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1
Erdem, Erem. "Digital Modulation Recognition." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611281/index.pdf.
Повний текст джерелаАнотація:
In this thesis work, automatic recognition algorithms for digital modulated signals are surveyed.
Feature extraction and classification algorithm stages are the main parts of a modulation recognition system. Performance of the modulation recognition system mainly depends on the prior knowledge of some of the signal parameters, selection of the key features and classification algorithm selection.
Unfortunately, most of the features require some of the signal parameters such as carrier frequency, pulse shape, time of arrival, initial phase, symbol rate, signal to noise ratio, to be known or to be extracted. Thus, in this thesis, features which do not require prior knowledge of the signal parameters, such as the number of the peaks in the envelope histogram and the locations of these peaks, the number of peaks in the frequency histogram, higher order moments of the signal are considered. Particularly, symbol rate and signal to noise ratio estimation methods are surveyed. A method based on the cyclostationarity analysis is used for symbol rate estimation and a method based on the eigenvector decomposition is used for the estimation of signal to noise ratio. Also, estimated signal to noise ratio is used to improve the performance of the classification algorithm.
Two methods are proposed for modulation recognition:
1) Decision tree based method
2) Bayesian based classification method
A method to estimate the symbol rate and carrier frequency offset of minimum-shift keying (MSK) signal is also investigated.
2
Ozturk, Uygar. "Chaotic Digital Modulation And Demodulation." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606895/index.pdf.
Повний текст джерелаАнотація:
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.
3
Shankar, Udaya. "Implementation of digital modulation techniques using direct digital synthesis." Master's thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03302010-020333/.
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4
Kempson, C. N. "Statistical techniques for digital modulation recognition." Thesis, Cranfield University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277938.
Повний текст джерелаАнотація:
Automatic modulation recognition is an important part of communications electronic monitoring and surveillance systems where it is used for signal sorting and receiver switching. ' This thesis introduces a novel application of multivariate statistical techniques to the problem of automatic modulation classification. The classification technique uses modulation features derived from time-domain parameters of instantaneous signal envelope, frequency and phase. Principal component analysis (PCA) is employed for data reduction and multivariate analysis of variance (MANOVA) is used to investigate the data and to construct a discriminant function to enable the classification of modulation type. MANOVA is shown to offer advantages over the techniques already used for modulation recognition, even when simple features are used. The technique is used to construct a universal discriminator which is independent of the unknown signal to noise ratio (SNR) of the received signal. The universal discriminator is shown to extend the range of signal-to-noise ratios (SNRs) over which discrimination is possible, being effective over an SNR range of 0-4OdB. Development of discriminant functions using MANOVA is shown to be an extensible technique, capable of application to more complex problems. i
5
Ramakonar, Visalakshi S. "Modulation classification of digital communication signals." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2002. https://ro.ecu.edu.au/theses/752.
Повний текст джерелаАнотація:
Modulation classification of digital communications signals plays an important role in both military and civilian sectors. It has the potential of replacing several receivers with one universal receiver. An automatic modulation classifier can be defined as a system that automatically identifies the modulation type of the received signal given that the signal exists and its parameters lie in a known range. This thesis addresses the need for a universal modulation classifier capable of classifying a comprehensive list of digital modulation schemes. Two classification approaches are presented: a decision-theoretic (DT) approach and a neural network (NN) approach. First classifiers are introduced that can classify ASK, PSK, and FSK signals. A decision tree is designed for the DT approach and a NN structure is formulated und trained to classify these signals. Both classifiers use the same key features derived from the intercepted signal. These features are based on the instantaneous amplitude, instantaneous phase, and instantaneous frequency of the intercepted signal, and the cumulates of its complex envelope. Threshold values for the DT approach are found from the minimum total error probabilities of the extracted key features at SNR of 20 to -5dB. The NN parameters are found by training the networks on the same data. The DT and NN classifiers are expanded to include CPM signals. Signals within the CPM class are also added to the classifiers and a separate decision tree and new NN structure are found far these signals. New key features to classify these signals are also introduced. The classifiers are then expanded further to include multiple access signals, followed by QAM, PSK8 and FSK8 signals. New features arc found to classify these signals. The final decision tree is able to accommodate a total of fifteen different modulation types. The NN structure is designed in a hierarchical fashion to optimise the classification performance of these fifteen digital modulation schemes. Both DT and NN classifiers are able to classify signals with more than 90% accuracy in the presence of additive white Gaussian within SNR ranging from 20 to 5dB. However, the performance of the NN classifier appears to be more robust as it degrades gradually at the SNRs of 0 and -5dB. At -5dB, the NN has an overall accuracy of 73.58%, whereas the DT classifier achieves only 47.3% accuracy. The overall accuracy of the NN classifier, over the combined SNR range of 20 to -5dB, is 90.7% compared to 84.56% for the DT classifier. Finally, the performances of these classifiers are tested in the presence of Rayleigh fading. The DT and NN classifier structures are modified to accommodate fading and again, new key features are introduced to accomplish this. With the modifications, the overall accuracy of the NN classifier, over the combined SNR range of 20 to -5dB and 120Hz Doppler shift, is 87.34% compared to 80.52% for the DT classifier.
