To see the other types of publications on this topic, follow the link: Ratio Signal / interference + Noise.
Dissertations / Theses on the topic 'Ratio Signal / interference + Noise'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Ratio Signal / interference + Noise.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Grant, Andrew G. "The performance of orthogonal frequency division multiplexing in a high noise, low signal-to-noise ratio environment with cochannel interference /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Dec%5FGrant.pdf.
Full text
2
Grant, Andrew G. "Performance of orthogonal frequency division multiplexing in a high noise, low signal-to-noise ratio environment with co-channel interference." Thesis, Monterey, California. Naval Postgraduate School, 2005. http://hdl.handle.net/10945/1782.
Full textAbstract:
Orthogonal Frequency Division Multiplexing (OFDM) is fast becoming the signal modulation technique of choice for many commercial and military wireless applications. Its resilience to cochannel interference and bandwidth efficiency make it ideal for many different applications. With its increasing popularity among disparate facets of society, it becomes likelier that enemy militaries and/or nonmilitary combatants will utilize the technique or a system that uses the technique. In light of this development, the need to develop techniques and algorithms to enable detection becomes apparent. This thesis will attempt to develop a model for OFDM and measure its performance in a multipath, outdoor environment with low signal-to-noise ratio, high noise and cochannel interference. Because of the unpredictability of the outdoor environment and the proliferation of various OFDM standards, the simulation will utilize only one algorithm for modeling outdoor environments and the IEEE 802.11a standard.
3
Gupta, Amit. "Signal-to-noise-plus-interference ratio estimation and statistics for direct sequence spread spectrum code division multiple access communications." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1176321495.
Full text
4
Gerbracht, Sabrina, Eduard A. Jorswieck, Gan Zheng, and Björn Ottersten. "Non-regenerative Two-Hop Wiretap Channels using Interference Neutralization." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-113245.
Full textAbstract:
In this paper, we analyze the achievable secrecy rates in the two-hop wiretap channel with four nodes, where the transmitter and the receiver have multiple antennas while the relay and the eavesdropper have only a single antenna each. The relay is operating in amplify-and-forward mode and all the channels between the nodes are known perfectly by the transmitter. We discuss different transmission and protection schemes like artificial noise (AN). Furthermore, we introduce interference neutralization (IN) as a new protection scheme. We compare the different schemes regarding the high-SNR slope and the high-SNR power offset and illustrate the performance by simulation results. It is shown analytically as well as by numerical simulations that the high SNR performance of the proposed IN scheme is better than the one of AN.
5
Shibata, Takafumi, Masaaki Katayama, and Akira Ogawa. "Performance of Asynchronous Band-Limited DS/SSMA Systems." IEICE, 1993. http://hdl.handle.net/2237/7200.
Full text
6
Gerbracht, Sabrina, Eduard A. Jorswieck, Gan Zheng, and Björn Ottersten. "Non-regenerative Two-Hop Wiretap Channels using Interference Neutralization." Technische Universität Dresden, 2012. https://tud.qucosa.de/id/qucosa%3A26894.
Full textAbstract:
In this paper, we analyze the achievable secrecy rates in the two-hop wiretap channel with four nodes, where the transmitter and the receiver have multiple antennas while the relay and the eavesdropper have only a single antenna each. The relay is operating in amplify-and-forward mode and all the channels between the nodes are known perfectly by the transmitter. We discuss different transmission and protection schemes like artificial noise (AN). Furthermore, we introduce interference neutralization (IN) as a new protection scheme. We compare the different schemes regarding the high-SNR slope and the high-SNR power offset and illustrate the performance by simulation results. It is shown analytically as well as by numerical simulations that the high SNR performance of the proposed IN scheme is better than the one of AN.
7
Pelteku, Altin E. "Adaptive Suppression of Interfering Signals in Communication Systems." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/138.
Full textAbstract:
The growth in the number of wireless devices and applications underscores the need for characterizing and mitigating interference induced problems such as distortion and blocking. A typical interference scenario involves the detection of a small amplitude signal of interest (SOI) in the presence of a large amplitude interfering signal; it is desirable to attenuate the interfering signal while preserving the integrity of SOI and an appropriate dynamic range. If the frequency of the interfering signal varies or is unknown, an adaptive notch function must be applied in order to maintain adequate attenuation. This work explores the performance space of a phase cancellation technique used in implementing the desired notch function for communication systems in the 1-3 GHz frequency range. A system level model constructed with MATLAB and related simulation results assist in building the theoretical foundation for setting performance bounds on the implemented solution and deriving hardware specifications for the RF notch subsystem devices. Simulations and measurements are presented for a Low Noise Amplifer (LNA), voltage variable attenuators, bandpass filters and phase shifters. Ultimately, full system tests provide a measure of merit for this work as well as invaluable lessons learned. The emphasis of this project is the on-wafer LNA measurements, dependence of IC system performance on mismatches and overall system performance tests. Where possible, predictions are plotted alongside measured data. The reasonable match between the two validates system and component models and more than compensates for the painstaking modeling efforts. Most importantly, using the signal to interferer ratio (SIR) as a figure of merit, experimental results demonstrate up to 58 dB of SIR improvement. This number represents a remarkable advancement in interference rejection at RF or microwave frequencies.
8
Krone, Stefan, and Gerhard Fettweis. "Communications with 1-Bit Quantization and Oversampling at the Receiver: Benefiting from Inter-Symbol-Interference." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-101473.
Full textAbstract:
1-bit analog-to-digital conversion is very attractive for low-complexity communications receivers. A major drawback is, however, the small spectral efficiency when sampling at symbol rate. This can be improved through oversampling by exploiting the signal distortion caused by the transmission channel. This paper analyzes the achievable data rate of band-limited communications channels that are subject to additive noise and inter-symbol-interference with 1-bit quantization and oversampling at the receiver. It is shown that not only the channel noise but also the inter-symbol-interference can be exploited to benefit from oversampling.
9
Ortega, Blanco Rubén. "Análise de SNIR e BER para redes acústicas submarinas." reponame:Repositório Institucional da UnB, 2015. http://repositorio.unb.br/handle/10482/19534.
