequently compared to the DGPS derived
position.
Prior to this activity, all vessel offsets in the NaviPac software must be zeroed to ensure
that the data logging recorded is from the DGPS antenna itself and not from any offsets
on the vessel.
For the DLB01, as the system has been verified from the earlier project, a transit fix by
the DLB01 AHT to the existing KE-5 CPP Platform will need to be conducted upon arrival
at work site.
8.8.2 Gyro/Heading Calibration
The Primary and Secondary heading calibration shall be performed in accordance with
SOP-003 Gyro Calibration and Verification Procedure.
The two Meridian Surveyor Gyros (Primary and Secondary heading) and DGPS Heading
will be calibrated against known ground control points on the wharf. This activity may be
conducted while the offshore vessel mobilizes in Loyang Offshore Supply Base,
Singapore (HILONG 106).
For the DLB01, as the gyros has been calibrated from the earlier project, a Sun
Observation by land survey method will be conducted to ensure that both gyros are
within the normal working tolerance and that the corrections (C-O) applied from the
earlier project, are still acceptable.