6
Arani, Faramarz Shayan. "Trellis coded modulation techniques." Thesis, University of Warwick, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387324.
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7
Doerr, Michael B., William H. Jr Hallidy, Gary B. McMillian, Lawrence W. Jr Burke, and Jonah N. Faust. "Digital FDM for the HSTSS DAC Program." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608712.
Повний текст джерелаАнотація:
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>This paper presents the design of an innovative approach to Frequency Division Multiplexing (FDM) for the STRICOM Hardened Subminiature Telemetry and Sensor System (HSTSS) Data Acquisition Chipset (DAC) program. An ASIC (Application Specific Integrated Circuit) is being developed by Systems & Processes Engineering Corporation (SPEC) that implements this new digital FDM approach for telemetry applications. The FDM ASIC provides six channels that are IRIG-106 compatible, and may be used in conjunction with a Delay/Repeater ASIC. Together these ASICs make a complete instrumentation system for those applications requiring very small size, simplicity of use, and low cost, e.g. munitions/armament testing.
8
Han, Yu. "Optimization of Modulation Constrained Digital Transmission Systems." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37097.
Повний текст джерелаАнотація:
The regular waterfilling(WF) policy maximizes the mutual information of parallel channels, when the inputs are Gaussian. However, Gaussian input is ideal, which does not exist in reality. Discrete constellations are usually used instead, such as $ M $-PAM and $ M $-QAM. As a result, the mercury/waterfilling (MWF) policy is introduced, which is a generalization of the regular WF. The MWF applies to inputs with arbitrary distributions, while the regular WF only applies to Gaussian inputs. The MWF-based optimal power allocation (OPA) is presented, for which an algorithm called the internal/external bisection method is introduced.
The constellation-constrained capacity is discussed in the thesis, where explicit expressions are presented. The expression contains an integral, which does not have a closed-form solution. However, it can be evaluated via the Monte Carlo method. An approximation of the constellation-constrained capacity based on the sphere packing method is introduced, whose OPA is a convex optimization problem. The CVX was used initially, but it did not generate satisfactory results. Therefore, the bisection method is used instead.
Capacities of the MWF and its sphere packing approximation are evaluated for various cases, and compared with each other. It turns out the sphere packing approximation has similar performances to the MWF, which validates the approximation. Unlike the MWF, the sphere packing approximation does not suffer from the loss of precision due to the structure of MMSE functions, which demonstrates its robustness.
9
Sandberg, Sara. "Modulation and channel effects in digital communication /." Luleå : Luleå University of Technology, 2005. http://epubl.luth.se/1402-1757/2005/49.
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10
Wong, Dennis Mou Ling. "Automatic classification of digital communication modulation schemes." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400128.
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11
Phillips, Andrew Julian. "Optically amplified digital pulse position modulation systems." Thesis, Manchester Metropolitan University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260069.
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12
Harrold, William. "Detection of continuous phase modulation." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235856.
Повний текст джерелаАнотація:
The use of coded modulations such as continuous phase modulation (CPM) can improve the power and bandwidth efficiency of digital communication links. The price paid for these gains is in increased receiver complexity. The power efficiency attainable with the highly redundant signal sets employed by coded modulations becomes limited by the ability of the receiver to achieve accurate carrier phase synchronisation. Power efficiency is assessed in terms of the bit error rate performance in white Gaussian noise. A new CPM detector called the partially coherent Viterbi algorithm (PCVA) is introduced which tries to preserve the power efficiency in the presence of mild phase perturbations. The detector employs the Viterbi algorithm with a new partially coherent decision metric. Carrier phase estimates are derived dynamically from the detector's own survivor paths. In the presence of phase jitter, the PCVA is superior to a Viterbi decision directed phase locked loop. The PCVA could be applied to the detection of modulation schemes other than CPM. An error analysis of the PCVA in the absence of phase jitter provides a new and more realistic way of assessing the relative merits of various CPM schemes. Unmerged error events have been found to occur when CPM is detected with carrier phase uncertainty. The carrier phase estimator pulls in the residual phase error in such cases. A reduced state Viterbi algorithm has been examined when using the partially coherent decision metric. Receiver complexity reduction is still possible even when the detector is not coherent. A method of acquiring the carrier frequency accurately from the received CPM signal is described. The other main research goal has been the development of a new low signal-to-noise ratio (SNR) error probability analysis for coherently detected CPM. CPM is designed for use on power limited channels, but the existing error probability analysis is only accurate at high SNR. The problem at low SNR is that several error events become significant, not just the one at minimum squared Euclidean distance. The new analysis considers many events and makes statistical allowance for their pairwise interaction. The probability of events intersecting and reclosing each other has not been analysed before. This work applies to maximum likelihood sequence detection on a memoryless channel in general. A new survey of CPM error performance is made and proves the existing minimum distance results to be often optimistic especially at low and intermediate signal-to-noise ratios. The new approximation is closer to the simulated error rates where these are available. The coherent error analysis involves some computation but it is still approximately three orders of magnitude faster than simulation.
