RTK positioning under trees

The paper presents the results of positioning by means of the RTK (Real Time Kinematic) method under forest conditions. The experiments were conducted over four consecutive days on hours when the configuration of GPS satellites over the test point was optimal. During the tests a Z-Xtreme receiver by Ashtech was used. On the first and the last day the corrections from the reference station were transmitted to the mobile receiver using the NTRIP application and on the other days the radio modem by SATEL was used for transmission of the corrections. The accuracy of measurement point coordinates in the GPS/RTK is expressed in centimeters; however, achievernent of that accuracy of results under forest conditions is highly difflcult as a consequence of the problem with ambiguity determination by the mobile receiver. Additionally, the mobile receiver is reached by GPS signals disturbed by signal multipath and cycle slip errors. The experiments presented in this paper indicate that despite very difficult measurement conditions it is possible to determine the coordinates of points under forest conditions with the accuracy of a few centimeters.