Full textAbstract:
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2015.<br>Submitted by Albânia Cézar de Melo (albania@bce.unb.br) on 2016-02-16T14:01:50Z
No. of bitstreams: 1
2015_RubenOrtegaBlanco.pdf: 78834010 bytes, checksum: 3420abfa3f7efe2d616b97f09d14ff70 (MD5)<br>Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-02-19T21:04:29Z (GMT) No. of bitstreams: 1
2015_RubenOrtegaBlanco.pdf: 78834010 bytes, checksum: 3420abfa3f7efe2d616b97f09d14ff70 (MD5)<br>Made available in DSpace on 2016-02-19T21:04:29Z (GMT). No. of bitstreams: 1
2015_RubenOrtegaBlanco.pdf: 78834010 bytes, checksum: 3420abfa3f7efe2d616b97f09d14ff70 (MD5)<br>O objetivo do seguinte trabalho é determinar um modelo matemático que permita-nos obter a Relação Sinal Ruído mais Interferência (SNIR do Inglês Signal-to-Noise plus Interference Ratio), a Taxa de Erro de Bits (BER do Inglês Bit Error Rate) de um salto e a Taxa de Erro de Bits fim-a-fim numa rede acústica submarina. Com esse propósito foi desenvolvido um modelo matemático que permite o cálculo destes parâmetros considerando a interferência para o protocolo de acesso ao meio (MAC do Inglês Medium Access Control) ALOHA puro. Também foi necessário desenvolver antes diferentes parâmetros da rede, tais como, distância média do salto, distância média até o nó central, distância média entre os nós, número médio de saltos na rota e desvio médio. Com o uso deste modelo também é possível obter o valor da frequência ótima utilizando uma função de otimização. Comparações entre a Taxa de Erro de Bits de um salto e fim-a fim também forem feitas, para diferentes valores de máximo ângulo de desvio na topologia de rede usada. Estas comparações demonstran quando pode ser mais convenente o uso de um salto ou múltiple-salto. Simulações Monte-Carlo e modelo forem comparados com o propósito de validar os resultados obtidos. Estas comparações demostram a grande similitude entre nosso modelo e as simulações de Monte-Carlo. Além disso foi possível o estudo do comportamento da SNIR e do BER variando importante parâmetros da rede tais como frequência de transmissão, número de nós, raio da esfera e máximo ângulo de desvio. Os resultados obtidos provarem que a SNIR para um salto diminui com o aumento do número de nós e o raio da esfera, mas aumenta com o incremento da potência de transmissão. O comportamento de BER é contrário ao comportamento de SNIR. Também foi possível observar a existência da frequência ótima, onde os melhores valores de SNIR e o BER são obtidos. ______________________________________________________________________________________________ ABSTRACT<br>The objective of this work is to nd a mathematical model that allow us to obtain the Signal-to-Noise plus Interference Ratio (SNIR), the One-Hop Bit Error Rate (BER) and the End-to-End Bit Error Rate for an Underwater Acoustic Network (UAN). Considering this, it was developed a model that includes the interference as an important impairment and for ALOHA MAC (Medium Access Control) protocol. In addition, it was necessary to obtain before several parameters from the network, such as, average distance of the hop, average distance between nodes, average distance to the central node, average number of hops and average deviation. With this model, it is also possible to nd the optimal value of frequency using an optimization function. It was made comparisons between the One-Hop BER and the End-to-End BER for various values of maximal deviation angle. This comparison shows when it is more adequate to either use one-hop or multi-hop. Finally, we compared numerical and Monte-Carlo simulation results, giving a rst validation to our model. These comparisons show a big similitude between the developed model and the Monte-Carlo simulation. In addition, it was possible to analyse the behaviour of the SNIR and BER by varying important parameters of the network, such as, transmission frequency, number of nodes and sphere radius among others. From the obtained results it was prove that the SNIR decreases with an increase from the number of nodes and the sphere radius, but increases with the transmission power. The End-to-End BER has an contrary behavior with the SNIR.
10
Krone, Stefan, and Gerhard Fettweis. "Communications with 1-Bit Quantization and Oversampling at the Receiver: Benefiting from Inter-Symbol-Interference." Technische Universität Dresden, 2012. https://tud.qucosa.de/id/qucosa%3A26362.
Full textAbstract:
1-bit analog-to-digital conversion is very attractive for low-complexity communications receivers. A major drawback is, however, the small spectral efficiency when sampling at symbol rate. This can be improved through oversampling by exploiting the signal distortion caused by the transmission channel. This paper analyzes the achievable data rate of band-limited communications channels that are subject to additive noise and inter-symbol-interference with 1-bit quantization and oversampling at the receiver. It is shown that not only the channel noise but also the inter-symbol-interference can be exploited to benefit from oversampling.
11
Johnson, Bruce. ""C" Band Telemetry an Aircraft Perspective." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595617.
Full textAbstract:
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada<br>This paper concentrates on aircraft specific issues and impacts of utilizing a "C" band telemetry system on a new or existing instrumentation system.
12
Kamanzi, Janvier. "Development of a low energy cooling technology for a mobile satellite ground station." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1072.
Full textAbstract:
Thesis submitted in fulfillment of the requirements for the degree
Master of Technology:Electrical Engineering
in the Faculty ofEngineering
at the Cape Peninsula University of Technology
Supervisor:Prof MTE KAHN
Bellville
December 2013<br>The work presented in this thesis consists of the simulation of a cooling plant for a future mobile satellite ground station in order to minimize the effects of the thermal noise and to maintain comfort temperatures onboard the same station. Thermal problems encountered in mobile satellite ground stations are a source of poor quality signals and also of the premature destruction of the front end microwave amplifiers. In addition, they cause extreme discomfort to the mission operators aboard the mobile station especially in hot seasons. The main concerns of effective satellite system are the quality of the received signal and the lifespan of the front end low noise amplifier (LNA). Although the quality of the signal is affected by different sources of noise observed at various stages of a telecommunication system, thermal noise resulting from thermal agitation of electrons generated within the LNA is the predominant type. This thermal noise is the one that affects the sensitivity of the LNA and can lead to its destruction. Research indicated that this thermal noise can be minimized by using a suitable cooling system. A moveable truck was proposed as the equipment vehicle for a mobile ground station. In the process of the cooling system development, a detailed quantitative study on the effects of thermal noise on the LNA was conducted. To cool the LNA and the truck, a 2 kW solar electric vapor compression system was found the best for its compliance to the IEA standards: clean, human and environment friendly. The principal difficulty in the development of the cooling system was to design a photovoltaic topology that would ensure the solar panels were always exposed to the sun, regardless the situation of the truck. Simulation result suggested that a 3.3 kW three sided pyramid photovoltaic topology would be the most effective to supply the power to the cooling system. A battery system rated 48 V, 41.6 Ah was suggested to be charged by the PV system and then supply the power to the vapor compression system. The project was a success as the objective of this project has been met and the research questions were answered.
13
Singh, Latchman. "Speech enhancement for forensic applications." Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36080/1/36080_Singh_1998.pdf.
Full textAbstract:
Forensic audio recordings are usually made with a single covert microphone in non-ideal conditions. In non-ideal conditions the recordings are highly susceptible
to various types of noise. The noise is usually broadband noise, co-talker interference, impulsive noise, narrow band noise or convolutional noise. There are existing speech enhancement techniques available to suppress most of the noise types mentioned, but when the noise is of a considerable level the performance of most enhancement techniques tend to decrease significantly. This thesis presents a study of speech enhancement techniques that are applicable to the enhancement of forensic audio recordings or that can be used in a forensic
recording environment. It considers both pre-processing and post-processing speech enhancement techniques. This thesis investigates the improvement of some of the existing speech enhancement techniques as well as proposing some new ones. The performance of the improved and proposed speech enhancement techniques were evaluated objectively using the segmental signal-to-noise ratio
(SNRseg) and subjectively using the mean opinion score (MOS). A review of the current speech enhancement techniques is presented in the thesis and is also used
as a reference in some comparisons. The current speech enhancement techniques considered are those that are
applicable to forensic audio recordings. The performance of the existing techniques are assessed in the comparisons with the speech enhancement
techniques proposed by this thesis.