13
Dong, Adam Xuesi Carleton University Dissertation Engineering Electrical. "Incorporation of digital angle-modulation into a fractional division synthesizer." Ottawa, 1992.
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14
Webb, William. "QAM techniques for digital mobile radio." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385448.
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15
Grewal, Sukhminder Singh. "Digital signal processor implementation of novel PWM strategies." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246284.
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16
Hatzichristos, George. "Classification of digital modulation types in multipath environments." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA390810.
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17
Okman, Osman Erman. "Quantization Index Modulation Based Watermarking Using Digital Holography." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607506/index.pdf.
Повний текст джерелаАнотація:
The multimedia watermarking techniques are evolved very quickly in the last years with the increase in the use of internet. The evolution of the internet makes the copyright issues very important and many different approaches are appeared to protect the digital content. On the other hand, holography is the method to store the 3-D information of an object but it is very applicable to use as a watermark because of the nature of the holographic data. The 3-D object can be reconstructed from the hologram even if the hologram is cropped or occluded. However, watermarking of an image with a hologram is a very novel approach and there are only a few works in the literature which are not very robust against the attacks like filtering or compression. In this thesis, we propose to embed the phase of the hologram to an image using quantization index modulation (QIM). QIM is utilized to make the watermarking scheme blind and degrade the host image as low as possible. The robustness of the proposed technique is also tested against several attacks such as filtering, compression, etc. The evaluated performance of this system is compared with the existing methods in the literature which uses either holograms or logos as the secret mark. Furthermore, the characteristics of the holograms are investigated and the findings about the hologram compression are reported in this work.
18
Jantzi, Stephen A. "Quadrature bandpass delta-sigma modulation for digital radio." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27669.pdf.
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19
Bax, Walter T. "Modulation and frequency synthesis for wireless digital radio." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/NQ48341.pdf.
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20
Hashimi, Seyed Bahauddin. "Coded modulation techniques for digital mobile communication systems." Thesis, Staffordshire University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321787.
Повний текст джерела
21
Kaluarachchi, Eraj Dulip. "Digital pulse interval modulation for optical communication systems." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/9101/.
Повний текст джерелаАнотація:
Pulse time modulation (PTM) techniques have drawn considerable attention over the years as suitable schemes for transmission of information over optical fibres. PTM schemes are known to utilise the vast optical bandwidth to provide efficient transmission characteristics. Pulse code modulation is one such modulation scheme that has been used widely in various communication systems. In this thesis digital pulse interval modulation (DPIM), a form of PTM, is proposed as a suitable modulation scheme for optical communication systems. In this scheme the information is represented by means of varying the anisochronous frame interval between two successive pulses. Each pulse fulfils the dual role of representing the frame boundaries and initiation of the next sampling event within the modulator or sample reconstruction in the demodulator. In this study DPIM frame structure is proposed and sampling criteria, information capacity, bandwidth requirements are discussed in depth. The spectral behaviour of the scheme is investigated and a mathematical model is developed to represent the spectra. The model was numerically evaluated and verified with the practical measurements to prove its validity. Spectral predictions were made for random as well as periodic information signals showing the existence of the distinct slot frequency component, which is used for slot synchronisation. Frame synchronisation is not required as DPIM has self synchronised frame structure. For random signals, slot component is found to be about 15 dB and for periodic single tone sinusoidal signal this was at about 5 dB. Dependency of this component on the various system parameters such as bit resolution, pulse width, pulse shape are discussed. A detailed account of the receiver performance is given. Receiver analysis was carried out for narrow band as well as for wide band channels. Possible error sources are presented and the system performance degradation with these error sources is discussed and a comparison is made with isochronous DPPM and PCM. For performance evaluation of analogue systems, signal-to-noise ratio was mathematically modelled and compared with PCM. This analysis showed that DPIM SNRs shows three important regions as compared to PCM. That is when the SNR is inferior, superior and identical to PCM performance. Threshold levels corresponding to the above regions vary depending on the system bit resolution. A prototype DPIM system was designed and implemented to transmit low speed analogue signal (≈15 kHz) at bit resolutions of 4, 5 and 6 where the slot frequencies are at 510, 990 and 1950 kHz, respectively. Measurements were carried out in order to verify the predicted performance. This results showed close agreement with the predicted. Receiver sensitivity of the prototype at bit error rate of 10<sup>-9</sup> was found to be about -45.5 dBm at all three cases with transmitted average power of -28.8 dBm allowing high optical power budget. The signal-to-noise ratio threshold level of the system was at -47 dBm. Finally, linearity measurements of the overall system were made at the above bit resolutions and the quantitative and qualitative results are presented.
