A transponder is a device that is used for tracking aircraft by mean of a secondary radar system, but it can be turned off deliberately, and it is an expensive item for small aircraft. These weaknesses have fatal consequences, as was shown with the terrorist attack on September 11 th , 2001, where four commercial aircraft under the control of international terrorists were used as missiles against the United Stated of America, killing thousands of people. These factors have shown a need for the development of an efficient aircraft tracking system, which does not rely on transponders. To this end a new tracking aircraft system is proposed, which will be referred to as the Positioning and Reporting Identification Beacon (PRIB) system. Due to size, mass, power, and financial constraints, the design must be small, light, power efficient, and cost-effective. The PRIB will acquire the aircraft's position from a dedicated GPS receiver and then transmit this information to a base station at a different location using a radio link. This thesis presents the design of a PRIB unit in light of the system constraints. In addition to the hardware design, the software needed by the unit to control and communicate with the ground stations is presented. The performance of the PRIB is analyzed and ways in which a PRIB could be manufactured using commercial off-the-shelf parts is discussed. / Master of Science

La réduction de la taille des transistors et des tensions d’alimentations permettent de concevoir des circuits intégrés de plus en plus complexes. Cependant, en abordant les limites de l’intégration des transistors et en fleuretant avec les tensions d’alimentation minimale, la fiabilité des circuits n’est plus garantie : des erreurs dues aux perturbations environnementales peuvent apparaitre. L’apparition de ces erreurs affectent le comportement du circuit et peuvent, par intermittence ou de façon permanente, le rendre inapte à rendre le service pour lequel il a été conçu. Par conséquent, il est de plus en plus important de considérer les effets de ces erreurs dans la conception des futurs circuits. L’objectif de la thèse est de traiter la fiabilité des systèmes numériques et d’introduire de nouvelles techniques de tolérance aux pannes permettant de construire des applications de traitement de signal fiables sur un électronique peu fiable. Un exemple d’application a été considéré durant la thèse : les modules de poursuite dans un récepteur GPS. Ces modules contiennent un ensemble d’applications de traitement de signal avec des exigences de fiabilité différentes : fonction de corrélation, boucles de rétroactions, machines d’états, générateurs de codes et de porteuses. À partir d’une version standard d’un récepteur GPS, des mécanismes de redondance ont été proposés et ajoutés pour concevoir un récepteur GPS plus tolérant aux erreurs. Un circuit intégré (ASIC) sera conçu en utilisant une technologie 28 nm pour valider les performances de ces techniques et faire les tests de mesures de consommation d’énergie. Au cours de la thèse, une plate-forme d’émulation a été conçue pour préparer l’environnement expérimental à utiliser une fois l’ASIC fondu. / There is continual motivation to scale down transistors size and to reduce the supply voltage of the circuits. However, by approaching the limits of transistor scaling and operating at a minimal supply voltage, circuit reliability has emerged as a critical concern. Circuits become more and more susceptible to errors due to Process, Voltage and Temperature (PVT) variations. Occurrence of errors can affect the behavior of circuits and generate a permanent system failure. Therefore, it is increasingly important to deal with errors effects in order to keep future devices working properly. The objective of the thesis is to address the reliability in digital systems and introduce new fault tolerant techniques to perform reliable signal processing applications on unreliable hardware. An example of application has been considered in the thesis: the tracking process of GPS receivers. It contains a very interesting set of different signal processing problem with different requirements of reliability: Correlation process, tracking loops (recursive operations), state machine, Gold and carrier generators. Starting from a noiseless GPS receiver, redundant mechanisms have been proposed and added to design a more resilient GPS receiver tolerant to errors. An Application-Specific Integrated Circuit (ASIC) will be designed, based on thesis results, using the 28 nm technology to validate the performances of the proposed techniques performances. During the thesis, an emulation platform was designed to prepare the experimental environment for the ASIC.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Despite the inherent resistance to narrowband signal interference afforded by GPS spread spectrum modulation, the low level of GPS signals makes them susceptible to narrowband interference. This paper discusses the application of a pre-correlation adaptive temporal filter for stationary and nonstationary narrowband interference suppression. Various adaptive algorithms are studied and implemented. Comparison of the convergence and tracking behavior of various algorithms is made.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / An integrated design, Test and Evaluation (T&E) system for GPS receiver is proposed in the paper, which can perform T&E early in R&D cycle, and combine new designs into a conceptual GPS receiver directly. The flowchart of its development mode is given. The architectures of the system, especially of the signal-computing software are described with frame diagrams. The mathematical models of three reference points are derived, with the impact of oscillator errors modeled. Future plans and further developments are also discussed.

