Academic literature on the topic 'Frequency-shift keying modulation'

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California<br>Presentation of Alcatel Espace last studies and developments regarding TT&C receiver Products for satellite. This document lays on 3 parts: · a technical point of view showing digital demodulation principles used (base band recovery, analytical head, PM or FM demodulation) and their related offered possibilities(digital controlling loop, lock status detection, jammer detection,....) · a technology/design description · a synthesis showing performance and results

The purpose of this semestral project is to explain the basic issues of simple digital modulations through the creation of simple digital modulations using direct digital synthesis. It begins with a short review of digital modulation theory and the theory about direct digital synthesis. All the technical documentation is attached, including schematics and boards of functional modulator.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>An all-digital high data rate parallel receiver architecture developed jointly by Goddard Space Flight Center and the Jet Propulsion Laboratory is pre- sented. This receiver utilizes only a small number of high speed components along with a majority of lower speed components operating in a parallel fre- quency domain structure implementable in CMOS, and can process over 600 Mbps with numerous varieties of QPSK modulation, including those incorpo- rating precise pulse shaping for bandwidth eÆcient modulation. Performance results for this receiver for bandwidth eÆcient QPSK modulation schemes such as square-root raised cosine pulse shaped QPSK and Feher’s patented QPSK are presented, demonstrating the great degree of exibility and high performance of the receiver architecture.

This work presents a spin torque nano-oscillator (STNO) based binary frequency shift keying (BFSK) modulation schema implemented on a printed circuit board (PCB). Maximal input data rate reaches 20 Mbit/s. Depending on the STNO used, carrier frequency can range from 1 to 10 GHz. Both DC and AC currents flowing through the STNO can be tuned between 0 to 4 mA. Using one magnetic tunnel junction (MTJ) STNO, a 380 MHz frequency shift around the center frequency 9 GHz was observed, when the modulated current was toggled between 0.8 mA and 1.2 mA at a rate of 20 Mbit/s. This is the first work demonstrating that the STNOs are applicable for BFSK modulation on the wireless application level.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>The aeronautical telemetry community is investigating alternative modulation methods to the commonly used non-return-to-zero (NRZ) pulse code modulation (PCM)/frequency modulation (FM). This paper outlines the important characteristics being investigated. Measured data comparing the spectral occupancy and bit error probability (BEP) performance of PCM/FM with that of a prototype constant envelope Feher’s quadrature phase shift keying (FQPSK) modulator and demodulator will also be presented. Measured results in several radio frequency bands demonstrate that the 99.99% and -60 dBc bandwidths of filtered FQPSK are only approximately one-half of the corresponding bandwidths of optimized PCM/FM even when the signal is non-linearly amplified. The signal energy per bit to noise power spectral density (E /N ) required for a BEP of 1×10 b 0 -5 for non-optimized FQPSK was approximately 12 dB which is approximately the same as limiter discriminator detected PCM/FM.

Thesis (MScEng)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: This thesis investigates orthogonal frequency division multiplexing (OFDM) as a viable modulation technique for an ultrasonic acoustic underwater modem. The underwater environment provides a challenging setting for acoustic communications. Long delay spreads due to multipath propagation, severe Doppler frequency shifts, frequency dependent absorption and very limited bandwidth are but some of the challenges to overcome. OFDM essentially provides the parallel transmission of symbols in the frequency domain by simultaneously modulating many closely spaced orthogonal subcarriers. The resulting long parallel symbol rate together with the cyclic extension of symbols render the signal robust against intersymbol interference (ISI) caused by multipath propagation. Intercarrier interference (ICI) between the overlapping frequency responses of subcarriers is mitigated by their property of orthogonality. Doppler spread contributes to the loss of orthogonality and can result in severe ICI. A method of measuring the Doppler shift