Two pre-processing speech enhancement techniques are presented in this thesis. The first pre-processing speech enhancement technique is designed to improve
existing broadband noise suppression techniques by the use of frequency shift keying (FSK) signals. It is based on a simple concept, which is to insert a known
tone of sufficient amplitude into the silent segments of a speech signal prior to transmission. At the receiver the detection of silent or non-speech segments used
in estimating the noise, becomes a simpler and more accurate task due to the inserted tone. The second pre-processing speech enhancement technique is designed to suppress a wide range of noises and it is based on zero padding. Zero padding involves inserting a zero value sample in between each speech signal sample prior to transmission. The inserted zero value samples allow accurate characterisation of the noise in the adjacent speech samples. At the receiver the noise is estimated from the sample positions allocated for the zero value samples. Several post-processing speech enhancement techniques are presented in this thesis. The first post-processing speech enhancement technique is designed for the suppression of co-talker interference and it uses a combination of dynamic time warping (DTW) and dual channel adaptive filtering. This technique is proposed for the suppression of co-talker interference, when the co-talker interference or noise reference signal is obtainable at a later instance as in the case of many covert forensic recordings. The corrupted speech signal and the noise reference signal are aligned using DTW and then the co-talker interference is suppressed using a dual channel adaptive filter.
The second post-processing speech enhancement technique is designed for broadband noise suppression and is based on spectral subtraction but it incorporates the masking properties of the human auditory system for improved
performance. Auditory masking is used to find the masking threshold, below which the noise is no longer perceivable. Only those noise components above the
masking threshold are suppressed. This approach is taken to reduce any byproducts such as musical noise.
The third post-processing speech enhancement technique is designed for broadband noise suppression and is based on spectral subtraction but it exploits the human auditory systems perception of frequency. Critical band analysis is used to group frequencies that are similarly perceived, which are then treated as a single
entity by the enhancement technique.
14
Nguyen, Van Minh. "Modélisation des liens de communication radio et optimisation de la gestion de mobilité dans les réseaux cellulaires." Phd thesis, Paris, Télécom ParisTech, 2011. https://pastel.hal.science/pastel-00610041.
Full textAbstract:
La qualité de communication dans un réseau sans fil est déterminée par la qualité du signal, et plus précisément par le rapport signal à interférence et bruit. Cela pousse chaque récepteur à se connecter à l'émetteur qui lui donne la meilleure qualité du signal. Nous utilisons la géométrie stochastique et la théorie des extrêmes pour obtenir la distribution de la meilleure qualité du signal, ainsi que celles de l'interférence et du maximum des puissances reçues. Nous mettons en évidence comment la singularité de la fonction d'affaiblissement modifie leurs comportements. Nous nous intéressons ensuite au comportement temporel des signaux radios en étudiant le franchissement de seuils par un processus stationnaire dollarX(t)dollar. Nous démontrons que l'intervalle de temps que dollarX(t)dollar passe au-dessus d'un seuil dollar\gamma \to -\inftydollar suit une distribution exponentielle, et obtenons également des résultats caractérisant des franchissements par dollarX(t)dollar de plusieurs seuils adjacents. Ces résultats sont ensuite appliqués à la gestion de mobilité dans les réseaux cellulaires. Notre travail se concentre sur la fonction de `handover measurement'. Nous identifions la meilleure cellule voisine lors d'un handover. Cette fonction joue un rôle central sur l'expérience perçue par l'utilisateur. Mais reste une question ouverte à cause des difficultés posées par la coopération entre plusieurs mécanismes de contrôle qu'elle nécessite. Nous traitons ce problème en proposant des approches analytiques pour les réseaux émergents de types macro et pico cellulaires, ainsi qu'une approche d'auto-optimisation pour les listes de voisinage utilisées dans les réseaux cellulaires actuels<br>The quality of communication in a wireless network is primarily determined by the wireless link signal quality expressed in term of signal to-interference-plus-noise ratio. The fact that better signal quality enhances the communication quality incites to look for states whereeach receiver connects to a transmitter providing it with the best signal quality. Using stochastic geometry and then extreme value theory,we obtain the distribution of the best signal quality, of the interference, and of the maximum signal strength in both bounded and unbounded path loss conditions. We then investigate temporal variations of wireless links, which are also essential to wireless networking, in terms of level crossings of a stationary process X(t). We prove that the length of an excursion of X(t) above a level γ→-∞ has an exponential distribution, and obtain results associated with the crossings of several levels. These results are then applied to mobility management in cellular networks. We focus on the handover measurement function, which differs from the handover decision-execution by identifying the best neighbouring cell to which a connection switching is to be decided and executed. This function has an important influence on the user's experience, though its operation has been questionable due to the complexity of combining control mechanisms. We firstly address this topic with an analytical approach for emerging macro cell and small cell networks, and then with a self-optimisation approach for neighbour cell lists used in today's cellular networks
15
Nguyen, Van Minh. "Modélisation des Liens de Communication Radio et Optimisation de la Gestion de Mobilité dans les Réseaux Cellulaires." Phd thesis, Télécom ParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00610041.
Full textAbstract:
La qualité de communication dans un réseau sans fil est déterminée par la qualité du signal, et plus précisément par le rapport signal à interférence et bruit. Cela pousse chaque récepteur à se connecter à l'émetteur qui lui donne la meilleure qualité du signal. Nous utilisons la géométrie stochastique et la théorie des extrêmes pour obtenir la distribution de la meilleure qualité du signal, ainsi que celles de l'interférence et du maximum des puissances reçues. Nous mettons en évidence comment la singularité de la fonction d'affaiblissement modifie leurs comportements. Nous nous intéressons ensuite au comportement temporel des signaux radios en étudiant le franchissement de seuils par un processus stationnaire $X(t)$. Nous démontrons que l'intervalle de temps que $X(t)$ passe au-dessus d'un seuil $\gamma \to -\infty$ suit une distribution exponentielle, et obtenons également des résultats caractérisant des franchissements par $X(t)$ de plusieurs seuils adjacents. Ces résultats sont ensuite appliqués à la gestion de mobilité dans les réseaux cellulaires. Notre travail se concentre sur la fonction de 'handover measurement'. Nous identifions la meilleure cellule voisine lors d'un handover. Cette fonction joue un rôle central sur l'expérience perçue par l'utilisateur. Mais reste une question ouverte à cause des difficultés posées par la coopération entre plusieurs mécanismes de contrôle qu'elle nécessite. Nous traitons ce problème en proposant des approches analytiques pour les réseaux émergents de types macro et pico cellulaires, ainsi qu'une approche d'auto-optimisation pour les listes de voisinage utilisées dans les réseaux cellulaires actuels.
16
Pauluzzi, David Renato. "Signal-to-noise ratio and signal-to-impairment ratio estimation in AWGN and wireless channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq22377.pdf.
Full text
17
Hamid, Syamsul Bahrin Abdul. "Enhancing signal to noise ratio for electrostatic transducers." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24250.
Full textAbstract:
This Thesis describes the design, manufacture and evaluation of a Fluidically Amplified Ultrasonic Transducer (FLAUT) for an air-coupled application. The transducer utilises a pipe as an amplification mechanism to increase the output pressure; and as a dissipation mechanism to reduce inherent noise within the transducer. The new transducer design introduces the concept of matched thin plate, cavity and pipe, of which the individual geometry enhances one another. Design methodologies, which consist of analytical modelling and Finite Element (FE) Modelling, have been implemented. The analytical modelling identifies the required geometry for the FLAUT based on the desired operating resonant frequency; while FE then verifies the vibrational characteristics of the design. Through the application of FE modelling and practical analysis, FLAUT devices have been designed, developed and compared with experiment. The sensitivity analysis is utilised to realise a design and manufacturing tolerance requirements. The devices were manufactured in the operating range of 25 kHz to 85 kHz. Air-coupled pulse-echo insertion loss was found to be 61.3 dB, an improvement of 9.1 dB over the conventional cavity only design. Results from the proof of concept prototype indicate that the output of the FLAUT is maximised when the pipe radius is designed to be as large as practically possible while maintaining the matched resonant frequencies. This correlates well with theory both in term of sensitivity and noise. Furthermore, the pressure output of a FLAUT array is maximised by arranging the cell spacing to be as close as practically possible. Thus, the cells were spaced at multiples of 2.25 to the cavity radius – to reduce the risk of cell damage. An analytical method to simulate, and a technique to measure the inherent noise using a specially designed hybrid isolation vessel has been developed. From the measurement, the FLAUT noise is found to be 5.8 W, an improvement of 2.7 dB compared to the conventional cavity only design.