This work explicates a simple GPS receiver intended for laboratory demonsration of DSSS signal demodulation and apparent distance measurement. The receiver will be able to seek for individual sattelite signals, measure their shift against local oscillator, demodulate navigational data, display information on LCD and communicate with PC via USB.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / Modern spectrally efficient telemetry transmitters are beginning to find their way on a variety of airborne test platforms. Many of these platforms also include Global Positioning System (GPS)-based Time-Space-Position-Information (TSPI) instrumentation systems. Due to space and other limitations, many of these platforms have demanding antenna placement limitations requiring closely spaced antennas. This paper describes steps taken to identify and mitigate potential interference to GPS-based TSPI instrumentation systems by these new technology transmitters. Equipment characterization was accomplished to determine interference potential of the proposed new transmitters and susceptibility of several GPS TSPI receivers. Several filtering techniques were identified as possible solutions to the anticipated interference problems. Telemetry (TM)/GPS system mockups and laboratory tests of the same were accomplished. Open-air testing was then accomplished to validate laboratory results. Finally, on aircraft tests were accomplished prior to performing any aircraft system modifications. Results of these test efforts are presented for others to consider when planning similar modifications to other platforms.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / Due to vehicle dynamics in mobile systems, GPS signal reception may be blocked by the body of the vehicle. This paper discusses various studies made on some vehicles such as the Space Shuttle, various aircraft, and analyzes the implementation of dual GPS antenna systems. Constructive and destructive interference characteristics of signal combining are considered. The author suggests an approach which uses a delay line on one of the antennas while analyzing the front end C/N0 needed for L1 GPS reception. An embedded Excel spreadsheet provides a front-end Noise Figure (NF) calculation tool based on user selected parameters.

International Telemetering Conference Proceedings / October 28-31, 1985 / Riviera Hotel, Las Vegas, Nevada / Demonstration results are presented for a high dynamic GPS receiver. The receiver tested is a breadboard unit capable of tracking one simulated satellite signal in pseudorange and range rate. The receiver makes approximate maximum likelihood estimates of pseudorange and range rate each 20 ms, and tracks these observables using a third order filter with a time constant of 0.14 s. Carrier phase is not tracked, which eliminates the typical failure mode of loss of carrier lock associated with PLLs at high dynamics. The receiver tracks with pseudorange lag errors of under 0.06 m when subjected to simulated 50 g turns with 40 g/s peak jerk. Pseudorange errors due to receiver noise alone are approximately 0.6 m rms at a carrier power to noise spectral density ratio of 34 dB-Hz. The tracking threshold SNR is approximately 28 dB-Hz, which provides 12 dB margin relative to the 40 dB-Hz that occurs with minimum specified satellite signal strength, 3.5 dB system noise figure, and 0 dBi antenna gain.

International Telemetering Conference Proceedings / October 22-25, 1984 / Riviera Hotel, Las Vegas, Nevada / A breadboard high dynamic GPS receiver capable of pseudorange tracking with accelerations of 50 g or higher without inertial aiding is presented. The receiver uses cross correlation followed by fast Fourier transformation to approximate maximum likelihood estimation of pseudorange and range rate, with no phase or delay locked loops. The breadboard system consists of a one channel receiver and a high dynamics signal simulator. A planned demonstration of the receiver is described and anticipated results are presented showing pseudorange lag errors of under 10 m with acceleration of 50 g.

This report intends to verify the possibility that the FastICA algorithm could be applied to the GPS system to eliminate the impulsive noise from the receiver end. As the impulsive noise is so unpredictable in its pattern and of great energy level to swallow the signal we need, traditional signal selection methods exhibit no much use in dealing with this problem. Blind Source Separation seems to be a good way to solve this, but most of the other BSS algorithms beside FastICA showed more or less degrees of dependency on the pattern of the noise. In this thesis, the basic mathematic modelling of this advanced algorithm, along with the principles of the commonly used fast independent component analysis (fastICA) based on fixed-point algorithm are discussed. To verify that this method is useful under industrial use environment to remove the impulsive noises from digital BPSK modulated signals, an observation signal mixed with additive impulsive noise is generated and separated by fastICA method. And in the last part of the thesis, the fastICA algorithm is applied to the GPS receiver modeled in the SoftGNSS project and verified to be effective in industrial applications. The results have been analyzed. / 6