vith fixed 
lires the 
data block 
Therefore 
400-9600 
stems are 
They are 
o transmit 
km. They 
le GPS- 
but are 
O tens or 
| network 
andatory. 
'T Station, 
erformed. 
onitoring 
an orbit 
elopment 
ode is the 
OCessing. 
increases 
nore reli- 
ng in the 
ate of the 
ange cor- 
measure- 
d, allow- 
ion, of a 
'ssibility 
ifference 
fixed in 
e receiv- 
maining 
ccuracy. 
lifferen- 
solution. 
; remain 
angular 
m is the 
is given 
1 1995 
  
343 
9. CONCLUSIONS 
Commercial DGPS-services broadcasting range corrections are already installed in many countries. They allows an on- 
line positioning with an accuracy of a few meters. By integrating the phase measurements the accuracy can be enhanced 
up to a few centimeters. The best result in this case is obtained when all double difference ambiguities are solved. The 
commercially available solutions until now are restricted to a range of some few kilometers, due to restricted data link 
capabilities and the problems of ambiguity resolution over large distances. Therefore, in the near future the off-line 
mode will remain at least for large scale applications the only practical measurement mode. Large networks of refer- 
ence stations which may provide in the future the user with an on-line cm-accuracy even over hundreds of kilometers 
are already under development. i: 
REFERENCES 
Beutler G., W. Gurtner, U. Hugentobler, M. Rothacher, T. Schildknecht, U. Wild (1988) : Ionosphere and GPS Process- 
ing pages Paper presented at the 1988 Chapman Conference on The Use of GPS for Geodynamics, Ft Lau- 
erdale, U.S.A. 
Blewitt G. (1989) : Carrier Phase Ambiguity Resolution for the Global Positioning System Applied to Geodetic Base- 
lines up to 2000 km. Journal of Geophysical Research. Vol. 94. No.B8. 
Bock Y., S.A. Gourevitch, C.C. Counselman, R.W. King, R.I. Abbot (1986) : Interferometric Analysis of GPS-Phase 
Observations. Manuscripta Geodaetica, Vol. 11, No. 4, pp. 282-268. 
Cocard M. (1994) : High Precision GPS-Processing in Kinematic Mode. Dissertation. ETH, No 10874. Institute of Ge- 
odesy and Photogrammetry. 
Cohen C.E., B.W. Parkinson (1992) : Aircraft Applications of GPS-Based Attitude Determination : Test Flights on a 
Piper Dakota, Proceedings of ION GPS-92, Albuquerque USA. 
Cohen C.E., B.W. Parkinson, B.D. McNally (1994) : Flight Tests of Attitude Determination Using GPS Compared 
Against an Inertial Navigation Unit, NAVIGATION, Journal of the Institute of Navigation, Vol. 41, No. 1. 
Counselman C.C., S.A. Gourevitch (1981) : Miniature Interferometric Terminals for Earh Surveying : ambiguity and 
multipath with Global Positioning System, IEEE Trans. Geosciences and Remote Sensing, GE-19-4, pp 244-252. 
Euler H.J., B. Schaffrin (1990) : On the Discernibility between Different Ambiguity Solutions in the Static-Kinematic 
GPS-mode. Kinematic Systems in Geodesy, Surveying and Remote Sensing, IAG Symposium No 107, Banff, Canada, 
September 1990, pp 285-292, Springer Verlag, Berlin. 
Euler H.J. (1992) : Fast GPS Ambiguity Resolution On-the-fly for Real Time Applications. in proceedings of the 6th 
International Symposium on Satellite Positioning , March 1992, Columbus, Ohio, pp 650-659. 
Frei E. (1991) : Rapid Differential Positioning with the Global Positioning System (GPS). Geodütisch-geophysikalische 
Arbeiten in der Schweiz, SGK-Publikation, Band 44. (publication of the Swiss Geodetic Commission). 
Hatch R.R. (1990) : Instantaneous Ambiguity Resolution, Kinematic Systems in Geodesy, Surveying and Remote Sens- 
ing, IAG Symposium No 107, Banff, Canada, September 1990, pp 299-308, Springer Verlag. 
Mader G. (1992) : Kinematic GPS Phase Initialization using the Ambiguity Function in proceedings of the 6th Interna- 
tional Symposium on Satellite Positioning , March 1992, Columbus, Ohio, pp 712-719. 
Remondi B.W. (1992) : Real-time Centimeter-Accuracy GPS without Static Initialization, in proceedings of the 6th 
International Symposium on Satellite Positioning , March 1992, Columbus, Ohio. pp 691-701. 
Sauer D., G. Beutler, H.-J. Euler (1994) : Phase Measurements in Kinematic GPS Applications : Theory and Summary 
of Processing Strategies. Proceedings on Kinematic Systems in Geodesy, Geomatics and Navigation, 
August/September 1992, Banff, Canada, pp. 255 - 263.