18
Armstrong, Juliane. "Random inter stimulus interval increases signal-to-noise ratio." Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/honors/29.
Full textAbstract:
Incremental improvements are continuously being made to P300-Speller BCI paradigms. Accurate classification depends on a high signal-to-noise ratio (SNR) between the target and nontarget items. Fixed presentation rates produce a large flash-evoked response that persists throughout the recording epoch, which can potentially undermine the classification of P300-responses. By introducing a random interstimulus interval (ISI) to a previously improved P300-Speller paradigm (i.e., Checkerboard Paradigm; CBP) we expect to reduce the deleterious flash-evoked responses and increase the P300 classification SNR. Data were recorded from 32 EEG locations (right mastoid referenced) from 13 subjects using the CBP with two conditions. In the Random ISI (RI) condition, ISI varied between 0 ms and 187.5 ms and averaged 93.75 ms. In the Fixed ISI (SI) condition, ISI remained static at 93.75 ms. In both conditions, participants were instructed to spell out 72 characters using an 8x9 matrix of alphanumeric characters by silently counting each target flash. The first 36 characters served as ‘calibration’ data for a stepwise linear discriminant analysis (SWLDA; 0 - 800 ms poststimulus epochs). This SWLDA classifier was then used to provide online feedback for an additional 36 character selections. Absolute amplitude of target and nontarget responses were summed across the recording epoch for each subject and averaged between Pz and Cz (maximum). Target averages were then divided by nontarget averages to create a SNR measure and compared between RI and FI conditions. The RI manipulation produced a significantly (p = .04) larger SNR (M = 5.85) than the FI condition (M =4.07).Further analysis of the averaged waveforms revealed a significantly (p = .05) greater positive peak at Cz (253 ms peak latency) for the RI condition. Classification performance measures for RI and FI conditions were high for accuracy (84 and 85%, respectively; NS) and bitrate (21 and 23 bits/min, respectively; NS). Together these results suggest that while randomizing ISI can yield higher SNR, response classification is not affected. It is possible that SWLDA is a useful classification method, in general; however, these data suggest that it does not capitalize on the additional information gained from the increase in SNR. Alternative classification techniques that can take advantage of specific subcomponents of the response may be able to utilize this additional information to improve BCI speed and accuracy.
19
Cheng, Lui. "Improvement of signal-to-noise ratio in uterine EMG recordings." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1548.
Full textAbstract:
The objective of this study is to remove or, at least, reduce the noise in uterine EMG recordings, which at their present noise level render the data unusable. Predicting when true labor will start and recognizing when labor actually starts are important for both normal and complex pregnancies. For normal pregnancy, the prognosis of labor is important for reducing unnecessary hospital costs. About 10% of the four million babies born each year in the United States are born prematurely. At $1,500 a day for neonatal intensive care, this comprises national health care expenses of well over $5 billion. Spectral analysis, filter design, and 1/3 octave analysis were applied to analyze the uterine EMG recordings. Signal-to-noise ratio was increased with IIR Butterworth bandstop filter. The spectral band between 0.25 and 0.4 Hz shows matching of the Toco belt via spectral analysis. Nevertheless, 1/3 octave analysis gives the highest correct detection percentage compare with frequency analysis and filter design.
20
Cheraghi, Parisa. "Fast and accurate spectrum sensing low signal noise ratio environment." Thesis, University of Surrey, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581799.
Full textAbstract:
Opportunistic Spectrum Access (OSA) [1] promises tremendous gain in improving spectral efficiency. The main objective of OSA is to offer the ability of identifying and exploiting the under-utilised spectrum in an instantaneous manner in a wireless device, without any user intrusion. Hence, the initial requirement of any OSA device is the ability to perform spectrum sensing. Local narrow-band spectrum sensing has been quite well investigated in the literature. However, it is realised that existing schemes can hardly meet the requirements of a fast and accurate spectrum sensing particulariy in very low signal-to-noise-ratio (SNR) range without introducing high complexity to the system. Furthermore, increase in the spectrum utilisation calls for spectrum sensing techniques that adopt an architecture to simultaneously search over multiple frequency sub-bands at a time. However, the literature of sub-band spectrum sensing is rather limited at this time. The main contributions of this thesis is two-fold: First a clusterd-based differential energy detection for local sensing of multi- carrier based system is proposed. The proposed approach can form fast and reliable decision of spectrum availability even in very low SNR environment. The underlying initiative of the proposed scheme is applying order statistics on the clustered differential Energy Spectral Density (ESD) in order to exploit the channel frequency diversity inherent in high data-rate communications. Second contribution is three-fold: 1) re-defining the objective of the sub- band level spectrum sensing device to a model estimator, 2) deriving the optimal model selection estimator for sub-band level spectrum sensing for fixed and variable number of users along with a sub-optimal solution based on Bayesian statistical modelling and 3) proposing a practical model selection estimator with relaxed sample size constraint and limited system knowledge for sub-band spectrum sensing applications in Orthogonal Frequency-Division Multiple Access (OFDMA) systems. The result obtained showed that through exploitation of the channel frequency selectivity the performance of the stat-of-the-art spectrum sensing techniques can be significantly improved. Furthermore, by modelling the sub-band level spectrum sensing through model estimation allows for new spectrum sensing approach. It was proved both analytically and through simulations that the proposed approach have significantly extended to state-of-the-art spectrum sensing. Key words: Differential, energy detection, low signal-to- noise ratio (SNR), multi- carrier, opportunistic spectrum access, spectrum sensing.
21
Koul, Ashish 1979. "Use of intermicrophone correlation in estimating signal to noise ratio." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29672.
Full textAbstract:
Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.<br>Includes bibliographical references (leaf 42).<br>This thesis presents the design, analysis, and simulation of a system that uses the correlation coefficient of audio inputs gathered at two spatially separate microphones to determine the signal to noise ratio in the environment. This work is motivated by past research in microphone array hearing aids, where accurate estimates of SNR were shown to improve performance. Signal to noise ratio is defined as the ratio of energy in the direct component (audio sources originating in front of a broadside array) to energy in the interference component (sources originating from the sides of the array). The design presented is a simple hypothesis testing mechanism for determining whether the SNR exceeds a fixed level. In the analysis, behavior of the system is studied theoretically under varying conditions of reverberation in the environment, and processing parameters are determined to optimize system performance. Finally, simulations test the true performance of the system to verify the validity of the theoretical analysis.<br>by Ashish Koul.<br>M.Eng.and S.B.
22
Liu, Janet (Janet Kay) 1976. "Determining signal-to-noise ratio in a burst coherent demodulator." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80142.
Full textAbstract:
Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.<br>Includes bibliographical references (leaves 59-60).<br>by Janet Liu.<br>S.B.and M.Eng.
