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Letteratura scientifica selezionata sul tema "Coded waveform"

Autore: Grafiati

Pubblicato: 14 settembre 2024

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Articoli di riviste sul tema "Coded waveform"

Bharadwaj, N., e V. Chandrasekar. "Phase Coding for Range Ambiguity Mitigation in Dual-Polarized Doppler Weather Radars". Journal of Atmospheric and Oceanic Technology 24, n. 8 (1 agosto 2007): 1351–63. http://dx.doi.org/10.1175/jtech2061.1.

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Abstract This paper evaluates the retrieval of polarimetric variables when phase-coded waveforms are employed to suppress range overlaid echoes. A phase-coded waveform tags transmitted pulses with a phase code and then decodes the received signal to separate the overlaid echoes. Two methods suggested for separating overlaid echoes use random and systematic phase-coding techniques. In this paper, random phase and systematic phase-coded waveforms are evaluated for dual-polarized operation. The random phased-coded and systematic phase-coded waveforms are known to provide fairly good estimates of the Doppler spectral moments. This paper presents results at S band to quantify the performance of phase-coded waveform in retrieving polarimetric variables. It is shown that the polarimetric variables for both strong and weak trip echoes are estimated with acceptable accuracy.

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Yongqiang, Guo, Wu Yumin e Liu Hui. "Construction of Waveform Library in Cognitive Radar". Polish Maritime Research 24, s2 (28 agosto 2017): 22–29. http://dx.doi.org/10.1515/pomr-2017-0060.

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Abstract Based on the thoughts of cognitive radar, Fractional Fourier Transform (FrFT) is used to generate a rotatable waveform libraries of Frank coded/Barker coded waveform in this paper. Then, the ambiguity function is used to analyze the delay resolution, Doppler resolution, delay side-lobe level, and Doppler side-lobe level of the waveform libraries and orthogonality of them is also analyzed. Furthermore, we proved theoretically that there is a fixed coordinate transformation between the waveforms of library and its origin waveform. Therefore, the Cramér-Rao low bound (CRLB) of motion parameters can be computed easily using the waveforms of the libraries, which facilitate the subsequent waveform scheduled work. Simulation results show that the library waveforms can reduce delay resolution to satisfy the different situations and can bring significant benefits for delay resolution, orthogonality and reuse interval.

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Liu, Tianqu, Jinping Sun, Guohua Wang, Xianxun Yao e Yaqiong Qiao. "Optimal Design of Group Orthogonal Phase-Coded Waveforms for MIMO Radar". Mathematics 12, n. 6 (19 marzo 2024): 903. http://dx.doi.org/10.3390/math12060903.

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Digital radio frequency memory (DRFM) has emerged as an advanced technique to achieve a range of jamming signals, due to its capability to intercept waveforms within a short time. multiple-input multiple-output (MIMO) radars can transmit agile orthogonal waveform sets for different pulses to combat DRFM-based jamming, where any two groups of waveform sets are also orthogonal. In this article, a group orthogonal waveform optimal design model is formulated in order to combat DRFM-based jamming by flexibly designing waveforms for MIMO radars. Aiming at balancing the intra- and intergroup orthogonal performances, the objective function is defined as the weighted sum of the intra- and intergroup orthogonal performance metrics. To solve the formulated model, in this article, a group orthogonal waveform design algorithm is proposed. Based on a primal-dual-type method and proper relaxations, the proposed algorithm transforms the original problem into a series of simple subproblems. Numerical results demonstrate that the obtained group orthogonal waveforms have the ability to flexibly suppress DRFM-based deceptive jamming, which is not achievable using p-majorization–minimization (p-MM) and primal-dual, two of the most advanced orthogonal waveform design algorithms.

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Hong, Sheng, Yantao Dong, Rui Xie, Yu Ai e Yuhao Wang. "Constrained Transmit Beampattern Design Using a Correlated LFM-PC Waveform Set in MIMO Radar". Sensors 20, n. 3 (31 gennaio 2020): 773. http://dx.doi.org/10.3390/s20030773.

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This paper considers the design of a desired transmit beampattern under the good ambiguity function constraint using a correlated linear frequency modulation-phase coded (LFM-PC) waveform set in multiple-input-multiple-output (MIMO) radar. Different from most existing beampattern design approaches, we propose using the LFM-PC waveform set to conquer the challenging problem of synthesizing waveforms with constant-envelope and easy-generation properties, and, meanwhile, solve the hard constraint of a good ambiguity behaviour. First, the ambiguity function of the LFM-PC waveform set is derived, and the superiority of LFM-PC waveforms over LFM and PC waveforms is verified. The temporal and spatial characteristic analysis of the LFM-PC waveform set demonstrates that both the transmit beampattern and sidelobe level are mainly affected by the frequency intervals, bandwidths, and phase-coded sequences of the LFM-PC waveform set. Finally, the constrained beampattern design problem is formulated by optimizing these parameters for desired beampatterns and low sidelobes at different doppler frequencies, which is a bi-objective optimization problem. To solve this, we propose a joint optimization strategy followed by a mandatory optimization, where the sequence quadratic programming (SQP) algorithm and adaptive clonal selection (ACS) algorithm are exploited iteratively. The simulation results demonstrate the efficiency of our proposed method.

