An active wearable dual-band antenna for GPS and Iridium satellite phone deployed in a rescue worker garment

An active wearable dual-band circularly polarized microstrip patch antenna for Global Positioning System and Iridium satellite phone applications is presented. It is constructed using flexible foam and fabric substrates, combined with copper-on-polyimide film conductors. A low-noise amplifier chip is integrated directly underneath the antenna patch. The antenna's performance is examined under bending and on-body conditions. The active antenna gain is higher than 25 dBi and the 3dB axial ratio bandwidth exceeds 183 MHz in free-space conditions. The antenna performance is robust to bending and on-body placement

MobGeoSen: facilitating personal geosensor data collection and visualization using mobile phones

Mobile sensing and mapping applications are becoming more prevalent because sensing hardware is becoming more portable and more affordable. However, most of the hardware uses small numbers of fixed sensors that report and share multiple sets of environmental data which raises privacy concerns. Instead, these systems can be decentralized and managed by individuals in their public and private spaces. This paper describes a robust system called MobGeoSens which enables individuals to monitor their local environment (e.g. pollution and temperature) and their private spaces (e.g. activities and health) by using mobile phones in their day to day life

Receiver-Autonomous Spoofing Detection: Experimental Results of a Multi-antenna Receiver Defense Against a Portable Civil GPS Spoofer

In this work we demonstrate the use of a dual antenna receiver that employs a receiver-autonomous angle-ofarrival spoofing countermeasure. This defense is conjectured to be effective against all but the most sophisticated spoofing attempts. The technique is based on observation of L1 carrier differences between multiple antennas referenced to a common oscillator. We first employ a moderately sophisticated spoofer to "fool" a single-antenna civil receiver. We then deploy the same attack after augmenting the receiver with an additional antenna and with receiver-autonomous spoofdetection software. The work discusses the experimental results together with various issues related to sensitivity, probability of false alarm, impact of carrier multipath, line-bias-calibration, and physical setup and security. We suggest that this work is important to the community as it provides experimental validation of a low-cost technique for receiver-autonomous spoofing detection. Furthermore, the technique, when combined with physical security of the antenna installation, provides a strong defense against even a sophisticated attack. The receiver employed is an L1-only civil GPS receiver with multiple antenna capability. The GPS chipset employed is the venerable GP2015/GP2021 that has been freely available for over a decade. As such, this receiver is representative of many civil receivers in use today for a variety of applications. Multiple antennas are enabled either through multiple independent RF front ends and correlators or via antenna multiplexing into a single RF front end and correlator bank.Aerospace Engineering and Engineering Mechanic

The GPS Assimilator: a Method for Upgrading Existing GPS User Equipment to Improve Accuracy, Robustness, and Resistance to Spoofing

Preprint of the 2010 ION GNSS Conference Portland, OR, September 21–24, 2010A conceptual method is presented for upgrading existing GPS user equipment, without requiring hardware or software modifications to the equipment, to improve the equipment’s position, velocity, and time (PVT) accuracy, to increase its PVT robustness in weak-signal or jammed environments, and to protect the equipment from counterfeit GPS signals (GPS spoofing). The method is embodied in a device called the GPS Assimilator that couples to the radio frequency (RF) input of an existing GPS receiver. The Assimilator extracts navigation and timing information from RF signals in its environment—including non-GNSS signals—and from direct baseband aiding provided, for example, by an inertial navigation system, a frequency reference, or the GPS user. The Assimilator optimally fuses the collective navigation and timing information to produce a PVT solution which, by virtue of the diverse navigation and timing sources on which it is based, is highly accurate and inherently robust to GPS signal obstruction and jamming. The Assimilator embeds the PVT solution in a synthesized set of GPS signals and injects these into the RF input of a target GPS receiver for which an accurate and robust PVT solution is desired. A prototype software-defined Assimilator device is presented with three example applications.Aerospace Engineerin

Time transfer using NAVSTAR GPS

A time transfer unit (TTU) developed for the U.S. Naval Observatory (USNO) has consistently demonstrated the transfer of time with accuracies much better than 100 nanoseconds. A new time transfer system (TTS), the TTS 502 was developed. The TTS 502 is a relatively compact microprocessor-based system with a variety of options that meet each individual's requirements, and has the same performance as the USNO system. The time transfer performance of that USNO system and the details of the new system are presented

A Multi Antenna Receiver for Galileo SoL Applications

One of the main features of the Galileo Satellite Navigation System is integrity. To ensure a reliable and robust navigation for Safety of Life applications, like CAT III aircraft landings, new receiver technologies are indispensable. Therefore, the German Aerospace Centre originated the development of a complete safety-of-life Galileo receiver to demonstrate the capabilities of new digital beam-forming and signal-processing algorithms for the detection and mitigation of interference. To take full advantage of those algorithms a carefully designed analogue signal processing is needed. The development addresses several challenging questions in the field of antenna design, frontend development and digital signal processing. The paper will give an insight in the activity and will present latest results

The Global Positioning System: Global Developments and Opportunities

International Relations/Trade,