Poboljšana elektromagnetska kompatibilnost (EMC) sklopnog energetskog pretvarača sa slučajnom modulacijom

This paper surveys some analytical and experimental results concerning different randomized modulation strategies in switched-mode power converters (SMPCs). After a short review of practical experiences within the literature it presents the benefits of several randomized schemes for power converters (i.e. reduced electromagnetic interference - EMI, and lower acoustic noise). It also introduces the mathematical background for dealing with randomized modulation within the medium-frequency range: power spectrum density (PSD). Finally, the EMI measurements confirm the improved EMC performances of the randomized boost rectifier, as also in the DC-DC buck converter.Ovaj članak istražuje analitičke i eksperimentalne rezultate različitih slučajnih strategija modulacije u sklopnim energetskim pretvaračima (SMPCs). Nakon kratkog pregleda praktičnih iskustava iz literature, predstavljene su prednosti nekoliko slučajnih shema za energetske pretvarače (smanjena elektromagnetska interferencija - EMI, i niži akustični šum). Također, uvedena je matematička podloga za rad sa slučajnom modulacijom u području srednjih frekvencija: spektralna gustoća snage (PSD). Konačno, EMI mjerenja potvrđuju poboljšanja EMC performansi slučajnih uzlaznih ispravljača, kao i DC-DC silaznih pretvarača

Zipf's Law in Short-Time Timbral Codings of Speech, Music, and Environmental Sound Signals

Timbre is a key perceptual feature that allows discrimination between different sounds. Timbral sensations are highly dependent on the temporal evolution of the power spectrum of an audio signal. In order to quantitatively characterize such sensations, the shape of the power spectrum has to be encoded in a way that preserves certain physical and perceptual properties. Therefore, it is common practice to encode short-time power spectra using psychoacoustical frequency scales. In this paper, we study and characterize the statistical properties of such encodings, here called timbral code-words. In particular, we report on rank-frequency distributions of timbral code-words extracted from 740 hours of audio coming from disparate sources such as speech, music, and environmental sounds. Analogously to text corpora, we find a heavy-tailed Zipfian distribution with exponent close to one. Importantly, this distribution is found independently of different encoding decisions and regardless of the audio source. Further analysis on the intrinsic characteristics of most and least frequent code-words reveals that the most frequent code-words tend to have a more homogeneous structure. We also find that speech and music databases have specific, distinctive code-words while, in the case of the environmental sounds, this database-specific code-words are not present. Finally, we find that a Yule-Simon process with memory provides a reasonable quantitative approximation for our data, suggesting the existence of a common simple generative mechanism for all considered sound sources

Switched capacitor filters : theory, analysis, and design /

Includes bibliographical references and indexes

Rapid Prototyping of Digital Systems with COTS/ASIC Components

Electronic Systems Design Automation (ESDA) is one of the challenging tasks in rapid prototyping and verification of digital systems. The goals of rapid prototyping include --- (i) Reduction in the design and verification time by an order of magnitude, (ii) Reduction in the cost of the design and lifecycle support process, and (iii) Capability for rapid insertion of new technology and algorithmic innovations into existing prototypes. This paper discusses the models and views in rapid prototyping, facilitated by VHDL, that allow rapid design and verification of large digital systems. I. Introduction The increasing complexity of subsystems realized by digital hardware has created an urgent need for new design methodologies and tools to reduce the complexity of the design to manageable levels, without compromising on the quality of the product. The design of any complex system starts from an abstract level, where only a set of requirements are known, and works its way down to a physical ..

Toward an Easy Programming Environment for Implementing Mobile Applications: A Fleet Application Case Study Using SyD Middleware

This paper describes the advantages of SyD (System on Mobile Devices), a middleware technology for mobile devices and e-services, in terms of technology and programming. Features of SyD are illustrated here through our prototype application, a complex communication system for a trucking fleet that operates an automated package delivery system. The fleet system has been implemented in three ways, with SOAP, with JDBC, and with SyD. Our implementation experience shows that SyD greatly simplifies coding by allowing heterogeneous devices, peer-to-peer communications, group transactions based on triggering events, and mobility support through proxies and directory service