This paper introduces a new error correction strategy using cyclic redundancy checks (CRC) for a trellis coded system in the presence of bit stuffing. The proposed receiver is designed to simultaneously demodulate, decode and correct the received message in the presence of bit stuffing. It is based on a Viterbi algorithm exploiting the conditional transitions of an appropriate extended trellis. The receiver is evaluated with automatic identification system (AIS) messages constructed with a 16 bit CRC and a Gaussian Minimum Shift Keying (GMSK) modulation. The stuffed bits are inserted after any sequence of five consecutive bits 1 as requested by the AIS recommendation. Simulation results illustrate the algorithm performance in terms of packet error rate. A gain of more than 2,5 dB is obtained when compared to the conventional GMSK receiver.

Digital Spectral Analysis provides a single source that offers complete coverage of the spectral analysis domain. This self-contained work includes details on advanced topics that are usually presented in scattered sources throughout the literature. The theoretical principles necessary for the understanding of spectral analysis are discussed in the first four chapters: fundamentals, digital signal processing, estimation in spectral analysis, and time-series models. An entire chapter is devoted to the non-parametric methods most widely used in industry. High resolution methods are detailed in a further four chapters: spectral analysis by stationary time series modeling, minimum variance, and subspace-based estimators. Finally, advanced concepts are the core of the last four chapters: spectral analysis of non-stationary random signals, space time adaptive processing: irregularly sampled data processing, particle filtering and tracking of varying sinusoids. Suitable for students, engineers working in industry, and academics at any level, this book provides a rare complete overview of the spectral analysis domain.

The delineation of P and T waves is important for the interpretation of ECG signals. We propose a Bayesian detection-estimation algorithm for simultaneous detection, delineation, and estimation of P and T waves. A block Gibbs sampler exploits the strong local dependencies in ECG signals by imposing block constraints on the P and T wave locations. The proposed algorithm is evaluated on the annotated QT database and compared with two classical algorithms.

Le NPR (noise power ratio) et l’EVM (error vector magnitude) sont deux méthodes de mesure des distorsions ou des dégradations, linéaires ou non, des modulateurs numériques et des chaînes de transmission de signaux modulés. Chaque méthode mesure un bruit qui peut être ajouté au bruit thermique du système dans le bilan de liaison. On montre dans quelles conditions ces deux mesures donnent la même valeur et comment on peut remplacer l’une par l’autre afin de simplifier les simulations ainsi que les bancs de mesure, en particulier pour des mesures en large bande.

Since no similar studies has been proposed, this work intends to present the first conclusions about the possibilities of satellite communications in the distribution of MANET routing signaling. The improvements on MANET routing protocols will be evaluated to figure out if it is interesting or not to introduce this new role for satellites. For that purpose we shall delimit the applicative context. Mobile ad hoc networks are suitable for a wide range of applications. However, the presence of satellite terminals are not always guaranteed. One of the objectives of this work is to identify the applicative contexts where the hybrid terrestrial-satellite signaling distribution is suitable. Another point is the routing protocol itself. A lot of MANET routing protocols are available from the literature. Therefore we need to analyze the different routing solutions so to identify the most adaptable to a hybrid terrestrialsatellite signaling distribution. Finally, we intend to describe the steps and the crucial points of MANET routing protocol evaluation. Several tasks are involved: network modeling, scenario and performance metrics, output analysis techniques, etc. Therefore we highlight the complexity of MANET routing evaluation and present guidelines to achieve valid and representative results

Broadcasting systems have to deal with channel variability in order to offer the best rate to the users. Hierarchical modulation is a practical solution to provide different rates to the receivers in function of the channel quality. Unfortunately, the performance evaluation of such modulations requires time consuming simulations. We propose in this paper a novel approach based on the channel capacity to avoid these simulations. The method allows to study the performance of hierarchical and also classical modulations combined with error correcting codes. We will also compare hierarchical modulation with time sharing strategy in terms of achievable rates and indisponibility. Our work will be applied to the DVB-SH and DVB-S2 standards, which both consider hierarchical modulation as an optional feature.

