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Digitally Assisted Multi-Channel ReceiversPentakota, Krishna Anand Santosh Spikanth 2010 August 1900 (has links)
This work presents a data estimation scheme for wide band multi-channel charge
sampling receivers with sinc filter banks together with a complete system calibration and
synchronization algorithm for the receiver. A unified model has been defined for the
receiver containing all first order mismatches, offsets and imperfections and a technique
based on least mean squares algorithm is employed to track these errors. The performance
of this technique under noisy channel conditions has been verified. The sinc filter bank is
compared with the conventional analog filter banks and it is shown that the sinc filter banks
have very low computational complexity in data estimation
Nextly, analytical tools for the design of clock-jitter tolerant multi-channel filterbank
receivers have been developed. Clock-jitter is one of the most fundamental obstacles
for the future generation of wideband receivers. Additionally all the trade-offs and
specifications of a design example for a multi-channel receiver that can process a 5 GHz
baseband signal with 40 dB of signal-to-noise-ratio (SNR) using sampling clocks that can
tolerate up to 5 ps of clock-jitter standard deviation are presented. A novel bandwidth
optimization technique has been presented. As a part of it the bandwidth of the filters present in each path is optimized thereby improving the performance of the receiver further
in the presence of sampling clock jitter. The amount of bandwidth reduction possible
depends on the order of the filter and the noise amplification provided by the reconstruction
matrix. It has been shown that 3rd order filters of bandwidth 1 GHz can be replaced with 1st
order filters of bandwidth 100 MHz without any depreciation in the output resolution,
implying huge power savings.
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Design of a Low Power and Area Efficient Digital Down Converter and SINC Filter in CMOS 90-nm TechnologyBillman, Steven John 27 June 2011 (has links)
No description available.
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Development of an embedded system platform for signal analysis and processingLind, Philip January 2023 (has links)
Information is often stored and transmitted through electrical signals. This information may need refinement, which may be done by processing and altering the electrical signals, in which it is transmitted. When refining a signal, a frequency selective filter is often used. It can be implemented through digital signal processing (DSP). DSP is a concept where signals are refined using a digital compute system. Digital systems are designed to replace their analog counterpart, mitigating their flaws in scalability, complexity and cost. A DSP system is typically implemented using software on a small computer, while analog systems are implemented through various electronic components. The objective of this project is to design a DSP system that filters analog input data using automatically synthesised filters from user-defined input specifications. The DSP system is implemented using a microcontroller. The system designed the filters and found the filter coefficients. It then uses analog to digital converter (ADC) to sample an input signal and applies the filter. Lastly, it uses the digital to analog converter (DAC) to reconstruct a filtered, analog result. A user interface is not designed for the system, and only a limited number of filters are implemented. However, the system is successful in designing filters and finding their coefficients.
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Implementation of a 1GHZ frontend using transform domain charge sampling techniquesKulkarni, Mandar Shashikant 15 May 2009 (has links)
The recent popularity and convenience of Wireless communication and the need for integration demands the development of Software Defined Radio (SDR). First defined by Mitoal, the SDR processed the entire bandwidth using a high resolution and high speed ADC and remaining operations were done in DSP. The current trend in SDRs is to design highly reconfigurable analog front ends which can handle narrow-band and wideband standards, one at a time. Charge sampling has been widely used
in these architectures due to the built in antialiasing capabilities, jitter robustness at high signal frequencies and flexibility in filter design. This work proposed a 1GHz wideband front end aimed at SDR applications using Transform Domain (TD) sampling techniques. Frequency Domain (FD) sampling, a special case of TD sampling, efficiently parallelizes the signal for digital processing, relaxing the sampling requirements and enabling parallel digital processing at a much
lower rate and is a potential candidate for SDR. The proposed front end converts the RF signal into current and then it is downconverted using passive mixers. The front end has five parallel paths, each acting on a part of the spectrum effectively parallelizing the front end and relaxing the requirements. An overlap introduced between successive integration windows for jitter robustness was exploited to create
a novel sinc2 downsample by two filter topology. This topology was compared to a conventional topology and found to be equivalent and area efficient by about 44%. The proposed topology was used as a baseband filter for all paths in the front end. The chip was sent for fabrication in 45nm technology. The active area of the chip was 6:6mm2. The testing and measurement of the chip still remains to be done.
