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Permanent GPS Stations

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Title: Permanent GPS Stations


1
Permanent GPS Stations and their Influence on the
Geodetic Surveys in Israel   Gershon Steinber
g Survey of Israel 1 Lincoln St. Tel-Aviv 65220,
Israel Gilad Even-Tzur Mapping and Geo-Inform
ation Engineering Technion, Haifa 32000, Israel
(consultant to SOI)
2
Permanent GPS Stations in Israel, October 2006
? 18 Stations Receivers 7 Ashtech Z-XII
6 Leica SR500 5 Leica 1200 PRO
Antennas 9 Ashtech DM 6 Leica DM
2 Topcon CR4 1 Trimble DM
Upgrade to GLONASS is coming up soon
3
Permanent GPS Stations in Israel, October 2006
? 11 stations are situated on stable roof
tops
NRIF
4
Permanent GPS Stations in Israel, October 2006
? 7 stations have geodynamic monumentation
LHAV
5
The Control Center
The GPS receivers are connected to a control
center, equipped with master and backup servers,
through IPVPN connections.
6
The Communication Network
7
The GPS Data Flow
? 1 sec sampling rate ? Data is downloaded in r
eal time ? The RINEX data is gathered
into 1-hour interval files and posted on
the internet
8
Operation Manager Software
The network is controlled by the RTD software.
9
Permanent GPS Stations in Israel, October 2006
? RAMO is the official IGS station in Israel
? All the data is processed at SOPAC (Scripps
Orbit and Permanent Array Center)
? The data from RAMO and DRAG is also
processed at EPN (EUREF Permanent Network)
10
The Permanent GPS Stations in Israel are called
APN
Active Permanent Network
11
The VRS and RTK Options
In order to enable GPS surveying over the entire
state of Israel with direct connection to the
permanent GPS network, VRS and RTK technologies
are applied.
The VRS and RTK are produced by the GEO software
12
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 (
3D) 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 (6cm)
13
Permanent GPS Network
A permanent GPS-based network is obviously more
accurate, reliable and homogenous than the
classical network.
Permanent GPS Network
Supreme Network
14
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
15
Horizontal residuals resulting from the seven
parameters transformation between the ITRF2000
(IGD05) datum and the Israeli Grid
16
New Datum for Israel Grid
A new set of plane coordinates were adopted for
the APN points by adding the residuals of the
transformation.
The new coordinates defined new datum for the
Israeli Grid called
IG05 Israel Grid 2005
17
Official 7 Parameters Transformation
18
A flow chart for calculating new control points
in IG05 coordinate system
19
Geodetic Control Networks
  • The National Geodetic Control Network will be
    defined as 3D control.
  • The network is based on the Permanent GPS
    stations of Israel (constitute the higher order).

  • - Primary 3D class G
  • - Secondary classes
  • S
    horizontal coordinates.
  • E ellipsoidal
    heights.

20
  Horizontal Control
  • The primary objective of the horizontal control
    network is to serve the cadastral surveys.
  • The goal is to define the cadastral boundaries
    with an accuracy of 5cm (95).

21
National Control Network Classification and
Required Accuracy
22
  Vertical Control
  • Ellipsoidal Control
  • There is neither practical possibility nor actual
    need to maintain a country-wide vertical
    orthometric control network.
  • SOI will maintain vertical ellipsoidal height
    control network.

23
National Control Network Classification and
Required Accuracy
24
Orthometric control
  • The transition to ellipsoidal heights only, is
    premature yet.
  • The orthometric heights will be used as having a
    local datum.
  • HL can be measured either by geometric leveling,
    trigonometric leveling or GPS based on local
    benchmarks.
  • HS (statutory heights) measured by GNSS and
    official geoid undulations model (OGUM).

25
THE IDEA OF OFFICIAL GEOID UNDULATIONS MODEL
(OGUM) AS A SUBSTITUTE FOR ORTHOMETRIC CONTROL
  • A very important objective of the leveling
    network is to bring consistent identical heights
    by every surveyor.
  • There is no need to wait for the "perfect" geoid
    model.
  • We suggest declaring the best available Geoid
    Undulations Model as an Official Model (OGUM).
  • The combination of OGUM with vertical Ellipsoidal
    Control based on CORS, produces a practical
    country-wide network of Orthometric Height
    Control, appropriate for most of the
    geodetic/surveying needs.

26
Vertical Local Orthometric Control Networks
Levels and Required Accuracy
  • New D is the horizontal distance.
  • HL1 and HL2 can be measured by leveling only.
  • HL3, HL4, HL5 can be measured by GPS also.
  • E1 will produce HS1 and E2 will produce HS2.

27
Experiments In Israel
  • Goal To examine the accuracy of orthometric
    height differences based on GPS measurements and
    OGUM in different locations in Israel.
  • Two alternatives for OGUM
  • 1. ILUM1.0 - Israeli Undulations Model, Based on
    750 Benchmarks.
  • 2. GPM98B- Global Geopotential Model (Wenzel),
    contains few gravity data from Israel.

28
Experiments In Israel (cont.)
  • Six height-differences (between 4 adjacent
    benchmarks) were measured simultaneously by GPS
    (40 minutes' sessions).
  • The relative accuracy of the known orthometric
    height -differences, as well as the measured
    ellipsoidal height- differences, is 1-2cm.

29
Experiments In Israel (cont.)
  • Eight locations where the OGUM experiment was
    held in Israel.
  • The numbers denote the place's name as appears in
    the next table.

30
Experiments - Results
  • The RMS and the mean PPM values of the
    differences between the known orthometric
    height-differences and the orthometric
    height-differences obtained by GPS and the two
    alternatives for the OGUM.

31
Discussion
  • For a reasonable orthometric control we
    actually need a height-differences accuracy of
    25mm for benchmarks 1km apart (25PPM).
  • We achieved this goal in all our experiments with
    the temporary Israeli OGUM. It was achieved also
    using the Global model, except for Eilat.
  • The results demonstrate the capability of the
    idea, for most of the engineering works.
  • Not instead of existing good networks.
  • A special benefit for areas were establishing a
    leveling network is practically impossible.
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