23
Lie, Chin Cheong Patrick. "Iterative algorithms for fast, signal-to-noise ratio insensitive image restoration." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63767.
Full text
24
Aldokhail, Abdullah M. "Automated Signal to Noise Ratio Analysis for Magnetic Resonance Imaging Using a Noise Distribution Model." University of Toledo Health Science Campus / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=mco1469557255.
Full text
25
Gleissner, Filip. "Koexistence mobilních komunikačních systémů GSM-EDGE a UMTS." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233470.
Full textAbstract:
The dissertation thesis deals with the investigation of the coexistence of GSM–EDGE and UMTS systems with focus on the physical layer of the systems. The aim is to provide a set of recommendations for practical cooperation while the systems operate in both the separated and the common radio bands. A detailed description of signal processing of both the systems on the physical layer is presented. On the basis of this description, models of both systems were created and implemented in the MATLAB environment. The simulations are focused on the physical layer quality parameters, especially the bit error ratio evaluation for various ratios of useful signal power to noise power during the transmission over the radio channel. Simulation is also used to examine the quality of received useful signal while it is interfered by signals from the same and adjacent channels. The purpose is to determine the isolation between these adjacent channels, when the bit error ratio of the useful signal does not exceed a certain reference value. The simulation results are subsequently subjected to comparison with the results of the experimental measurements in laboratory conditions. Before the measurements are carried out, a study of possible interference types is performed. Consequently, the crucial parameters of the measuring equipment used are verified. From the results of simulations and measurements, the proposal of a minimum and recommended carrier separation between both the systems is presented in order to efficiently utilize the assigned frequency spectrum. Furthermore, for the cooperation in both the separated and the common radio bands, the necessary precautions are given for reaching the required isolation and thereby inter-system interference minimization.
26
Siddhichai, Supakorn. "Algorithms and structures for noise robust blind image deconvolution." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248791.
Full text
27
Fan, Yun-Hui. "A stereo audio coder with a nearly constant signal-to-noise ratio." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14788.
Full text
28
Anzaloni, Alessandro. "Frame Synchronization in Digital Burst Telecommand at Low Signal to Noise Ratio." International Foundation for Telemetering, 1989. http://hdl.handle.net/10150/614676.
Full textAbstract:
International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California<br>Frame synchronization was extensively studied usually supposing that the bit pattern to acquire frame synchronization was imbedded in sequences of random bits. In this paper, the determination of a bit pattern for frame synchronization in digital burst telecommand at low signal to noise ratio is investigated, considering the a priori knowledgement of a bit pattern for bit synchronization and the format of the frame. The a priori knowledgement of a bit pattern for bit synchronization is used to find a bit sequence that minimize the false probability to acquire frame synchronization. A simple strategy using the aperture technique is stablished. An engineering model is used to find experimentally the mean probability of true synchronization after one burst. This initial research to find a bit pattern for frame synchronization presented good results.
29
Anzaloni, Alessandro, and de Almeida José Carlos Juliano. "FRAME SYNCHRONIZATION IN DIGITAL BURST TELECOMMAND AT LOW SIGNAL TO NOISE RATIO." International Foundation for Telemetering, 1989. http://hdl.handle.net/10150/615211.
Full textAbstract:
International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California<br>Frame synchronization was extensively studied usually supposing that the bit pattern to acquire frame synchronization was imbeded in sequences of random bits. In this paper, the determination of a bit pattern for frame synchronization in digital burst telecommand at low signal to noise ratio is investigated, considering the a priori knowledgement of a bit pattern for bit synchronization and the format of the frame. The a priori knowledgement of a bit pattern for bit synchronization is used to find a bit sequence that minimize the false probability to acquire frame synchronization. A simple strategy using the aperture technique is stablished. An egineering model is used to find experimentally the mean probability of true synchronization after one burst. This initial research to find a bit pattern for frame synchronization presented good results.
30
Crotty, Maureen. "Signal to Noise Ratio Effects on Aperture Synthesis for Digital Holographic Ladar." University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1355245759.
Full text
31
Haboosheh, Ronette. "Diagnostic auditory brainstem response analysis : evaluation of signal-to-noise ratio criteria using signal detection theory." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31575.
Full textAbstract:
This study evaluated an online measure of signal-to-noise ratio (SNR) as a response-detection tool for threshold auditory brainstem response (ABR) testing. Threshold-ABR data were analysed for 98 infants and young children tested at BC Children's Hospital, and results were validated on an additional 10 patients. Using signal detection theory, it was possible to assess test performance for the SNR measure, with expert-clinician judgement as the gold standard. In addition, a range of SNR criteria were assessed in terms of sensitivity (the ability to accurately identify a response) and specificity (the ability to accurately reject waveforms that do not contain a response). The effect of residual noise (RN) exclusion criteria on SNR test performance, sensitivity, and specificity was also investigated. Waveforms to 500-, 2000-, and 4000-Hz air-conducted brief-tone stimuli were included in this study. Overall, SNR was found to have a test performance of A=.91, with improved performance (A=.93) when high residual-noise waveforms (RN>0.08 μV) were excluded. When low-RN data were separated by frequency, test performance for each frequency was A=.94. Results suggest that the optimal SNR criterion is slightly lower for 500-Hz recordings than for 2000- or 4000-Hz recordings. However, when high-RN recordings were excluded, a SNR criterion of 0.98 achieved a minimum specificity of 95% for each stimulus frequency, with sensitivity values ranging from 64%(for 500 Hz) to 79% (for 4000 Hz). Findings confirm the hypotheses that SNR accurately distinguishes response-present from response-absent waveform, and that quiet recordings are more easily interpreted than noisy recordings using SNR. Guidelines are provided for the clinical use of SNR as an objective response-detection tool.<br>Medicine, Faculty of<br>Audiology and Speech Sciences, School of<br>Graduate
32
Brown, Christopher K. "Detection of frequency-hopped signals embedded in interference waveforms." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Jun%5FBrown.pdf.
Full text
33
Hurley, Sean M. "Signal-to-noise ratio gains and synchronization requirements of a distributed radar network." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FHurley.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2006.<br>Thesis Advisor(s): Murali Tummala, Phillip E. Pace. "June 2006." Includes bibliographical references (p. 59-60). Also available in print.
34
Nayak, Aravind Ratnakar. "Iterative Timing Recovery for Magnetic Recording Channels with Low Signal-to-Noise Ratio." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5018.
Full textAbstract:
Digital communication systems invariably employ an underlying analog communication channel. At the transmitter, data is modulated to obtain an analog waveform which is input to the channel. At the receiver, the output of the channel needs to be mapped back into the discrete domain. To this effect, the continuous-time received waveform is sampled at instants chosen by the timing recovery block. Therefore, timing recovery is an essential component of digital communication systems.
A widely used timing recovery method is based on a phase-locked loop (PLL), which updates its timing estimates based on a decision-directed device. Timing recovery performance is a strong function of the reliability of decisions, and hence, of the channel signal-to-noise ratio (SNR). Iteratively decodable error-control codes (ECCs) like turbo codes and LDPC codes allow operation at SNRs lower than ever before, thus exacerbating timing recovery.
We propose iterative timing recovery, where the timing recovery block, the equalizer and the ECC decoder exchange information, giving the timing recovery block access to decisions that are much more reliable than the instantaneous ones. This provides significant SNR gains at a marginal complexity penalty over a conventional turbo equalizer where the equalizer and the ECC decoder exchange information. We also derive the Cramer-Rao bound, which is a lower bound on the estimation error variance of any timing estimator, and propose timing recovery methods that outperform the conventional PLL and achieve the Cramer-Rao bound in some cases.
