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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004 
  
3. RESULTS AND DISCUSSIONS 
This experiment aimed at the precision estimation of RTK-GPS 
positioning by VRS, which depended on the correction data 
provided by LBS provider. Table 4 gives the statistics of 
experimental results and their precisions according to the 
different surveying conditions and methods. The following 
observations can be made from the results shown in Table 4: 
1. In general, well precision has been obtained from experiment. 
As the result of RTK-GPS positioning by VRS, the standard 
deviation was about +-2 cm in horizontal components and +- 3 
to 4 cm in vertical component. It is considered that there is no 
remarkable difference between two different types of GPS 
receiver. 
2. The results of RTK-GPS positioning by VRS based on the 
smaller reference network (the nearest station is Minoo) are 
consistent with that of the traditional RTK (the reference station 
is Minoo). Both of their positioning results under the “Geodetic 
Coordinates 2000" are most closed to the public coordinates of 
the local control points. 
3. There are some systematic errors in positioning results 
especially at the North-south component irrespective of the 
reference networks or the types of GPS receiver when the 
"recent analytic coordinates" are used to the reference stations. 
A main reason for the general deviation between the “Geodetic 
Coordinates 2000" and the "recent analytic coordinates" could 
be caused by crustal deformation during the past several years. 
4. Due to the variedness in the velocities of crustal deformation, 
there are systematic errors in coordinates of local control points 
between the public results in *Geodetic Coordinates 2000" and 
the VRS-GPS positioning results based on the reference stations 
with the coordinates in “Geodetic Coordinates 2000”. Still more, 
the systematic differences vary remarkably with the size of 
reference network. 
It should be mentioned that the RTK-GPS positioning by VRS 
suffered the effects of multi-path of carrier waves and sky 
visibility of GPS satellites because more than half of surveying 
points in the experimental field are located in such cases as near 
the curve mirrors, street lighters, buildings and so on. There are 
some similar wrongs of positioning results at some specific 
points owing to surrounding the worse environment. Therefore, 
it is considered potential to improve the positioning precision in 
comparatively better environment for surveying. In fact, it is 
possible to get the VRS positioning in high precision as that as 
the results achieved by static observation with the enough 
number of GPS satellites and stable better PDOP. 
However, there are also some problems in the actual field 
observations. For example, it is necessary to remove the 
systematic errors caused by crustal deformation and make a 
consistency processing between the public results in “Geodetic 
Coordinates 2000” of the existing control points and the VRS- 
GPS positioning results of new points surveyed. Moreover, it is 
also necessary to use the others measuring methods, such as the 
current method by TS (Total Station) for surveying in and 
around such environment where GPS positioning in real time is 
impossible at present. 
4. CONCLUSION 
This paper introduced a new GPS positioning way of RTK-GPS 
by VRS using in surveying of local control point for public 
survey. The precision estimation of positioning results surveyed 
by VRS is also proposed. As the result of filed experiment, the 
standard deviations of 3-components of real-time positioning by 
VRS are about +-2 cm in horizontal and less than 4-4 cm in 
vertical and meet the demand for survey precision of local 
control point. Since the field environment for RTK-GPS 
observation by VRS is not very good in and around the 
residential area where the experiment was carried out, the 
potentiality and possibility for higher positioning precision are 
expected in better environment. 
Since most of the local control points in residential. area are 
located nearby the houses, trees and so on, it is expected that 
the current method of TS could take the place of RTK-GPS by 
VRS for surveying at such points. Now, The combined 
surveying method called *VRS-TS" is being used in our public 
surveys, and the validity is proved with its effectivities and 
higher precision. 
BIBLIOGRAPHY 
WU. X. et al, 2002. Report on the Japan Earth Planetary 
Science Joint Meeting, D058 GPS. 
http://www-jm.eps.s.u-tokyo.ac.jp/2002cd-rom/pdf/d058/d058- 
006 e.pdf 
WU. X. et al, 2003. Report on the Association of Precise 
Survey & Applied Technology, No.85 (in Japanese). 
https://www.sokugikyo.or.jp/pdf/apa85 2003 09/APA8504.pdf 
WU. X. et al, 2003. The effects of GEONET deformation on 
positioning by VRS. / 00" Meeting of the Geodetic Society of 
Japan, Tokyo, Japan, PROGRAM AND ABSTRACTS, pp. 55- 
56 (in Japanese). 
Matsumura. S., WU. X. et al, 2004. A new technology for 
RTK-GPS by using VRS based on the GEONET. IEICE A, 
Vol.J87-A, No.1, pp. 68-77 (in Japanese). 
ACKNOWLEDGEMENTS 
The experimental surveying in the field was supported by Leica 
Geosystemes K.K. , Nikon-Trimble Co., Ltd. And JENOBA 
Corporation. The authors wish to thank for their supports. 
We also would like to thank Toyonaka City Hall for providing 
the experimental field and lending the public control points to 
our VRS surveying. 
Acknowledgement should be given to the GSI for allowing us 
to use the recent coordinates by routine analysis of GEONET. 
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