by means of including a preamble and postamble symbol with each data frame is proposed. The detected frequency offset is corrected by resampling the frame at the desired sample rate. Not only do the ambles serve as a mechanism for timing and frequency synchronisation, but they are also applied in the channel estimation process. The equalisation of channel response is required for the coherent demodulation of the received symbols. An investigation into different phase shift keying (PSK) and quadrature amplitude modulation (QAM) constellations reveal optimal arrangements for minimal symbol errors. The optimised QAM constellations do not lend themselves to Gray-coding, so that an efficient interleaving scheme is needed to mitigate the non-uniform distribution of bit errors among symbol errors. Forward error correction is provided via a Bose Chaudhuri Hocquenghem (BCH) block code. Variable code rates, together with the ability to switch between different constellations, enable the modem to perform so-called variable modulation in an attempt to maximise the throughput under specific channel conditions. The modulation/demodulation scheme is wholly defined in software as to provide flexibility and facilitate experimentation with different signal processing methods. The accompanying hardware platform allows for the transmission of a pre-generated signal and the recording of a received signal for off-line processing. The prototype design serves as a proof of concept and thus provides only simplex communication. Field tests over limited distances demonstrate the successful operation of the prototype modem. We conclude that OFDM is indeed a suitable modulation technique for acoustic underwater communication.<br>AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die toepassing van ortogonale frekwensiedeling multipleksering (OFDM) as modulasie tegniek op ʼn onderwater kommunikasie modem. Die onderwater omgewing bied vele uitdagings vir akoestiese kommunikasie. Lang vertraging-verstrooiings as gevolg van multipad voortplanting, Doppler frekwensieskuif, frekwensieafhanklike absorpsie, en beperkte bandwydte is van die uitdagings wat oorkom moet word. In essensie bied OFDM die parallelle versending van ʼn aantal simbole deur die gelyktydige modulasie van verskeie nou-gespasieerde subdraers in die frekwensiegebied. Die gevolglike lang parallelle simboolperiodes, tesame met die sikliese uitbreiding van simbole, verleen immuniteit teen intersimbool steurnisse (ISI) wat ontstaan as gevolg van multipad voortplanting. Die ortogonaliteit van naburige draers in die frekwensiegebied beperk interdraer steuring (ICI) tussen hul oorvleuelende frekwensie weergawes. Doppler frekwensieskuif kan egter lei tot die verlies aan ortogonaliteit en bydra tot ernstige interdraer steurings. ʼn Metode wat gebruik maak van aanhef en slot simbole, ingesluit by elke raam, word voorgestel om die Dopplerskuif te meet. Die bepaalde frekwensieafset word gekorrigeer deur die monstertempo van die raam aan te pas na die verlangde tempo. Buiten die tyd- en frekwensie-sinkronisasie funksies van die aanhef en slot simbole, speel dit ook ʼn belangrike rol in die ontrekking van die frekwensie weergawe van die kanaal. Die effening van die kanaal se frekwensieweergawe is noodsaaklik vir die koherente demodulasie van die ontvangde simbole. ʼn Ondersoek na verskillende fase verskuif sleuteling (PSK) en kwadratuur amplitude modulasie (QAM) konstellasies het optimale rangskikkings opgelewer vir minimale simboolfoute. Hierdie optimale QAM konstellasies verleen hulself egter nie na Gray-kodering nie. ʼn Effektiewe invlegtegniek is nodig om die nie-uniforme verspreiding van bisfoute tussen simboolfoute te beperk. Fout korrigering funksionaliteit word gebied deur ʼn Bose Chaudhuri Hocquenghem (BCH) blokkode. Verstelbare koderingstempo’s en die vermoë om tussen verskillende konstellasies te skakel, stel die modem in staat om sogenaamde verstelbare modulasie te gebruik in ʼn poging om die data deurset te optimeer onder spesifieke kanaal kondisies. Die modulasie en demodulasie skema is volledig in sagteware gedefinieer. Dit verleen buigbaarheid en vergemaklik eksperimentering met verskeie seinverwerkingstegnieke. Die meegaande hardeware platvorm stel die modem in staat om vooraf opgewekte seine uit te saai en rou ontvangde siene op te neem vir na-tydse verwerking. Die prototipe ontwerp dien as ʼn konseptuele bewys en bied dus slegs simplekse kommunikasie. Die suksesvolle werking van die modem is gedemonstreer deur toetsing oor beperkte afstande. Hieruit word afgelei dat OFDM inderdaad geskik is vir akoestiese onderwater kommunikasie.

