Shlomo Engelberg

• Ph.D.
• Professor at Jerusalem College of Technology

Often, data stored in memory must be protected from naturally occurring and malicious errors. Methods for constructing codes that are robust with respect to errors injected into the data as well as into the address (in which the data are to be stored) are described. Several ways of extending data-protecting codes to address-and-data protecting code...

In this note, we examine coherent sampling—a technique generally used to characterize the performance of analog to digital converters (ADCs) [1]–[4]. Coherent sampling causes the spectrum of a pure tone to be as simple as possible, and when used properly, it has additional advantages, which we discuss.

When making measurements, it is often important to have a signal generator that outputs accurate sine waves that can be used as inputs to the system under test. One nice, conceptually simple way to implement such an instrument is to make use of direct digital synthesis. Synthesizers that use this technique, described below, have many nice features....

Moving average filters output the average of N samples, and it is easy to see (and to prove) that they are low-pass filters.

In this “Lecture Notes” column, we show that it is possible to use deterministic arguments to gain some intuition into why using periodograms without averaging does not work well and why they “fail” in the way they do. We then explain how the probabilistic case can be seen as an extension of the deterministic case. Next, we give a brief description...

The imaging depth of field (DOF) of white-light illuminated objects is extended by carefully integrating two image-processing techniques, one optical and one digital. The optical technique makes use of a tailored phase mask positioned at the pupil of the imaging system to cause different color channels to have different focal lengths; accordingly,...

The Nyquist-Shannon sampling theorem states that if all that you know about a signal is that its highest frequency is no greater than B, then if you want to sample the signal without any loss of information, you must sample it at a rate that is greater than 2B. If we call the rate at which we sample Fs, then we find that B <; Fs/2, and Fs/2 is call...

Objective The commonly used noninvasive techniques for blood pressure measurement, auscultatory Korotkoff-based sphygmomanometry and oscillometry, both have limitations in their clinical use. The former is relatively accurate but is limited to use in a physician's office because its automatic variant is subject to noise artifacts. Automatic oscillo...

Transmission across a bus modelled as a parallel asynchronous communication channels is subject to fault injection attacks which cause glitches – pulses that are added to the transmitted signal at arbitrary times – and delays. We present self-synchronizing coding schemes with no latency at the receiver that do not require any acknowledgment to be s...

Cyclic codes were introduced as a classical result of coding theory. The relation between these codes and the algebra of polynomials allows us to obtain polynomial‐based procedures for decoding cyclic codes. The development of coding theory has been characterized by dealing with semicontinuous communication channels. Making use of turbo‐codes or lo...

This chapter introduces the corresponding mathematical description of the statistical effects that accompany real signal fading in multipath communication channels. It examines some specific statistical descriptions of the probability density function and the cumulative distribution function based on well‐known stochastic distributions and laws. Fo...

This chapter focuses on the effects of the troposphere on optical wave propagation starting with a definition of the troposphere as a natural layered air medium consisting of different gaseous, liquid, and crystal structures. In optical communication, the dense aerosol/dust layers, as part of the wireless atmospheric communication channel, can caus...

This chapter provides a comparison between two stochastic approaches for optical and radio communication links, the classical and the approximate, by analyzing changes in the capacity as a function of Ricean parameter, i.e. as a function of different conditions of optical wireless channel. It also provides a detailed analysis of the key parameters...

The light waves, as electromagnetic continuous waves, can be regarded as a probability function whose intensity at any point in space defines the probability of finding a photon there. According to this wave–particle dualism, the emission and/or the absorption spectrum of any material can be used for its identification and to determine the quantity...

To understand dispersive properties of fiber optic structures that transmit optical continuous or pulse signals at long distances, propagating along such optical waveguides, this chapter introduces several important engineering parameters that characterize the corresponding processes of optical communication via fiber links. A problem of transmissi...

An optical communication system transmits analog and digital information from one place to another using high carrier frequencies lying in the range of 100—1000 THz in the visible and near‐infrared region of the electromagnetic spectrum. This chapter describes the basic elements of the optical communication channel, including the transmitter, as a...

This chapter presents a mathematical description of both types of signals – continuous wave and pulses. It provides a canonical statistical description of optical signals, mostly mentioned in the literature of radio and optical communications. The Clarke 2‐D model is a more suitable statistical model for satisfactory description of multipath ray ph...

Atmospheric propagation of optical waves was investigated parallelly with improvements in optical lasers and understanding of the problems of optical wave's generation both in the time and space domains. The theoretical analysis of optical wave propagation, as a part of the whole electromagnetic spectrum, is based on Maxwell's equations. Mathematic...

This chapter presents information on different types of fiber optic structures. The first usually used kind of fiber optic structure is the step‐index fiber. In the step‐index fiber the index change at the core–cladding interface is abrupt, whereas in the graded‐index fiber the refractive index decreases gradually inside the core. To understand the...