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Lei, Wei, Yue Zhang, Zengping Chen, Xiaolong Chen e Qiang Song. "Spatial–Temporal Joint Design and Optimization of Phase-Coded Waveform for MIMO Radar". Remote Sensing 16, n. 14 (19 luglio 2024): 2647. http://dx.doi.org/10.3390/rs16142647.

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By simultaneously transmitting multiple different waveform signals, a multiple-input multiple-output (MIMO) radar possesses higher degrees of freedom and potential in many aspects compared to a traditional phased-array radar. The spatial–temporal characteristics of waveforms are the key to determining their performance. In this paper, a transmitting waveform design method based on spatial–temporal joint (STJ) optimization for a MIMO radar is proposed, where waveforms are designed not only for beam-pattern matching (BPM) but also for minimizing the autocorrelation sidelobes (ACSLs) of the spatial synthesis signals (SSSs) in the directions of interest. Firstly, the STJ model is established, where the two-step strategy and least squares method are utilized for BPM, and the L2p-Norm of the ACSL is constructed as the criterion for temporal characteristics optimization. Secondly, by transforming it into an unconstrained optimization problem about the waveform phase and using the gradient descent (GD) algorithm, the hard, non-convex, high-dimensional, nonlinear optimization problem is solved efficiently. Finally, the method’s effectiveness is verified through numerical simulation. The results show that our method is suitable for both orthogonal and partial-correlation MIMO waveform designs and efficiently achieves better spatial–temporal characteristic performances simultaneously in comparison with existing methods.

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Chang, Shaoqiang, Fawei Yang, Zhennan Liang, Wei Ren, Hao Zhang e Quanhua Liu. "Slow-Time MIMO Waveform Design Using Pulse-Agile-Phase-Coding for Range Ambiguity Mitigation". Remote Sensing 15, n. 13 (4 luglio 2023): 3395. http://dx.doi.org/10.3390/rs15133395.

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This paper proposed a Pulse-Agile-Phase-Coding slow-time MIMO (PAPC-st-MIMO) waveform, where the phase-coded signal is utilized as the intra-pulse modulation of the slow-time MIMO waveform. Firstly, the signal model of the proposed waveform is derived. To improve the orthogonality of the phase-coded waveform sets, a novel hybrid evolutionary algorithm based on Cyclic Algorithm New (CAN) is proposed. After the optimization process of the phase-coded waveform sets, the signal processing method of the PAPC-st-MIMO waveform is derived. Finally, the effectiveness of the proposed method is verified with a simulation experiment. The mitigation ratio of the near-range detection waveform can achieve −30 dB, while the long-range detection waveform can achieve −35 dB. This approach ensures waveform orthogonality while enabling the slow-time MIMO waveform to achieve distance selectivity. By conducting joint pulse-Doppler processing across multiple range segments, range ambiguity can be suppressed, increasing the system’s Pulse Repetition Frequency (PRF) without introducing ambiguity.

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Meng, Huadong, Yimin Wei, Xuhua Gong, Yimin Liu e Xiqin Wang. "Radar Waveform Design for Extended Target Recognition under Detection Constraints". Mathematical Problems in Engineering 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/289819.

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We address the problem of radar phase-coded waveform design for extended target recognition in the presence of colored Gaussian disturbance. Phase-coded waveforms are selected since they can fully exploit the transmit power with sufficient variability. An important constraint, target detection performance, is considered to meet the practical requirements. The waveform is designed to achieve maximum recognition performance under a control on the achievable signal-to-noise ratio (SNR) of every possible target hypothesis. We formulate the code design in terms of a nonconvex, NP-hard quadratic optimization problem in the cases of both continuous and discrete phases. Techniques based on semidefinite relaxation (SDR) and randomization are proposed to approximate the optimal solutions. Simulation results show that the recognition performance and the detection requirements are well balanced and accurate approximations are achieved.

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Vierinen, Juha, Jorge L. Chau, Nico Pfeffer, Matthias Clahsen e Gunter Stober. "Coded continuous wave meteor radar". Atmospheric Measurement Techniques 9, n. 2 (3 marzo 2016): 829–39. http://dx.doi.org/10.5194/amt-9-829-2016.

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Abstract. The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products.

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Kim, Dong-Hoon, Hyung-Jung Kim e Jae-Han Lim. "Design of Optimized Coded LFM Waveform for Spectrum Shared Radar System". Sensors 21, n. 17 (28 agosto 2021): 5796. http://dx.doi.org/10.3390/s21175796.