22
Cryan, Robert Anthony. "High sensitivity optical digital pulse position modulation systems." Thesis, University of Huddersfield, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306086.
Повний текст джерелаАнотація:
Digital pulse position modulation (PPM) is a transmission format that can be used to exchange excess channel bandwidth for improved receiver sensitivity. This thesis is concerned with the performance of digital PPM for use in optical fibre systems such that increased single-span transmission distances can be achieved. It includes a literature survey and a thorough theoretical investigation into uncoded directly detected and coherently detected digital PPM, along with an evaluation of forward error correction coded PPM. Original contributions are described for digital PPM systems employing PIN-BJT transimpedance and PIN -FET high impedance pre-amplifiers. In the PIN -BJT case, a new analysis is presented that accounts for the band-limiting effect of the preamplifier and the non-white noise power spectral density, resulting from equalisation. For the PIN-FET, a causal noise-whitening filter is considered and the factors that limit the maximum bit-rate determined. By using an upper Chernoff Bound to the average binary error probability, results are calculated for APD-BJT and APD-FET PPM systems. The practical implementation of the optimal PPM filter is considered and two novel techniques are described for automating the realisation process. Coherent PPM is investigated and new work is presented for Reed-Solomon coded homodyne PPM. The influence of the Reed-Solomon code rate on receiver sensitivity is studied and it is shown that a 3/4 code rate leads to optimum sensitivity. Digital PPM employing soliton pulses is examined and it is shown that, under ideal conditions, a higher bit-rate than PCM can be achieved. The influence of timing jitter, associated with soliton pulse energy fluctuations and the Gordon-Haus effect, on the performance of digital PPM is investigated. The simplification of the PPM pre-detection filter is studied and a range of suboptimum filters investigated. The calculations demonstrate that the optimal predetection filter can be replaced by a simple 3rd order filter without incurring a severe sensitivity penalty. The sensitivity results of the various digital PPM systems investigated in this thesis are compared to those of equivalent PCM systems. It is illustrated that digital PPM offers an improvement of between 5-10 dB depending upon which coding format/ detection technique is employed. This represents an increase in transmission distance of 25-50 km and demonstrates that digital PPM is a promising modulation format and has potential for future high performance telecommunication routes.
23
Young, Andrew F. "Classification of digital modulation types in multipath environments." Thesis, Monterey California. Naval Postgraduate School, 2008.
Знайти повний текст джерелаАнотація:
Approved for public release, distribution unlimited<br>As the digital communications industry continues to grow and evolve, the applications of this discipline continue to grow as well. This growth, in turn, has spawned an increasing need to seek automated methods of classifying digital modulation types. This research is a revision of previous work, using the latest mathematical software including MATLAB version 7 and Simulink ®. The program considers the classification of nine different modulation types. Specifically, the classification scheme can differentiate between 2, 4, and 8 PSK, 256-QAM from other types of M-QAM signals, and also M-FSK signals from PSK and QAM signals in various types of propagation channels, including multipath fading and a variety of signal-to-noise levels. This method successfully identifies these modulation types without the benefit of a priori information. Higher-order statistical parameters are selected as class features and are tested in a classifier for their ability to identify the above modulation types. This study considers the effects due to realistic multipath propagation channels and additive white Gaussian noise. Using these features, and considering all fading conditions, it was determined that the classifier was correct for a randomly sent signal under randomly high or low SNR levels (low: 0dB to 8dB; high: 50dB to 100dB) over 83.9% of the time.
24
Calvert, N. "An optical fibre digital pulse position modulation system." Thesis, University of Huddersfield, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382254.
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25
Schoonees, Johann August. "A likelihood ratio analysis of digital phase modulation." Doctoral thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/19508.
Повний текст джерелаАнотація:
Bibliography: p. 180-188.<br>Although the likelihood ratio forms the theoretical basis for maximum likelihood (ML) detection in coherent digital communication systems, it has not been applied directly to the problem of designing good trellis-coded modulation (TOM) schemes. The remarkably simple optimal receiver of minimum shift keying (MSK) has been shown to result from the mathematical simplification of its likelihood ratio into a single term. The log-likelihood ratio then becomes a linear sum of metrics which can be implemented as a so-called simplified receiver, comprising only a few adders and delay elements. This thesis project investigated the possible existence of coded modulation schemes with similarly simplifying likelihood ratios, which would have almost trivially simple receivers compared to the Viterbi decoders which are typically required for maximum likelihood sequence estimation (MLSE). A useful notation, called the likelihood transform, was presented to aid the analysis of likelihood ratios. The work concentrated initially on computer-aided searches, first for trellis codes which may give rise to simplifying likelihood ratios for continuous phase modulation (CPM), and then for mathematical identities which may aid in the simplification of generic likelihood ratios for equal-energy modulation. The first search yielded no simplified receivers, and all the identities produced by the second search had structures similar to the likelihood ratio of MSK. These observations prompted a formal proof of the non-existence of simplified receivers which use information from more than two symbols in their observation period. This result strictly bounds the error performance that is possible with a simplified receiver. It was also proved that simplified receivers are only optimal for modulation schemes which use no more than two pairs of antipodal signals, and that only binary modulation schemes can have simplified receivers which use information from all the symbols in their observation period.