At low SNR, timing recovery suffers from cycle slips, where the receiver drops or adds one or more symbols, and consequently, almost always the ECC decoder fails to decode. Iterative timing recovery has the ability to corrects cycle slips. To reduce the number of iterations, we propose cycle slip detection and correction methods. With iterative timing recovery, the PLL with cycle slip detection and correction recovers most of the SNR loss of the conventional receiver that separates timing recovery and turbo equalization.
35
Kakade, Rohan. "Improved resolution and signal-to-noise ratio performance of a confocal fluorescence microscope." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33699/.
Full textAbstract:
A culmination of theory, techniques and devices stemming from a wide variety of sources and disciplines, optical microscopy presents vast possibilities for visualisation of small structures. One of the most fundamental yet significant optical microscopy techniques is Confocal Fluorescence Microscopy (CFM). CFM is studied here by analysing its performance with respect to the two most important metrics - Signal-to-noise ratio and 3D optical resolution. Several authors have commented on the inherent inefficiency of imaging systems such as CFM to utilise the available light when providing resolution beyond the well-known diffraction limit, primarily due to the precise mechanisms that help realise the resolution gain in the first place. In CFM, the detection pinhole is the key mechanism that helps realise up to 1.4 times resolution improvement over conventional wide-field microscopy techniques by trading off SNR. First, an investigation of the inherent SNR-resolution trade-off in a CFM system is studied; the impact of the detection pinhole geometry on the performance of a CFM is examined by means of an effective trade-off curve. Using alternative pinhole geometries in conjunction with new detection schemes, it is next shown how performance gains are realised in both the lateral and axial directions. Examined next is a recently developed detection scheme called subtractive imaging; wherein a special annular pinhole is used to divide the confocal point spread function signal into two detectors. By using fast point detectors in place of CCD arrays, it is shown how using numerical optimisation yields an optimum “differential pinhole” to achieve considerable 3D resolution gains over conventional (circular pinhole based) CFM systems. By examining the trade-off curves it is also shown that the proposed design is able to offer simultaneous and maximum performance gains up to a considerably high SNR in comparison to conventional (circular pinhole) based CFM systems. Lastly, the work will propose the use of a deconvolution technique and an alternative detection scheme to demonstrate substantially higher improvements in the quality of images acquired by a CFM system. Image reconstruction is a tried and tested image post processing strategy to realise super resolution. An image reconstruction technique, based on an expectation maximisation maximum likelihood (EM-ML) algorithm is used in conjunction with array detectors to demonstrate enhanced resolution and noise performance of a CFM system. The point scan method used here renders the algorithm slow with long run times. To mitigate this, structured illumination is used to show how similar resolution gains in the array detector based CFM systems could be realised but in a much shorter time.
36
Tsuda, Hirofumi. "Study on Communication System From the Perspective of Improving Signal-to-Noise Ratio." Kyoto University, 2019. http://hdl.handle.net/2433/242440.
Full text
37
Hmamouche, Yassine. "Applications of stochastic geometry in the modeling and analysis of wireless networks." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2020. http://www.theses.fr/2020IMTA0212.
Full textAbstract:
Les réseaux sans fil de la cinquième génération (5G) et au-delà (B5G), devraient être très hétérogènes, multicouches, et dotés d’une intelligence intégrée à la fois au cœur et à la périphérie du réseau. Dans un tel contexte, l’évaluation des performances au niveau du système revêtira une importance cruciale pour formuler des enseignements judicieux sur les compromis qui régissent un tel système complexe et ainsi prévenir le besoin de simulations logicielles coûteuses et fastidieuses. Au cours de la dernière décennie, la géométrie stochastique est considérée comme un puissant outil d’analyse permettant d’évaluer les performances des réseaux sans fil au niveau du système et de cerner leur tendance à l’hétérogénéité. Cette thèse examine les nouveaux modèles et techniques de la géométrie stochastique développés au cours de la précédente décennie en matière de modélisation et d’analyse des réseaux sans fil du futur. Les discussions sont suffisamment affinées pour être accessibles aux lecteurs peu spécialisés et faire en sorte que les lecteurs débutants, intermédiaires ou avancés puissent se familiariser rapidement avec ce domaine de recherche. Ensuite, nous nous appuyons sur la géométrie stochastique pour examiner plusieurs aspects des réseaux sans fil 5G et B5G, afin d’illustrer sa flexibilité mathématique et sa capacité à saisir l’analyse de scénarii peu conventionnels. Nous discutons également de nouvelles perspectives qui apporteront un nouveau souffle à l’utilisation de la géométrie stochastique au cours de cette décennie cruciale. En bref, les discussions furent étendues à des thématiques plus larges telles que les communications optiques en espace libre (FSO), les communications en lumière visible, les systèmes de drones, l’architecture d’accès radio en brouillard (F-RAN), l’intelligence artificielle et l’apprentissage machine, ainsi que les communications moléculaires<br>Next generation wireless networks, i.e., fifth generation (5G) and beyond (B5G), are expected to be highly heterogeneous, multilayered, with embedded intelligence at both thecore and edge of the network. In such a context, system-level performance evaluation will be very important to formulate relevant insights into tradeoffs that govern such a complex system and then prevent the need for onerous and timeconsuming computer simulations. Over the past decade, stochastic geometry has emerged as a powerful analytical tool to evaluate system-level performance of wireless networks and capture their tendency towards heterogeneity. This dissertation reviews first novel stochastic geometry models and techniques developed during the last decade in modeling and analysis of modern wireless networks. The discussions are refined enough to be accessible for non-specialist readers and help new, intermediate, or advanced readers familiarize quickly with this field of research. Next, we leverage stochastic geometry frameworks to investigate several aspects of 5G and B5G wireless networks and then illustrate its mathematical flexibility and ability to capture the analysis of the rather unconventional scenarios. Also, new perspectives that will breathe new life into the use of stochastic geometry during this crucial decade are discussed. In a nutshell, extensive discussions were held on broader topics such as free space (FSO) optical communications, visible light communications, unmanned aerial vehicle systems, fog radio access architecture (F-RAN) , artificial intelligence and machine learning, and molecular communications
38
Miller, Matthew P. "Strategies to increase the signal to noise ratio in three-dimensional positron emission tomography." Thesis, University of Surrey, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322456.
Full textAbstract:
Positron Emission Tomography (PET) is an imaging technique that uses biologically relevant molecules labelled with positron emitting radioisotopes to measure regional tissue function in living organisms. To maximise the detection efficiency, data are acquired in 3D, that is, all possible detector combinations in a scanner without inter-ring shielding (septa). The gain in sensitivity afforded by 3D PET is offset by the increase in random coincidences, scattered coincidences and deadtime. These problems must be overcome for the gain in sensitivity to be fully realised. The aim of this research project was to investigate strategies to increase the signal to noise ratio of the 3D PET data. Additional side shielding, both in neuro and body scanning, has been implemented and assessed. Large gains were achieved using the neuro shields in experimental and clinical studies. The potential of the body shields was tested in experimental and in-vivo studies which showed that they were scan dependent. For example, no gain was found for a cardiac blood flow (H2 IS0) study. A model-based scatter correction was assessed by companng compartment ratios within the 'Utah' phantom with radioactivity outside the field of view, with and without neuroshielding. Recovered ratios were within 6% of their actual values. The integration time was reduced in an effort to decrease the system deadtime. A peak increase of 150/0 in noise equivalent count rate was measured for a uniform cylinder inside the field of view. A random coincidence variance reduction technique was implemented and assessed to reduce the noise contained in the delayed window random coincidence estimate. The algorithm was evaluated using phantoms and tested on clinical data. A mean 16% reduction in coefficient of variation was measured for a C15O torso study.
