GPS has been used in positioning and navigation for decades. However, there are still many unsolved problems existing, for instance the degradation of positioning precision when the view of sky is obstructed. Pseudolite, a ground-based GPS satellite-like signal transmitter, can provide extra measurements in order to improve the positioning precision from GPS alone in the obstructed areas. In th...

Navigation based on GPS data has been the most commonly used methodology for the autonomous run of a mobile robot in indoor and outdoor environments. However, the reading of the GPS receivers fluctuates over a considerable range esp. in countries like India where there is a dearth of GPS signals and locally available correction table. So the commonly received value by GPS receiver can be accura...

Although existing integrated GPS/INS systems can overcome inherent drawbacks of each system, such as no result without line-of-sight for GPS and INS errors that grow with time, performance is nevertheless degraded in difficult operational circumstances. Some typical examples are when the duration of satellite signal blockage is excessive, resulting in large accumulated INS errors that are not a...

A real-time positioning technology that can operate indoors and outside anywhere in the world, with sub-cm accuracy, and at low cost, is the ultimate goal for many researchers. GPS can achieve cmlevel kinematic positioning accuracy, but with some major constraints. First and foremost the use of GPS signals for indoor positioning poses very difficult challenges, due to the very weak signal level...

Near real-time data downlinks from aircrafts, satellites and high altitude platforms via high-speed laser communication links is an important research topic at the Institute of Communications and Navigation of the German Aerospace Center (DLR). Ground stations for such scenarios are usually fixed at a certain location. With a motivation to provide a ground station that is quickly and easily dep...

The requirement for GPS receivers with low Time To First Fix (TTFF) is increasing with the deployment of new standards like E911. Mean Acquisition Time (MAT) determines the TTFF in GPS receivers. In this paper we analyze a scheme called Sequential Muti-Tap correlator, which reduces MAT by an order of magnitude compared to a serial search correlator, without increasing the hardware significantly...

The need for high-quality teaching practices and general practitioners (GPs) skilled in teaching is ever increasing. The authors determined the quality of teaching in the Göttingen general practice teaching network with regard to equipment, student participation and GPs' motivation for teaching. A questionnaire was mailed to all GPs in the Göttingen teaching network. The response rate was 81% (...

Autonomously operating unmanned aerial vehicles (UAV) have a great potential for many applications such as reconnaissance, mapping and surveillance. Whilst needing low cost and light weight navigation systems in their implementations, sensors like GPS or low cost inertial sensors can’t separately provide either the complete set of information or the required degree of accuracy. Multi-sensor sol...

Like other Small to Medium Enterprises (SMEs), medical practices can gain a great deal by adopting and using Information and Communication Technologies (ICTs). Unlike other SMEs, little is known about General Practitioners’ (GPs) perceptions of the benefits of ICT use or about the differences between these perceptions by male and female GPs. This chapter reports a survey of these perceptions of...

Dual-frequency GPS TEC monitors have been used to study the response of the ionosphere to the solar eclipses of 22 July 2009 and 15 January 2010. The receivers were located at three stations, Calcutta, Kharagpur and Baharampore which are situated outside the umbra zone in the Indian longitude sector with each baseline being ∼200 km. Effects of obscuration of the solar disc were noted in the amb...