Dissertations / Theses on the topic 'Demodulation'
To see the other types of publications on this topic, follow the link: Demodulation.
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 'Demodulation.'
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
Laster, Jeffery D. "Robust GMSK Demodulation Using Demodulator Diversity and BER Estimation." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30618.
Full textAbstract:
This research investigates robust demodulation of Gaussian Minimum Shift Keying (GMSK) signals, using demodulator diversity and real-time bit-error-rate (BER) estimation. GMSK is particularly important because of its use in promi- nent wireless standards around the world (GSM, DECT, CDPD, DCS1800, and PCS1900). The dissertation begins with a literature review of GMSK demodu- lation techniques (coherent and noncoherent) and includes an overview of single- channel interference rejection techniques in digital wireless communications. Vari- ous forms of GMSK demodulation are simulated, including the limiter discrimina- tor and di erential demodulator (i.e., twenty-five variations in all). Ten represent new structures and variations. The demodulator performances are evaluated in realistic wireless environments, such as additive white Gaussian noise, co-channel interference, and multipath environments modeled by COST207 and SMRCIM. Certain demodulators are superior to others for particular channel impairments, so that no demodulator is necessarily the best in every channel impairment.
This research formally introduces the concept of demodulator diversity, a new idea which consists of a bank of demodulators which simultaneously demodulate the same signal and take advantage of the redundancy in the similar signals. The dissertation also proposes practical real-time BER estimation techniques which have tremendous ramifications for communications. Using Parzen's estimator for probability density functions (pdfs) and Gram-Charlier series approximation for pdfs, BER can be estimated using short observation intervals (10 to 500 training symbols) and, in some cases, without any training sequence. We also introduce new variations of Gram-Charlier estimation using robust estimators. BER (in place of MSE) can now drive adaptive signal processing. Using a cost function and gradient for Parzen's estimator (derived in this paper), BER estimation is applied to demodulator diversity with substantial gains of 1-10 dB in carrier- to-interference ratio over individual receivers in realistic channels (with adaptive selection and weighting). With such gains, a BER-based demodulator diversity scheme can allow the employment of a frequency reuse factor of N = 4, instead of N = 7, with no degradation in performance. A lower reuse factor means more channels are available in a cell, thus increasing overall capacity. The resulting techniques are simple and easily implemented at the mobile. BER estimation techniques can also be used in BER-based equalization and dynamic allocation of resources.Ph. D.
2
Ahmad, Jamil. "All digital OQPSK demodulation for an on-board processing multicarrier demodulator." Thesis, University of Surrey, 1992. http://epubs.surrey.ac.uk/843678/.
Full textAbstract:
New payload concepts of low cost earth stations for future mobile satellite communications can only be realised by using dedicated on-board processing satellites. The satellite uplink and downlink are optimised by the use of FDMA/SCPC for uplink and TDM on the down link. This scheme allows mobile transmitters to transmit a narrow band, low power signal, resulting in smaller dishes and HPAs with lower output power. On the uplink, there are hundreds of FDM channels to be demodulated on-board. The most promising approach is the use of all-digital multicarrier demodulators (MCDs), where analogue and digital hardware are efficiently shared amongst the channels and digital signal processing is used at an early stage to take advantage of VLSI technology. A MCD consists of a channeliser for separation of FDM channels followed by individual demodulators for each channel. The major research areas in MCD's are efficient implementation of channelisers and the optimal demodulation algorithms for the demodulator. This thesis is focused on the demodulator part of an MCD using OQPSK modulation which haye received attention recently due to its spectral advantages in non-linear mobile satellite channels. Most of the research carried out on the OQPSK modulation has been addressed to its spectral performance under satellite channel non-linearities, but little attention has been paid to efficient receiver designs. The most important requirements of the demodulator in a mobile environment is fast acquisition with minimum overhead. This over-head includes long preambles in data frames to aid the acquisition of the carrier and the symbol timing recovery loops. In this thesis, research on preambleless all-digital demodulators for OQPSK has been carried out. The performance of the most suitable OQPSK synchronisation algorithms have been evaluated using extensive computer simulations. These algorithms have been selected after a comprehensive survey of digital synchronisation techniques. It is shown how these algorithms are related to the maximum likelihood (ML) principle and these algorithms are classified according to their technique of parameter extraction from the likelihood function. The synchronisation problems associated with OQPSK are pointed out with possible solutions. On the basis of the performance results of individual synchronisers, various demodulation algorithms for OQPSK have been developed for fixed, mobile and deep space applications. The DSP implementation of the all- digital OQPSK demodulator developed for the MCD for mobile applications is described in detail and its performance compared with simulation results.
3
Erdem, Ozden. "Chaotic Demodulation Under Interference." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607690/index.pdf.
Full textAbstract:
Chaotically modulated signals are used in various engineering areas such as communication systems, signal processing applications, automatic control systems. Because chaotically modulated signal sequences are broadband and noise-like signals, they are used to carry binary signals especially in secure communication systems.
In this thesis, a target tracking problem under interference at chaotic communication systems is investigated. Simulating the chaotic communication system, noise-like signal sequences are generated to carry binary signals. These signal sequences are affected by Gaussian channel noise and interference while passing through the communication channel. At the receiver side, target tracking is performed using Optimum Decoding Based Smoothing Algorithm. The estimation performances of optimum decoding based smoothing algorithm at one dimensional chaotic systems and nonlinear chaotic algorithm map are presented and compared with the performance of the Extended Kalman Filter application.
4
Brooks, Paul. "Acousto-optic FM demodulation." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240983.
Full text
5
Wang, John Szeming. "Motion-compensated NTSC demodulation." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14513.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1989.Includes bibliographical references (p. 201-207).
by John Szeming Wang.
Ph.D.
6
Ozturk, Uygar. "Chaotic Digital Modulation And Demodulation." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606895/index.pdf.
Full textAbstract:
This thesis considers a communication system with chaotic modulation. Noise-like signals are generated by chaotic systems with different parameters to modulate binary digital signals. Demodulation is performed by both the Extended Kalman Filter (EKF) and Optimum Decoding Based Smoothing Algorithm (ODSA). Simulations are performed using both of these algorithms for different parameters affecting the performance of the communication system. Simulation results of these algorithms are compared.