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Joint synchronization and calibration of multi-channel transform-domain charge sampling receiversKotte Prakasam, Pradeep 2009 May 1900 (has links)
Transform-domain (TD) sampling is seen as a potential candidate for wideband
and ultra-wideband high-performance receivers and is investigated in detail in this
research. TD receivers expand the signal over a set of basis functions and operate on
the digitized basis coefficients. This parallel digital signal processing relaxes the sampling requirements opening the doors to higher dynamic range and wider bandwidth
in receivers. This research is focused on the implementation of a high performance
multi-channel wideband receiver that is based on Frequency-domain (FD) sampling,
a special case of TD sampling.
To achieve high dynamic ranges in these receivers, it is critical that the digital
post processing block matches the analog RF front end accurately. This accurate
matching has to be ensured across several process variations, mismatches and o�sets
that can be present in integrated circuit implementations. A unified model has been
defined for the FD multi-channel receiver that contains all these imperfections and
a joint synchronization and calibration technique, based on the Least-mean-squared
(LMS) algorithm, is presented to track them. A maximum likelihood (ML) algorithm
is used to estimate the frequency offset in carriers which is corrected prior to LMS
calibration. Simulation results are provided to support these concepts.
The sampling circuits in FD receivers are based on charge-sampling and a multi-channel charge-sampling receiver creates an inherent sinc filter-bank that has several
advantages compared to the conventional analog filter banks used in other multi-channel receivers. It is shown that the sinc filter banks, besides reduced analog
complexity, have very low computational complexity in data estimation which greatly
reduces the digital power consumption of these filters. The digital complexity of data
estimation in the sinc fiter bank is shown to be less than 1=10th of the complexity
in analog filter banks.
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Reduced Area Discrete-Time Down-Sampling Filter Embedded With Windowed Integration SamplersRaviprakash, Karthik 2010 August 1900 (has links)
Developing a flexible receiver, which can be reconfigured to multiple standards,
is the key to solving the problem of embedding numerous and ever-changing
functionalities in mobile handsets. Difficulty in efficiently reconfiguring analog blocks
of a receiver chain to multiple standards calls for moving the ADC as close to the
antenna as possible so that most of the processing is done in DSP. Different standards
are sampled at different frequencies and a programmable anti-aliasing filtering is needed
here. Windowed integration samplers have an inherent sinc filtering which creates nulls
at multiples of fs. The attenuation provided by sinc filtering for a bandwidth B is directly
proportional to the sampling frequency fs and, in order to meet the anti-aliasing
specifications, a high sampling rate is needed. ADCs operating at such a high
oversampling rate dissipate power for no good use. Hence, there is a need to develop a
programmable discrete-time down-sampling circuit with high inherent anti-aliasing
capabilities. Currently existing topologies use large numbers of switches and capacitors
which occupy a lot of area.A novel technique in reducing die area on a discrete-time sinc2 ↓2 filter for
charge sampling is proposed. An SNR comparison of the conventional and the proposed
topology reveals that the new technique saves 25 percent die area occupied by the sampling
capacitors of the filter. The proposed idea is also extended to implement higher downsampling
factors and a greater percentage of area is saved as the down-sampling factor is
increased. The proposed filter also has the topological advantage over previously
reported works of allowing the designers to use active integration to charge the
capacitance, which is critical in obtaining high linearity.
A novel technique to implement a discrete-time sinc3 ↓2 filter for windowed
integration samplers is also proposed. The topology reduces the idle time of the
integration capacitors at the expense of a small complexity overhead in the clock
generation, thereby saving 33 percent of the die area on the capacitors compared to the
currently existing topology.
Circuit Level simulations in 45 nm CMOS technlogy show a good agreement
with the predicted behaviour obtained from the analaysis.