39
Walsh, Norman J. "Bandwidth and signal-to-noise ratio enhancement of the NPS Transient Electromagnetic Scattering Laboratory." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/25710.
Full text
40
Mookherjea, Shayan 1977. "Optical distribution networks : signal-to-noise ratio optimization and distributed erbium-doped fiber amplifiers." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9087.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.<br>Includes bibliographical references (leaves [149]-151) and index.<br>Two important issues related to the use of remotely-pumped erbium-doped fiber amplifiers in optical distribution networks are analyzed. We investigate the optimal allocation of gain and loss among the stages of a lumped amplifier chain, using the concepts of a Nash solution and Pareto optimality. The propagation of optical channels along an erbium-doped fiber is derived from basic physical considerations, and compared with the well-known Desurvire model. We demonstrate a simple method of constructing bus distribution networks, but this approach is particularly sensitive to the numerical values of the parameters. A second approach is then discussed, extending the analysis of Sun et al. from ab-initio principles to model the effect of detectors (users) along a distribution network. Theoretical closed-form results indicate that the number of optical receivers that can be supported using this scheme is at least two orders of magnitude higher than without optical amplification. Finally, we analyze the effect of dynamic perturbations in the power that is extracted at the receivers. Though our focus is on bus networks, we also discuss tree distribution networks as extensions of the basic models. Our results have implications on the architecture of optical distribution networks.<br>by Shayan Mookherjea.<br>S.M.
41
Bokulic, Robert S. "SIGNAL-TO-NOISE RATIO PERFORMANCE OF THE SAWTOOTH PHASE DETECTOR WHEN DEMODULATING PM SUBCARRIERS." International Foundation for Telemetering, 1986. http://hdl.handle.net/10150/615560.
Full textAbstract:
International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, Nevada<br>The noise performance of the sawtooth phase detector when demodulating a sinusoidal subcarrier plus direct data modulation is studied. At predetection signal-to-noise ratio (SNR) levels of about 10 dB or more, significant improvements in the postdetection SNR of the subcarrier can be obtained using the sawtooth detector rather than a linear multiplier. Below predetection SNR levels of about 10 dB, significant improvements can still be obtained; however, a threshold occurs and the performance degrades until leveling off at 3.2 dB worse than that of a linear multiplier. The predetection SNR level where the sawtooth detector performance becomes worse than that of a linear multiplier depends upon the subcarrier and direct data modulation indices. Performance curves are given between predetection SNR levels of -20 dB and +20 dB for various values of subcarrier modulation index and direct data modulation index.
42
Chhabra, Saurbh. "An Analytical Tool for Calculating Co-Channel Interference in Satellite Links That Utilize Frequency Reuse." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/35122.
Full textAbstract:
This thesis presents the results of the development of a user-friendly computer code (in MATLAB) that can be used to calculate co-channel interferences, both in the downlink and in the uplink of a single satellite/space-based mobile communications system, due to the reuse of frequencies in spot beams or coverage cells. The analysis and computer code can be applied to any type of satellite or platform elevated at any height above earth. The cells or beams are defined in the angular domain, as measured from the satellite or the elevated platform, and cell centers are arranged in a hexagonal lattice. The calculation is only for a given instant of time for which the system parameters are input into the program.
The results obtained in one program run are for the overall carrier to interference ratio (CIR) along with CIR for both the uplink and downlink paths. An overall carrier to noise plus interference ratio (CNIR) is also calculated, which exemplifies the degradation in the carrier to noise ratio (CNR) of the system.
Comparisons for systems with differing system scenarios are also made. For example, overall CIRs are compared for different reuse numbers (3, 4, 7, and 13) in LEO and GEO satellite systems.
In conclusion, as expected, it is observed that the co-channel interference generally increases as we decrease the reuse number employed for the frequency reuse in the cells. It is also observed that co-channel interference can cause substantial degradation to the overall CNR of a system.<br>Master of Science
43
Zhu, Ying. "Signal detection on two-dimensional intersymbol interference channels correlated sources and reduced complexity algorithms /." [Pullman, Wash.] : Washington State University, 2008. http://www.dissertations.wsu.edu/Dissertations/Fall2008/y_zhu_081408.pdf.
Full textAbstract:
Thesis (Ph. D.)--Washington State University, December 2008.<br>Title from PDF title page (viewed on Sept. 23, 2008) "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 83-90).
44
Sciré, Scappuzzo Francesca. "Phase multipath estimation for global positioning system (GPS) using signal-to-noise-ratio (SNR) data." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/45487.
Full textAbstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997.<br>Includes bibliographical references (p. 83-87).<br>by Francesca Scrié Scappuzzo.<br>M.S.
45
Hassana, Ramesh Rakesh Kashyap. "Transform Domain Acquisition of Spread Spectrum Signals in a Low Signal to Noise Ratio Environment." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1289579500.
Full text
46
Leong-Hoï, Audrey. "Etude des techniques de super-résolution latérale en nanoscopie et développement d'un système interférométrique nano-3D." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAD048/document.
Full textAbstract:
Ce manuscrit de thèse présente l’étude des techniques de super-résolution latérale en nanoscopie optique, qui est une des nouvelles techniques d'imagerie haute résolution, aujourd'hui largement utilisée en biophysique et en imagerie médicale, pour imager et caractériser des nanostructures, tout en conservant les avantages de l'imagerie optique en champ lointain comme un vaste champ, la visualisation et l’analyse en temps réel…Un des défis futurs de la microscopie 3D super-résolue est d’éviter l’utilisation des marqueurs fluorescents. La microscopie interférométrique fait partie des techniques d’imagerie 3D sans marquage permettant la détection de nanostructures. Pour améliorer le pouvoir de détection de ce système optique, un premier protocole de traitement d’images a été développé et implémenté, permettant ainsi de révéler des structures initialement non mesurables. Puis, pour améliorer la résolution latérale du système, une nouvelle technique combinant l’interférométrie et le principe du nano-jet photonique a été développée permettant l’observation d’objets de taille inférieure à la limite de diffraction de l’instrument optique<br>This manuscript presents the study of the lateral super-resolution techniques in optical nanoscopy, which is a new high-resolution imaging method now widely used in biophysics and medical imaging, to observe and measure nanostructures, with the advantages of far field optical imaging, such as a large field of view, visualization and analysis in real time…One of the future challenges of 3D super resolution microscopy is to avoid the use of fluorescent markers. Interferometric microscopy is a 3D label-free imaging technique enabling the detection of nanostructures. To improve the detection capability of this optical system, a first version of a protocol composed of image processing methods was developed and implemented, revealing structures initially unmeasurable. Then, to improve the lateral resolution of the system, a new technique combining interferometry and the principle of the photonic nano-jet has been developed, thus allowing the observation of objects of a size smaller than the diffraction limit of the optical instrument
47
Tsoumanis, Andreas. "Performance analysis of the effect of pulsed-noise interference on WLAN signals transmitted over a Nakagami fading channel." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FTsoumanis.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering and M.S. in Systems Engineering)--Naval Postgraduate School, March 2004.<br>Thesis advisor(s): R. Clark Robertson. Includes bibliographical references (p. 67-68). Also available online.