7
Meisingseth, Andreas. "Demodulation Techniques in Gearbox Diagnostics." Thesis, Uppsala universitet, Signaler och System, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177275.
Full textAbstract:
This thesis covers the scope of one out of many ways to diagnose gearboxes, demodulating the excited vibrational signals to enhance fault detection and identification. The topic is not only of academic interest since the achievements that can be made by successful machine condition monitoring in the industry. It has a potential value that is close to be absurd, for example unplanned production stops is commonly known to be one of the worst nightmares for manufacturing companies and if one can detect faults in early stages one can improve the possibilityto plan a production stop and therefore increase the profit. Four demodulation algorithms were developed and implemented in MATLAB on data characterized by close to stationarity and distinctive energy centered around the harmonics of the gearmesh frequency. The resulting algorithms for narrowband phase and amplitude demodulation was shown to outperform Hilbert transform based phase and amplitude demodulation algorithms in gearbox diagnostics. One of the goals with the thesis was therefore reached; demodulation algorithms were developed and implemented on data. A comparison of these algorithms was done and a conclusion of which demodulation technique is superior was done. Experimental work was carried out on a test-rig and both local and distributed faults were introduced to two gearboxes, one kind of fault per gearbox. However, the data acquired from the test-rig showed severe non-stationarity and smeared spectrum properties even when angular resampling was performed and therefore a major drawback of the demodulation techniques was exploited since the methods for demodulation in this thesis are not applicable for signals with smeared spectrums. The other goal was therefore not accomplished; to distinguish a local fault from a distributed fault in data acquired by experimental work by applying the selected demodulation techniques.
8
Weikert, Oomke Einar. "Blinde Demodulation in MIMO-Übertragungssystemen." Berlin dissertation.de, 2007. http://www.dissertation.de/buch.php3?buch=5228.
Full text
9
Goh, J. G. "Advanced noncoherent demodulation and decoding." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599459.
Full textAbstract:
This dissertation is concerned with some advanced noncoherent communication techniques. In many practical cases, phase coherent communication is not desired or impractical due to its disadvantages of long acquisition time, data loss in phase estimation overhead, loss of lock associated with a phase estimation circuitry and high performance loss resulting from phase estimation error. The dissertation is divided into three main parts. In the first part, a new noncoherent detection scheme called the Noncoherent Viterbi algorithm (NVA) for constant amplitude signals is presented. In this algorithm, a complex path is derived for each state of the trellis, and the complex paths are then used to compute the path metrics. The algorithm is applied in Trellis-coded multilevel PSK and uncoded continuous phase modulation (CPM). It is shown analytically that the performance of NVA approaches that of the coherent detection, in a constant phase channel. A forgetting factor is introduced in order for the algorithm to dynamically track the channel. The bit error probabilities and lower bounds which are derived in terms of the forgetting factor provide an insight of the sensitivity of a scheme with respect to the channel phase noise. In the presence of random walk phase noise, the NVA is superior to the decision directed phase-locked loop (DDPLL). The second part of the dissertation presents the application of parallel concatenated codes with a recently discovered iterative decoding, namely 'Turbo-codes', to various types of binary noncoherent channels in AWGN as well as Rayleigh fading environments. The metrics of the binary noncoherent schemes are derived for the two popular iterative decoding algorithms: maximum a posteriori (MAP) algorithm and soft-output Viterbi algorithm (SOVA). Performance of iterative decoding in coherent and noncoherent detections are compared. As in the coherent channel, Turbo-codes converge well in the noncoherent channels investigated and outperform the conventional convolutional codes by a large margin. In the third part, the multiple-access capabilities of two types of noncoherent frequency-hopped code-division multiple-access channels have been studied and compared.
10
Griffin, Anthony. "Coding CPFSK for differential demodulation." Thesis, University of Canterbury. Electrical and Electronic Engineering, 2000. http://hdl.handle.net/10092/6031.
Full textAbstract:
A differential encoder is developed that preserves the phase trellis of continuous phase frequency shift keying (CPFSK) through differential demodulation. This differential encoder interfaces well with the decomposed model of CPFSK, creating a decomposed model of differentially-encoded and differentially-demodulated CPFSK (DCPFSK). The normalised minimum squared Euclidean distance d2min of uncoded DCPFSK is calculated. A code search model is developed, allowing codes over rings to be specifically designed for DCPFSK. The results of code searches show that there is very little loss in d2min when comparing coded DCPFSK systems with coherently-demodulated coded CPFSK systems. The performance of uncoded and coded DCPFSK systems in both additive white Gaussian noise (AWGN) and Rayleigh flat fading is analysed and simulated. DCPFSK is shown to be relatively robust to medium to slowly-varying fading, without the use of any additional techniques.
Rate-1/2 encoded quaternary DCPFSK with modulation index h = 1/4 is compared with coherently-demodulated uncoded MSK and differentially-encoded and differentially- demodulated minimum shift keying (DMSK) without error-control coding, in AWGN and Rayleigh flat fading. The coded system shows that significant performance improvement can be obtained through simple coding, particularly in Rayleigh flat fading.
11
Roberts, R. H., and George F. Tremain. "Recent Trends in PSK Demodulation." International Foundation for Telemetering, 1987. http://hdl.handle.net/10150/615264.
Full textAbstract:
International Telemetering Conference Proceedings / October 26-29, 1987 / Town and Country Hotel, San Diego, CaliforniaIncreased usage of PSK signals in TT&C formats has generated unique challenges for ground support equipment developers. DSI has met this challenge with the introduction of its model 7133 BPSK / QPSK modem. Enhanced on the Aerojet / USAF GS-14 program, the 7133 is the latest addition to the company's modem product line. The 7133 uses a dual mode cross arm Costas loop to demodulate BPSK or QPSK data. With an implementation loss averaging 0.8 dB, the 7133 demodulates asynchronous 2.56 MBps QPSK data. It also processes BPSK data at rates up to 2.56 MBps, with a loss of less than 0.5 dB. We present the 7133 demod design and test results. Current work at DSI extends the basic 7133 design to handle unbalanced QPSK formats. DSI's new model 7750 receiver-demodulator processes quadrature input signals either in pairs or independently. The 7750 uses phase locked loops to demodulate PSK, FM, PM or AM. We present the 7750 extended Costas loop design and preliminary test results. Finally, we look at applying recent DSP and NCO IC's to multi-mode TT&C demodulation.