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To meet the increasing demands for remote sensing, a number of radar systems using Linear Frequency Modulation (LFM) waveforms have been deployed, causing the problem of depleting frequency resources. To address this problem, several researchers have proposed the Spectrum Shared Radar System (SSRS) in which multiple radars share the same frequency band to transmit and receive their own signals. To mitigate the interferences caused by the signal transmission by other radars, SSRS employs orthogonal waveforms that inherit the orthogonality of the waveforms from orthogonal codes. However, the inherited orthogonality of the codes is significantly reduced when incorporating LFM waveforms with the codes. To solve this problem, in this paper, we propose a novel but simple scheme for generating a set of optimized coded LFM waveforms via new optimization framework. In the optimization framework, we minimize the weighted sum of autocorrelation sidelobe peaks (ASP) and cross-correlation peaks (CP) of the coded LFM waveforms to maximize the orthogonality of the waveforms. Through computer simulations, we show that the waveforms generated by the proposed scheme outperform the waveforms created by previous proposals in terms of ASP and CP.

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Zhang, J. D., X. H. Zhu e H. Q. Wang. "Adaptive radar phase-coded waveform design". Electronics Letters 45, n. 20 (2009): 1052. http://dx.doi.org/10.1049/el.2009.1099.

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Più fonti

Tesi sul tema "Coded waveform"

Saleh, Mahdi. "Contributions to High Range Resolution Radar Waveforms : Design of Complete Processing Chains of Various Intra-Pulse Modulated Stepped-Frequency Waveforms". Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0024.

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Dans divers systèmes radar, un grand intérêt a été porté à la sélection d’une forme d’onde et à la conception d’une chaîne de traitement complète, de l’émetteur au récepteur, afin d’obtenir un profil distance haute résolution (HRRP, acronyme de High Range Resolution Profile en anglais). Au cours des dernières décennies, les concepteurs d’algorithmes de traitement du signal radar ont concentré leur attention sur différentes formes d’onde telles que les techniques de compression d’impulsion et les systèmes à bande synthétique (SF acronyme de stepped frequency, en anglais).D’une part, trois types de formes d’onde de compression d’impulsions large bande ont été proposés dans la littérature : la forme d’onde modulée linéairement en fréquence (Linear Frequency Modulation), celle à codes de phase (Phase Coded) et la forme d’onde modulé non linéairement en fréquence (Non Linear Frequency Modulation). Ces approches sont très populaires, mais elles requièrent une fréquence d’échantillonnage généralement élevée au niveau du récepteur, et par voie de conséquence un convertisseur analogique-numérique coûteux. De plus, les formes d’onde PC et NLFM peuvent être préférables dans certaines applications à haute résolution, car elles conduisent à de meilleurs PSLR et ISLR que ceux obtenus avec la forme d’onde LFM.D’autre part, lorsqu’il s’agit de schémas SF, une fréquence d’échantillonnage moins élevée peut être envisagée, ce qui permet d’utiliser un CAN meilleur marché.Ces deux approches peuvent être combinées pour tirer avantage des deux familles. Bien que la combinaison standard mène à l’exploitation d’un CAN bon marché, les performances en termes de PSLR et ISLR ne sont pas nécessairement adaptées. Comme le PSLR et l’ISLR ont une grande influence sur la probabilité de détection et la probabilité de fausse alarme, notre objectif est de trouver des solutions alternatives. Ainsi, notre contribution dans ce mémoire de thèse consiste à proposer deux nouvelles chaînes de traitement, de l’émetteur au récepteur :1) Dans la première approche, le spectre de la forme d’onde à large bande est décomposé en un nombre prédéterminé de portions. Puis, les versions temporelles de ces dernières sont successivement transmises. Le signal reçu est alors traité soit en utilisant un algorithme FD (pour Frequency domain en anglais) modifié, soit un algorithme de reconstruction de forme d’onde réalisé directement dans le domaine temporel (TWR pour time wave reconstruction). Dans cette thèse, les formes d’ondes PC et NLFM ont été sélectionnées. Une étude comparative est alors menée entre les différentes chaînes de traitement, de l’émetteur au récepteur, que l’on peut constituer. Nos