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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Trellis quantizers and trellis coded modulation : optimal performance over noiseless, awgn, and fading channels

Nassar, Carl R. January 1990 (has links)
Note:
2

Networked Control Systems with Unbounded Noise under Information Constraints

Johnston, Andrew 06 December 2012 (has links)
We investigate the stabilization of unstable multidimensional partially observed single-station, multi-sensor (single-controller) and multi-controller (single-sensor) linear systems controlled over discrete noiseless channels under fixed-rate information constraints. Stability is achieved under communication requirements that are asymptotically tight in the limit of large sampling periods. Through the use of similarity transforms, sampling and random-time drift conditions we obtain a coding and control policy leading to the existence of a unique invariant distribution and finite second moment for the sampled state. We use a vector stabilization scheme in which all modes of the linear system visit a compact set together infinitely often. / Thesis (Master, Mathematics & Statistics) -- Queen's University, 2012-12-06 15:06:37.449
3

DATA COMPRESSION SYSTEM FOR VIDEO IMAGES

RAJYALAKSHMI, P.S., RAJANGAM, R.K. 10 1900 (has links)
International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, Nevada / In most transmission channels, bandwidth is at a premium and an important attribute of any good digital signalling scheme is to optimally utilise the bandwidth for transmitting the information. The Data Compression System in this way plays a significant role in the transmission of picture data from any Remote Sensing Satellite by exploiting the statistical properties of the imagery. The data rate required for transmission to ground can be reduced by using suitable compression technique. A data compression algorithm has been developed for processing the images of Indian Remote Sensing Satellite. Sample LANDSAT imagery and also a reference photo are used for evaluating the performance of the system. The reconstructed images are obtained after compression for 1.5 bits per pixel and 2 bits per pixel as against the original of 7 bits per pixel. The technique used is uni-dimensional Hadamard Transform Technique. The Histograms are computed for various pictures which are used as samples. This paper describes the development of such a hardware and software system and also indicates how hardware can be adopted for a two dimensional Hadamard Transform Technique.
4

An implementation of an AMPS digital base station with adaptive Automatic Gain Control

Hale, Jason Matthew 29 August 2008 (has links)
We consider the problem of designing a wide-band digital receiver for an Advanced Mobile Phone Service (AMPS) cellular system, and the associated problem of choosing an appropriate Analog-to-Digital (ADC) converter. The probability density function of the voltage across a cellular receiving antenna is shown to be dependent on various cellular parameters. These parameters include mobile transmit power, mobile distance from the base station, mobile transmit frequency, and transmitting and receiving antenna characteristics. Given a high-resolution, wideband, uniform and symmetric quantizer, optimal gain factors are computed for uniformly-, sinusoidally- and normally-distributed input signals. These gain factors maximize the quantizer's Signal-to-Quantization Noise Ratio (SQNR) in a mean-square sense. Together, these techniques can be used to implement an adaptive Automatic Gain Control for cellular communications. Results from a comprehensive AMPS base station simulation will also be discussed in detail. These results illustrate several design tradeoff's including Signal-to-Noise Ratio (SNR), Carrier-to-Noise Ratio (CNR), system loading and quantizer resolution. / Master of Science
5

Asymptotic theory for decentralized sequential hypothesis testing problems and sequential minimum energy design algorithm

Wang, Yan 19 May 2011 (has links)
The dissertation investigates asymptotic theory of decentralized sequential hypothesis testing problems as well as asymptotic behaviors of the Sequential Minimum Energy Design (SMED). The main results are summarized as follows. 1.We develop the first-order asymptotic optimality theory for decentralized sequential multi-hypothesis testing under a Bayes framework. Asymptotically optimal tests are obtained from the class of "two-stage" procedures and the optimal local quantizers are shown to be the "maximin" quantizers that are characterized as a randomization of at most M-1 Unambiguous Likelihood Quantizers (ULQ) when testing M >= 2 hypotheses. 2. We generalize the classical Kullback-Leibler inequality to investigate the quantization effects on the second-order and other general-order moments of log-likelihood ratios. It is shown that a quantization may increase these quantities, but such an increase is bounded by a universal constant that depends on the order of the moment. This result provides a simpler sufficient condition for asymptotic theory of decentralized sequential detection. 3. We propose a class of multi-stage tests for decentralized sequential multi-hypothesis testing problems, and show that with suitably chosen thresholds at different stages, it can hold the second-order asymptotic optimality properties when the hypotheses testing problem is "asymmetric." 4. We characterize the asymptotic behaviors of SMED algorithm, particularly the denseness and distributions of the design points. In addition, we propose a simplified version of SMED that is computationally more efficient.

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