12
Bishop, Daniel W. "GMSK Demodulation Methods and Comparisons." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1216081075.
Full text
13
Larkin, Kieran Gerard. "Topics in Multi dimensional Signal Demodulation." University of Sydney. Physics, 2001. http://hdl.handle.net/2123/367.
Full textAbstract:
Problems in the demodulation of one, two, and three-dimensional signals are investigated. In one-dimensional linear systems the analytic signal and the Hilbert transform are central to the understanding of both modulation and demodulation. However, it is shown that an efficient nonlinear algorithm exists which is not explicable purely in terms of an approximation to the Hilbert transform. The algorithm is applied to the problem of finding the envelope peak of a white light interferogram. The accuracy of peak location is then shown to compare favourably with conventional, but less efficient, techniques. In two dimensions (2-D) the intensity of a wavefield yields to a phase demodulation technique equivalent to direct phase retrieval. The special symmetry of a Helmholtz wavefield allows a unique inversion of an autocorrelation. More generally, a 2-D (non-Helmholtz) fringe pattern can be demodulated by an isotropic 2-D extension of the Hilbert transform that uses a spiral phase signum function. The range of validity of the new transform is established using the asymptotic method of stationary phase. Simulations of the algorithm confirm that deviations from the ideal occur where the fringe pattern curvature is larger than the fringe frequency. A new self-calibrating algorithm for arbitrary sequences of phase-shifted interferograms is developed using the aforementioned spiral phase transform. The algorithm is shown to work even with discontinuous fringe patterns, which are known to seriously hamper other methods. Initial simulations of the algorithm indicate an accuracy of 5 milliradians is achievable. Previously undocumented connections between the demodulation techniques are uncovered and discussed.
14
Larkin, Kieran Gerard. "Topics in Multi dimensional Signal Demodulation." Thesis, The University of Sydney, 2000. http://hdl.handle.net/2123/367.
Full textAbstract:
Problems in the demodulation of one, two, and three-dimensional signals are investigated. In one-dimensional linear systems the analytic signal and the Hilbert transform are central to the understanding of both modulation and demodulation. However, it is shown that an efficient nonlinear algorithm exists which is not explicable purely in terms of an approximation to the Hilbert transform. The algorithm is applied to the problem of finding the envelope peak of a white light interferogram. The accuracy of peak location is then shown to compare favourably with conventional, but less efficient, techniques. In two dimensions (2-D) the intensity of a wavefield yields to a phase demodulation technique equivalent to direct phase retrieval. The special symmetry of a Helmholtz wavefield allows a unique inversion of an autocorrelation. More generally, a 2-D (non-Helmholtz) fringe pattern can be demodulated by an isotropic 2-D extension of the Hilbert transform that uses a spiral phase signum function. The range of validity of the new transform is established using the asymptotic method of stationary phase. Simulations of the algorithm confirm that deviations from the ideal occur where the fringe pattern curvature is larger than the fringe frequency. A new self-calibrating algorithm for arbitrary sequences of phase-shifted interferograms is developed using the aforementioned spiral phase transform. The algorithm is shown to work even with discontinuous fringe patterns, which are known to seriously hamper other methods. Initial simulations of the algorithm indicate an accuracy of 5 milliradians is achievable. Previously undocumented connections between the demodulation techniques are uncovered and discussed.
15
Larkin, Kieran Gerard. "Topics in multi-dimensional signal demodulation." Connect to full text, 2000. http://hdl.handle.net/2123/367.
Full textAbstract:
Thesis (Ph. D.)--University of Sydney, 2000.Title from title screen (viewed Apr. 23, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Includes bibliography. Also available in print form.
16
Achelengwa, Edison M. "Emona-based interactive amplitude modulation/demodulation iLab." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66402.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 76-78).
The MIT iLab Project has developed online laboratories (iLabs) which are lab stations that can be accessed and controlled remotely over the Internet. With iLabs, students can conduct real experiments on real equipment over the Internet. With the introduction of the National Instrument's Educational Laboratory Virtual Instrument Suite, NI ELVIS, in the development of iLabs, students to gain a better understanding of engineering concepts by obtaining real data from electronic labs. One of such crucial engineering concepts is telecommunications which plays a key role in transmitting information between people, systems and computers. There are many telecommunication schemes which exist today. The iLab developed in this thesis implements an experiment for studying one of such schemes, Amplitude Modulation. The NI ELVIS is used together with a device called the Emona Digital and Analog Telecommunications Experimenter (DATEx) to achieve the Amplitude Modulation lab setup. This iLab is an Interactive iLab, which gives one student at a time complete, real-time control over the lab set up. The Amplitude Modulation iLab will permit students to tune various controls and observe the behavior and changes of relevant signals, both in time domain and frequency domain. It will also permit students to compare different signals and retrieve data locally for post processing.
by Edison M. Achelengwa.
M.Eng.
17
Strömberg, Erik. "Modulation and demodulation for radio based pricing." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199401.
Full text
18
Cronin, Christopher Joseph. "Digital frequency demodulation for a laser vibrometer." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-11102009-020344/.
Full text
19
Wu, Yik-chung, and 胡奕聰. "Demodulation and symbol timing recovery in software radio." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B2975785X.
Full text
20
Hicks, Matthew Graham. "Applications of acousto-optic demodulation and decoding techniques." Thesis, University of Plymouth, 1997. http://hdl.handle.net/10026.1/2563.