Les Oscillateurs Spintronique (STNO) sont un nouveau type d'oscillateurs à fréquence radio (RF) qui utilisent l'effet « Spin Transfer Torque (STT) » dans un dispositif de jonction tunnel magnétique (MTJ) pour produire des oscillations entretenues à haute fréquence. Les STNO fournissent des solutions compactes pour la communication sans fil utilisées dans « wireless sensor network (WSN) » car leur fréquence peut être réglée via un courant continu. Ce réglage de fréquence permet de coder l'information via « Frequency shift keying (FSK) » par modulation numérique entre deux valeurs discrètes sans besoin d'un RF mixer, ce qui conduit à des composants RF potentiellement moins complexes. Dans cette thèse, la faisabilité de FSK a été étudiée pour des STNO MTJ à aimantation dans le plan en vue des communications sans fil utilisées dans les WSN. Les paramètres abordés dans cette étude sont le décalage de fréquence et le taux de modulation maximum, auquel la fréquence peut être décalée entre deux valeurs discrètes.Pour caractériser le taux de modulation maximum, des simulations macrospin et des études expérimentales ont été réalisées. Les simulations révèlent que le taux de modulation maximum pour FSK par courant est limité par la fréquence de relaxation du STNO, qui est de l'ordre de quelques centaines de MHz pour les STNO à aimantation dans le plan. Cela signifie que le taux de modulation maximum est limité à quelques centaines de Mbps, ce qui est ciblé ici pour une communication sans fil à débit de données modéré utilisées dans les WSN. Des études expérimentales du FSK par modulation de courant dans les STNO ont été effectuées pour des STNO autonomes et pour des STNO intégrés dans des systèmes hyperfréquences. Le FSK sur les STNO autonomes montre un décalage de fréquence autour de 200 MHz (le décalage de fréquence entre ≈ 8,9 GHz et ≈9,1 GHz) au taux de modulation de 10Mbps. Ce taux de modulation est inférieur à la limite supérieure donnée par la fréquence de relaxation du STNO comme prévu dans la simulation numérique en raison du bruit de phase relativement élevé du dispositif mesuré. Afin de tester la faisabilité du STNO dans les systèmes hyperfréquences, la modulation FSK des STNO a été effectuée sur un émetteur de carte de circuit imprimé (PCB). L'émetteur de PCB a été réalisé et développé par le partenaire du projet Mosaic FP7, TUD University. L'analyse confirme qu'un changement de fréquence autour de 300 MHz (le décalage de fréquence entre ≈9 GHz et ≈9,3 GHz) a été observé avec un taux de modulation de 20 Mbps. Le taux de données est limité par les caractéristiques de l'émetteur de PCB et non intrinsèque au STNO. Les études de simulation et d'expérience de la modulation de fréquence des STNO démontrent que le débit de données est adéquat pour la communication sans fil utilisée dans WSN.Cependant, d'autres améliorations dans les matériaux et la nanofabrication de STNO sont nécessaires pour améliorer la puissance de sortie et améliorer les caractéristiques spectrales des oscillations pour pousser les débits de données à des valeurs plus élevées avec un grand décalage de fréquence<br>Spin Transfer Nano-Oscillators (STNOs) are a novel type of Radio Frequency (RF) oscillators that make use of the Spin Transfer Torque (STT) effect in a magnetic tunnel junction (MTJ) device to produce high-frequency auto-oscillations. STNOs are attractive for applications in wireless communications due to their nanometric size and their frequency tuning capabilities via either a dc current or an applied field. This frequency tuning permits to encode the information via frequency shift keying (FSK) by digital modulation of the current or applied field between two discrete values without the need of an external RF mixer, leading to potentially less complex RF components. In this thesis, the feasibility of the digital frequency modulation (frequency shift keying (FSK)) using in-plane magnetized MTJ STNOs has been studied. For this, the maximum modulation rate, up to which a signal can be modulated or the frequency can be shifted between two discrete values, is an important aspect that need to be characterized.The characterization of the maximum modulation rate for in-plane magnetized MTJ STNOs has been studied via numerical macrospin simulation for different modulation configurations, i.e. modulation by a sinusoidal RF current and a sinusoidal RF field. It revealed that the maximum modulation rate under RF current modulation is given by the amplitude relaxation frequency fp of the STNO. Under RF field modulation, i.e. an RF field applied parallel to the easy axis, an enhanced modulation rate