Title :
Status of GNSS reflectometry related receiver developments and feasibility studies within the German Indonesian Tsunami Early Warning System
Author :
Helm, Achim ; Stosius, Ralf ; Beyerle, Georg ; Montenbruck, Oliver ; Rothacher, Markus
Author_Institution :
GeoForschungsZentrum Potsdam, Potsdam
Abstract :
In the frame of the German Indonesian Tsunami Early Warning System (GITEWS) project a multi-frequency Global Navigation Satellite System (GNSS) Occultation & Reflectometry & Scatterometry (GORS) space receiver is developed. It is based on commercial off-the-shelf (COTS) GNSS receiver technology, as the core instrument for a future tsunami detection constellation of small low Earth orbit (LEO) satellites. For use in reflectometry, scatterometry and radio-occultation measurements as well as high-precision navigation applications, specific adaptations of the GNSS receiver firmware are desirable, which require a close interaction between scientists and the receiver manufacturer. Within the GITEWS project GFZ has set up a team consisting of GFZ, DLR and JAVAD GNSS (JAVAD) to adapt and extend their new generation GNSS receivers for advanced scientific space applications. Specific adaptations address the improvement of the cold start time-to-first-fix, the selection of optimal tracking loop parameters and channel slaving for monitoring of reflected signals. Besides pseudorange, phase and signal-to-noise measurements, the modified receiver allows output of in-phase (I) and quadrature-phase (Q) accumulations at 5 msec intervals (200 Hz). As a major step forward compared to current space receivers, the new receiver supports tracking of the civil L2C signal of the GPS constellation. An overview of the current status is given and first results are discussed. Within GITEWS the feasibility of a tsunami detection mission is studied, including the constellation mission design, the options for operating the system and the ways to develop an end-to-end system for the quick response to tsunami events. In parallel simulation studies of the GNSS signals reflected to a LEO satellite are carried out. This will be realised by a Zavorotny and Voronovich scattering model with a two-scale model approach using an Elfouhaily sea wave spectrum. An overview of the current activities is - given and first results are discussed.
Keywords :
UHF radio propagation; oceanographic equipment; oceanographic techniques; receivers; reflectometry; remote sensing; satellite navigation; tsunami; DLR; GFZ; GITEWS; GNSS Occultation & Reflectometry & Scatterometry; GNSS receiver firmware; GNSS reflectometry; GORS space receiver development; GORS space receiver feasibility study; German Indonesian Tsunami Early Warning System; Global Navigation Satellite System; JAVAD; channel slaving; civil L2C signal tracking; cold start time to first fix; frequency 200 Hz; high precision navigation applications; in phase accumulation; multifrequency GNSS; optimal tracking loop parameters; quadrature phase accumulation; radiooccultation measurements; reflected signal monitoring; reflectometry measurements; scatterometry measurements; small LEO satellites; small low Earth orbit satellites; time 5 ms; tsunami detection; Alarm systems; Global Positioning System; Low earth orbit satellites; Radar measurements; Reflectometry; Satellite broadcasting; Satellite navigation systems; Space technology; Spaceborne radar; Tsunami;
Conference_Titel :
Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International
Conference_Location :
Barcelona
Print_ISBN :
978-1-4244-1211-2
Electronic_ISBN :
978-1-4244-1212-9
DOI :
10.1109/IGARSS.2007.4424005