Full textAbstract:
This thesis describes the operation and performance of an acousto-optic demodulator system consisting of a laser source, an acousto-optic cell and a bi-cell detector. The bi-cell detector is made up of two photodiodes positioned side by side, separated by a small gap. Theory is developed to predict the following; the linear operating range for different gap sizes, absolute frequency sensitivity, system output in response to discrete phase changes, optimum gap size for phase demodulation, absolute descrete phase change sensitivity, the performance of the system in the presence of carrier noise and the effect of clipping the carrier signal on both frequency and phase modulated signals. A detailed model of the system has been written, using the software package Mathcad, which incorporates all the parameters that affect the performance of the physical system. The model has been used to study how the performance of the system changes as these parameters are varied. It is shown that the AO demodulator can be used in a number of ways; as a frequency demodulator, a phase demodulator and to demodulate digitally modulated signals, and that the optimum values of some parameters are different for each application. The model is also used to investigate the response of the system to a number of the most common forms of digital modulation. It is shown that it is possible, without any a priori knowledge of the signal, to identify each of these forms of modulation, and ultimately decode messages contained on the signals. The system can also be used to measure the frequency shift on pulse doppler radar. It is shown that the rms frequency error on a pulse using the AO demodulator is 150% better than that of existing systems. Experimental results are presented that are in good agreement with the results gained from both the theoretical and modelled analysis of the system. Finally suggestions are made for areas of further work on the signal processing of the output signals and possible uses of the demodulator in the future.
21
Brooks, Lane Gearle 1975. "Amplitude and frequency demodulation controller for MEMS accelerometer." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8938.
Full textAbstract:
Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 121-122).
Draper Laboratory is developing a high precision MEMS accelerometer. This thesis describes and analyzes the electronics which produce the acceleration estimate and control the actuators within the sensor. The Vector Readout method of amplitude and frequency demodulation is described and shown to be a high precision, environmentally stable method of demodulation. The Vector Readout method of demodulation uses a Hilbert Transform filter and the CORDIC algorithm to simultaneously estimate both the amplitude and phase of a signal. A feedback controller is designed to hold the oscillation of a mass resonator at a constant amplitude.
by Lane Gearle Brooks.
M.Eng.and S.B.
22
Black, Jacob A. "Neural Networks For Phase Demodulation In Optical Interferometry." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/93263.
Full textAbstract:
Neural Networks (NNs) (or 'deep' neural networks (DNNs)) have found great success in many applications across all fields of engineering, and in particular have found recent success in the field of Photonics. In this work we discuss the application of NNs to optical interferometry for the purpose of quantitative phase imaging (QPI). We show that NNs are capable of quantifying the optical pathlength difference in an interferogram with sensitivities that achieve the fundamental limit given by the Cramér-Rao bound (CRB). As an application, we consider a particular QPI technique known as wavelength shifting interferometry (WSI) which obtains the OPL by acquiring multiple interferograms at different, evenly spaced wavenumbers. Traditional phase demodulation algorithms for WSI fail to reach the theoretical OPL sensitivity limit set by the CRB. We have designed NNs which are capable of achieving this bound across a wide range of OPL differences. The NNs are trained on simulated data, and then applied to experimental data. In both simulation and experiment, the NNs outperform the existing analytical demodulation techniques and provide highly sensitive signal demodulation in cases where the analytical approach fails. Thus, NNs provide better performance and more flexibility in the design and use of a WSI system. We expect that the techniques developed in this work can be extended to other two-beam interference based QPI system.M.S.
Neural Networks (NNs) (or 'deep' neural networks (DNNs)) have found great success in many applications across all fields of engineering, and in particular have found recent success in the field of Photonics. In this work we discuss the application of NNs to making so-called 'phase' images of biological cells and tissues (e.g. red blood cells, sperm cells). This is necessary for many biological samples which are transparent under traditional bright field microscopy. We show that NNs are capable of quantifying the phase of these samples to produce images with higher contrast than possible in a typical microscope image. As an example, we introduce a particular phase microscopy system and study the application of NNs to this system. We show that the NNs are capable of providing solutions for this phase in situations where existing analytical techniques fail. The NNs are also capable of making more precise calculations of the phase than the traditional algorithms in many situations where either technique could be used. Therefore, NNs can provide simultaneously higher performance and more flexibility when designing phase microscopy systems.
23
Gdeisat, Munther Ahmad. "Fringe pattern demodulation using digital phase locked loops." Thesis, Liverpool John Moores University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521754.
Full text
24
Hägglund, Kristoffer. "Symmetric alpha-Stable Adapted Demodulation and Parameter Estimation." Thesis, Luleå tekniska universitet, Signaler och system, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70719.
Full textAbstract:
Transmission and reception of signals in wireless communication systems is affected by additive interference corrupting the signal. Traditionally, the interference is assumed to be AWGN and the system designs are usually based on that assumption. Modern military platforms consists of many electrical components and systems and as such the noise affecting the signals is often a product of interference between the components and systems. This type of noise tend to be very impulsive in nature. The standard AWGN model is not suited for impulsive noise which leaves an opportunity to investigate the performance of a demodulation scheme adapted to the current interference environment in order to increase the performance gain. To properly analyze the performance of an interference-adapted demodulator, knowledge about the characteristic parameters of the chosen noise model is required to perform the necessary calculations. This project combines the aspect of adaptive demodulation with parameter estimation evaluation. Four different parameter estimation techniques specifically customized for Symmetric alpha-Stable distributed noise were implemented and examined. The four methods were the Empirical Characteristic Function (ECF) method, Fractional Lower-Order Moments (FLOM) method, Extreme-Order Statistics (EOS) method as well as the Quantiles method. The effectiveness and performance of the methods were investigated in two Symmetric alpha-Stable processes of varying level of impulsiveness as well as two Class A processes in order to monitor the performance in noise not specifically distributed according to the intended model, functioning as an arbitrary representation of non-Gaussian interference. The results were evaluated using the measure of Kullback-Leibler Divergence. The demodulator was designed for Symmetric alpha-Stable distributed noise and implemented using an LLR-algorithm. The simulations were performed using an LDPC-coding protocol and the experiment was conducted in both Class A and Symmetric alpha-Stable distributed noise. The modulation schemes were 4-QAM and BPSK. The simulations showed that ECF was the most consistent parameter estimation method overall, regardless of distribution model or number of available samples. FLOM performed well in alpha-Stable noise but struggled in Class A processes. EOS and Quantiles shared the struggles of fewer available samples. The experiments show that an alpha-Stable adapted demodulator coupled with a parameter estimation technique based on the empirical characteristic function (ECF) is a very competitive and viable option in impulsive interference environments regardless of the origin of the noise distribution. The performance gain vis-a-vis demodulation using the standard AWGN option exceeded thresholds of upwards 25 dB for impulsive noise processes.