simulations montrent que les performances obtenues à partir de l’algorithme TWR sont le plus souvent meilleures que celles de l’algorithme FD modifié. La contre-partie est une augmentation du coût calculatoire. De plus, que ce soit avec une forme d’onde PC ou NLFM, l’approche présentée fournit de meilleurs résultats en termes de PSLR et ISLR que les formes d’onde SF classiques.2) La seconde démarche proposée consiste à approximer une forme d’onde NLFM à large bande par une forme d’onde LFM par morceaux, puis de la combiner avec une approche de type SF. Cela donne lieu à une forme d’onde combinant SF et un train d’impulsions LFM ayant différentes durées et largeurs de bande. La sélection des paramètres de cette forme d’onde est faite en minimisant un critère multi-objectif, tenant compte du PSLR, de l’ISLR et de la résolution distance. Cette estimation est opérée par algorithmes génétiques. Selon les poids utilisés dans le critère multi-objectif et le nombre d’impulsions LFM pris en compte, les performances des les formes d’onde résultantes varient.Une annexe est en outre fournie qui présente des travaux complémentaires sur la comparaison de modèles à partir de la divergence de Jeffreys
In various radar systems, a great deal of interest has been paid to selecting a waveformand designing a whole processing chain from the transmitter to the receiver toobtain the high range resolution profile (HRRP). For the last decades, radar designershave focused their attentions on different waveforms such as the pulse compressionwaveforms and the stepped frequency (SF) waveform:On the one hand, three different types of wide-band pulse compression waveforms havebeen proposed: the linear frequency modulation (LFM) waveform, the phase coded(PC) waveform, and the non-linear frequency modulation (NLFM) waveform. They arevery popular but the sampling frequency at the receiver is usually large. This hence requiresan expensive analog-to-digital convertor (ADC). In addition, the PC and NLFMwaveforms may be preferable in some high range resolution applications since they leadto peak sidelobe ratio (PSLR) and integrated sidelobe ratio (ISLR) better than the onesobtained with the LFM waveform.On the other hand, when dealing with SF waveforms, a small sampling frequency canbe considered, making it possible to use a cheap ADC.Pulse compression and SF waveforms can be combined to take advantage of both. Althoughthe standard combination of PC or NLFM with SF leads to the exploitation ofa cheap ADC, the performance of the PC waveform or NLFM waveform in terms ofPSLR and ISLR cannot be attained. As the PSLR and the ISLR have a great influenceon the probability of detection and probability of false alarm, our purpose in the PhDdissertation is to present two new processing chains, from the transmitter to the receiver:1) In the first approach, the spectrum of a wide-band pulse compression pulse is splitinto a predetermined number of portions. Then, the time-domain transformedversions of these various portions are transmitted. At the receiver, the receivedechoes can be either processed with a modified FD algorithm or a novel timewaveformreconstruction (TWR) algorithm. A comparative study is carried outbetween the different processing chains, from the transmitter to the receiver, thatcan be designed. Our simulations show that the performance in terms of PSLRand ISLR obtained with the TWR algorithm is better than that of the modified FDalgorithm for a certain number of portions. This comes at the expense of an additionalcomputational cost. Moreover, whatever the pulse compression used, the approach we present outperforms the standard SF waveforms in terms of PSLRand ISLR.2) In the second approach, we suggest approximating the wide-band NLFM by apiecewise linear waveform and then using it in a SF framework. Thus, a variablechirp rate SF-LFM waveform is proposed where SF is combined with a train ofLFM pulses having different chirp rates with different durations and bandwidths.The parameters of the proposed waveform are derived from the wide-band NLFMwaveform. Then, their selection is done by considering a multi-objective optimization issue taking into account the PSLR, the ISLR and the range resolution.The latter is addressed by using a genetic algorithm. Depending on the weightsused in the multi-objective criterion and the number of LFM pulses that is considered, the performance of the resulting waveforms vary.An appendix is finally provided in which additional works are presented dealing withmodel comparison based on Jeffreys divergence

