GPS Observations By STRE

In November 1993, a group from the Squadron of Technical Royal Engineers (STRE) of the United Kingdom observed with TRIMBLE GPS L1/L2 receivers on 5 existing Doppler points and 9 new GPS stations in Peninsular Malaysia. In addition to that, 7 existing Doppler points and 4 old trigonometric stations were also observed in Sabah and Sarawak. The aim is to establish better transformation parameters from Doppler to WGS84 for the region and to connect Peninsular Malaysia to Sabah and Sarawak. In Dec, 1993, the GPS observations were successfully completed and computations and analysis were subsequently conducted based on the WGS84 reference frame. Results of STRE adjustments show that the absolute accuracy of WGS84 coordinates is at the 1m level for the X,Y and Z axes respectively.

ASIA AND PACIFIC REGIONAL GEODETIC PROJECT (APRGP) UNDER PERMANENT COMMITTEE FOR GIS INFRASTRUCTURE FOR ASIA AND THE PACIFIC (PCGIAP)

The primary objective of the ASIA AND PACIFIC REGIONAL GEODETIC PROJECT is to facilitate the establishment of a single regional datum through a network of compatible geodetic datums. Through this project, it is hoped to

Establish a regional reference datum

Determine the transformation values between the regional datum and the local geodetic datums of the individual countries

The first ASIA AND PACIFIC REGIONAL GEODETIC PROJECT 1997 (APRG97) campaign was organized by AUSLIG to establish a geodetic infrastructure to support GIS in the Asia and the Pacific region. The APRG97 results had been discussed  in Canberra, Australia from 2 to 4 July 1998 and matters involved in the discussion are as follows:

The results show that the final coordinates have a comparatively high relative accuracy of up to 0.1-0.3 ppb and an absolute accuracy of better than ± 3 cm in the ITRF global reference frame.

The second campaign of the APRGP98 also coincided with GEODYSSEA and was made in October 1998. The results of APRG98 and other related matters had been discussed in Ho Chi Minh City, Vietnam from 11 to 14 July 1999 with member countries presenting their final solutions and derived velocities and comparison made with the GEODYSSEA results.

DSMM has also participated in the EC-ASEAN Geodynamic project, known as the GEODYSSEA Project. This project which was initiated in 1994 and was completed in 1997, was to study the plate motion and crustal deformation in the region of the South and South East Asia. GPS campaigns were carried out in December 1994 and April 1996 to study such motions. This is followed by a GEODYSSEA Symposium in April 1997 in which results of the campaign were tabled and discussed.

Even though the GEODYSSEA project was officially terminated in 1997, the studies in the geodynamics of the region were still persued with a GPS campaign carried out in October 1998. The purpose of the endeavour was to further gauge and confirm the plate movements in the region as initiated by the GEODYSSEA project. With the available of such data, a time series dynamics of the region could be collected and studied.

From the two GPS campaigns of 1994 and 1997, a zero order network had also been able to be set-up in Malaysia with coordinates referring to ITRF94 and ITRF96 and with an absolute accuracy of better than ± 3cm.

MAP 19shows the stations of the GEODYSSEA network. The two Malaysian stations involved in both GEODYSSEA campaigns are Bkt. Pak Apil, Kuala Trengganu (KUAL) and Tinagat, Tawau, Sabah (TAWA). As indicated in Wim et. al, 1998, from the GEODYSSEA 94/96 combined solution, their computed velocities related to ITRF 94 & 96 are shown in TABLE 2 and TABLE 3 respectively. The mean resultant velocities for station KUAL is about 50mm/year and TAWA 30mm/yr.

GEODYSSEA 94/96 - Combined Solution Velocity Estimates W.R.T. ITRF94 (as from Wim et al 1998)

Station	KUALA, K.Trengganu	TAWA, Tawau
North (mm/yr)	3.477	-10.168
East (mm/yr)	43.015	27.364
Up (mm/yr)	15.463	20.114
Std.N (mm/yr)	2.147	2.058
Std.E (mm/yr)	2.543	2.241
Std.U (mm/yr)	4.090	4.034