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:: RTK SURVEY USING COMBINED GPS+GLONASS L1/L2 CARRIER PHASES. Crocetto N. - Gatti M. - Marchesini M. - Negroni F. - Russo P.

Document type:: Monograph

Structure type:: Chapter

RTK SURVEY USING COMBINED GPS+GLONASS L1/L2 CARRIER PHASES Crocetto N. (i) - Gatti M. (ii) - Marchesini M. (iii) - Negroni F. (iv) - Russo P. (ii) (i) Department of Civil Engineering. Second University of Naples, via Roma 29, Aversa (Italy), (ii) Department of Engineering. University of Ferrara, via Saragat 1, Ferrara (Italy). (iii) Guido Veronesi s.r.l., via Caselle 46, Bologna (Italy). (iv) Studio Negroni, via Salvador Allende 32/34, Bologna (Italy). ISPRS WG VI/3 International Co-Operation and Technology Transfer and WG IV/3 Temporal Aspects and Topographic Database Maintenance KEY WORDS: GPS, GLONASS, RTK, CARRIER PHASE. ABSTRACT. This paper describes some experiments carried out with the RTK technique (Real Time Kinematic Survey) to combine GPS and GLONASS measurements on carrier phases LI and L2. These experiments involved: 1) marking out transverse sections of a road embankment; 2) localising reference points in woodland for a water supply tunnel. The measurement technique is described and compared, in terms of productivity and precision, with similar techniques using conventional topographical instruments and satellite instruments with GPS measurements only. RESUME. Ce document décrit quelques expériences réalisées à l’aide de la technique de cinématique temps réel combinant les mesures GPS et GLONASS des phases de support L1 et L2. Ces expériences concernent: 1) le marquage des sections transversales d’un remblai de route ; 2) la localisation de points de référence en terrain boisé pour la construction d’une conduite d’eau. La technique de mesure est illustrée en termes de production et de précision, notamment dans le cadre d’expériences similaires faisant appel à des instruments topographiques traditionnels et des instruments satellites utilisant uniquement des mesures GPS. INTRODUCTION The GPS "Real Time Kinematic Survey" (RTK) technique differs from the classical GPS (Continuous Kinematic) technique in that the relative position of one receiver (Rover receiver) with respect to another (Master receiver) can be calculated instantaneously (Real Time). This technique, tested in Italy since the mid-1990s (Bitelli et al., 1994; Gatti et ah, 1995), allows us to extend the applications of the GPS to the measurements of traditional field surveyor. However, some factors have inhibited its more widespread use: 1. the use of radio modem apparatuses approved for use in Italy with maximum power in the UHF band of 1 Watt; 2. the GPS satellite configuration, which is limited to the contemporaneous presence of 7-8 satellites for the measurements and values of PDOP greater than 2. 3. the number of components of the signal observed and the quality of the acquired signal. The range of a single radio link device, at the indicated power, is a little more than 1.5 km from the Master receiver. This can considerably limit the operational area of measurement '. The satellite configuration can instead increase the times of static initialisation and dynamic re initialisation of the Rover receiver * 2 . The components of The range of the radio link device can obviously be increased if one uses another radio link as a radio bridge (radio repeater). 2 For example, with at least 6 visible satellites and a PDOP less than 3, the static initialisation with only GPS measurements is performed after the signal and its quality can affect the instantaneous resolution of a double difference. In unfavourable operating conditions or in the presence of electromagnetic fields (Gatti et al., 1998), it can be difficult to perform the positioning in real time with GPS receivers alone. The application of the method is thus limited to open and sparsely inhabited zones, i.e. areas in which it is possible to receive both the radio link signal and the GPS signal from at least 6 satellites without interruptions of the signal in one or more components. The introduction on the market of receivers designed to acquire signals on LI and L2 carrier phases from both GPS and GLONASS satellites has greatly increased the possibilities of employment of the RTK technique. The acquisition of the GLONASS signal combined with the GPS signal has led to the following advantages: • an increased number of operational satellites, from the usually 7-8 for the GPS system to around 10-11 for the GPS+GLONASS system (Fig. 1) • improved reception of the signal even in the presence of electromagnetic disturbances poorly tolerated by the GPS receivers alone (Misra, 1993; 1996); • decrease of the PDOP (Fig. 2-a and 2-b) (Contreras, 1998); at least 5 minutes of reception without interruption of the signal; the re initialisation, which in the GPS receivers with double frequency is performed in movement (so-called dynamic initialisation or O.T.F.), occurs after 2 minutes of reception, i.e. after having received with continuity at least 120 periods after the loss of the signal. If the number of satellites decreases or the PDOP changes, the indicated times can increase considerably. 38

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