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nonuniform-sampling
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An efficient method for demodulating ppm signals based on reed-solomon decoding algorithm
, Article Signal Processing ; Volume 84, Issue 10 , 2004 , Pages 1823-1836 ; 01651684 (ISSN) ; Meleas, D ; Marvasti, F ; Sharif University of Technology
Elsevier
2004
Abstract
In this paper, we propose an efficient method for demodulating pulse position modulation (PPM) signals based on Reed-Solomon decoding algorithm. It is shown that the proposed technique outperforms other demodulating methods such as those based on Lagrange, Spline, and Iterative algorithms. Furthermore, the proposed method is generalized to the case that the PPM signal is corrupted by additive white Gaussian noise. © 2004 Elsevier B.V. All rights reserved
Convergence analysis of an iterative method for the reconstruction of multi-band signals from their uniform and periodic nonuniform samples
, Article Sampling Theory in Signal and Image Processing ; Volume 7, Issue 2 , 1 May , 2008 , Pages 113-129 ; 15306429 (ISSN) ; Marvasti, F ; Sharif University of Technology
2008
Abstract
One of the proposed methods for recovery of a band-limited signal from its samples, whether uniform or nonuniform, is the so-called Frame Method. In this method the original signal is reconstructed by iterative use of sampling-filtering blocks. Convergence of this method for linear invertible operators has been previously proved. In this paper we show that this method for non-invertible periodic nonuniform samplings as well as non-invertible uniform samples of bandpass (or multi-band) signals will lead to the pseudo-inverse solution. Convergence conditions in case of additive noise will also be discussed. © 2008 Sampling Publishing
A novel demodulation technique for recovering PPM signals in the presence of additive noise
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Volume 3124 , 2004 , Pages 541-547 ; 03029743 (ISSN); 3540225714 (ISBN); 9783540225713 (ISBN) ; Marvasti, F ; Sharif University of Technology
Springer Verlag
2004
Abstract
In this paper, we propose a novel method for demodulating Pulse Position Modulation (PPM) signals based on Reed-Solomon decoding algorithm. It is shown that the proposed technique outperforms the conventional demodulating method base on Reed-Solomon algorithm in case that the PPM signals are corrupted by Additive White Gaussian Noise (AWGN). © Springer-Verlag 2004
Sampling and distortion tradeoffs for bandlimited periodic signals
, Article 2015 International Conference on Sampling Theory and Applications, SampTA 2015, 25 May 2015 through 29 May 2015 ; 2015 , Pages 468-472 ; 9781467373531 (ISBN) ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, the optimal sampling strategies (uniform or nonuniform) and distortion tradeoffs for stationary bandlimited periodic signals are studied. We justify and use both the average and variance of distortion as the performance criteria. To compute the optimal distortion, one needs to find the optimal sampling locations, as well as the optimal pre-sampling filter. A complete characterization of the optimal distortion for the rates lower than half the Landau rate is provided. It is shown that nonuniform sampling outperforms uniform sampling. In addition, this nonuniform sampling is robust with respect to missing samples. Next, for the rates higher than half the Landau rate, we find...
SNR Improvement in A/D Converters Using Iterative Algorithm
, M.Sc. Thesis Sharif University of Technology ; Marvasti, Farrokh (Supervisor)
Abstract
Converting analog signal to digital one is one of the most important issues in signal processing which can be done by using analog to digital converter (A/D). In the first part of this thesis, sigma delta converters based on minimum support filter are investigated. Then, we will show that iterative algorithm can be used in order to improve the performance of the overall system significantly. Asynchronous converters can be utilized for the sake of decreasing power in the process of analog to digital converting. In these converters, a few numbers of samples will be taken from the regions which signal has high autocorrelation. In other words, samples in the asynchronous converters have more...
Sampling and Distortion Tradeoffs for Band-limited Periodic Signals
, Ph.D. Dissertation Sharif University of Technology ; Marvasti, Farokh (Supervisor)
Abstract
One of the funadmental problems in signal processing is finding the best sampling strategy of a continuous time signal, and then finding the best strategy for compressing the obtained signal samples. The sampling and compression steps are designed with the aim of minimizing the distortion of the reconstructed signal. The problem of finding the best sampling strategy has been widely studied in the signal processing literature. In particular, the Nyquist–Shannon sampling theorem gives a sufficient condition for perfect reconstruction of a continuous-time signal of finite bandwidth. Most of the signal processing literature deals with deterministic signals, with relatively less attention paid to...
Design of Mti Filters with Non-Uniform Sampling
, M.Sc. Thesis Sharif University of Technology ; Nayebi, Mohammad Ali (Supervisor)
Abstract
In MTI radars, digital filters utilizing non-uniform sampling are used to remove the echo of stationary targets or the ones with minor Doppler shift. These targets usually are associated with significant reflection causing small, high-speed targets not to be detected. In this type of filters, the use of non-uniform sampling prevents the blind speed issue and causes the first blind speed to occur at higher frequencies. The performance of such filters is characterized by two criteria: Coefficients and periods. Therefore, coefficient optimization in filter design has a dominant role in maximizing clutter rejection. Also, period optimization is used to prevent generating deep nulls in the...
