The second precise levelling network of Peninsular Malaysia

The measurement of Second Precise Levelling Network (PLN) for the Peninsular Malaysia which was completed in 2000 by Department of Surveying and Mapping Malaysia (DSMM) is set to replace the First Order Levelling Network of 1967. The new network consists of 113 levelling lines with more than 5000 bench marks and covers a total distance of over 5000 km. Precise levelling technique is used to establish the network where the allowable misclosure between fore and back levelling is less than 3 mm per root kilometre of length along a line. Its configuration is predominantly dictated by the land transportation pattern. The mean sea level (MSL) at Port Kelang, based upon a 10-year tidal observation (1984-93), was later being adopted as the new Peninsular Malaysia Geodetic Vertical Datum (PMGVD). A consistent and accurate set of adjusted heights of benchmarks has been achieved in the adjustment of the Precise Levelling Network of Peninsular Malaysia on the datum defined by MSL height at Port Klang. These adjusted heights are based on the Helmert orthometric height system. By fixing Port Kelang, the precision of the PLN can be expressed as 1.14 mmvkm. This implies that for any of the 5,295 first-order levelling bench mark across the nation, a height precision of better than 3 cm can be expected

Enhancement of height system for Malaysia using space technology: the study of the datum bias inconsistencies in Peninsular Malaysia

The algorithm for orthometric height transfer using GPS has been widely presented. Its practical limitations are mostly due to datum bias inconsistencies and lack of precise geoid. In most applications, datum biases are assumed to be systematic over short baselines and therefore could be eliminated by differential heighting techniques. In this study, optimal algorithms were investigated to model biases between local vertical datum in Peninsular Malaysia and the datums implied by by EGM96, OSU91A and the regional Gravimetric Geoid in South_East Asia. The study has indicated that local vertical datum is not physically parallel to the datums implied by the above geoids. The shift parameters between the datums implied by the GPS/leveling data, and the EGM96, OSU91A and the gravimetric datums are about – 41cm, -54 cm and – 8 cm respectively. Also the maximum tilts of the planes fitting the residual geoids above these datums relative to GPS/Leveling datum are of the order of 36, 51 and 33 centimeters per degree. It is therefore necessary to take into account the effect of inconsistent datum bias particularly for baseline height transfer. The level of accuracy achieved by the bias corrected relative orthometric height differences of the EGM96, OSU91A and the gravimetric geoid models combined with GPS/leveling data for baseline lengths up to 36 km, is sufficient to replace the conventional tedious, time consuming ordinary leveling technique for rapid height transfer for land surveying and engineering applications

Modeling of the communication link for data correction in network-rtk

The current communication in several network-RTK systems is frame relay technology that applied packet switching network (leased line) based on IPVPN which services data transmission between reference stations to control station. The most significant shortcoming of frame relay technology is depend on cabling networks and bandwidth limitation that is not effective for the rural or suburban area. In other hand the channel speed of frame relay is relative small for data transmission. This limitation has an effect on bandwidth, cost and time delay of the data transmission. In this paper we propose the system model of the 3G technology that is capable to overcome cabling dependency due to complicated installation, cost and time delay due to low data rate that will be applied for Network-RTK system in Metro-Area of Iskandar Malaysia. 3G technologies offer users a wider range of more advanced services while achieving greater network capacity through improved spectral efficiency. Services include widearea wireless voice telephony, video calls, and broadband wireless data, all in a mobile environment. It can be expected by applying of 3G technology in network-RTK, the performance system of real time data transmission are improved in bandwidth capacity, channel speed and diminish the expenditure of cablinginstallation

Gridding digitized bathymetry in the Straits of Malacca

Maritime charts in the form of bathymetry from the Straits of Malacca were digitised to form the data set that was operated on by the Kriging algorithm to provide gridded digital data sets. There were two forms of algorithms tested, the Kriging and the Minimum Curvature, of these two Kriging was found to be the most suitable. Along with these two algorithms different grid sizes were also experimented with, these were 1 minute and 5 minutes (I' & 5'). The I' grid size and the Kriging were found to be the best combination for the gridding of the digitised bathymetry. The bathymetry was digitised 'on screen' using Golden Software's Didger3. The maps were of mixed scales 1:200000 and 1:300000, scanned at a resolution of 150 dpi, this was done in order to decrease the size of the digital file, namely the TIF format. Affine polynomial calibrations were performed on all charts and were within acceptable limits. A total of 18357 points were digitised induding soundings and coastlines, the minimum height being -358.86 m the maximum being 0 m. All soundings were transformed to Mean Sea Level (MSL) using the tidal information published by the Department of Surveying and Mapping Malaysia (JUPEM) Tide Tables for the year 1998. A comparison of the gridded (Kriging) digitised points is accomplished through comparing an independent set of digitised points (approximately 10%) with the gridded digitised data. Also a comparison with ETOP05 is made, the results are as follows: a mean of the differences of -0.332 m and the standard deviation of the mean of ±7.784m, for the digitised data set and a mean of the differences of -0.281 m and the standard deviation of the mean of ±15.812m for ETOP05. This tends to show that ETOPOS is not as representative of the bathymetry of the Straits of Malacca and that the gridding process followed by the authors is suitable enough for the data to be used in other applications, such as tidal studies or current analysis for offshore and coastal engineering processes

