Labor


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 uses the IfEN NavX-NCS (Navigation Constellation Simulator) 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.