| Laboratory
The Institute
of Geodesy and Navigation maintains a variety of scientific instruments and
has its own GNSS/INS Laboratory ("Geodaetische Messkuppel"). The tasks of
the Laboratory comprise practical tests, permanent and field measurements
as well as experiments related to the various research projects.
 The broad
range of GNSS equipment available at the Institute can be divided into
static/permanent, field and real-time kinematic receivers. A GPS Reference
Station is operated as aid for several projects using a dual-frequency
Ashtech Z-Sensor together with a choke ring antenna having a highly stable
antenna phase centre by its Dorne Margoline dipole elements. Other receivers
like the NovAtel MiLLennium OEM3 (L1/L2 and WAAS/EGNOS) and OEM4 can be easily
set up for reference station tasks, and European Septentrio PolaRx 2-frequency
receivers (L1/L2, WAAS/EGNOS) are currently in the evaluation process as
reference receivers. Most of these devices can also be set up for field campaign
jobs and, additionally, Trimble 4000 SSE receivers with integrated data logging
can be employed for such tasks. Finally, several receiver pairs are capable
of Real-Time Positioning in range- or carrier phase-differential
mode, e.g. the SAPOS-enabled Trimble 5800 Rover or the NovAtel OEM4-RT and
the NAVCOM NCT-2000D offering a high accuracy of 5 to 10 mm. Data communication
is either realized via the University Intranet by fibre optic wire or via
wireless telemetry links. Several Telemetry Systems are available
in order to enable real-time positioning. A wide-range system (25 W transmission
power, transmission frequency near 400 MHz, up to 80 km transmission range)
and several short-range systems (1 mW up to 1 W, spread spectrum systems
at 900 MHz and conventional telemetry at 400 MHz) are in use. Moreover, a
wireless local area network with several access points (roaming capabilities
included) at a frequency of 2.4 GHz is used to provide network communications
where no wire-LAN is available.
The Institute
owns a L1 GPS Hardware Simulator STR 4760 of GSS (Global Simulation Systems,
now Spirent) that is used for simulation tests as well as for the receiver
calibration (e.g. inter-channel biases). The pseudolite group of the institute
working on precise landing approaches is supported by a Pseudolite
System of Stanford Telecom (prototype system, C/A code-based) and an
IntegriNautics IN500 (P code-based) which both aid in the flight experiments
conducted by the group. The research group on GPS/INS integration carries
out experiments
using
several Attitude and Heading Reference as well as Inertial Navigation
Systems like the Systron Donner MotionPack and the Boeing DQTS, the
medium-precise Litton LN200 (fiber-optic gyros and micro-mechanical
accelerometers) and the precise Sagem SIGMA (3 laser gyros with a drift of
only 0.001 degrees per hour). 3-axis Turn Tables are available at
the institute's laboratory and serve for the calibration of inertial and
attitude sensors.
Permanent
observation of stationary and time varying parts of the gravity field is
possible with the ASKANIA Earth-Tide Gravity Meter. A relative LaCoste
& Romberg gravity meter and a Scintrex CG-5 Autograv are available
for field surveys. Precise time determination and time transfer, GPS time
receiver and a precise cesium time reference standard are available.
The Astronomical Station is located on the roof of the laboratory
building. It allows star field observations and by use of a CCD star camera
and proper image processing software, the derivation of astronomical positions
and - together with the ellipsoidal coordinates collected by GPS-techniques
- deflections of the vertical can be computed. |