25
Young, Emily Clark. "GPU-Accelerated Demodulation for a Satellite Ground Station." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7635.
Full textAbstract:
One consequence of the increasing number of small satellite missions is an increasing demand for high data rate downlinks. As the satellites transmit at high data rates, ground-side receivers need to demodulate the transmitted data as quickly as possible. While application specific hardware can be designed, software defined radio solutions for ground stations are attractive for their flexibility, adaptability, and portability.
Another industry trend is the increasing use of Graphics Processing Units (GPUs) in general-purpose processing. By performing many operations simultaneously, GPUs are capable of accelerating processing when given a problem that can be implemented in a parallel manner. Furthermore, once a parallel algorithm is implemented, further speedups are possible by increasing hardware resources without need for any revision in the algorithm.
This project combines the above ideas by implementing a software defined radio algorithm to quickly demodulate high-speed data on a GPU. It demonstrates the viability of the GPU in software defined radio applications and particularly in the area of fast demodulation.
26
Booysen, Samuel. "The design of a high speed topology for a QPSK demodulator with emphasis on the synchronization algorithms needed for demodulation." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4107.
Full textAbstract:
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: This thesis describes the design and implementation of a software based QPSK demodulator with a demodulation speed of 100 Mbps. The objective of the thesis was to identify a topology for the QPSK demodulator that would allow for high data rates and the design of the synchronization algorithms for carrier and symbol recovery. The QPSK demodulator was implemented on an Altera Stratix II field programmable gate array (FPGA), which does complex I and Q sampling on a down converted 720 MHz QPSK signal. The I and Q down converted baseband signals are sent through matched filters which are implemented with discrete components to maximize the signal to noise ratio of the received rectangular baseband pulses. A 1 GSPS direct digital synthesizer (DDS) is used to generate the synchronous clock for the analog to digital converters which samples the matched filter outputs. The demodulator uses two samples per symbol to demodulate the QPSK signal. A dual locking system is implemented to have a wide pre-locking filter for symbol synchronization and a narrow band post-lock filter to minimize the loop noise. A symbol lock detection algorithm decides when the symbol recovery loop is locked and switches between the loop filters. A second 1 GSPS DDS output is mixed with a local oscillator to generate the 1.44 GHz LO signal for the quadrature down conversion. The carrier recovery loop uses a numerically controlled oscillator inside the FPGA for initial carrier acquisition which allows for very wide locking bandwidth. After lock is achieved, the external carrier recovery loop takes over and removes any frequency offset in the complex baseband signal by changing the frequency of the DDS. A QPSK modulator was also developed to provide a QPSK signal with known data. The modulator can generate any constellation diagram up to 256 points.
AFRIKAANSE OPSOMMING: Hierdie tesis bespreek die ontwerp en implementasie van ’n sagteware gebaseerde QPSK demodulator met ’n demodulasie spoed van 100 Mbps. Die doelstelling is om ’n topologie te identifiseer vir ’n QPSK demodulator wat ’n hoë datatempo sal toelaat en ook om sinkronisasie algoritmes te ontwikkel vir draer en simbool herkenning. Die QPSK demodulator is geïmplimenteer op ’n Stratix II FPGA van Altera wat kompleks basisband monstering doen op infase en kwadratuur basisband seine. Die basisband seine word gegenereer van ’n 720 MHz QPSK sein met ’n kwadratuur menger wiese uittrees deur puls passende filters gestuur word om die sein tot ruis verhouding te maksimeer. ’n Een gigamonster per sekonde direk digitale sintetiseerder (DDS) is gebruik om die klok vir die analoog na digitaal omsetters te genereer vir sinkrone monstering van die pulse passende filter uittrees. Die demodulator gebruik twee monsters per simbool om ’n QPSK sein te demoduleer. ’n Tweevoudige sluit algoritme word gebruik vir die simbool sinkronisasie waar ’n wyeband filter die inisiële sluit funksie verrig en dan word daar oorgeslaan na ’n nouband filter vir fase volging wat die ruis in die terugvoerlus verminder. Daar is ’n simbool sluit detektor wat identifiseer wanneer die simbool beheerlus gesluit is en selekteer dan die gepaste filter. ’n Tweede DDS en ’n sintetiseerder se uittrees word gemeng om ’n 1.44 GHz draer te genereer vir kohurente frekwensie translasie in die kwadratuur menger. Die draer sinkronisasie gebruik ’n numeries beheerbare ossilator vir die inisiële frekwensie en fase sluit wat baie vinnig geimplenteer kan word omdat dit alles in sagteware binne in die FPGA gebeur. Na die interne draer beheerlus gesluit is, neem die eksterne beheerlus oor om enige fase of frekwensie afsette in die kompleks basisband seine van die kwadratuur menger te verwyder deur die frekwensie van die draer DDS te beheer. ’n QPSK modulator is ook ontwikkel om verwysings data te genereer. Enige konstelasie vorm tot 256 punte kan geimplementeer word.
27
Meehan, Timothy J. "Joint demodulation of low-entropy narrow band cochannel signals." Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion.exe/06Dec%5FMeehan%5FPhD.pdf.
Full textAbstract:
Thesis (Ph.D. in Electrical Engineering)--Naval Postgraduate School, December 2006.Dissertation supervisor(s): Frank E. Kragh. "December 2006." Includes bibliographical references (p. 167-177). Also available in print.
28
Juntti, M. (Markku). "Multiuser demodulation for DS-CDMA systems in fading channels." Doctoral thesis, University of Oulu, 1997. http://urn.fi/urn:isbn:9514247558.
Full textAbstract:
Abstract
Multiuser demodulation algorithms for centralized receivers of asynchronous direct-sequence (DS) spread-spectrum code-division multiple-access (CDMA) systems in frequency-selective fading channels are studied. Both DS-CDMA systems with short (one symbol interval) and long (several symbol intervals) spreading sequences are considered.
