Signal Processing Concepts Research Articles

Application of Fourier transformation as the basic algorithm for processing cardiorespiratory data of newborn infants

The multiple possibilities for the application of Fast Fourier Transformation (FFT) in the cardiorespirography of neonates are shown as a summary of our own results. The basis is the power spectral analysis of instantaneous heart rate and respiratory movements, which can be complemented by a coherence analysis of both parameters. A model-aided method for quantification of respiratory sinus arrhythmia (RSA) as an additional application for power spectral and coherence analysis is discussed. The realization of Hilbert transformation by FFT makes possible the interval-related calculation of respiration rate. The necessity of this supplementation, as well as the resulting strategies of additional processing steps are emphasized. The results is a concept of signal processing which increases the efficiency of previously employed methods in computer-aided cardiorespirography.

Acquisition and analysis of fire sensor signals in selected environments

An intelligent measurement acquisition system is introduced. The integration of microprocessor, memory and modem at the installation site makes it possible to transmit signals from temperature and aerosol sensors to a security control center via the public telephone network. This concept is eminently suited for reducing the data volume because only the relevant information concerning status changes in an environment that exceed a preset threshold is stored. By analyzing the data it is possible to assess the performance of sensor technologies in specific environments and to evaluate new signal processing concepts.

Bipolar optical modulation and demodulation using dual-mode fiber and a fast diffusion-driven photodetector

A bipolar fiber-optic signal processing and photodetection concept which combines a dual-mode optical fiber with a fast diffusion-driven photodetector is demonstrated. A discussion of the concept is given, and the results of a simple experiment are given. Various permutations of the ideas described can permit different kinds of coherent and incoherent optical-signal processing and optical control of pulsed photodetection.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Improving TV picture quality with linear-median type operations

The FMH filter concept for video signal processing which combines the features of linear and median filters is introduced. In FMH (FIR median hybrid) filters, the overall output is the median calculated over the outputs of FIR subfilters, and the central input sample, the number of values to be sorted, is independent of the filter size; only the size of the FIR subfilters is altered. The noise reduction properties of FMH filters are similar to those of median filters. Applications within the field of digital enhanced TV, EDTV, and HDTV are presented with emphasis on noise suppression and image coding. >

Automatic design and partitioning of systolic/wavefront arrays for VLSI

In this paper we show how systolic/wavefront arrays can be automatically designed and partitioned to solve problems of arbitrary size. Buffer memory and control of a resulting array is regular and simple, and is generated automatically. Also, the throughput of the array is matched with the I/O speed of the host to which it is to be attached. The approach strongly relies upon classical concepts in signal processing, such as signal flow graphs and state transition functional behavior. Some illustrative examples are included.

Ion beam effects in diacetylenes

Due to their unique backbone structure and crystalline organization, polydiacetylenes (PDAs) are considered to be prototype one-dimensional systems. They were shown to have properties considered important to realize concepts of all-optical signal processing. Macroscopic, nearly defect-free, highly anisotropic PDA single crystals are prepared by exposure of diacteylene monomers to various forms of radiation. These materials can also be prepared as thin film crystals and Langmuir-Blodgett (LB) assemblies. We have studied and compared the effects of ion beam irradiation on different configurations of diacetylenes: bulk crystals, thin films and LB structures. Exposure of monomeric diacetylene films to very low fiuence ion beams results in their polymerization and in the formation of good quality anisotropic films of controlled thickness. Significant changes in optical and electrical properties of PDAs were observed and studied by optical absorption and do temperature dependent conductivity measurements.

CONCEPTS FOR DESIGN OF CW RADARS FOR AIRBORNE APPLICATIONS

In this paper it is discussed some concepts in signal design and processing intended to increase the potential capabilities of CW radar system with double modulation to cover certain applications. The signal is phase modulated by pseudo random sequence and frequency modulated -b04, sinewave. The first system is based on parallel range gates and group-of doppler filter banks which is suitable for airborne surveillance. It enables automatic detection of several targets simultaneously and measur-ing range with high resolution, velocity unambigiously and bearing. It also suppresses the leakage and reflections from close-in clutter which are the main problems facing classical CW radars. The second system discussed used the idea of filtering several harmonics of the FM spectrum in the receiver instead of filtering only the third harmonic, then the detected outputs are further combined. This approach enables, beside suppressing leakage, to reduce the losses of power in the receiver. It offers opportunity to increase the maximum range substantialy, nearly double the value, as compared to system using the 3rd harmonic only. This option can use smaller value of the FM frequency. The presented version is suitable for airborne fire control application. The system is evaluated showing advantagesin addition to the properties attained by the system using double modulation.