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Bourduge, Jocelyn. "Shémas de codage binaires et non-binaires pour l'Internet des Objets". Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP059.

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L'Internet des Objets (IoT), permettant l'interconnectivité de dispositifs physiques capables de collecter et d'échanger des données, connait depuis quelques années un immense intérêt. Son cercle d'influence touche de nombreux domaines très diverses comme par exemple la santé, l'agriculture, l'industrie ou bien encore les villes connectées.Cependant, le déploiement à grande échelle des équipements IoT peut présenter des difficultés, notamment pour des applications nécessitant des communications longue portée avec une faible consommation énergétique, tout en assurant des transmissions sans erreur dans des environnements très diverses. Les réseaux longue portée et à faible consommation énergétique (LPWANs) sont une solution qui proposent diverses technologies répondant aux contraintes des applications. L'une de ces technologies très populaires est la solution LoRa déployée dans les réseaux LoRa longue portée (LoRaWANs). Cette technologie basée notamment sur une modulation par étalement de spectre en utilisant un chirp (CSS), assure une transmission longue portée avec un faible débit et garantissant une bonne durée de vie des batteries des dispositifs IoT dans des environnements très contraignants. De plus, les codes correcteurs d'erreurs jouent un rôle primordial dans les communications modernes en détectant et corrigeant des erreurs de transmission en ajoutant de la redondance dans les messages envoyés. Pour les applications IoT, ces derniers peuvent éviter la retransmission de messages érronnés ou bien de diminuer la puissance d'émission, ce qui permet dans les deux cas de sauvegarder la batterie des équipements. Dans le contexte LoRaWAN, le choix de codes simples comme des codes de Hamming a été fait afin d'assurer un certain seuil de performance tout en ayant une complexité faible au niveau du décodage.Dans cette thèse, nous proposons tout d'abord une étude approfondie de la modulation LoRa et de nouvelles modulations basées sur LoRa proposées dans la littérature afin d'optimiser l'efficacité spectrale du signal. Ces nouvelles modulations proposent notamment l'ajout d'information dans la phase, l'emploi d'autres types de chirp ou bien l'utilisation de la composante en quadrature du signal. On s'intéresse aussi aux codes correcteurs d'erreurs pour ce type de modulation et pour des messages de petite taille dans divers environnements. On met notamment en lumière l'intérêt de schémas binaires codés itératifs utilisant des codes LDPC optimisés ou bien des schémas binaires codés à plusieurs étages (MLC) employant des codes polaires. Enfin, nous nous intéressons à des schémas codés non-binaires contraints par des ordres de modulations très élevés et des mots de code très courts en mettant en exergue le rapport performance/coût
The Internet of Things (IoT), enabling the interconnection of physical devices capable of collecting and exchanging data, has garnered immense interest in recent years. Its sphere of influence encompasses numerous diverse domains such as healthcare, agriculture, industry, and smart cities.However, the large-scale deployment of IoT devices can pose challenges, especially for applications requiring long-range communication with low power consumption, while ensuring error-free transmissions in highly diverse environments. Low-power wide area networks (LPWANs) offer a solution by providing various technologies that address application constraints. One such widely adopted technology is LoRa, deployed in LoRa wide area networks (LoRaWANs). This technology, based on chirp spread spectrum modulation (CSS), enables long-range transmission with low throughput, ensuring extended battery life for IoT devices in challenging environments.Furthermore, error-correcting codes play a pivotal role in modern communications by detecting and correcting transmission errors through redundancy in sent messages. For IoT applications, these codes can prevent the retransmission of erroneous messages or reduce transmission power, thereby conserving device battery life. In the context of LoRaWAN, the choice of simple codes such as Hamming codes has been made to ensure a certain performance threshold while maintaining low decoding complexity.In this thesis, we first propose a comprehensive study of LoRa modulation and new modulations based on LoRa proposed in the literature to optimize spectral efficiency. These new modulations include adding information in the phase, employing different types of chirps, or utilizing the quadrature component of the signal. We also investigate error-correcting codes for this type of modulation and for small message length in various environments. We particularly highlight the interest in iterative binary coded schemes using optimized LDPC codes or multi-level coded binary schemes employing polar codes. Finally, we delve into non-binary coded schemes constrained by very high modulation orders and very short codewords, emphasizing the performance-to-cost ratio

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Friedrich, Konrad Jens. "Development of an active SONAR platform for AUV applications in a closed environment". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20026.

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Thesis (MScEng)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: In recent years Autonomous Underwater Vehicles (AUVs) have become interesting for harbor mapping and protection. AUVs require a SONAR sensor for observing their surroundings, thus enabling them to perform collision avoidance manoeuvres and scanning their operating environment for intruders or foreign objects, e.g. mines. To perform such actions the SONAR sensor is required to supply very fine range resolution for target imaging, as well as providing information about possible target velocity. Basic SONAR theory is discussed, as well as different approaches to signal design and processing techniques, for achieving the required resolution in range and target velocity. Two of the discussed approaches are selected for processing range and target velocity, respectively. Both approaches are simulated for their validity before being tested by using a custom-built platform. The platform is highly configurable and designed for capacity of testing a variety of SONAR signals and set ups. Furthermore, the platform is built by using off-the-shelf components to minimize development costs. The results of simulations and practical tests are presented. A high correlation between theory and practice is achieved. The knowledge and the platform presented form the stepping stone for further SONAR sensor developments.
AFRIKAANSE OPSOMMING: In die laaste jare het outonome onderwater voertuie (OOV) toenemend belangrik geword vir die kartografie en beskerming van hawens. OOV’s vereis SONAR sensore wat hulle in staat stel, om hulle omgewing waar te neem en sodoende botsing vermydings take te verrig en ook om hul werksomgewing noukeurig te skandeer om indringers of vreemde voorwerpe, bv. myne, op te spoor. Om sulke werk te verrig, word van die SONAR sensor vereis, om baie fyn afstand oplossings vir teiken te verskaf, insluitend die moontlike snelheid van die teiken. Basiese SONAR teorie word bespreek, en dan verskeie benaderings van sein ontwerp en verwerkings tegnieke. Twee van die bespreekte benaderings word gekies om afstand en teiken snelheid onderskeidelik te verwerk. Altwee benaderings word gesimuleer om hul geldigheid vas te stel, voor dat hulle getoets word op ’n pasmaat vervaardigde platform. Die platform is hoogs aanpasbaar en is ontwerp vir sy vermoë om ’n verskeidenheid SONAR seine en verwerkings te hanteer. Verder is die platform vervaardig met standard rakonderdele om ontwikkelingskoste so laag as moontlik te hou. Die uitslae van die simulerings en praktiese toetse word voorgestel. ’n Hoë mate aan korrelasie is bereik tussen teorie en praktyk. Die kennis en die platvorm, wat hier voorgestel word, vorm die eerste trappie vir toekomstige SONAR sensor ontwikkeling.

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Bilgi, Akdemir Safak. "An Overview Of Detection In Mimo Radar". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612589/index.pdf.