Non-uniform sampling based on an adaptive level-crossing scheme
, Article IET Signal Processing ; Volume 9, Issue 6 , 2015 , Pages 484-490 ; 17519675 (ISSN) ; Kafashan, M. M ; Ghassemian, M ; Marvasti, F ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
Level-crossing (LC) analog-to-digital (A/D) converters can efficiently sample certain classes of signals. An LC A/D converter is a real-time asynchronous system, which encodes the information of an analog signal into a sequence of nonuniformly spaced time instants. In particular, this class of A/D converters uses an asynchronous data conversion approach, which is a power efficient technique. In this study, the authors propose adaptive and multi-level adaptive LC sampling models as alternatives to conventional LC schemes and apply an iterative algorithm to improve the reconstruction quality of LC A/D converters. This simulation results show that multi-level adaptive LC outperforms...
Sampling and distortion tradeoffs for indirect source retrieval
, Article 2016 IEEE Global Conference on Signal and Information Processing, GlobalSIP 2016, 7 December 2016 through 9 December 2016 ; 2017 , Pages 545-549 ; 9781509045457 (ISBN) ; Fallah, A ; Marvasti, F ; IEEE Signal Processing Society; The Institute of Electrical and Electronics Engineers ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
We study the problem of remote reconstruction of a continuous signal from its multiple corrupted versions. We are interested in the optimal number of samples and their locations for each corrupted signal to minimize the total reconstruction distortion of the remote signal. The correlation among the corrupted signals can be utilized to reduce the sampling rate. For a class of Gaussian signals, we show that in the low sampling rate region, it is optimal to use a certain nonuniform sampling scheme on all the signals. On the other hand, in the high sampling rate region, it is optimal to uniformly sample all the signals. We also show that both of these sampling strategies are optimal if we are...
Sampling and distortion tradeoffs for bandlimited periodic signals
, Article IEEE Transactions on Information Theory ; 2017 ; 00189448 (ISSN) ; Marvasti, F ; Sharif University of Technology
Abstract
In this paper, the optimal sampling strategies (uniform or nonuniform) and distortion tradeoffs for Gaussian bandlimited periodic signals with additive white Gaussian noise are studied. Our emphasis is on characterizing the optimal sampling locations as well as the optimal pre-sampling filter to minimize the reconstruction distortion. We first show that to achieve the optimal distortion, no pre-sampling filter is necessary for any arbitrary sampling rate. Then, we provide a complete characterization of optimal distortion for low and high sampling rates (with respect to the signal bandwidth). We also provide bounds on the reconstruction distortion for rates in the intermediate region. It is...
Sampling and distortion tradeoffs for bandlimited periodic signals
, Article IEEE Transactions on Information Theory ; Volume 64, Issue 3 , March , 2018 , Pages 1706-1724 ; 00189448 (ISSN) ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this paper, the optimal sampling strategies (uniform or nonuniform) and distortion tradeoffs for Gaussian bandlimited periodic signals with additive white Gaussian noise are studied. Our emphasis is on characterizing the optimal sampling locations as well as the optimal presampling filter to minimize the reconstruction distortion. We first show that to achieve the optimal distortion, no presampling filter is necessary for any arbitrary sampling rate. Then, we provide a complete characterization of optimal distortion for low and high sampling rates (with respect to the signal bandwidth). We also provide bounds on the reconstruction distortion for rates in the intermediate region. It is...
Clipping noise cancellation in uplink MC-CDMA system using signal reconstruction from non-uniform samples
, Article 2008 International Conference on Telecommunications, ICT, St. Petersburg, 16 June 2008 through 19 June 2008 ; 2008 ; 9781424420360 (ISBN) ; Azmi, P ; Marvasti, F ; Sharif University of Technology
2008
Abstract
In this paper, an iterative signal reconstruction method is extended to cancel multi-user clipping noise in a uplink MC-CDMA systems. Clipping is the simplest method to overcome high peak-to-average power ratio of multi-carrier signals but it makes the multi-carrier signals distorted. Reconstruction methods use non-distorted samples to reconstruct distorted samples in the receiver but multi-user interference causes the methods do not work properly because all the received samples are distorted by clipping and interference and so there is no undistorted samples to be used in recovering clipped samples. On the other hand, multi-user interference cancellation methods do not work properly...
Self-Aware data processing for power saving in resource-constrained iot cyber-physical systems
, Article IEEE Sensors Journal ; Volume 22, Issue 4 , 2022 , Pages 3648-3659 ; 1530437X (ISSN) ; Taherinejad, N ; Rabbani, R ; Azizi, Z ; Mohin, S ; Fotowat Ahmady, A ; Mirabbasi, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Given the emergence of the Internet of Things (IoT) Cyber-Physical Systems (CPSs) and their omnipresence, reducing their power consumption is among the major design priorities. To reduce the power consumption of such systems, we propose the use of a signal-dependent sampling method in a bottom-up fashion, which can lead to up to a 94% reduction in the overall system power with negligible or no loss in performance. Moreover, the proposed technique provides further flexibility for self-aware CPSs to dynamically adjust the number of data samples that are needed for processing (and consequently reduce the power consumption) based on the application at hand and the desired trade-off between...