International cooperation and technology transfer

Fras, Mojca Kosmatin

Bibliographic data

Monograph

Persistent identifier:: 856490555

Author:: Fras, Mojca Kosmatin

Title:: International cooperation and technology transfer

Sub title:: Ljubljana, Slovenia, February 2 - 5, 2000 : proceedings of the workshop

Scope:: VI, 163 Seiten

Year of publication:: 2000

Place of publication:: London

Publisher of the original:: RICS Books

Identifier (digital):: 856490555

Illustration:: Illustrationen, Diagramme

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: HIGHWAY SURVEYING WITH DGPS BASED ON RTCM SATELLITE CORRECTIONS. S. COSSI, M. MARSELLA, C. NARDINOCCHI, L. TOMBOLINI

Document type:: Monograph

Structure type:: Chapter

33 Owning to the receiver hardware development a very performing differential kinematic method can be presently adopted for road survey. This technique can be applied with the availability of a single receivers, of course the ROVER. The differential positioning is possible thanks to corrections send to GPS ROVER receiver trough a satellite communications link. The corrections computed using a network of reference stations are transmitted in a standard format known as RTCM-104 (Radio Technical Commission for Maritime Services, 1990). The receivers is equipped with to different antennas, one for receiving GPS signal and one for the differential corrections. The performance of this technique, still within the range of 1 -s- 2 meters, is not distance dependent since it do not require any reference station. The only limitation is the visibility of the communications satellite. This flexible and low cost positioning method was carefully examined in this work in consideration of its potential suitability for road survey. 3. FIELD EXPERIMENTS In order to check the effective performance of differential GPS techniques for highway survey, different field experiments were carried out. Different models of TRIMBLE receivers were used with particular attention to the Pro XR/XRS receiver, which support the use of satellite transmitted RTCM-104 correction. The receivers and the software adopted during tests are listed in table 1. RECEIVER Trimble Pro XR/XRS (single frequency) Trimble 4700 (dual frequency) Trimble GPS TS 4800 (dual frequency) SOFTWARE ASPEN (acquisition and navigation) PATHFINDER OFFICE (differential correction) GPSURVEY (phase processor) The dual frequency receivers were used to compute very accurate co-ordinates adopted in the validation of results from Pro XR/XRS receivers and as MASTER station. The software Aspen was used by the operator during the acquisition on the road, allowing to monitor different parameters, such as the satellite constellation and the status of satellite correction, to insert quickmarks and features and to display corrected co-ordinate and the trajectory. The performance of three different survey modes was investigated by means of the following preliminary field experiments executed with non-dedicated vehicles: Testl - Static GPS in Real Time with RTCM-104 correction transmitted via OMNISTAR to Pro XRS receiver; Test2 - Differential GPS in Post-Processing with a Rover Pro XR receiver and a 4700 Trimble receiver as Base Station; Test3 - Differential GPS in Real Time with RTCM-104 correction transmitted via OMNISTAR to Pro XRS receiver. The Post Processing differential mode was supported by a MASTER station located in a selected site by the Centro Rilevamento Dati of the Company Autostrade. The reference point was monumented on the roof of a building and precisely measured by means of a static session using two dual frequency receivers. 3.1 TEST 1: Accuracy assessment of Pro XRS -RTCM corrected position (transmitted via satellite) The aim of this test was to define the absolute accuracy of co ordinates determined by the Pro XRS receiver operating with RTCM-104 satellite transmitted correction (via OMNISTAR). The receiver was placed at the Reference Point DITS, located on the roof of the Department 37 of the University "La Sapienza" of Roma, which position was already known with millimetre accuracy. The period of acquisition was five hours long with a sampling interval of 30 seconds. More than 600 points were successfully collected providing horizontal accuracy of about 70 cm (Figure 2). The bias observed in the NE direction can be adduced to signal disturbances effective on the site. Figure 2 TEST 1 Distribution of points measured in a static survey using RTCM satellite transmitted correction. 3.2 TEST 2: Performance of Post-Processed corrected DGPS This test was carried out along 3 kilometres of the urban highway Roma EST. The route was covered twice back and forth, including a cloverleaf connection, in order to examine the consistency and reliability of the computed trajectory.

Access restriction

Copyright

fullscreen: International cooperation and technology transfer

Monograph

Chapter

Table of contents

Cite and reuse

Monograph

Chapter

Image

Image fragment

Citation links

Citation recommendation