NAvlC.vno~: Journal of The Institute ofNavigation zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM Vol. 37, No. 1, Spring 1990 Rinted in U.S.A. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA High-Accuracy GPS Semikinematic Positioning: Modeling and Results M. ELIZABETH CANNON The University of Calgary, Calgary, Alberta, Canada Received September 1989 Revised November 1989 ABSTRACT The concept of GPS semikinematic positioning is reviewed, with an emphasis on accuracies at the centimeter level. Details of the mathematical model used herein are given. A two-step approach combines a Kalman filter to process kinematic carrier phase, phase rate, and pseudorange data, while a batch least-squares adjust- ment processes static carrier phase data. A semikinematic test performed over a well-controlled traverse in a mountainous region near Calgary is used to assess the performance of the algorithm. Several runs of the traverse were made with the station occupation time at 2-3 min. The analysis shows that centimeter-level accuracies can be achieved when five satellites are observed in good geometery, even when frequent cycle slips occur. An accuracy improvement technique of reverse processing is also investigated. Recommendations for improving semi- kinematic surveying are made. INTRODUCTION GPS semikinematic positioning is a procedure in which stations along a traverse are occupied for a short time, e.g. 2-4 min, and then the receiver is moved to the next station along the traverse. The name semikinematic refers to the two dynamic states of the receiver; part of the time is spent static on a station, while the rest of the time the receiver is in pure kinematic mode en route to the next station. This method is an extension of conventional GPS relative static surveying, which normally requires l-2 h of data per station to obtain centimeter accuracy. The goal of semikinematic surveying is to maintain the centimeter-level accuracy while reducing the site occupation time from hours to minutes. By achieving this goal, dramatic cost and time savings can be made on a precise GPS survey. One application of the semikinematic technique is for densification of control points in geodetic networks. A number of semikinematic tests have been performed to date, for example, those described in [l-6]. Centimeter accuracies have been achieved under varying conditions, ranging from very short baselines, for example, as described in [5 and 61, to baselines of up to 20 km [21. Most of the processing techniques do not use the kinematic GPS data collected between the static stations. A method is presented in this paper which uses both the static and kinematic data in a two-step processing technique. A least-squares batch adjustment is used to process the static data, while a Kalman filter is implemented on 53