15 research outputs found
Classic OFDM Systems and Pulse Shaping OFDM/OQAM Systems
No full textIn this report, we provide a comparative study of state-of-the-art in Orthogonal Frequency Division Multiplexing (OFDM) techniques with orthonormal analysis and synthesis basis. Two main categories, OFDM/QAM which adopts base-band Quadrature Amplitude Modulation (QAM) and rectangular pulse shape, and OFDM/OQAM which uses baseband offset QAM and various pulse shapes, are intensively reviewed. OFDM/QAM can provide high data rate communication and effectively remove intersymbol interference (ISI) by employing guard interval, which costs a loss of spectral efficiency and increases power consumption. Meanwhile it remains very sensitive to frequency offset which causes inter-carrier interference (ICI). In order to achieve better spectral efficiency and reducing combined ISI/ICI, OFDM/OQAM using well designed pulses with proper Time Frequency Localization (TFL) is of great interest. Various prototype functions, such as rectangular, half cosine, Isotropic Orthogonal Transfer Algorithm (IOTA) function and Extended Gaussian Functions (EGF) are discussed and simulation results are provided to illustrate the TFL properties by the ambiguity function and the interference function.QC 20111026A hard copy is available in ICT/ECS archive. Electronic copy is available on www.ee.kth.se/~jinfengNGFDM - small project of Wireless@KT
Swedish system-on-chip conference focuses on meter to nanometer scale electronics R&D
No full textLiLaS
No full textThis paper describes a generic link layer simulation environment for multiple antenna systems in MATLAB and OCTAVE, for both Windows and Unix/Linux operating systems: LiLaS. The simulator is functionally divided into modules, sub-modules and models with a common interface for the convenience of modification and reconfiguration. Currently, it accommodates a variety of transmission schemes, including single-carrier and multiple-carrier MIMO, Orthogonal Frequency-Division Multiplexing (OFDM), OFDM/Offset QAM, Wideband Code Division Multiple Access (W-CDMA), filtered multitone (FMT) and RFID which have extensive applications in modern communication technologies, e.g.. WLAN 802.11 a/b/g/n, WiMAX, UWB, 3G, LTE, LTE advanced, IMT advanced, xDSL, DVB, etc.</p
Effects of Noise and Jitter in Bandpass Sampling
No full textBandPass Sampling (BPS) is an undersampling technique by intentional aliasing. BPS enables one to have an interface between the IF stage and the ADC in a radio receiver. Conventional uniform BPS at Nyquist rate normally results in a low Signal-to-Noise Ratio (SNR) due to noise spectrum aliasing. The noise (e.g. kT/C noise introduced in a voltage-mode sampler) is combined in each of the Nyquist bands within the bandwidth of the sampling device. Also timing jitter causes a performance degradation in BPS. In this paper, signal spectrum aliasing, noise aliasing and jitter effects in BPS is analyzed. It is verified by simulation that NonUniform Sampling (NUS) has the potential to suppress signal spectrum aliasing and relax the requirement on the anti-aliasing (AA) filter. Jitter effects in BPS are compared to LowPass Sampling (LPS) case. However, a signal cannot be reconstructed from its nonuniform samples by using only ideal lowpass filtering (classic Shannon's reconstruction). Finally, signal reconstruction in the presence of noise and jitter are investigated for three Reconstruction Algorithms (RAs) aimed at NUS.</p
Single clock charge pump designed in 0.35μm technology
No full textAn on-chip novel design of a single clock charge pump for high voltage applications is being presented in this paper. The proposed charge pump is designed using AMS 0.35μm technology. Three stages of the proposed charge pump are being used for the results verification and comparing them with the six stages of Dickson charge pump designed with diode connected PMOS. The proposed charge pump gives an output voltage of 5.34V at no-load. The proposed charge pump gives maximum efficiencies of 89% on 1MHz frequency and 87.4% on 5MHz frequency using 1Mohm load resistance. The efficiency and the output voltage including voltage gain per stage of the proposed charge pump are higher than the Dickson charge pump measured under similar conditions mediating that the performance of proposed charge pump is better than the Dickson charge pump.</p
A highly linear 1.2 V 12bit 5-45 MS/s CMOS pipelined ADC with CM-sensing-and-input-interchanged OTA sharing
No full textA 1.2 V 12bit programmable pipelined ADC is presented and implemented in 0.13 mu m CMOS technology. A common-mode-sensing-and-input-interchanged OTA-sharing technique is proposed to address the non-resetting and successive-stage crosstalk issues in conventional OTA-sharing technique. Speed options of 5-45 MS/s are available with scalable power obtained by adjusting the bias currents for OTAs, comparators, and reference buffers, etc., or the global bias current. The measured signal-to-distortion-and-noise ratio is in range of 62.5-69.2 dB, and the peak spurious free dynamic range is 80.7 dB for all speed options, while the figure-of-merit is in the range of 0.26-0.49 pJ/conversion. The core area is 1.5 mm(2).</p