26
Bax, Walter T. (Walter Timothy) Carleton University Dissertation Engineering Electronics. "Modulation and frequency synthesis for wireless digital radio." Ottawa, 1999.
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27
Bullard, Jason Mark. "New modulation technique to improve supply ripple rejection of a digital pulse width modulator." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0007548.
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28
Gendron, Paul John. "A comparison of digital beacon receiver frequency estimators." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09292009-020307/.
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29
Thorlby, J. Paul. "Equalisation techniques for coded modulation." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338549.
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30
Li, Xiaodong. "Bandwidth-efficient coded modulation and iterative decoding /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/6017.
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31
Ghate, Dilip B. "Implementation of a digital communication system using QPSK modulation." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA305334.
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32
Stark, Stefan. "Direct Digital Pulse Width Modulation for Class D Amplifiers." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8476.
Повний текст джерелаАнотація:
<p>Class D amplifiers are becoming increasingly popular in audio devices. The strongest reason is the high efficiency which makes it advantageous for portable battery-driven products.</p><p>Infineon Technologies is developing products in this area, and has recently filed a patent application regarding an implementation of a part of the class D amplifier. The aim of this Master’s thesis is to evaluate a digital open-loop implementation of a class D amplifier, using the pending patent solution, and discuss the differences from an analog closed-loop implementation.</p><p>The focus has been on generating a high resolution PWM signal with a relatively low clock frequency. To achieve this, a hybrid of a counter and a self-calibrating tapped delay-line are used as a pulse generator. A model of the pulse generator was developed which made it possible to study how sampling frequency and different types of quantization affected quality parameters such as THD and SNR. With the results from the model two systems were implemented and simulated in HDL and as circuit schematics.</p><p>The proposed digital open-loop class D amplifier was found to be useful in voice-band applications and for music. Since the open-loop structure suffers from poor rejection of power supply ripple, either error correction or a regulated power supply is needed. If much effort is put on the different parts of the amplifier the result can be really good but, depending on other constraints on the system, it may be simpler and less time consuming to use the analog circuit with feedback to achieve hi-fi quality.</p><p>In summary, the combination of a counter and a self-calibrating tapped delay-line as a pulse generator is very useful in high resolution low-power systems. To avoid errors the delay-line and calibration can be made very accurate but with the expense of higher power consumption and area. However, the technique benefits from the small and fast logic devices available in deep sub-micron process technologies, which may finally lead to an advantage in power consumption and cost over the closed-loop analog solution.</p>
33
Sieben, Michael James. "Single sideband modulation for digital fiber optic communication systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0024/NQ34832.pdf.
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34
Esslinger, Rolf. "One-bit Sigma-Delta Modulation for digital power amplifiers." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401393.
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35
Torrance, Jeffrey Mark. "Adaptive full response digital modulation for wireless communication environments." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242748.
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36
Jacobs, Deon. "Digital pulse width modulation for Class-D audio amplifiers." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1574.
Повний текст джерелаАнотація:
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.<br>Digital audio data storage mediums have long been used within the consumer
market. Today, because of the advancement of processor clock speeds and increased
MOSFET switching capabilities, digital audio data formats can be directly amplified
using power electronic inverters. These amplifiers known as Class-D have an
advantage over there analogue counterparts because of their high efficiency.
This thesis deals with the signal processing algorithms necessary to convert the
digital audio data obtained from the source to a digital pulse width modulated signal
which controls a full bridge inverter for audio amplification. These algorithms
address difficulties experienced in the past which prevented high fidelity digital pulse
width modulators to be implemented.
The signal processing algorithms are divided into modular blocks, each of
which are defined in theory, designed and simulated in Matlab® and then
implemented within VHDL firmware. These firmware blocks are then used to realize
a Class-D audio amplifier.
37
Verdin, Dan. "Synchronisation in sampled receivers for narrowband digital modulation schemes." Thesis, University of York, 1995. http://etheses.whiterose.ac.uk/10839/.
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38
Fortune, P. M. "Multi-level modulation schemes for digital cellular mobile radio." Thesis, University of Southampton, 1988. https://eprints.soton.ac.uk/421471/.
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Wu, Xiping. "Wireless communication systems based on spatial modulation MIMO." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10505.