48
Abdullah, Mohammad Faiz Liew. "Techniques for signal to noise ratio adaptation in infared optical wireless for optimisation of receiver performance." Thesis, University of Warwick, 2006. http://wrap.warwick.ac.uk/2450/.
Full textAbstract:
The challenge of creating a new environment of links for wireless infrared and optical local area networks (LANs) is driving new innovations in the design of optical transceivers. This thesis is concerned with a systematic approach to the design of receivers for indoor optical wireless communication. In particular, it is concerned with how to offer bandwidth adjustment capability in a receiver according to the dynamic service quality of the incoming signals. Another part of the discussion of the thesis is how one can properly choose the front-end preamplifier and biasing circuitry for the photodetector. Also, comparison is made between different types of amplifier, and the methods of bandwidth enhancement. The designs of six different techniques of integrating transimpedance amplifiers, with photodetectors to adapt an adjustable bandwidth control receiver are discussed. The proposed topologies provide an adjustable range of bandwidths for different frequency ranges, typically between 52Hz to 115MHz. The composite technique designs were used to incorporate into a system with an automatic gain control to study its effect, on an optical wireless receiver which had bandwidth adjustment and automatic gain adjustment. Theoretical analysis of noise performance for all the designed circuits is also presented. The theory and design of obstacles of indoor optical wireless receiver delivery, in addition to techniques for mitigating these effects, are discussed. This shows that infrared is a viable alternative to ratio for certain applications.
49
Watkins, Gregory Douglas. "Speech Intelligibility Prediction for Cochlear Implant Recipients: An investigation of the Output Signal to Noise Ratio." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/22909.
Full textAbstract:
Cochlear implants (CI) can achieve excellent hearing outcomes for people with severe or profound hearing loss. However, outcomes vary significantly, and hearing in noise is challenging. Evaluation of new sound processing ideas with recipient testing is a lengthy process. A metric which reliably predicted CI speech intelligibility would allow more sound processing ideas and parameter sets to be evaluated. Prediction for normal hearing people has been extensively investigated but CIs have received little attention. In this thesis, it was hypothesised that an extended Output Signal to Noise Ratio (OSNR) metric would be a reliable predictor of individual CI speech intelligibility. A series of retrospective CI experiments found i. OSNR was sensitive to changes in a range of test parameters, including Input Signal to Noise Ratio (ISNR), presentation level, noise type, and processing algorithms. ii. OSNR predicted mean speech scores for a group of recipients at least as accurately as other tested metrics. Being calculated at the sound processor output OSNR predicted scores in scenarios where other metrics could not. iii. A novel method, combining OSNR and test scores from a reference condition, predicted psychometric functions for individual CI recipients relatively accurately in many other conditions. Small differences in performance between test and reference conditions were accurately predicted. OSNR was not accurate in the presence of aggressive spectral masking. The feasibility of combining OSNR and Output Speech Power as an accurate predictor in this scenario was demonstrated. The author is not aware of any published works which predict psychometric functions for individual CI recipients listening to speech processed by novel algorithms, using scores from a separate, reference condition. Overall, there was considerable support for the hypothesis that OSNR was an accurate predictor. OSNR shows promise as a metric with research and clinical applications.
50
Constable, Christopher. "Investigation of the Effects of Image Signal-to-Noise Ratio on TSPO PET Quantification of Neuroinflammation." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/9341.
Full textAbstract:
Neuroinflammation may be imaged using positron emission tomography (PET) and the tracer [11C]-PK11195. Accurate and precise quantification of 18 kilodalton Translocator Protein (TSPO) binding parameters in the brain has proven difficult with this tracer, due to an unfavourable combination of low target concentration in tissue, low brain uptake of the tracer and relatively high non-specific binding, all of which leads to higher levels of relative image noise. To address these limitations, research into new radioligands for the TSPO, with higher brain uptake and lower non-specific binding relative to [11C]-PK11195, is being conducted world-wide. However, factors other than radioligand properties are known to influence signal-to-noise ratio in quantitative PET studies, including the scanner sensitivity, image reconstruction algorithms and data analysis methodology. The aim of this thesis was to investigate and validate computational tools for predicting image noise in dynamic TSPO PET studies, and to employ those tools to investigate the factors that affect image SNR and reliability of TSPO quantification in the human brain. The feasibility of performing multiple (n≥40) independent Monte Carlo simulations for each dynamic [11C]-PK11195 frame- with realistic modelling of the radioactivity source, attenuation and PET tomograph geometries- was investigated. A Beowulf-type high performance computer cluster, constructed from commodity components, was found to be well suited to this task. Timing tests on a single desktop computer system indicated that a computer cluster capable of simulating an hour-long dynamic [11C]-PK11195 PET scan, with 40 independent repeats, and with a total simulation time of less than 6 weeks, could be constructed for less than 10,000 Australian dollars. A computer cluster containing 44 computing cores was therefore assembled, and a peak simulation rate of 2.84x105 photon pairs per second was achieved using the GEANT4 Application for Tomographic Emission (GATE) Monte Carlo simulation software. A simulated PET tomograph was developed in GATE that closely modelled the performance characteristics of several real-world clinical PET systems in terms of spatial resolution, sensitivity, scatter fraction and counting rate performance. The simulated PET system was validated using adaptations of the National Electrical Manufacturers Association (NEMA) quality assurance procedures within GATE. Image noise in dynamic TSPO PET scans was estimated by performing n=40 independent Monte Carlo simulations of an hour-long [11C]-PK11195 scan, and of an hour- long dynamic scan for a hypothetical TSPO ligand with double the brain activity concentration of [11C]-PK11195. From these data an analytical noise model was developed that allowed image noise to be predicted for any combination of brain tissue activity concentration and scan duration. The noise model was validated for the purpose of determining the precision of kinetic parameter estimates for TSPO PET. An investigation was made into the effects of activity concentration in tissue, radionuclide half-life, injected dose and compartmental model complexity on the reproducibility of kinetic parameters. Injecting 555 MBq of carbon-11 labelled TSPO tracer produced similar binding parameter precision to 185 MBq of fluorine-18, and a moderate (20%) reduction in precision was observed for the reduced carbon-11 dose of 370 MBq. Results indicated that a factor of 2 increase in frame count level (relative to [11C]-PK11195, and due for example to higher ligand uptake, injected dose or absolute scanner sensitivity) is required to obtain reliable binding parameter estimates for small regions of interest when fitting a two-tissue compartment, four-parameter compartmental model. However, compartmental model complexity had a similarly large effect, with the reduction of model complexity from the two-tissue compartment, four-parameter to a one-tissue compartment, two-parameter model producing a 78% reduction in coefficient of variation of the binding parameter estimates at each tissue activity level and region size studied. In summary, this thesis describes the development and validation of Monte Carlo methods for estimating image noise in dynamic TSPO PET scans, and analytical methods for predicting relative image noise for a wide range of tissue activity concentration and acquisition durations. The findings of this research suggest that a broader consideration of the kinetic properties of novel TSPO radioligands, with a view to selection of ligands that are potentially amenable to analysis with a simple one-tissue compartment model, is at least as important as efforts directed towards reducing image noise, such as higher brain uptake, in the search for the next generation of TSPO PET tracers.