Spatial distribution of water level impacting back-barrier bays
No full text© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Aretxabaleta, A. L., Ganju, N. K., Defne, Z., & Signell, R. P. Spatial distribution of water level impacting back-barrier bays. Natural Hazards and Earth System Sciences, 19(8), (2019): 1823-1838, doi: 10.5194/nhess-19-1823-2019.Water level in semi-enclosed bays, landward of barrier islands, is mainly driven by offshore sea level fluctuations that are modulated by bay geometry and bathymetry, causing spatial variability in the ensuing response (transfer). Local wind setup can have a complementary role that depends on wind speed, fetch, and relative orientation of the wind direction and the bay. Bay area and inlet geometry and bathymetry primarily regulate the magnitude of the transfer between open ocean and bay. Tides and short-period offshore oscillations are more damped in the bays than longer-lasting offshore fluctuations, such as a storm surge and sea level rise. We compare observed and modeled water levels at stations in a mid-Atlantic bay (Barnegat Bay) with offshore water level proxies. Observed water levels in Barnegat Bay are compared and combined with model results from the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system to evaluate the spatial structure of the water level transfer. Analytical models based on the dimensional characteristics of the bay are used to combine the observed data and the numerical model results in a physically consistent approach. Model water level transfers match observed values at locations inside the bay in the storm frequency band (transfers ranging from 50 %–100 %) and tidal frequencies (10 %–55 %). The contribution of frequency-dependent local setup caused by wind acting along the bay is also considered. The wind setup effect can be comparable in magnitude to the offshore transfer forcing during intense storms. The approach provides transfer estimates for locations inside the bay where observations were not available, resulting in a complete spatial characterization. An extension of the methodology that takes advantage of the ADCIRC tidal database for the east coast of the United States allows for the expansion of the approach to other bay systems. Detailed spatial estimates of water level transfer can inform decisions on inlet management and contribute to the assessment of current and future flooding hazard in back-barrier bays and along mainland shorelines.This work was supported by the US Geological Survey, Coastal and Marine Hazards/Resources Program
Intelligent Equalisation Principles and Techniques for Minimising Masking when Mixing the Extreme Modern Metal Genre.
No full textThe intensity, complexity and energy of performance, combined with the power and density of the tones involved are characteristics of the extreme metal genre. These characteristics present numerous problems when striving to achieve the clarity, definition and hyper-realism of performance required for this genres production. Avoiding masking in a mix is a fundamental
aspect of clarity, definition, intelligibility and perceived loudness and due to the fact that masking especially occurs in a dense mix, and is more pronounced in low frequencies, is particularly applicable to mixing the downtuned extreme metal genre. Masking in simple terms is the ability of frequencies of one sound to obscure or inhibit (i.e. mask) the frequencies of
another sound. This paper will draw upon the first author’s eight years of experience producing within the metal genre, including releases through Sony and Universal and working with the likes of Colin Richardson and Andy Sneap
Collaboration tools and techniques for large model datasets
No full textAuthor Posting. © The Author(s), 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 69 (2008): 154-161, doi:10.1016/j.jmarsys.2007.02.013.In MREA and many other marine applications, it is common to have multiple models running with different grids, run by different institutions. Techniques and tools are described for low-bandwidth delivery of data from large multidimensional data sets, such as those from meteorological and oceanographic models, directly into generic analysis and visualization tools. Output is stored using the NetCDF CF Metadata Conventions, and then delivered to collaborators over the web via OPeNDAP. OPeNDAP datasets served by different institutions are then organized via THREDDS catalogs. Tools and procedures are then used which enable scientists to explore data on the original model grids using tools they are familiar with. It is also low-bandwidth, enabling users to extract just the data they require, an important feature for access from ship or remote areas. The entire implementation is simple enough to be handled by modelers working with their webmasters – no advanced programming support is necessary.S. Carniel was partially supported by the Office of Naval Research (ONR grant number N00014-05-1-0730). I. Janekovic was supported by the Croatian Ministry of Science, Education and Sport (grant number 0098113)
