Geoscience Reference
In-Depth Information
• The streaming of raw observations data from both the reference and roving
stations to the control centre implies that all available information can be
effectively utilized.
The main advantages that the server-based processing technique can provide for
landslide monitoring application are that the costs and tasks of the monitoring
scheme will be drastically reduced, as low-cost receiver hardware will be utilized
for real-time streaming of raw GPS measurements and complex algorithms and
computations at the user end will be eliminated.
3 Continuously Operating Reference Stations (CORS)
Networks of GNSS are being established in many regions of the world to provide
valuable infrastructure for real-time kinematic positioning and applications in
areas such as surveying, mapping, navigation and environmental monitoring. The
server-based processing technique usually utilizes existing GPS/GNSS CORS
infrastructure. The CORS facilities utilized for this study is the ISKANDARnet.
The control centre of ISKANDARnet is located in the Faculty of Geoinformation
and Real Estate, Universiti Teknologi Malaysia (Shariff et al.
2009
). ISKAN-
DARnet was developed to provide infrastructure for strategic research in areas
such as atmosphere, meteorology, and precise positioning in the Iskandar region of
Johor, Southern Malaysia. At the time of writing this chapter, ISKANDARnet
consists of four reference stations (ISK1, ISK2, ISK3, and ISK4), while more
reference stations are being planned for the future. The distribution of the current
ISKANDARnet reference stations is given in Fig.
3
.
The conventional RTK method employs radio links to transmit reference
receiver data (or observation corrections) to the rover receiver. The rover unit
utilizes this data together with its own raw measurements to resolve the ambiguity
of the differenced carrier phase data and to estimate the rover's position. The main
problem of the single-base RTK technique is the restriction of the baseline length
to 10-20 km, due to distance-related errors (e.g. orbit errors, and atmospheric
signal refraction) (Rizos et al.
2010
). The network RTK technique, on the other
hand, uses a network of CORS to acquire a large amount of data, over a wide
geographical scale, for the determination of the position solutions. The NRTK
allows the separation between the reference stations at significantly longer baseline
lengths, and has been able to address the baseline length restriction of the single-
base RTK technique. In this study, the reverse approach is being implemented
based on the standard single-base RTK technique (i.e. RRTK).