Linear multiuser receivers process ideally the complete received data block. The approximation of ideal infinite memory-length (IIR) linear multiuser detectors by finite memory-length (FIR) detectors is studied. It is shown that the FIR detectors can be made near-far resistant under a given ratio between maximum and minimum received power of users by selecting an appropriate memory-length. Numerical examples demonstrate the fact that moderate memory-lengths of the FIR detectors are sufficient to achieve the performance of the ideal IIR detectors even under severe near-far conditions.
Multiuser demodulation in relatively fast fading channels is analyzed. The optimal maximum likelihood sequence detection receiver and suboptimal receivers are considered. The parallel interference cancellation (PIC) receiver is demonstrated to achieve better performance in known channels than the decorrelating receiver, but it is observed to be more sensitive to channel coefficient estimation errors than the decorrelator. At high channel loads the PIC receiver suffers from bit error rate (BER) saturation, whereas the decorrelating receiver does not. Choice of channel estimation filters is shown to be crucial if low BER is required. Data-aided channel estimation is shown to be more robust than decision-directed channel estimation, which may suffer from BER saturation caused by hang-ups at high signal-to-noise ratios.
Multiuser receivers for dynamic CDMA systems are studied. Algorithms for ideal linear detector computation are derived and their complexity is analyzed. The complexity of the linear detector computation is a cubic function of KL, where K and L are the number of users and multipath components, respectively. Iterative steepest descent, conjugate gradient, and preconditioned conjugate gradient algorithms are proposed to reduce the complexity. The computational requirements for one iteration are a quadratic function of KL. The iterative detectors are also shown to be applicable for parallel implementation. Simulation results demonstrate that a moderate number of iterations yields the performance of the corresponding ideal linear detectors. A quantitative analysis shows that the PIC receivers are significantly simpler to implement than the linear receivers and only moderately more complex than the conventional matched filter bank receiver.
29
Watson, Stephen M. "Frequency demodulation in the presence of multiplicative speckle noise." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246382.
Full text
30
BALAY, PASCAL. "Application des reseaux de neurones a la demodulation numerique." Rennes 1, 1995. http://www.theses.fr/1995REN10112.
Full textAbstract:
L'objet de cette these est l'application des reseaux de neurones aux communications numeriques et plus particulierement aux fonctions d'egalisation et de decodage de canal. L'utilisation de reseaux de neurones a permis d'aborder deux problemes non resolus tels que le decodage optimal d'un long code en bloc dans un temps raisonnable ou le traitement des non linearites lors d'une transmission par satellite. Un autre axe de recherche interessant est de coupler egalisation et decodage dans un seul reseau. Pour les simulations, l'essentiel des etudes concerne le perceptron multicouche car le modele de kohonen s'est avere moins performant. En decodage, on montre qu'un reseau de neurones permet de decoder les codes courts. Cependant, il n'a pas ete possible de mettre assez de relations entre les poids pour simplifier l'apprentissage des codes longs. La transmission par satellite genere des non linearites dues a l'amplificateur. Elles sont efficacement corrigees quand la structure du neurone est adaptee a la modulation employee. A partir de la sigmoide classique, on construit une fonction d'activation en escalier dont le nombre de niveaux depend de la constellation. Un procede d'initialisation du reseau permettant l'utilisation du perceptron en mode aveugle est egalement etudie. Les resultats sont degrades, mais approchent les performances des autres egaliseurs en mode adaptatif avec une meilleure resistance au bruit. Les resultats obtenus en egalisation pour la modulation quadrature partial response signaling montrent qu'un perceptron est capable d'egaliser et de decorreler les signaux en meme temps. On montre ainsi qu'il est possible de rassembler les deux operations (egalisation et decodage) dans un seul reseau. La derniere partie propose des solutions pour adapter la structure du perceptron a un probleme donne
31
Hoffmann, Lars. "Spektroskopische Instrumente zur Demodulation von Faser-Bragg-Gitter-Sensorsignalen." Aachen Shaker, 2008. http://d-nb.info/989550087/04.
Full text
32
Lin, Chun-Ching. "Demodulation of Narrowband Radio Frequency Signals by Aliasing Sampling." PDXScholar, 1996. https://pdxscholar.library.pdx.edu/open_access_etds/5286.
Full textAbstract:
The objective of this thesis is to study the demodulation of narrowband radio frequency signals by aliasing sampling in order to reduce the sampling rate. The spectrum can be recreated at the lower frequency position by aliasing sampling. However, if the sampling rate is deviated from the desired one, error will occur. The sensitivity to the frequency error of aliasing sampling is studied. One main reason of the deviation of the sampling rate is the frequency drifting of the local oscillator. Being able to compensate the oscillator drifting errors inexpensively, automatic frequency control (AFC) loops are important at receivers. Two major digital AFC algorithms are studied. One is the Phase method AFC, and the other is the Magnitude method AFC. Study indicates that both methods perform almost equally well. One adaptive AFC algorithm is also proposed. The scheme of the adaptive AFC algorithm is to use Upper-bound and Lower-bound techniques to squeeze the frequency errors. It is shown that the adaptive AFC algorithm can achieve up to 20 dB average signal-to-noise power ratio over the Magnitude method AFC under a noisy environment.
33
Chappell, Laurie. "Development of a tunable laser based Bragg grating demodulation system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0012/MQ34103.pdf.
Full text
34
Tönder, Nico. "Kanalschätzung, Demodulation und Kanalcodierung in einem FPGA-basierten OFDM-Funkübertragungssystem." Aachen Shaker, 2007. http://d-nb.info/98784976X/04.
Full text
35
Campbell, Heather A. (Heather Alyce). "Simulation of quadrature amplitude demodulation in a digital telemetry system." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38783.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 122-123).
by Heather A. Campbell.
M.Eng.
36
Ng, Wai-Hung, and Tony Leung. "INVESTIGATION OF CHIRP INTERFERENCE ON M-FSK DEMODULATION USING RAC." International Foundation for Telemetering, 1990. http://hdl.handle.net/10150/613764.
