Intelligent Transportation Systems (ITS) require reliable location information with emphasis being put on sensor level integration and low power consumption. The Global Positioning System (GPS) has been proposed as a potential technology to provide this information but has been hampered by poor performance (in urban environments) and power hungry board level solutions. Increased pressure on in-vehicle sensor power consumption has driven SiRF Technology Inc. to develop the SiRFstarI/LX GPS chipset. Recent advances in silicon, GPS chipset architecture and software technology have enabled new methods to increase the signal availability (through rapid signal acquisition), accuracy and use of GPS solutions in difficult satellite tracking environments using 1 or 2 satellites for updates. A test vehicle was used to collect GPS position data under normal traffic conditions in downtown San Francisco (a difficult urban area for signal reception). Multiple test data show that the navigation solution availability with the SiRFstarI and the SiRFstarI/LX GPS receiver maintain the near 100% contiguous coverage. Other GPS receivers tested showed lesser navigation availability under the same conditions. The results and architecture used for the tests demonstrate the feasibility of the SiRFstarI/LX GPS receiver as a low power, reliable navigation component for vehicle location information as part of an ITS system.
Abstract