This chapter describes the most important principles of discrete signal coding and decoding. K. Shannon's theorems are fundamental results in coding theory. These theorems were formulated for communication channels and show that channels of the type considered by Shannon can be characterized by the value, called the throughput capacity or simply th...

There are two main types of optical signals propagating in wired or wireless communication links: time continuously varied or analog, which corresponds to narrowband channels, and time discrete varied or pulse‐shaped, which corresponds to wideband channels. Therefore, there are different types of modulation that are usually used for such types of s...

In this brief introduction to tracking using state estimation, we compare two techniques. We compare the performance of the well known Kaiman filter to that of a simple receding horizon filter, a less well known technique. Our goal is to introduce the less well known family of techniques and show some of its advantages and disadvantages relative to...

Oxygen saturation in arterial blood (SaO2) provides information about the performance of the respiratory system. Non-invasive measurement of SaO2 by commercial pulse oximeters (SpO2) make use of photoplethysmographic pulses in the red and infrared regions and utilizes the different spectra of light absorption by oxygenated and de-oxygenated hemoglo...

One way of characterizing a system is to consider its response to a unit step function (a function whose value is zero until l t = 0 and is one thereafter). When considering the system's step response , a typical goal is to determine whether it is ever negative (even though the steady-state response is positive), in which case the system suffers...

Introduction: In the work "Error-Correcting Codes for Ternary Content Addressable Memories", Krishnan et al. show that under certain assumptions, using 2t + 1 copies of a word is an optimal strategy for guaranteeing the reliable operation of a ternary content addressable memory in the presence of up to t errors. Purpose: To present a new proof of t...

Transmission across asynchronous communication channels is subject to laser injection attacks which cause glitches, pulses that are added to the transmitted signal at arbitrary times, and delays. We present self-synchronizing coding schemes with low latency at the receiver that require no acknowledgement and can decode transmissions subject to rand...

This note provides a self-contained introduction to Rader's fast Fourier transform (FFT). We start by explaining the need for an additional type of FFT. The properties of the multiplicative group of the integers modulo a prime number are then developed and their relevance to the calculation of the discrete Fourier transform is explained. Rader's FF...

Transmissions across asynchronous communication channels are subject to delay injection attacks which can cause an arbitrary number of skews. That is, such attacks can cause an arbitrary number of transmitted signals to arrive after the first signal of the next transmission has arrived. The (common) assumption that despite the delays all signals fr...

Transmission across asynchronous communication channels can be subjected to delay injection attacks. Delay injection attacks cause arbitrary skews - arbitrary numbers of transmitted signals can arrive after the first signal of the next transmission has arrived. The (common) assumption that all signals form the ith transmission arrive at the decoder...

Over the preceding nearly 20 years, I have taught a "standard" first course in control theory many times. During that time, a way of describing and working with one property of bounded-input, bounded-output (BIBO) stable linear time-invariant (LTI) systems, that such systems forget the distant past, has been developed. Students and instructors may...

The assessment of oxygen saturation in arterial blood by pulse oximetry (SpO2) is based on the different light absorption spectra for oxygenated and deoxygenated hemoglobin and the analysis of photoplethysmographic (PPG) signals acquired at two wavelengths. Commercial pulse oximeters use two wavelengths in the red and infrared regions which have di...

Reading about things is all fine and good, but the best way to understand a concept is to put it into practice. After years of one of us (Shlomo) teaching about analog to digital converters (ADCs) and digital to analog converters (DACs) in general, pipelined ADCs in particular [1], and discussing, experimenting with, and writing about compressive s...

In the current study, a non-invasive technique for systolic blood pressure (SBP) measurement based on the detection of photoplethysmographic (PPG) pulses during pressure-cuff deflation was compared to sphygmomanometry—the Korotkoff sounds technique. The PPG pulses disappear for cuff-pressures above the SBP value and reappear when the cuff-pressure...

We consider the problem of securing data using linear and nonlinear codes over the binary numbers. We start by developing a conservation law for codes. Then we explain why linear codes, which are easy to understand and implement, are useful when protecting data from rarely occurring random errors. By a simple argument, we demonstrate that linear co...

In engineering, as in life, it is sometimes necessary to "harm" something in order to help it. When windowing data before calculating its discrete Fourier transform (DFT), we corrupt "pristine" data to minimize certain types of distortion to the DFT. It has been shown that sometimes it is beneficial to add some noise to a signal, to "corrupt" it, b...

When I started writing this column, I had just finished teaching a required course called "Analog and Digital Electronics" during a short summer semester. This course is given several times each year and is a semester-long course. It is given to a wide variety of students; the common factor is they are not students of electrical or electronics engi...

In mid-February, the IEEE Instrumentation and Measurement Magazine was evaluated by the IEEE. The magazine is reviewed every five years, and the review involves researching and writing a report about the magazine and meeting with the group that evaluates the society's publications. It is also a time for those of us who work on the magazine to refle...