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In this thesis study, an overview of MIMO radar is presented. The differences in radar cross section, channel and received signal models in different MIMO radar configurations are examined. The performance improvements that can be achieved by the use of waveform diversity in coherent MIMO radar and by the use of angular diversity in statistical MIMO radar are investigated. The optimal detector under Neyman-Pearson criterion for Coherent MIMO radar when the interfering signal is white Gaussian noise is developed. Detection performance of phased array radar, coherent MIMO radar and Statistical MIMO radar are compared through numerical simulations. A detector for MIMO radar that contains the space time codes explicitly is also examined.

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Choy, Eddie L. T. "Waveform interpolation speech coder at 4 kbs". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20901.

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Speech coding at bit rates near 4 kbps is expected to be widely deployed in applications such as visual telephony, mobile and personal communications. This research focuses on developing a speech coder based on the waveform interpolation (WI) scheme, with an attempt to deliver near toll-quality speech at rates around 4 kbps. A WI coder has been simulated in floating-point using the C programming language. The high performance of the WI model has been confirmed by subjective listening tests in which the unquantized coder outperforms the 32 kbps G.726 standard (ADPCM) 98% of the time under clean input speech conditions; the reconstructed speech is perceived to be essentially indistinguishable from the original. When fully quantized, the speech quality of the WI coder at 4.25 kbps has been judged to be equivalent to or better than that of G.729 (the ITU-T toll-quality 8 kbps standard) for 45% of the test sentences. Further refinements of the quantization techniques are warranted to bring the coder closer to the toll-quality benchmark. Yet, the existing implementation has produced good quality coded speech with a high degree of intelligibility and naturalness when compared to the conventional coding schemes operating in the neighbourhood of 4 kbps.

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Choy, Eddie L. T. "Waveform interpolation speech coder at 4 kb/s". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0028/MQ50596.pdf.

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Aivaliotis, Theodoros. "Performance analysis of a JTIDS/link-16-type waveform using 32-ary orthogonal signaling with 32 chip baseband waveforms and a concatenated code". Thesis, Monterey, California: Naval Postgraduate School, 2009. http://hdl.handle.net/10945/4472.

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Approved for public release, distribution unlimited
The Joint Tactical Information Distribution System (JTIDS)) is a hybrid frequency-hopped, direct sequence spread spectrum system which used cyclic code-shift keying (CCFK) for M-ary symbol modulation and minimum shift-keying (MSK) for chip modulation. In addition JTIDS uses a (31, 15) Reed Solomon (RS) code for channel coding. In this thesis an alternative waveform consistent with the original JTIDS waveform is analyzed. The system to be considered uses a concatenated code consisting of a (31, k) Reed Solomon inner code and a 4/5 convolutional outer code. The coded symbols are transmitted on the in-phase (I) and quadrature (Q) components of the carrier using 32-ary orthogonal signaling with 32 chip basedband waveforms such as Walsh functions. Performance with both coherent and noncoherent detection is analyzed. For noncoherent detection only one five bit symbol is transmitted on the I and Q components of the carrier per symbol duration, so the data throughput for noncoherent detection 1/2 that of coherent detection. No diversity, consistent with JTIDS single-pulse structure, and a sequential diversity of two, consistent with JTIDS double-pulse structure, are both considered. For the double-pulse structure, performance is examined both for the case of linear soft diversity combining and also for soft diversity combining with perfectside information. Performance is examined for both AWGN only, as well as for AWGN and pulse-noise interference. Based on the results of this thesis, the proposed waveform is found to outperform the existing JTIDS/Link-16 waveform in all cases considered in this research. Indeed, the best performance for the atlernative waveform is obtained when an (31, 25) RD inner code is used. When only AWGN is present, the proposed waveform with no diversity has a gain of 2.6 dB and 2.5 dB as compared to the existing JTIDS/Link-16 wavefoorm for coherent and noncoherent demodulation, respectively, when Pb =10-5. Likewise in an AGWN only environment with a diversity of two, the proposed waveform outperforms the existing JTIDS/Link-16 waveform by 3.15 dB and 23 dB for coherent and noncoherent detection, respectively. When PNI is also present, the proposed waveform performs significantly better than the existing JTIDS waveform in all cases considered. Finally, the use of a concatenated code consisting of a (31, 25) RS inner code and a 4/5 convolutional outer code results in a 33% improvement in throughput as compared to the existing JTIDS/Link-16 waveform.

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Khan, Mohammad M. A. "Coding of excitation signals in a waveform interpolation speech coder". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32961.