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Numerical evaluation of acoustic Green's functionsHarwood, Adrian Roy George January 2014 (has links)
The reduction of noise generated by new and existing engineering products is of increasing importance commercially, socially and environmentally. Commercially, the noise emission of vehicles, such as cars and aircraft, may often be considered a selling point and the effects of noise pollution on human health and the environment has led to legislation restricting the noise emissions of many engineering products. Noise prediction schemes are important tools to help us understand and develop a means of controlling noise. Acoustic problems present numerous challenges to traditional CFD-type numerical methods rendering all but the most trivial problems unsuitable. Difficulties relate to the length scale discrepancies which arise due to the relatively tiny pressure and density fluctuations of an acoustic wave propagating over large distancesto the point of interest; the result being large computational domains to capture wave behaviour accurately between source and observer. Noise prediction may be performed using a hybrid Computational Aero-Acoustics (CAA) scheme, an approach to noise prediction which alleviates many issues associated with exclusively numerical or analytical approaches. Hybrid schemes often rely on knowledge of a Green’s function, representing the scattering of the geometry, to propagate source fluctuations to the far-field. Presently, these functions only exist in analytical form for relatively simple geometries. This research develops principles for the robust calculation of Green’s functions for general situations. In order to achieve this, three techniques to computeGreen’s functions for the Helmholtz equation within an extended class of 2D geometries are developed, evaluated and compared. Where appropriate, their extension to 3D is described. Guidance is provided on the selection of a suitable numerical method in practice given knowledge of the geometry of interest. Through inclusion of the numerical methods for the construction of Green’s functions presented here, the applicability of existing hybrid schemes will be significantly extended. Thus, it is expected that noise predictions may be performed on a more general range of geometries while exploiting the computational efficiency of hybrid prediction schemes.
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Implementation of a Software-Defined Radio Transceiver on High-Speed Digitizer/Generator SDR14Björklund, Daniel January 2012 (has links)
This thesis describes the specification, design and implementation of a software-defined radio system on a two-channel 14-bit digitizer/generator. The multi-stage interpolations and decimations which are required to operate two analog-to-digital converters at 800 megasamples per second (MSps) and two digital-to-analog converters at 1600 MSps from a 25 MSps software-side interface, were designed and implemented. Quadrature processing was used throughout the system, and a combination of fine-tunable low-rate mixers and coarse high-rate mixers were implemented to allow frequency translation across the entire first Nyquist band of the converters. Various reconstruction filter designs for the transmitter side were investigated and a cheap implementation was done through the use of programmable base-band filters and polynomial approximation.
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Integrated Sinc Method for Composite and Hybrid StructuresSlemp, Wesley Campbell Hop 07 July 2010 (has links)
Composite materials and hybrid materials such as fiber-metal laminates, and functionally graded materials are increasingly common in application in aerospace structures. However, adhesive bonding of dissimilar materials makes these materials susceptible to delamination. The use of integrated Sinc methods for predicting interlaminar failure in laminated composites and hybrid material systems was examined. Because the Sinc methods first approximate the highest-order derivative in the governing equation, the in-plane derivatives of in-plane strain needed to obtain interlaminar stresses by integration of the equilibrium equations of 3D elasticity are known without post-processing. Interlaminar stresses obtained with the Sinc method based on Interpolation of Highest derivative were compared for the first-order and third-order shear deformable theories, the refined zigzag beam theory and the higher-order shear and normal deformable beam theory. The results indicate that the interlaminar stresses by the zigzag theory compare well with those obtained by a 3D finite element analysis, while the traditional equivalent single layer theories perform well for some laminates.
The philosophy of the Sinc method based on Interpolation of Highest Derivative was extended to create a novel weak form based approach called the Integrated Local Petrov-Galerkin Sinc Method. The Integrated Local Petrov-Galerkin Sinc Method is easily utilized for boundary-value problem on non-rectangular domains as demonstrated for analysis of elastic and elastic-plastic plane-stress panels with elliptical notches. The numerical results showed excellent accuracy compared to similar results obtained with the finite element method.
The Integrated Local Petrov-Galerkin Sinc Method was used to analyze interlaminar debonding of composite and fiber-metal laminated beams. A double-cantilever beam and a fixed-ratio mixed mode beam were analyzed using the Integrated Local Petrov-Galerkin Sinc Method and the results were shown to correlate well with those by the finite element method. An adaptive Sinc point distribution technique was implemented for the delamination analysis which significantly improved the methods accuracy for the present problem. Delamination of a GLARE, plane-strain specimen was also analyzed using the Integrated Local Petrov-Galerkin Sinc Method. The results correlate well with 2D, plane-strain analysis by the finite element method, including interlaminar stresses obtained by through-the-thickness integration of the equilibrium equations of 3D elasticity. / Ph. D.
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