Full textAbstract:
International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, NevadaRecently, many satellite systems started to employ reflective-array compressor (RAC) to demodulate their M-FSK communication signals. Because the RAC’s time delay varies with the temperature, pilot-tones are usually introduced as the operational reference. In this paper, the basic chirp Fourier transform (CFT) is briefly reviewed. Then, investigation into possible pilot-tone interference caused by various chirp signals with RAC’s dispersive delay properties is presented and discussed.
37
Daqing, Huang. "Programming Code-Modulator and Demodulation-Decoder Suited to PCM Systems." International Foundation for Telemetering, 1989. http://hdl.handle.net/10150/614707.
Full textAbstract:
International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, CaliforniaIn order to suit the development of computer telemetry systems, we have developed the intelligent code-modulator and demodulation-decoder. In hardware, they consist of a monolithic processor and some high-integrated devices. Different code or decode ways and several subcarrier modulation or demodulation systems can be varied by carrying out corresponding software programs. In this paper, the equipments' hardware constructions and software cnarts and their main principles are presented.
38
Shi-Yan, Liu, and Yao-Jun. "The PPK Intelligent Demodulator." International Foundation for Telemetering, 1992. http://hdl.handle.net/10150/608923.
Full textAbstract:
International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, CaliforniaThis paper introduces a PPK intelligent demodulator used in the PCM--PPK (pulse position keying) telemetry system. It describes the basic requirement of the system for the PPK signal demodulator and analyses the insufficiancy of the full-hardware PPK demodulator. It also advances a PPK demodulating scheme based on the TMS32020 digital signal processor and a block diagram of the demodulator, states the method of detecting frame synchronization, analyses the precision of sync-building and gives the way of calculating the miss and error probability of frame sync. The result makes it clear that the demodulator based on TMS32020 has programmable feature for the bit rate and frame synchronization and realizes easily the system demand of the separate demodulating of output signals of the multi-channel receiver and then the synthesis processing of the realtime data.
39
Dahlhaus, Dirk Dahlhaus Dirk Dahlhaus Dirk. "Gemeinsame Demodulation in CDMA-Mobilfunksystemen unter Ausnutzung von Raum- und Zeitdiversität /." Zürich, 1998. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=12698.
Full text
40
Balzer, Dirk. "Online-Demodulation stark gestörter winkelmodulierter Signale mit dem Extended-Kalman-Filter." [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=958729964.
Full text
41
Garcia, Peña Axel Javier. "Optimization of demodulation performance of the GPS and GALILEO navigation messages." Phd thesis, Toulouse, INPT, 2010. http://oatao.univ-toulouse.fr/12022/1/garcia_pena_partie_1_sur_2.pdf.
Full textAbstract:
The demodulation performance achieved by any of the existing GPS signals, L1 C/A, L2C or L5, is satisfactory in open environments where the available C/N0 is quite high. However, in indoor/urban environments, the C/N0 level of the received signal is often very low and suffers fast variations which can further affect the GNSS messages demodulation. Therefore, since the mass-market applications being designed nowadays are aimed at these environments, it is necessary to study and to search alternative demodulation/decoding methods which improve the GNSS messages demodulation performance in these environments. Moreover, new GNSS signals recently developed, such as GPS L1C and GALILEO E1, must also be considered. These signals aim at providing satellite navigation positioning service in any kind of environment, giving special attention to indoor and urban environments. Therefore, the demodulation performances of the new GNSS signals as they are defined in the current public documents is also analysed. Moreover, new GALILEO E1 message structures are proposed and analysed in order to optimize the demodulation performance as well as the quantity of broadcasted information. Therefore, the main goal of this dissertation is to analyse and to improve the demodulation performance of the current open GNSS signals, specifically in indoor and urban environments, and to propose new navigation message structures for GALILEO E1. A detailed structure of this dissertation sections is given next. First, the subject of this thesis is introduced, original contributions are highlighted, and the outline of the report is presented. Second, this dissertation begins by a description of the current structure of the different analysed GNSS signals, paying special attention to the navigation message structure, implemented channel code and their decoding techniques. In the third section, two types of transmission channel models are presented for two different types of environments. On one hand, an AWGN channel is used to model the signal transmission in an open environments. On the other hand, the choice of a specific mobile channel, the Perez-Fontan channel model, is chosen to model the signal transmission in an urban environment. In the fourth section, a tentative to make a binary prediction of the broadcasted satellite ephemeris of the GPS L1 C/A navigation message is presented. The prediction is attempted using the GPS L1 C/A almanacs data, a long term orbital prediction program provided by TAS-F, and some signal processing methods: spectral estimation, the PRONY method, and a neural network. In the fifth section, improvements to the GPS L2C and GPS L5 navigation message demodulation performance are brought by using their channel codes in a non-traditional way. Two methods are inspected. The first method consists in sharing information between the message inner and outer channel codes in order to correct more received words. The second method consists in using the ephemeris data probabilities in order to improve the traditional Viterbi decoding. In the sixth section, the GPS L1C and GALILEO E1 Open Service demodulation performance is analysed in different environments. First, a brief study of the structure of both signals to determine the received C/N0 in an AWGN channel is presented. Second, their demodulation performance is analysed through simulations in different environments, with different receiver speeds and signal carrier phase estimation techniques.
42
Hoffmann, Lars [Verfasser]. "Spektroskopische Instrumente zur Demodulation von Faser-Bragg-Gitter-Sensorsignalen / Lars Hoffmann." Aachen : Shaker, 2008. http://d-nb.info/1162791950/34.
Full text
43
Xingwen, Ding, Zhong Yumin, Chang Hongyu, and Chen Ming. "Noncoherent Demodulation with Viterbi Decoding for Partial Response Continuous Phase Modulation." International Foundation for Telemetering, 2013. http://hdl.handle.net/10150/579651.
Full textAbstract:
ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NVWith the characteristics of constant envelope and continuous phase, Continuous Phase Modulation (CPM) signal has higher spectrum efficiency and power efficiency than other modulation forms. A noncoherent demodulation with Viterbi decoding for partial response CPM signals is proposed. Simulation results indicate that the demodulation performance of proper partial response CPM is better than the traditional PCM-FM, which is a typical modulation of full response CPM. And higher spectral efficiency is also obtained by partial response CPM.