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The goal of this thesis is to improve the quality of the Waveform Interpolation (WI) coded speech at 4.25 kbps. The quality improvement is focused on the efficient coding scheme of voiced speech segments, while keeping the basic coding format intact. In the WI paradigm voiced speech is modelled as a concatenation of the Slowly Evolving pitch-cycle Waveforms (SEW). Vector quantization is the optimal approach to encode the SEW magnitude at low bit rates, but its complexity imposes a formidable barrier.
Product code vector quantizers (PC-VQ) are a family of structured VQs that circumvent the complexity obstacle. The performance of product code VQs can be traded off against their storage and encoding complexity. This thesis introduces split/shape-gain VQ---a hybrid product code VQ, as an approach to quantize the SEW magnitude. The amplitude spectrum of the SEW is split into three non-overlapping subbands. The gains of the three subbands form the gain vector which are quantized using the conventional Generalized Lloyd Algorithm (GLA). Each shape vector obtained by normalizing each subband by its corresponding coded gain is quantized using a dimension conversion VQ along with a perceptually based bit allocation strategy and a perceptually weighted distortion measure. At the receiver, the discontinuity of the gain contour at the boundary of subbands introduces buzziness in the reconstructed speech. This problem is tackled by smoothing the gain versus frequency contour using a piecewise monotonic cubic interpolant. Simulation results indicate that the new method improves speech quality significantly.
The necessity of SEW phase information in the WI coder is also investigated in this thesis. Informal subjective test results demonstrate that transmission of SEW magnitude encoded by split/shape-gain VQ and inclusion of a fixed phase spectrum drawn from a voiced segment of a high-pitched male speaker obviates the need to send phase information.

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Koromilas, Ioannis. "Performance analysis of the link-16/JTIDS waveform with concatenated coding". Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FKoromilas.pdf.

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Thesis (M.S. in Electronic Warfare Systems Engineering)--Naval Postgraduate School, September 2009.
Thesis Advisor(s): Robertson, Ralph C. "September 2009." Description based on title screen as viewed on 5 November 2009. Author(s) subject terms: Link-16/JTIDS, Reed-Solomon (RS) coding, Cyclic Code-Shift Keying (CCSK), Minimum-Shift Keying (MSK), convolutional codes, concatenated codes, perfect side information (PSI), Pulsed-Noise Interference (PNI), Additive White Gaussian Noise (AWGN), coherent detection, noncoherent detection. Includes bibliographical references (p. 79). Also available in print.

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Gunawardana, Upul, e Kurt Kosbar. "OPTIMIZATION OF REFERENCE WAVEFORM FILTERS IN COHERENT DELAY LOCKED LOOPS". International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/606804.

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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada
In this paper, a new coherent correlation-loop architecture for tracking direct-sequence spread-spectrum signals is proposed. In the proposed correlation loop model, the mean-square tracking error is minimized by varying the cross-correlation function between the received signal and the locally generated signal. The locally generated signal is produced by passing a replica of the transmitted signal through a linear time-invariant filter, which is termed the VCC filter. The issue of bandwidth of a correlation loop is addressed and a bandwidth definition for comparative purposes is introduced. The filter characteristics to minimize the tracking errors are determined using numerical optimization algorithms. This work demonstrates that the amplitude response of the VCC filter is a function of the input signal-to-noise ratio (SNR). In particular, the optimum filter does not replicate a differentiator at finite signal-to-noise ratio as is sometimes assumed. The optimal filter characteristics and the knowledge of the input SNR can be combined to produce a device that has very low probability of loosing lock.

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Libri sul tema "Coded waveform"

Investigation of Doppler Effects on the Detection of Polyphase Coded Radar Waveforms. Storming Media, 2003.

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Li, Jian, Antonio De Maio, Guolong Cui e Alfonso Farina. Radar Waveform Design Based on Optimization Theory. Institution of Engineering & Technology, 2020.

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Radar Waveform Design Based on Optimization Theory. Institution of Engineering & Technology, 2020.

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Capitoli di libri sul tema "Coded waveform"

Zheng, Z., A. M. Weiner, K. R. Parameswaran, M. H. Chou e M. M. Fejer. "Spectral phase correlator for coded waveform recognition using second harmonie generation". In Ultrafast Phenomena XII, 159–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56546-5_46.

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Zeng, Wei-gui, Ying-feng Sun e Ming-gang Liu. "A New Waveform Design for Phase-Coded Quasi-CW Radar System". In The 19th International Conference on Industrial Engineering and Engineering Management, 1–11. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37270-4_1.

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Kim, Byounggi, Cheolhun Na e Sangjin Ryoo. "Feasibility Study of 32 Trellis-Coded OFDM Waveform for Tactical Information Communication". In Lecture Notes in Electrical Engineering, 53–62. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6516-0_7.

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Kayani, Jahangir K., e Steve F. Russell. "Choice of Coded Waveform and Correlation Filter for Self-Noise Suppression in Ultrasonic Correlation Systems". In Review of Progress in Quantitative Nondestructive Evaluation, 2097–104. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0383-1_275.

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Roja Reddy, B., e M. Uttara Kumari. "Generation of Orthogonal Discrete Frequency Coded Waveform Using Accelerated Particle Swarm Optimization Algorithm for MIMO Radar". In Advances in Intelligent and Soft Computing, 13–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30157-5_2.

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Milstein, Laurence B., e Jiangzhou Wang. "Interference Suppression for CDMA Overlays of Narrowband Waveforms". In Code Division Multiple Access Communications, 147–60. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-2251-5_8.

