Réunion du Projet GEOIDE ENV#14

tenue le 2 novembre 2001 à Montréal (Viasat)


Meeting of the GEOIDE Project ENV#14

held on November 2nd, 2001 at Montreal (Viasat)


9:00 Mots de bienvenue / Welcome addresses

People present at the meeting :

CRG-UL : Rock Santerre, Brian Morse, Stéphanie Michaud, Nicolas Balard

UNB : Richard Langley, Sunil Bisnath

McGill: Xiao-Wen Chang

Viasat: Denis Parrot, Claude St-Pierre, Luc Lamoureux

GSD : Pierre Tétreault


9:05 Résumé des activités de recherche depuis juin 2001/ Summary of research activities since June 2001


Dr. Kim has continued his work on an optimised least-squares ambiguity search technique, cycle-slip corrections and quality control for real-time applications. The research has also dealt with physical and mathematical correlations. Dr. Langley summarized Dr. Kim’s most recent work, because Dr. Kim is working right now on a research contract in South Korea. He will be back at UNB by the end of November. Full papers on this work, published in the proceedings of ION-GPS 2001 and KIS-2001, can be found on the UNB Web site <http://gauss.gge.unb.ca/papers.pdf/>. Dr. Kim also submitted a refereed paper to the U.S. Journal of Navigation.

S. Bisnath, a Ph.D. student at UNB, who joined the Project ENV#14 team last summer has worked on reliable cycle slip detection and repair and precise point positioning (PPP) software. Full papers describing his work, published in the proceedings of ION-GPS 2001 and KIS-2001, can be found on the UNB Web site. He presented results from PPP which were obtained from both static and kinematic data (including Low Earth Orbit satellite CHAMP). Initital rms values for 3-D positioning of 20 cm have been attained.



L. Lamoureux presented some PPP results obtained from the software originally developed by GSD (P. Héroux). This modified software is going to be added to the Viasat GPS software suite. Close cooperation between Viasat and UNB is planned to compare results from the two PPP software packages independently developed and to possibly unify the two approaches.

C. St-Pierre showed results obtained from Dr. Zhu’s algorithm (CRG-U.Laval) to calculate a smoothed float ambiguity solution which takes also into account the occurrence of several cycle slips. Drastic improvement, in comparison to the original float solution actually coded in the Viasat’s EzSurv software, is clearly demonstrated. IP agreement has to be signed between Viasat and the CRG about this new algorithm.



Dr. Zhu also worked on the use of a priori height, obtained from the tide gauges, as a quasi observation in GPS-OTF data processing. A paper has been submitted to Geomatica, last August. Dr. Zhu returned to South Central University, China, in July. He is planning to come back to the CRG, next February.

Brian Morse, a professor of Civil Engineering, worked with Stéphanie Michaud (a research assistant at the CRG) and Jimmy Siles (a civil engineer with an M.Sc. in hydrodynamics, now a research assistant working on Project ENV#14, since September 2001) on the determination of ship under keel clearance for secure maritime navigation. Data from field tests collected during the Fall 2000, for the St. Lawrence Seaway, are now available to the Project ENV#14 research team. In relation to these works, Dr. Morse got a mandate (a contract) with the Centre de développement des Transports (CDT), to further process and analyse squat and under-keel clearance algorithms. An abstract, summarizing the results obtained thus far has been submitted to the Canadian Civil Engineering Conference to be held next June.


12:15 – 13:00 Lunch time

13:00 Planification des futures activités de recherche / Planning of future research activities

Dr. Chang, from the Department of Computer Science at McGill University, officially joined the Project ENV#14 Team. He is a specialist in computer algorithm optimisation and GPS integrity solutions. Two of his graduate students will be working to topics related to the project (see the Appendix for a short description of their future works).


Technology Transfer

Many pieces of software, new algorithms and results have been developed, tested and analysed. It is now time for technology transfer to our industrial partner. In this perspective, several agreements should be signed to protect Intellectual Property, namely:

    • The development of the algorithm for smoothed float GPS phase solution (CRG-Viasat).
    • The fusion of PPP software (UNB-Viasat).
    • The software modules related to cycle slip detection and stochastic modelling (UNB-Viasat).
    • The squat model equation (U.Laval-CDT).



Refereed papers

Two new refereed papers have been submitted, one by Dr. Kim (Navigation) and another one by Zhu and Santerre (Geomatica). Planning of other papers to be submitted to refereed journals has been made. Here are some proposals:

    • A paper on PPP combining Viasat and UNB algorithms and software (Action: S. Bisnath and L. Lamoureux).
    • A paper on squat and UKC based on the presentation to the Canadian Civil Engineering Conference (Action: B. Morse and S. Michaud).
    • A paper on the efficiency and robustness of precise GPS navigation (Action: X.-W. Chang)
    • A collective paper on the current status and future trends into the field of precise GPS marine navigation (Action: B. Morse).




A Centre of Innovation in GNSS has been proposed by UofC. Presentations have been given to representatives from UNB, Viasat and GSD. The GEOIDE Network is aware of this proposal. Coordination will have to be addressed between GEOIDE and this new CoI in GNSS, if this project really goes ahead…



The full proposal of the Galileo Project (LOI#19), involving the 3 universities active in GPS (Laval, UNB and Calgary) and McGill University, has been submitted to the GEOIDE Business Office, by October 15th, 2001. The other participants are: GSD, Viasat, NovAtel and Thales. The acceptance will be known at the beginning of February and if the answer is positive the project will start April 1st, 2002, for a 3-year period.


15:00 Visite des nouveaux locaux de Viasat / Visit of Viasat’s new facilities


15:30 Fin de la réunion / End of the meeting

The next project meeting is scheduled for the second week of March 2002. Again, the meeting will probably be held at Viasat’s office, in Montréal. The date will be announced later.



Appendix: Description of the projects of the two McGill M.Sc. students

Ms. Lan Yin:

Chris Paige and Xiao-Wen Chang have recently developed an efficient and numerically reliable recursive least squares algorithm for carrier phase based positioning. In the algorithm, ambiguities are not fixed as integers, because for many applications like those VIASAT Geo-Technologies Inc. has, float ambiguity solutions are enough for the desired accuracy of position estimates. In order to apply our algorithm to real data, we need to incorporate an algorithm for cycle slip detection and/or correction. Ms. Yin is doing comparisons of some typical available methods for cycle slip detection and/or correction. She will incorporate one of the best methods in our positioning algorithm. She is also expected to extend our current positioning algorithm to handle both carrier phase measurements and code pseudorange measurements.


Ms. Ying Guo:

Recently a few people in the GPS community have applied adaptive robust estimation techniques to GPS based positioning. Some test results suggest the techniques are promising. However there are two main problems with the literature. One is that no any paper we have seen deals with the implementation issue.   When we implement a method, we have to consider a few key issues like efficiency, numerical reliability, and memory. The other is that the methods in the literature are for general estimation problems.  But the estimation problems arising from GPS have special structures, which should be used to make the methods more efficient. Ms. Guo is developing efficient and numerically reliable algorithms for Kalman filtering based adaptive robust estimation for general purposes. After that, she will develop specific algorithms for GPS based positioning by taking advantages of the special structures of the position estimation problems.

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