Geophone frequency calibration and laser verification

A geophone frequency calibration procedure has been developed that provides both amplitude and phase information over a selectable frequency range with a single measurement. It is easy to perform in either a field or laboratory environment using a two‐channel analog input spectrum analyzer, and an inexpensive, easily constructed, shaker table. A second calibration procedure that uses laser interferometry was also developed and implemented to verify the first, more practical method. Agreement between the two procedures is within the uncertainty limits of the test equipment at all frequencies including those near and at physical resonance. Some concepts of digital signal processing were reviewed that affect the interpretation of both calibration and seismic test data.

Computer-based experimental modal analysis at Michigan Tech

The computer has applications in nearly every facet of engineering. At Michigan Tech, to complement our CAD/CAM system we have introduced experimental modal analysis to our undergraduate students. The course assumes a background in vibrations and numerical methods, from which we introduce concepts in digital signal processing, and the use of the discrete Fourier transform. The emphasis of this course is to apply numerical techniques to experimental vibrations. Commercially available modal analysis software is used to extract modal parameters from the structures under test. The core of the student experience is a project exploring state-of-the-art concepts in modal analysis. A discussion of the projects and their results is presented. The results of student polling at the conclusion of the course indicated that problems existed in scheduling of computer time, and that project definitions were insufficient for the level of the student. Changes to be made in the course structure include the application of personal computers equipment to the course and the incorporation of a common data base with the on-line CAD/CAM software.

Computer vision: Signals, segments, and structures

In a computer vision system, we are given one or more digitized images of a scene, and our goal is to construct a description of the scene in terms of known types of objects that appear in it. Thus computer vision deals with digital images, but the techniques it uses are quite different from those used in digital image processing. In this article we describe some of these techniques, and indicate how they differ from methods based on signal-processing concepts.

The NEC μPD7720 Digital Signal Processor — A Laboratory-Based Case Study

The concepts of single-chip digital signal processing are presented via a student-oriented tutorial/laboratory case study. This involves the design of a highpass digital filter using the first-difference design method and its implementation using the NEC μPD7720 Signal Processor.

Dynamic photoelasticity as an aid in developing new ultrasonic-test methods

A prerequisite for the development of quantitative ultrasonic-inspection techniques for surface flaws is a thorough understanding of the ways in which elastic waves interact with defects. Analytical and numerical approaches are presently inadequate. Experimental methods are needed for a better understanding of wave interactions with real geometries. This paper describes how dynamic photoelasticity was used to study the interaction between Rayleigh waves and slots. To fully interpret the interactions between an incident Rayleigh wave and a surface slot, the problem was subdivided as follows: first, the reflections and mode conversions of a Rayleigh wave at a corner were studied. This simulated the Rayleigh-wave interaction with a slot opening. Then, the interaction when a Rayleigh wave ran off the tip of a slot was observed, and, finally, the total interaction with slots perpendicular to the surface was studied. The results for these three cases are presented. It is suggested that the most important property of a Rayleigh wave that can be used to size surface and near-surface defects is the subsurface particle motions. These motions persist up to a depth of the order of a wavelength. The shape (that is, the frequency spectrum of the transmitted wave) should, therefore, be affected by the depth of the slot. Spectroscopic analysis is applied to the photoelastic data to develop a simple method for sizing slots. Results from ultrasonic tests on slots in steel confirm the validity of the suggested method. By applying contemporary concepts of signal processing to photoelastic data, a powerful new area of experimental investigation is introduced. It promises to overcome the current inability of scatter theories to predict the interactions between real-life defects and acoustic waves as used in ultrasonic testing. Applications of this approach will improve the quantitative ability of ultrasonic-inspection methods.

Response to note on the Fourier Series Method

Cooper’s [J. Acoust. Soc. Am. 68, 989 (1980)] recent comments concerning the Fourier Series Method (FSM) demonstrate his total lack of physical understanding of signal processing for line array systems. For example, in his comments, Cooper stated that FSM was not correct because it could not estimate the nonomnidirectional component of the acoustic field using a one-element array or omnidirectional hydrophone. Large aperture, multielement line array systems have been developed because it is fundamentally impossible to measure the directionality of the acoustic field widh a single omnidirectional hydrophone. Cooper’s other comments show a similar low level of physical understanding of very basic signal processing concepts. Two examples are presented to show that the FSM estimates are very accurate indeed.