44
Krause, Lloyd O., Carlos Reyes-Nieves, and Ivor Frazier. "DPSK MODULATION AND DEMODULATION USING BULK ACOUSTIC WAVE (BAW) DELAY ELEMENTS." International Foundation for Telemetering, 1986. http://hdl.handle.net/10150/615573.
Full textAbstract:
International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, NevadaDPSK modulation and demodulation are usually based on logical selection of the difference phase before modulation and the recovery sum phase after detection. Here, we describe an analogue procedure done directly on the PSK’d I-F. BAW delay elements are used in arrangements of feed-forward for difference modulation and of feedback for demodulation. Characteristics are described, and results of laboratory implementation tests for data rate and carrier frequency variations are given. An I-F of 60 MHz and a bit rate of 200 kHz were used as nominal values. Robust performance is indicated.
45
Ahmed, Yasir. "A Model-Based Approach to Demodulation of Co-Channel MSK Signals." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/36265.
Full textAbstract:
Co-channel interference limits the capacity of cellular systems, reduces the throughput of
wireless local area networks, and is the major hurdle in deployment of high altitude communication platforms. It is also a problem for systems operating in unlicensed bands such as the 2.4 GHz ISM band and for narrowband systems that have been overlaid with spread spectrum systems.
In this work we have developed model-based techniques for the demodulation of co-channel
MSK signals. It is shown that MSK signals can be written in the linear model form, hence a minimum variance unbiased (MVU) estimator exists that satisfies the Cramer-Rao lower bound (CRLB) with equality. This framework allows us to derive the
best estimators for a single-user and a two-user case. These concepts can also be extended to wideband signals and it is shown that the MVU estimator for Direct Sequence Spread Spectrum signals is in fact a decorrelator-based multiuser detector.
However, this simple linear representation does not always exist for continuous phase modulations. Furthermore, these linear estimators require perfect channel state information and phase synchronization at the receiver, which is not always implemented in wireless communication systems. To overcome these shortcomings of the linear estimation techniques, we employed an autoregressive modeling approach. It is well
known that the AR model can accurately represent peaks in the spectrum and therefore can be used as a general FM demodulator. It does not require knowledge of the exact signal model or phase synchronization at the receiver. Since it is a non-coherent reception technique, its performance is compared to that of the limiter discriminator. Simulation results have shown that model-based demodulators can give significant gains for certain phase and frequency offsets between the desired signal and an interferer.Master of Science
46
Xiros, Nikolaos I. DEng. "Exact Feedback Linearization of Systems with State-Space Modulation and Demodulation." ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2657.
Full textAbstract:
The control theory of nonlinear systems has been receiving increasing attention in recent years, both for its technical importance as well as for its impact in various fields of application. In several key areas, such as aerospace, chemical and petrochemical industries, bioengineering, and robotics, a new practical application for this tool appears every day. System nonlinearity is characterized when at least one component or subsystem is nonlinear. Classical methods used in the study of linear systems, particularly superposition, are not usually applied to the nonlinear systems. It is necessary to use other methods to study the control of these systems. For a wide class of nonlinear systems, a rather important structural feature comes from the strong nonlinearity appearing as coupling between spectrally decoupled parts of the system. Even in the case of low frequencies, where lumped models can still be employed the nonlinear coupling between parts of the system requires specific treatment, using advanced mathematical tools. In this context, an alternative, frequency domain approach is pursued here. In the rest of this work, a specific system form of linearly decoupled but nonlinearly coupled subsystems is examined. The mathematical toolbox of the Hilbert transform is appropriately introduced for obtaining two low-pass subsystems that form an equivalent description of the essential overall system dynamics. The nonlinear coupled dynamics is investigated systematically by partitioning the coupled system state vector in such a way as to fully exploit the low-pass and the band-pass intrinsic features of free dynamics. In particular, by employing the Hilbert Transform, a low-pass equivalent system is derived. Then, a typical case is investigated thoroughly by means of numerical simulation of the original coupled low and band-pass, real-state-variable system and the low-pass-equivalent, complex-state-variable derived one. The nonlinear model equations considered here pave the way for a systematic investigation of nonlinear feedback control options designed to operate mechatronic transducers in energy harvesting, sensing or actuation modes.
47
Lane, William D. "Spread spectrum multi-h modulation." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/16944.
Full text
48
Osborne, William P., Don Whiteman, and Sharmin Ara. "ON THE PERFORMANCE OF PCM/FM+ FM/FM SYSTEMS." International Foundation for Telemetering, 1993. http://hdl.handle.net/10150/608872.
Full textAbstract:
International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, NevadaMuch modem telemetry is transmitted in a digital format and to be compatible with existing range equipment the digital data is impressed on the carrier using FM modulation. The receiving system in common use employs an FM limiter/discriminator as a detector followed by an integrate and dump matched filter for bit detection. This system has been studied by previous authors [1] and it is well known that in the absence of frequency uncertainty the optimum transmission parameters consist of a modulation index of .7 (peak-to-peak deviation divided by the bit rate) and an IF filter bandwidth equal to the bit rate followed by a limiter discriminator. In many cases, there is a need for some small amount of analog telemetry transmission in addition to the digital data discussed above. In these cases it is common practice to include analog subcarriers on the main carrier with the digital data modulating the carrier at baseband, the resulting system is called PCM/FM + FM/FM. These hybrid analog/digital systems are the subject of this paper. In particular this paper addresses the performance of these systems through simulation using the Block Oriented System Simulator (BOSS) from Comdisco and with analytical techniques to obtain the BER versus SNR curves for these systems. The simulation is used over a wide range of parameters to find the optimum values of modulation index and IF bandwidth for these systems.
49
Jarosch, Andreas W. S. "Verfahren zur robusten Demodulation in der Abwärtsstrecke von UMTS mit breitbandigem Codevielfachzugriff /." Zürich, 2001. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14078.
Full text
50
Taylor, Douglas. "Advanced demodulation techniques for digital audio broadcast signals over fast fading channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/MQ48185.pdf.
Full text