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Lazarov, Andon, Chavdar Minchev e Ivan Garvanov. "Barker Phase-Code-Modulation Waveform in ISAR Imaging System". In Communications in Computer and Information Science, 1–22. Cham: Springer Nature Switzerland, 2022. http://dx.doi.org/10.1007/978-3-031-23226-8_1.

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Song, Xijin, Xuelong Wang e Peng Li. "Electromagnetic Response Characteristics of Local Conductors with Pseudo-random Coded Waveforms". In Proceedings of the International Field Exploration and Development Conference 2018, 1684–705. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7127-1_160.

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Bhamre, Pooja, e S. Gupta. "A Review on Poly-Phase Coded Waveforms for MIMO Radar with Increased Orthogonality". In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 230–36. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-73712-6_24.

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Ma, Chunjiang, Xiaomei Tang, Yingxiang Liu, Zhibin Xiao e Guangfu Sun. "A Method of Carrier Phase Multipath Mitigation Based on Punctual Code Correlation Reference Waveform". In Lecture Notes in Electrical Engineering, 477–87. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0029-5_42.

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Atti di convegni sul tema "Coded waveform"

Kumbul, Utku, Nikita Petrov, Cicero S. Vaucher e Alexander Yarovoy. "Automotive Radar Interference Mitigation using Phase-Coded FMCW Waveform". In 2024 IEEE 4th International Symposium on Joint Communications & Sensing (JC&S), 1–6. IEEE, 2024. http://dx.doi.org/10.1109/jcs61227.2024.10646233.

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Bell, Mark, e Chieh-fu Chang. "Frequency Coded Waveforms for Adaptive Waveform Radar". In 2006 40th Annual Conference on Information Sciences and Systems. IEEE, 2006. http://dx.doi.org/10.1109/ciss.2006.286522.

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Zoltowski, Michael, Matthew Shuman e Murali Rangaswamy. "Virtual Waveform Diversity with Phase-Coded Radar Waveforms". In 2021 55th Asilomar Conference on Signals, Systems, and Computers. IEEE, 2021. http://dx.doi.org/10.1109/ieeeconf53345.2021.9723390.

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Lei, Wang, e Cha Hao. "The modulate frequency by coded pulse signal". In 2004 International Waveform Diversity & Design Conference. IEEE, 2004. http://dx.doi.org/10.1109/iwddc.2004.8317568.

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Nelander, Anders. "Continuous coded waveforms for noise radar". In 2007 International Waveform Diversity and Design Conference. IEEE, 2007. http://dx.doi.org/10.1109/wddc.2007.4339457.

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Shaw, Christopher, e Michael Rice. "Turbo-coded APSK for aeronautical telemetry". In 2009 International Waveform Diversity and Design Conference. IEEE, 2009. http://dx.doi.org/10.1109/wddc.2009.4800368.

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Sykora, Jan, e Kamil Anis. "Spatially irregular space-waveform coded CPFSK with full rank optimized waveforms". In 2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC 2009). IEEE, 2009. http://dx.doi.org/10.1109/pimrc.2009.5450263.

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Nelson, Tom, e Michael Rice. "On the design of bandwidth and power efficient coded modulation". In 2006 International Waveform Diversity & Design Conference. IEEE, 2006. http://dx.doi.org/10.1109/wdd.2006.8321478.

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Suvorova, Sofia, Bill Moran, Elena Kalashyan, Peter Zulch e Robert J. Hancock. "Radar performance of temporal and frequency diverse phase-coded waveforms". In 2006 International Waveform Diversity & Design Conference. IEEE, 2006. http://dx.doi.org/10.1109/wdd.2006.8321487.

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Paichard, Yoann. "Orthogonal multicarrier phased coded signal for netted radar systems". In 2009 International Waveform Diversity and Design Conference. IEEE, 2009. http://dx.doi.org/10.1109/wddc.2009.4800351.

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Rapporti di organizzazioni sul tema "Coded waveform"

Brock, Billy. The Frequency-Coded Pulse-Burst Waveform and the Costas Sequence. Office of Scientific and Technical Information (OSTI), febbraio 2016. http://dx.doi.org/10.2172/1603860.

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Kretschmer, Jr, Lin F. F. e F. C. Huffman-Coded Pulse Compression Waveforms. Fort Belvoir, VA: Defense Technical Information Center, maggio 1985. http://dx.doi.org/10.21236/ada155322.

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Gabriel, W. F. Phase-Coded Waveforms and Range Superresolution. Fort Belvoir, VA: Defense Technical Information Center, novembre 1990. http://dx.doi.org/10.21236/ada229530.

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Suvorova, Sofia, Bill Moran, Elena Kalashyan, Peter Zulch e Robert J. Hancock. Radar Performance of Temporal and Frequency Diverse Phase-Coded Waveforms. Fort Belvoir, VA: Defense Technical Information Center, gennaio 2006. http://dx.doi.org/10.21236/ada475484.

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