Towards the optimum design of GPS monitoring network for subsidence monitoring of offshore platforms in Malaysia waters

The GPS Ground Segment (also referred to as Control Segment or Operational Control System) is the responsible for the proper operation of the GPS system. The GPS Control Segment is composed by a network of Monitor Stations (MS), a Master Control Station (MCS), a backup of the MCS and the Ground Antennas

An appraisal of multibeam echo sounder calibration

One of the most impressive hydrographic technique developed over the past few decade is multibeam sonar systems. Sounding data from these systems is a result of processing information from several data sources. Among them, positional data from Global Positioning System (GPS), vessels heading and attitude data from gyrocompass and motion sensor systems, vertical reference data from tide gauge and sound speed data, in addition to the multibeam data itself. There must be a good coordination between these systems in order to obtain reliable data. To determine this, a proper and thorough field calibration procedure has to be carried out on the system as a whole. This process begins with measurement of static offsets between each sensor system with reference to a fixed point on the vessel. Preferably, the point of centre of gravity (COG). Then the patch test is carried out to determine the mounting offsets and GPS latency and lastly a performance test to verify whether the data meet the accuracy requirements for the survey. This is achieved through a comparison of data with a reference surface. This paper discusses the theoretical aspects, steps involved and results of the calibration procedures for multibeam sonars, using RESON SeaBat 8124 multibeam system. Finally, a summary of multibeam sonar calibration criteria is also presented showing the methodology involve which include when to perform each test and applying corrections

A Study of Geopotential Geoid in the Peninsular of Malaysia

Geo idal heights can be computed for a single point value or a grid of values.A program to compute goidal heights from a set of high degree potential coefficients was developed. Backward recurrence formulae have been used to evaluate the value of normalized Legendre functions.The regional and global geopotential geo id evaluated from the available sets of potential coefficients were shown in the form of contoured maps. The computed geo idal heights derived from different sets of potential coefficients were compared with Doppler derived values at six points in Peninsular Malaysia. The results indicate that, of the models tested OSU86 gives the best solution to the geopotential geoid in the regio

Recovery of Bearings and Distances for Internal Lots From Cadastral Perimeter Survey Data: Case Studies in Several States of Peninsular Malaysia

A study is being carried out to investigate the most appropriate way of determining the missing bearings and distances for internal cadastral lots where the boundary lines are mainly represented on the certified plans (CPs) by scaled distances only. A computer program has been written to compute the bearing and distance for the related lines using the perimeter of the lots which were defined by second class surveys. The computed bearings and distances were later used to re-compute the area of the internal lots and compared with areas given by the certified plans. Results from test computations which has been carried out in selected areas in several states of Peninsular Malaysia indicate that the average differences between the computed and certified areas for the internal lots is less than 1%. Further efforts are being made so that the differences could be well distributed and mirlimized within the area specified by the perimeters

Preliminary Analysis of Precise Levelling Network for The Southern Peninsular Malaysia

Precise levelling has been planned and implemented by the Department of Surveying and Mapping Malaysia (DSMM) for the provisioning of the levelling framework of the country. The precise levelling network provides the vertical reference datum for mapping and engineering purposes as well as for scientific research work, which includes tectonic movement monitoring and mean sea level studies. At present, twelve loops of precise levelling which cover the southern part of the Peninsular Malaysia were surveyed, processed and adjusted. The precise levelling was made with high precision levelling instruments which are currently used by DSMM, namely, Zeiss NI002A and digital automatic level, Wild NA3000. These instruments are capable of storing data in computer readable form for the purpose of processing and adjustment. Data acquired from the field were processed by RAPC-1 and DELTA processing software. Adjustment and analysis were made using Geolab network adjustment software. For future investigations on Peninsular Malaysia Height Datum, the levelling network has been tied to first order GPS network and tide gauge" stations. This paper briefly described the procedures for the acquisition, processing and adjustment of the levelling data for the twelve levelling loops covering the southern half of Peninsular Malaysia