In our thesis, we investigate the application of multi user detection techniques to a Low Polar Orbit (LPO) satellite used in the Argos system. Argos is a global satellite-based location and data collection system dedicated for studying and protecting the environment. User platforms, each equipped with a Platform Transmitter Terminal (PTT), transmit data messages to a 850 km LPO satellite. An ARGOS satellite receives, decodes, and forwards the signals to ground stations. All PTTs transmit at random times in a 100 kHz bandwidth using different carrier frequencies. The central carrier frequency f0 is 401.65 MHz. Due to the relative motion between the satellite and the platforms, signals transmitted by PTTs are affected by both a different Doppler shift and a different propagation delay. Thus, the Argos satellite receives overlapping signals in both frequency and time domains inducing Multiple Access Interference (MAI). One common approach to mitigate the MAI problem is to implement Multi User Detection (MUD) techniques at the receiver. To tackle this problem, several MUD techniques have been proposed for the reception of synchronous and asynchronous users. In particular, the Successive Interference Cancelation (SIC) detector has been shown to offer a good optimality-complexity trade-off compared to other common approaches such as the Maximum Likelihood (ML) receiver. In an Argos SIC receiver, users are decoded in a successive manner, and the signals of successfully decoded users are subtracted from the waveform before decoding the next user. This procedure involves a parameter estimation step and the impact of erroneous parameter estimates on the performance of Argos SIC receiver has been studied. Argos SIC receiver has been shown to be both robust to imperfect amplitude and phase estimation and sensitive to imperfect time delay estimation. The last part of our work focuses on the implementation of digital estimators for the Argos system. In particular, we propose a time delay estimator, a frequency estimator, a phase estimator and an amplitude estimator. These estimators are derived from the ML principle and they have been already derived for the single user transmission. In our work, we adapt successfully these estimators for the multi user detector case. These estimators use the Non Data Aided (NDA) cases in which no a priori information for the transmitted bits is required. The performance of these different estimators are compared to the Cramer Rao Bound (CRB) values. Finally, we conclude in our work by showing the different results obtained during this dissertation. Also, we give some perspectives for future work on Argos system.

This paper describes existing and new criteria for comparison and optimization of non-linear power amplifiers such as RF or microwave transmitters. In addition to intermodulation, receiver noise, and losses in the transmission system, the proposed new criteria take into account efficiency or consumed power. This results in the global optimization of a combined signal-to-noise-plus-intermodulation ratio as a function of saturated or nominal power but also consumed or dissipated power. Saturated power is limited by available technology. Consumed power and dissipated power are some of the main constraints in telecommunication satellite payloads, mobile phone handsets, and RFID (Radio Frequency IDentification). Another constraint comes from the limited size of antennas, which limits the system equivalent isotropic radiated power and gain-to-temperature ratio. With the proposed criteria the designer will be able to compare different amplifier technologies and to optimize the design and operating point of each stage of a multistage amplifier or a linearizer for a given amplifier. Interference from same or other systems is also introduced in the optimization through the use of signal-to-noise-plus-IM-plus-interference ratio criteria.

The SARGOS project aims to satisfy the strong emerging need to improve safety for the civilian offshore infrastructures, sensitive to the actions conducted by spite, piracy or terrorism on sea. SARGOS brings a new and innovative answer in this field of maritime security. A special care is taken to comply with the infrastructures operational constraints and the contractual and legislative rules. The innovative part of the project is mainly the global approach used, based on three levels: a) The level of a safe detection of a small size marine object, in a small range protection area, with rough sea, using innovative CW radar waveforms improved by new efficient signal processing algorithms b) The level of construction of a response plan facing a detected intrusion, taking into account the progressive improvement of the knowledge and the kind of detected object defined by its characterisation attributes. The acquisition process allows appropriate responses taking into account the crisis situation. (Platform safety rules, geopolitical environment and legal aspects). c) The managing level of the variety of non-lethal response means, either internal to the offshore platform (predefined security procedures, safety mode), or external to reply to the menace (injunction, intimidation or, as a last resort, activation of authorised means) and broadcast the alert to the local authorities. This article presents more specifically the main functionalities and the design of SARGOS system.