above fp can be achieved since the frequency is modulated directly via the field and not via the amplitude. This suggests an important strategy for the design of STNO-based wireless communications and to achieve high data rates. Besides numerical simulation, experimental studies of frequency shift keying (FSK) by current modulation in STNOs have been also demonstrated. The first demonstration is the FSK in standalone STNOs. The analysis confirmed that the FSK was successfully observed with a frequency shift around 200MHz (the frequency shift between ≈8.9 GHz and ≈9.1 GHz) at the modulation rate of 10Mbps. This modulation rate is however less than the upper limit, which is given by the relaxation frequency fp of the STNO as predicted in the numerical simulation, because of the relatively high phase noise of the device measured. In order to test the feasibility of the STNO within microwave systems, the FSK modulation of STNOs was performed on a printed circuit board (PCB) emitter. FSK with a frequency shift around 300MHz (the frequency shift between ≈9 GHz and ≈9.3 GHz) was observed with a modulation rate of 20 Mbps. The data rate here was limited by characteristics of the PCB emitter and not intrinsic to the STNO. The simulation and experiment studies of frequency modulation of STNOs demonstrate that the data rate of is adequate for wireless communication used in WSN. However, further improvements in materials and nanofabrication of STNOs are required to enhance the output power and improve the spectral characteristics of the oscillations to push the data rates to higher values with large frequency shift

Railway signaling is of paramount importance to ensure traffic management andsafety on the rail network. The main lines are divided into sections called ‘blocks’,which are governed by a fixed signal installation. To prevent trains from colliding,each block allows one train at once. In France (and most European countries),train detection is performed by an electrical device called track circuit that consistsof a transmitter and a receiver installed at the track-side, and connected via therails. In the absence of a train, an electrical signal flows from the transmitter tothe receiver through the rails. As a train enters a track circuit, its axles shuntthe rails, provoking a short circuit (also called ‘shunt’): the signal transmitted tothe receiver drops. The detection of that signal drop results in the detection of atrain. This method rarely fails throughout the network, but there can be criticalcases where it may be inefficient. In this Master’s Thesis, new detection criteriaproposed in previous studies have been tested on signals measured in poor shuntingconditions. Three approaches have been tested: one in the time domain and two inthe frequency domain. The time approach compares the short-term and long-termstatistics of the received signals. The observation of a change in the spectra of thereceived signals around the 3rd order harmonic (3OH) has led to the implementationof two frequency criteria: the estimation of the band power around the 3OH andthe detection of the 3OH peaks. The obtained results show that better detection isachieved when the new criteria and the existing one are combined.<br>Tågsignalsystem är väsentliga för att garantera trafikstyrning och säkerhet i tågnätet.Spåren är indelade i sektioner, s.k. block, som övervakas med fasta signalinstallationer.För att hindra tåg från att krocka, tillåts bara ett tåg i taget per block. IFrankrike (och de flesta andra europeiska länder), detekteras tågen med en elektriskspårkrets som består av en sändare och en mottagare som är installerad bredvidspåret och ansluten till rälsen. När inget tåg finns på spåret, flyter en elektrisk signalfrån sändaren till mottagaren via spåret. När ett tåg anländer, kortsluts kretsenav hjulaxeln och signalen försvinner från mottagaren. Minskningen i signalstyrkaanvänds för att detektera tåget. Denna metod sällan misslyckas i tågnätet, men iovanliga fall kan det uppstå farliga situationer. I detta examensarbete utvärderasnya detektionsmetoder, som har föreslagits i tidigare studier, på signaler som haruppmätts under förhållanden med dålig kontakt mellan hjul och spår. Tre olika metoderhar testats, en i tidsdomänen och två i frekvensdomänen. Tidsdomänsmetodenjämför kortvarig och långvarig statistik för den mottagna signalen. I spektrum förden mottagna signalen, har man observerat en förändring runt den tredje övertonen,samt detektering av frekvenstoppar vid tredje övertonen. De erhållna resultatenvisar på förbättrad detektering när de nya och existerande kriterierna kombineras.