35
Fig. 10. Standard deviation from the RTK measurements at the
test traverse points
Analysis of results as received demonstrates that
measurements using the RTK technique utilizing the
Internet and GPRS for the transmission of
corrections provide a highly accurate solution at
distances of up to 30 km from the reference station.
Receiver initialization time grows longer at distances
in excess of 30 km.
7 SUMMARY
We have confirmed, on the basis of experimental
measurements aimed at examining the usefulness
and effectiveness of the application of the Internet
and GSM in DGPS and RTK measurements, that the
presented solutions form an effective medium for the
transmission of corrections in the RTCM formats. It
may be predicted that transmission using the RTCM
v. 3.0 format, will be equally effective.
The proposed tele–transmission solutions do not
require investment in special infrastructure, they
have a very large range, and they demonstrate no
significant dependence on obstruction in the field
and electromagnetic interference. The proposed
solution only necessitates the startup of the data
server program at the reference stations. On the
user’s side, in work in the field, what is required is
connection to the Internet, which can be achieved
through an inexpensive GPRS connection in the
GSM networks. What is needed for currently used
receivers is an additional module for the reception of
corrections that can be implemented through the use
of personal computers of the PDA type or GSM
telephones servicing the JAVA or SYMBIAN
languages. The newest GPS and GPS/GLONASS
receivers are equipped in software facilitating direct
reception of corrections through the Internet and the
GSM network.
After conducting the experiments, it was
confirmed that delays in transmission through the
Internet and GPRS are insignificant and do not have
an impact on the effectiveness of the applied
technology. After conducting the measurements on
the test base it was confirmed that the effective range
of RTK measurements using the Internet and GSM
telephony amounts to approximately mainly 30 km
from the reference station and is determined by
limitations in RTK techniques. Together with an
increase in distance from the reference station,
initialization time of he measurement grows in
length and amounts to two minutes at a distance of
5 km, increasing to 10 minutes at distances of over
30 km. Measurement using RTK techniques is an
effective technology providing results of significant
accuracy that can be applied in most high–precision
surveying and navigation.
The experience gained thanks to the series of
measurement experiments demonstrates that
measurements using the RTK technique with the
greatest of precision should be conducted twice at
the same point with different satellite configurations
in order to eliminate errors that may occur.
The availability of RTK and DGPS measurements
utilizing corrections in the RTCM format transmitted
through the Internet and GPRS amounts to over
99%. Breaks in reception of corrections are very
short and have a duration of not more than
4 seconds.
The proposed solution may find broad application
in the transmission of corrections generated by the
reference stations of the fixed network. It is also
possible to transmit other data in real time, including
orbit parameters, coefficients of the current models
of the ionosphere and troposphere, observation data
in the receiver’s format (RAW), and others.
REFERENCES
Kujawa L., Leszczyński M., Rogowski J., Accessibility and
reliability of RTK measurements by Internet. Materials of
NTRIP Seminar & Woprkshops „Streaming GNNS Data via
Internet” Frankfurt a Man 2006.
Rogowski J.B., Kujawa L., Leszczyński M., Studies on
accessibility and reliability of RTK measurements by
internet. Procedings of Euref Symposium , Viena 2005.
Kujawa L., Leszczyński M., Rogowski J., Precyzyjna nawiga-
cja z wykorzystaniem Internetu i telefonii. Sesja naukowa z
okazji 85-lecia Wydziału Geodezji i Kartografii Poli-
techniki Warszawskiej, 2006.
Kujawa L., Leszczyński M., Rogowski J., Studies on accessibility
and realiabity of RTK measurements by Internet. The
EUREF Symphosium of the IAG Commision. Riga 2006,