Повний текст джерелаАнотація:
Spatial modulation (SM) is a unique single-stream, multiple-input multiple-output (MIMO) transmission technique. Unlike traditional MIMO schemes, SM sends out signals through a single active antenna, and achieves multiplexing gains by encoding information bits into the index of the currently active antenna. In contrast to multi-stream MIMO systems, this particular characteristic offers great superiority in two main aspects. Firstly, SM completely avoids inter-channel interference. Secondly, SM requires a single radio-frequency chain, regardless of the number of antennas used, and therefore exhibits a significant energy saving. However, the property of a single active antenna challenges the channel estimation process for SM: the transmit antennas have to be activated sequentially for sending pilot signals. As a result, the time consumed in pilot transmission is proportional to the number of transmit antennas. However, this fact has so far been neglected in related research. Also, published research on SM has focused on point-to-point communications, and few have covered a network perspective. In this thesis, a comprehensive study is undertaken on SM systems in single-user, multi-user and multi-cell scenarios. As a unique three-dimensional modulation scheme, SM enables a trade-off between the size of the signal constellation diagram and the size of the spatial constellation diagram. In this thesis, an optimum transmit structure is proposed for SM to employ an adaptive scale of antennas against channel correlations. Unlike traditional antenna selection methods, this new approach is not sensitive to fast fading, due to the exploitation of statistical channel state information (CSI) instead of instant CSI. The proposed transmit structure is demonstrated to have a near-optimal performance against exhaustive search, while achieving very low computational complexity. In addition, three novel methods are developed to improve the channel estimation process for SM. A first method estimates the entire MIMO channel by sending pilot signals through only one of the transmit antennas, among which the channel correlation is exploited. In a similar way but focusing on the receiver, a second method can improve the estimation accuracy without increasing the pilot sequence length. A third method balances the transmission power between pilot and data to minimise the bit error rate. A framework of combined channel estimation is also proposed, in which the three methods are jointly applied. Furthermore, the antenna allocation in multi-user SM is studied, in order to explore multi-user diversity gains. A method that jointly manages transmit antennas and receive antennas for all co-channel users is proposed. The aim of this new method is to maximise the channel capacity for each user, and the fairness among users is taken into account. It is demonstrated that the proposed method significantly improves the performance of multi-user SM, especially when serving a large number of users. Finally, a novel cooperative scheme is proposed for SM in a multi-cell scenario. Based on the concept of coordinated multi-point transmission (CoMP), this scheme enables the coordinated users to swap the base station antennas pertaining to them. A three-tier cellular architecture is further developed to switch between CoMP and the cooperative scheme.
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Gray, Andrew, Meera Srinivasan, Marvin Simon, and Tsun-Yee Yan. "FLEXIBLE ALL-DIGITAL RECEIVER FOR BANDWIDTH EFFICIENT MODULATIONS." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608745.
Повний текст джерелаАнотація:
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>An all-digital high data rate parallel receiver architecture developed jointly by Goddard Space Flight Center and the Jet Propulsion Laboratory is pre- sented. This receiver utilizes only a small number of high speed components along with a majority of lower speed components operating in a parallel fre- quency domain structure implementable in CMOS, and can process over 600 Mbps with numerous varieties of QPSK modulation, including those incorpo- rating precise pulse shaping for bandwidth eÆcient modulation. Performance results for this receiver for bandwidth eÆcient QPSK modulation schemes such as square-root raised cosine pulse shaped QPSK and Feher’s patented QPSK are presented, demonstrating the great degree of exibility and high performance of the receiver architecture.
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Tuthill, John D. "Frequency dependent digital compensation in DSP based FM modulators." Thesis, Curtin University, 2000. http://hdl.handle.net/20.500.11937/797.
Повний текст джерелаАнотація:
This thesis reports original work on digital compensation for frequency dependent transfer characteristics and errors in digital PAM/CPFSK (Pulse Amplitude Modulation/Continuous Phase Frequency Shift Keying) quadrature modulators.A particularly flexible and cost effective approach to the implementation of the base-band section of a radio transmitter is to synthesise base-band signals digitally using a DSP (Digital Signal Processor). This approach is limited, however, by the transfer characteristics and errors in the implementation of practical analogue sub-systems. These practical limitations result in undesirable in-band frequency-dependent shaping of the transmitted signals. In the case of FM (Frequency Modulation) signals, this leads to the generation of unwanted side-lobes in the transmitted RF signal spectrum that interfere with signals in adjacent frequency channels. This results in the transmitted signal failing to meet transmission standards requirements.The digital compensation techniques developed and presented in this thesis allow the reduction of undesirable in-band frequency-dependent signal shaping. It is shown that this enables strict requirements on the spectral emissions from the FM transmitter to be met using a flexible and cost effective DSP based modulator system.The contributions of the thesis are in three primary areas:(i) The development of a structure for frequency dependent digital compensation.(ii) The formulation and solution of an optimisation problem that allows the free parameters within the structure to be determined such that effective reduction of unwanted in-band frequency-dependent signal shaping is achieved.(iii) The development of techniques that allow the digital compensation procedure to be successfully implemented on a practical DSP platform.The new digital compensation structure that is proposed uses two digital FIR (Finite Impulse Response) filters in the digital base-band section of the quadrature modulator: one in the in-phase (I) channel and one in the quadrature (Q) channel. The tap-weights of the FIR filters are determined by solving two optimisation problems: one for each channel. The optimisation problems are formulated using a new approach that ensures that the degrees of freedom in the optimisation i.e., the FIR filter tap-weights, are used effectively to meet the objective of reducing in-band frequency-dependent signal shaping in analogue sub-systems further down the transmission path.A characterisation of the solutions to the optimisation problems enables the identification of techniques that need to be adopted to successfully implement the proposed digital compensation on a practical DSP-based system.The digital compensation technique is demonstrated by implementing and testing the technique on a DSP platform. The results of experimental studies are presented which clearly demonstrate that the digital compensation technique leads to substantial reductions in adjacent channel interference.