Integrated Broad-Band Communication Using Optical Networks--Results of an Experimental Study

This paper reports on an experimental system of an integrated communication network built with components representing the state-of-the-art in the area of optical fiber transmission and large-scale integration of logic functions. These components make it possible to apply new concepts for signal processing, transmission, and switching in the experimental system. The large bandwidth of optical channels allows the transmission of all kinds of communication services including data, audio, and video, while semiconductor technology offers low cost realization and mass production of complex signal processing and switching functions to handle all these services within one network. The concept of the system is presented and results on system components and subsystems are given.

Isolated and Connected Word Recognition--Theory and Selected Applications

The art and science of speech recognition have been advanced to the state where it is now possible to communicate reliably with a computer by speaking to it in a disciplined manner using a vocabulary of moderate size. It is the purpose of this paper to outline two aspects of speech-recognition research. First, we discuss word recognition as a classical pattern-recognition problem and show how some fundamental concepts of signal processing, information theory, and computer science can be combined to give us the capability of robust recognition of isolated words and simple connected word sequences. We then describe methods whereby these principles, augmented by modern theories of formal language and semantic analysis, can be used to study some of the more general problems in speech recognition. It is anticipated that these methods will ultimately lead to accurate mechanical recognition of fluent speech under certain controlled conditions.

Interpolation and decimation of digital signals—A tutorial review

The concepts of digital signal processing are playing an increasingly important role in the area of multirate signal processing, i.e. signal processing algorithms that involve more than one sampling rate. In this paper we present a tutorial overview of multirate digital signal processing as applied to systems for decimation and interpolation. We first discuss a theoretical model for such systems (based on the sampling theorem) and then show how various structures can be derived to provide efficient implementations of these systems. Design techniques for the linear-time-invariant components of these systems (the digital filter) are discussed, and finally the ideas behind multistage implementations for increased efficiency are presented.

Rehabilitation Strategies for Sensorineural Hearing Loss,

This book comprises clinical and research articles presented at the Second Symposium on the Application of Signal Processing Concepts to Hearing Aids, Pennsylvania State University, March 23-24, 1979. The initial article presents the role of the otolaryngologist, as viewed by an otolaryngologist, in the hearing rehabilitation process. There are four articleson hearing aid selection procedures. One stresses the need for working closely with the patient during a period of weeks in matching electroacoustical factors with needs in everyday situations. Another compares different real-ear procedures in which amplification is evaluated by behavioral responses. In a third article, the question of binaural vs monaural hearing aids is discussed, and it is emphasized that the decision must rest on thorough testing of hearing aid use in both modes. The fourth article points out the advantages of frequency-selective amplification and output limiting in providing maximum speech intelligibility and comfort. Topics treated in other articles

The ABCD's of Digital Signal Processing (Part 1)

In this article, the basic concepts of digital signal processing will be introduced, leading to a mathematical description of a digital signal processor in terms of, first, a difference equation and, second, a z-domain transfer function. In the process, the effects of sampling and quantization will be briefly touched upon. Implementation of a processor by special purpose hardware and discrete Fourier transform technique will be discussed. The Fast Fourier Transform (FFT) will be introduced and several of its applications will be presented, along with the pitfalls and incorrect usage of the technique.‡

The Application of Signal Processing Concepts to Hearing Aids

It could be argued that there are more symposia today than there are research data to go around. This book, based on some of the proceedings of the First Symposium on the Application of Signal Processing Concepts to Hearing Aids (New Jersey, 1977), is light on research data, concentrating rather on reviews of certain aspects of both signal processing concepts and current hearing aid technology. Despite its title, it also includes chapters on cochlear hydrops and metabolic factors in sensorineural deafness. Some explanation for this is given in the introduction, which states that the book's main intent is to provide useful information to members of the hearing health care team concerned with the improvement of rehabilitative procedures in the area of sensorineural deafness. To this end, the contributors are drawn from the fields of audiology, engineering, otology, and the hearing aid industry. Other topics covered are distortions in impaired ears,

Book Review: The Application of Signal Processing Concepts to Hearing Aids

Book Review: The Application of Signal Processing Concepts to Hearing Aids