Development of a system to enhance the accuracy of GPS observations via Internet | |
| Author | Dammalage, Thilantha Lakmal |
| Call Number | AIT Thesis no.RS-06-25 |
| Subject(s) | Global Positioning System Internet |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Remote Sensing and Geographic Information Systems |
| Publisher | Asian Institute of Technology |
| Abstract | Networked Transport of RTCM via Internet Protocol or NTRIP is a recently developed (application level) protocol streaming Global Navigation Satellite System (GNSS) data over Internet. NTRIP was developed by the Federal Agency for Cartography and Geodesy of Germany, and it was become the world standard protocol for GNSS data streaming by end of year 2004. NTRIP enables streaming of DGPS or RTK correction data for stationary and mobile users via Internet using GPRS or other future technologies such as EDGE, or UMTS. This allows simultaneous PC, Laptop, PDA, or receiver connections to correction data broadcasting host. The Geoinformatics Center at Asian Institute of Technology successfully established the first real-time GPS data streaming station in Thailand using this technique. This contributes to the network of global GNSS reference stations, providing real-time GPS data since March 2006. This research examines the technical concepts of NTRIP and illustrates the data distribution structure installed at AIT. Furthermore, this includes a detail accuracy analysis and practical benefits of the NTRIP technique over the conventional RTK and DGPS correction methods that presently in use. The results discussed in this paper are based on field observations carried out during March to September 2006. The accuracies of DGPS corrected and uncorrected GPS observations with respect to base line distance, PDOP value, internet traffic and standard deviation were analyzed and discussed. It was found that NTRIP technique has high potential to replace conventional realtime or post-processing differential GPS techniques. Even for the precise GPS instruments, such as high-cost (dual frequency L1/L2) or medium-cost (single frequency L I), it shows significant benefit while maintaining the same accuracy as radio RTK or post-processing DGPS. NTRIP technique provides more reliable and safe method of RTCM correction streams than transmitting it with radio signals. Furthermore, it was identified that NTRIP is a technique to enhance low-cost (handheld) GPS receiver observations in real-time. The other significant finding of this study was that NTRIP enhances the observation accuracies with distance (base line) independent manner. It was tested up to 500 km's and achieves the identical accuracy levels as of post-processing DGPS technique which carried out using local reference station with a shorter base line. NTRIP technique will overcome the single user problem, providing simultaneous multiple user possibility of real-time differential GPS. Hence it does away with maintaining additional GPS instrument as a reference station and minimizes the cost of DGPS significantly. This method has some drawbacks such as sudden disconnections from the server during the survey and high latency time (delay time due to internet traffic). This would be minimized with the development of advance mobile communication technologies such as EDGE and UMTS, also this will reduce the communications costs |
| Year | 2006 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Remote Sensing (RS) |
| Chairperson(s) | Susaki, Junichi |
| Examination Committee(s) | Samarakoon, Lal;Chen, Xiaoyong |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2006 |