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Aldera, Mario Antonio. "A study of the minimum shift keying modulation scheme." Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/21863.
Повний текст джерелаАнотація:
This thesis concerns itself with the study of the Minimum Shift Keying (MSK) modulation scheme. The aspects considered are its operation under non-linear conditions as well as an investigation into the hardware implementation of both coherent and non-coherent MSK modems. The literature on digital data transmission and MSK in particular is surveyed, and a comprehensive theoretical description of MSK is given. In addition, papers on the operation of MSK under non-linear conditions were studied, and their major findings are presented. Due to the lack of theory on the effects of incorrect modulation index on the error performance of MSK, an investigation into this avenue was performed. The design of a correction mechanism for maintaining the modulation index at its correct value is described, and aspects of its implementation are considered. Using the available literature, various modules of which a coherent MSK modem is comprised were developed, and their design is discussed. The design of a non-coherent MSK demodulator is also described.
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Chindapol, Aik. "Evaluation of improved designs for two-dimensional bit-interleaved coded modulation with iterative decoding in fading channels /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5992.
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Garcia, Julian. "Digitally Enhanced Continuous-Time Sigma-Delta Analogue-to-Digital Converters." Doctoral thesis, KTH, Integrerade komponenter och kretsar, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95447.
Повний текст джерелаАнотація:
The continuous downscaling of CMOS technology presents advantagesand difficulties for IC design. While it allows faster, denser and more energy efficient digital circuits, it also imposes several challenges which limit the performance of analogue circuits. Concurrently, applications are continuously pushing the boundaries of power efficiency and throughput of electronic systems. Accordingly, IC design is increasingly shifting into highly digital systems with few necessary analogue components. Particularly, continuous-time (CT) sigma-delta (ΣΔ) analogue-to-digital converters (ADCs) have recently received a growing interest, covering high-resolution medium-speed requirementsor offering low power alternatives to low speed applications. However, there are still several aspects that deserve further investigation so as to enhancethe ADC’s performance and functionality. The objective of the research performed in this thesis is the investigation of digital enhancement solutions for CT ΣΔ ADCs. In particular, two aspects are considered in this work. First, highly digital techniques are investigated to minimize circuit impairments, with the objective of providing solutions with reduced analogue content. In this regard, a multi-bit CT ΣΔ modulator with reduced number of feedback levels is explored to minimize the use of linearisation techniques in the DAC. The proposed architecture is designed and validated through behavioural simulations targeting a mobile application. Additionally, a novel self-calibration technique, using test-signal injection and digital cancellation, is proposed to counteract process variations affecting single loop CT implementations. The effectiveness of the calibration technique is confirmed through corner simulations using behavioural models and shows that stability issues are minimized and that a 7 dB SNDR degradation can be avoided. The second aspect of this thesis investigates the use of high order CT modulators in incremental ΣΔ (IΣΔ) and extended-range IΣΔ ADCs, with the objective of offering low-power alternatives for low-speed high-resolution multi-channel applications. First, a 3rd order single loop CT IΣΔ ADC, targeting an 8-channel 500 Ksamples/sec rate per channel recording system for neuropotential sensors, is proposed, fabricated and tested. The proposed architecture lays the theoretical groundwork and demonstrates a competitive performance of high-order CT IΣΔ ADCs for low-power multi-channel applications. The ADC achieves 65.3 dB/64 dB SNR/SNDR and 68.2 dB dynamic range. The modulator consumes 96 μW from a 1.6 V power supply. Additionally, the use of extended range approach in CT IΣΔ ADCs is investigated,so as to reduce the required number of cycles per conversion while benefiting from the advantages of a CT implementation. The operation, influence of filter topology and impact of circuit non-idealities are first analysed using a general approach and later validated through a test-case. It was found that, by applying analogue-digital compensation in the digital domain, it is possible to minimize the noise leakage due to analogue-digital transfer function mismatches and benefit from relaxed amplifiers’ finite gain-bandwidth product and finite DC gain, allowing, as a consequence, a power conscious alternative.<br>QC 20120528
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Horley, Niall. "Advanced practical coding and modulation techniques for time varying channels." Thesis, Lancaster University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387440.
