In this paper, a new forward error correction (FEC) protocol is proposed for point-to-multipoint satellite links. Link-layer error control protocols in point-to-multipoint satellite links impose several problems such as unreliability and receiver-heterogeneity. To resolve the problem of heterogeneous error rates at different receivers, the proposed scheme exploits multiple multicast channels to...

This paper evaluates the performance of receiver-based compensation methods for distortion caused by nonlinear bandlimited satellite channels. Speci ̄cally, the performance of Volterra equalizers and maximum-likelihood sequence detection (MLSD) receivers for nonlinear bandlimited satellite systems are quanti ̄ed. In addition, the performance of a receiver with a fractionaly-spaced equalizer follo...

This paper is in the field of vehicle positioning technology for the Intelligent Transportation Systems. The ideas of an innovative light-emitting diode (LED)-based location beacon system are developed and verified. The system developed is a combination of several latest technologies which include a CMOS vision sensor, high brightness LEDs, and digital image processing techniques. It belongs to...

The Formation Autonomy Spacecraft with Thrust, Relnav, Attitude, and Crosslink (FASTRAC) project from the University of Texas at Austin has developed two nanosatellites as the winner of the University Nanosat-3 Competition. Both satellites have been manifested for a launch provided by the Space Test Program (STP) in December of 2009. The FASTRAC satellites will demonstrate the following enablin...

This paper is on a novel use of lighting or signaling devices constructed by light-emitting diodes (LEDs) as a positioning beacon. The idea is that the surface of the LED lighting device is divided into regions and used to show different visual patterns that are not noticeable by the human eye due to the high-frequency switching of the LEDs. A digital camera is used as a receiver to capture a s...

The time required to search a buried person using an avalanche beacon contributes significantly to the overall rescue time. This paper investigates the technical requirements and psychological demands with respect to minimal search time. The earlier ones define a beacon's technical specification, the latter ones the design of the user interface. The first search phase is mainly characterized by...

Accurate descriptions of electron density distributions in the ionosphere and the meteorological condition in the troposphere, covering most of the entire globe is needed for various operational, technical and scientific purposes. Measurements of integrated electron densities using transmissions from GPS, NNSS or other beacon satellites can be used to retrieve the height distribution of electro...

j a n u a r y / f e b r u a r y 2 0 1 1 www.insidegnss.com In satellite navigation, a GNSS receiver must account for several sources of error such as relativistic effects, atmospheric propagation delay, offset of satellite clocks from system time and satellite ephemeris. In order to accurately compute user position, velocity, and time (PVT), these errors need to be predicted/estimated precisely...

Advanced Receiver Autonomous Integrity Monitoring (ARAIM) seeks to exploit the large number of ranging signals provided by the multiplicity of Global Navigation Satellite System (GNSS) core constellations. Including more satellites increases the number of potential fault modes and the number of subset solutions that need to be evaluated by the receiver. In this paper we describe methods for red...