Permanent GPS Stations in Israel

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Permanent GPS Stations in Israel as Basis for
Updated Geodetic Network   Gilad
Even-Tzur Faculty of Civil and Environmental
Engineering Mapping and Geo-Information
Engineering Technion, Haifa 32000, Israel Moshe
Rozenblum, Einat Salomon Survey of Israel 1
Lincoln St. Tel-Aviv 65220, Israel
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Permanent GPS Stations in Israel, Sept. 2005
? 17 Stations Receivers 11 Ashtech
Z-XII 5 Leica SR530 1 Trimble
5700 Antennas 9 Ashtech DM 5 Leica
DM 2 Topcon CR4 1 Trimble DM
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Permanent GPS stations in Israel, Sept. 2005
? 10 stations are situated on stable roof
tops
NRIF
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Permanent GPS Stations in Israel, Sept. 2005
? 7 stations have geodynamic monuments
LHAV
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The Control Center
The GPS receivers are connected to a control
center, equipped with master and backup servers,
through frame relay connections.
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The Communication Network
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The GPS Data Flow
? 5 sec sampling rate ? Data is downloaded in
real time ? The RINEX data is gathered
into 1-hour interval files and posted on
the internet
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Operation Manager Software
The network is controlled by the RTD software.
It is based on epoch-by-epoch technology, which
enables monitoring any changes in the station
coordinates due to deformation and lost qualities.
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Permanent GPS Stations in Israel, Sept. 2005
? RAMO is the official IGS station in
Israel ? The data is processed at
SOPAC ? The data from RAMO and DRAG is
also processed at GIBS (GPS-Informations- und
Beobachtungssystem )
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The Permanent GPS Stations in Israel are called
APN Active Permanent Network
Free 30 sec sampling rate data is available
at ftp//212.179.112.235
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The APN Network
Until recently, the APN network was mainly used
for geodetic and geophysical research.

• The APN was used less for surveying purposes
• - Short sessions
• - OTF ambiguity resolution used
• - Lack of transformation between WGS84 and
  ITM

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VRS - Virtual Reference Station
Economically and practically, there is no need to
increase the number of permanent GPS stations in
Israel.
In order to enable GPS surveying over the entire
state of Israel with direct connection to the
permanent GPS network, VRS technology is applied.
The VRS is produced by the GEO software
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User Interface for Receiving Data
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• Advantages of Using the APN
• Uniformity
• Accuracy
• Reliability
• Simplicity

? In the near future an RTK option will be added
to the APN network
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Datum Definition
? Geodetic datum is a set of parameters and
control points used to ? Define the size and
shape of the earth. ? Define the origin and
orientation of the coordinate systems used to
map the earth.
? Geodetic datums range from flat-earth models
used for plane surveying to complex models used
for international applications.
? The datum is the basis for a plane-coordinate
system.
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Datum Definition (continuance)
? GPS positions and vectors are referenced in
the WGS-84 datum
? The Israeli coordinate system is referenced in
the GRS-80 reference ellipsoid with geodetic
projection called ITM - Israel Transverse
Mercator
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Datum Transformation
Transformation parameters describe the relations
between two different datum systems.
7 Parameter transformation
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Datum Transformation (continuance)
The set of transformation parameters is
determined by a least-squares solution
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The Plane Coordinates of the APN Points
? Each point from the APN network was connected
by GPS observations to the nearest 1st order
control points. ? A local datum transformation
was calculated in order to assign plane
coordinates to each permanent GPS station.
The accuracy of the coordinates is equivalent to
the accuracy of the classical 1st order control
network (10cm)
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Permanent GPS Network
A permanent GPS-based network is obviously more
accurate, reliable and homogenous than a
classical network.
Permanent GPS Network
Supreme Network
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New Datum for APN
A set of coordinates that was valid for GPS day
275 of the year 2004 (October 1st , 2004) in the
ITRF2000 coordinate system was set as the fixed
coordinates set for the permanent GPS stations
This set of coordinates defined a new datum for
APN, called IGD05 Israel Geodetic Datum 2005
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Horizontal residuals resulting from the seven
parameters transformation between the ITRF2000
(IGD05) datum and the Israel Grid datum
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New Datum for Israel Grid
A new set of plane coordinates were adopted for
the APN points.
The new coordinates defined actually new datum
for the Israeli Grid called IG05 Israel Grid
2005
The adopted plane coordinates is a result of
similarity transformation between two datums
(IGD05 and IG05) which supplied practically zero
residuals in the least-squares process.
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Official 7 Parameters Transformation
Calculate official 7 parameter transformation
between the two systems
IGD05 IG05
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A flow chart for calculating new control points
in IG05 coordinate system
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Measuring methods for establish new control point
1. Relative to APN station 2. Relative to VRS 3.
Relative to base station 4. Geodetic network
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Field Work Guidelines
? Two independent Observation sessions
? Observation sessions of at least 10 min
? Time duration between two sessions of at least
60 min
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1. Measuring relative to APN station
First session
10min
10min
10min
10km
TELA
10min
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1. Measuring relative to APN station
Second session
10min
10min
TELA
10min
Time duration between sessions 60 min
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2. Measuring relative to VRS
First session
10min
5km
10min
10min
VRS1
10min
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2. Measuring relative to VRS
Second session
10min
10min
VRS1
10min
VRS2
VRS3
The distance between two VRS should be at least
120m
Time duration between sessions 60 min
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2. Measuring relative to VRS
Measured vectors
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3. Measuring relative to base station
IGD05
? Connect the base station to IGD05 system
10km
90min
BASE
IGD05
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3. Measuring relative to base station
IGD05
? Measuring new control points First Session
10min
10min
10min
BASE
10min
IGD05
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3. Measuring relative to base station
ILGD05
? Measuring new control points Second Session
10min
10min
BASE
10min
ILGD05
Time duration between sessions 60 min
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4. Measuring Geodetic Network
Assume work with 3 receivers
IGD05
1

• Sessions of at least 10 min
• Each new point should be measured in two
  independent sessions

2
3
4
IGD05
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The Geodetic-Geodynamic Network (G1)
? Includes 160 points that homogeneously cover
the state of Israel ? The location of the points
was determined mainly according to geological
considerations ? The points were built according
to very high technical specifications, to ensure
their geotechnical stability
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The goal of the Geodetic-Geodynamic Network
? A potential geodetic network for monitoring
deformations in primary and secondary known
faults ? Serves as the major geodetic control
network of Israel
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The Measurement Campaigns
? During 1996 the G1 network was measured for the
first time (Blue circles and Red squares) ? The
second campaign was held in 2002 ? Only 100
points were measured (Blue circles) ? 5 new
points were fixed in the northern part of the
network (Yellow circles ) ? 11 continuous
permanent GPS stations were operated (Green
triangles) ? the accuracy of the points is better
than 1cm
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The G2 Network
? Abut 1000 points that organized in closed
loops ? Most of the points are BMs from the
Israeli vertical control network ? The points
were measured during long period and not as one
campaign ? The network accuracy is not
homogeneous and not satisfactory (5cm)
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Vertical Control
? Survey of Israel (SOI) decided that the future
vertical control in Israel will be based on
ellipsoidal heights instead of orthometric
heights ? SOI will support and maintain spatial
geodetic network which will serve as horizontal
and vertical control ? The APN and G1 will be
used as basis for ellipsoidal vertical control ?
Undulation model will be used to convert
ellipsoidal heights to orthometric heights