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Geisinger, Nathan P. "Classification of digital modulation schemes using linear and nonlinear classifiers." Thesis, Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/theses/2010/Mar/10Mar%5FGeisinger.pdf.
Повний текст джерелаАнотація:
Thesis (Electrical Engineer and M.S. in Electrical Engineering)--Naval Postgraduate School, March 2010.<br>Thesis Advisor(s): Fargues, Monique P. ; Cristi, Roberto ; Robertson, Ralph C. "March 2010." Description based on title screen as viewed on .April 27, 2010. Author(s) subject terms: Blind Modulation Classification, Cumulants, Principal Component Analysis, Linear Discriminant Analysis, Kernel-based functions. Includes bibliographical references (p. 211-212). Also available in print.
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Van, Wyk Daniel Jacobus. "Four-dimensional Q2PSK modulation and coding for mobile digital communication." Pretoria : [s.n.], 2000. http://upetd.up.ac.za/thesis/available/etd-10272005-122450.
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Caouras, Nestor. "Fast all-digital carrier synchronization techniques for linear modulation formats." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/MQ47824.pdf.
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Hayes, Andrew Robert. "Digital pulse interval modulation for indoor optical wireless communication systems." Thesis, Sheffield Hallam University, 2002. http://shura.shu.ac.uk/7263/.
Повний текст джерелаАнотація:
Over the past decade, infrared has attracted a considerable amount of interest as an alternative medium to radio for short-range indoor wireless local area networks. Infrared offers a number of significant advantages over its radio frequency counterpart, such as the abundance of bandwidth that is currently unregulated worldwide, the availability of low cost emitters and detectors, inherent security and resistance to multi path fading. The work presented in this thesis focuses on modulation techniques, the fundamental aim being to assess the suitability of digital pulse interval modulation (DPIM) for use in indoor optical wireless communication systems. Infrared transceivers are subject to eye safety regulations, and consequently power efficiency is an important criterion when evaluating modulation techniques. From the error probability analysis carried out on the non-distorting additive white Gaussian noise channel, it is shown that DPIM is able to trade off power efficiency against bandwidth efficiency by increasing the number of bits per symbol. Furthermore, by encoding an additional bit per symbol, DPIM can outperform pulse position modulation (PPM) both in terms of power efficiency and bandwidth efficiency when simple threshold detection is employed. Indoor optical wireless systems generally operate in the presence of intense ambient light, emanating from both natural and artificial sources. Along with contributing to the generation of shot noise, artificial ambient light sources also introduce a periodic interference signal which can have a detrimental effect on link performance. Original analysis is presented which examines the error performance of DPIM in the presence of interference from a fluorescent lamp driven by a high-frequency electronic ballast, which is potentially the most degrading source of ambient light. It is found that such interference results in an average optical power requirement that is almost independent of the bit rate. The analysis then goes on to consider the effectiveness of electrical high-pass filtering as a simple means of mitigating the effect of the interference, taking into account the baseline wander introduced by the high-pass filter. DPIM was found to be more susceptible to the effects of baseline wander compared with PPM, a finding which is supported by the original analysis carried out on the power spectral density of the scheme. Consequently, whilst electrical high-pass filtering was found to be very effective at high bit rates, significant power penalties are still incurred at low to medium bit rates. In non-directed line of sight and diffuse link configurations, multipath propagation gives rise to intersymbol interference (ISI), which must be taken into account for data rates above 10 Mbit/s. Original analysis is presented which examines the unequalized performance of DPIM in the presence of ISI. From this analysis, it is found that on any given channel, the improved bandwidth efficiency of DPIM results in lower average optical power penalties, compared with PPM. One novel technique which can be used to make DPIM more resistant to the effects of ISI is to add a guard band to each symbol, immediately following the pulse. Original contributions are presented which evaluate the effectiveness of this technique. To quantify the results obtained, analysis is also carried out on DPIM using a zero-forcing decision feedback equalizer (ZF-DFE), which represents a more traditional approach to mitigating the effects of ISI. It is shown that the guard band technique offers a similar level of performance to the ZF-DFE on all but the most severe channels, and has the advantage of reduced cost and complexity compared with implementing a ZF-DFE. To support the theoretical and simulated performance of DPIM carried out in this thesis, details are given of a prototype 2.5 Mbit/s diffuse infrared link employing 16-DPIM which has been designed and constructed. The error performance of the link is measured under a variety of ambient light conditions, and the effectiveness of electrical high-pass filtering in mitigating the resulting interference is assessed. It is shown that whilst a fluorescent lamp driven by a high frequency electronic ballast has the potential to significantly degrade link performance, the power penalty introduced by this source can be made manageable by careful selection of the high-pass filter cut-on frequency.
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Wang, Y. "Linecoded digital pulse position modulation for repeatered optical fibre telecommunications." Thesis, University of Essex, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376832.
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