The tabernacle, the Jewish nation's central point of worship while in the desert and for many years after, was designed in a modular fashion and was meant to be assembled and disassembled on a regular basis. Its component parts were works of beauty and were built by the best craftsmen of their day. In the description of the assembly of the tabernac...

There are seemingly harmless decisions that I made and habits I got into years ago that I now regret. It seems like every year I work a bit more. You wouldn¿t think that adding five or ten minutes to your workday would be a big problem, but if you add a few minutes about once a year, over the course of twenty years , those minutes easily become a c...

When measuring a signal, there are rules that must be followed. Given a low-pass signal, the Nyquist sampling theorem states that if you want to be able to reconstruct the signal from its samples, you must sample the signal at a rate that is greater than twice the signal's bandwidth [1]. As with most rules, there are "exceptions" to this rule. As y...

Recently, my family and I camped out on the beach at Beit Yannai, Israel. While standing in the waves with my children, nieces, and nephew, I looked out over the Mediterranean Sea (while keeping a close eye on the children, of course). Watching and feeling the waves, I was swept away by the power and grandeur of the sea. Feeling the strength of the...

In this paper, we describe our experiences running a "partially virtual" microcontroller lab. We show that though the virtual portion of the lab can contribute to the students' understanding, there are also several pitfalls that must be avoided or dealt with. We have found that our "virtual microcontroller" simulates a true microcontroller to a rea...

Some time ago my older daughter turned twelve, and my wife and I threw a large party to celebrate her coming of age. Then we came to New York to visit my parents and my extended family. Because my parents were not able to come to the celebration that my wife and I held, they decided to throw a party as well, and they invited friends and family who...

This paper presents generalizations of the Karpovsky–Taubin nonlinear code. The generalizations lead to robust and partially robust single error detecting codes and single error correcting codes.

We engineers are generally "number people," and we should do what we can to help our fellow citizens see how numbers can help them understand the world around them. One area where many people could use some help is risk analysis.

In engineering, as in life, it pays to be polite. When polite folk engage in conversation, one does not interrupt the other. If two people do happen to start talking at the same time, one of them stops and listens to the other person until that person finishes speaking. Polite people constantly make 'measurements' of what is happing around them, an...

I am writing this while flying from Israel to the United States. As usual, I am flying economy class, and college professors' salaries being what they are, this is not likely to change any time soon. Though I enjoy visiting different locales, flying is not something I do for pleasure. From the time I go through the initial security check to the tim...

I am an engineer, and like many engineers, I am quite conservative. Though I love learning about new technology, I do not like to migrate from the familiar to the new - even if the new may be better. For a long time, I had my doubts about people who dreamed of making revolutionary changes, but now I know better. Without dreamers, little progress wo...

Recently my family celebrated a couple of life cycle events. In both cases, we cooked up massive dairy meals for our nearest and dearest. At the second party, one of our friends came to me with a smile and said, "I see that you caved in again. First, you got a dog, and now you are making dairy parties." She knows that I do not like most dairy foods...

Fourier analysis is often thought of as a technique for measuring the spectral content of a signal over the period in which the signal was measured. In this column, we discuss techniques that allow you to use Fourier analysis to provide accurate measurements of the instantaneous frequency of a signal. We discuss the short-time Fourier transform and...

Each time we interact with the world at large, we choose how to structure the interaction. We probably do our best to behave responsibly and to carry out the duties with which we have been entrusted. This, however, is not enough. We should try to help people even when a narrow (and perhaps even correct) definition of our duties does not require it.

Life is a process of continual learning, and for children and young adults this is even truer than for adults. As a father of children whose character and personality are still developing rapidly, I often think about what I want my children to learn and how I want them to learn it. As a parent and a teacher of young adults, I try to determine how t...

At this time each year, we publish the AUTOTESTCON issue. In this issue, we cover the 45th edition of AUTOTESTCON which was held in Anaheim, California from September 14 ߝ 17, 2009.

Presents the editorial for this issue of the publication.

Capacitive sensing is a way of sensing changes by measuring changes in capacitance. We decided to build a very simple mouse using home-grown capacitive sensors. Using an analog microcontroller (the Analog Devices ADuC841), a few simple chips, and a few cents worth of copper we put together a very simple capacitive-sensing based mouse. Along the way...

Control theory is one of the courses that I most enjoy teaching. I have been teaching the course for well over a decade now, and I still find the material very interesting. Sometimes the parallels between this engineering discipline and real life ¿ the kind that is often not amenable to mathematical analysis ¿ seem very clear to me.

Iam approaching my mid-forties. As a young child, I used to speak to my dad and to my uncle Stevie about computers. As a twelve year old, I went to work with my dad and learned to program a computer. (I used a TRS-80 Model I, Level II at Queensborough Community College.) I went to college and studied engineering and learned more about science and t...

For many years now, there has been a move toward modular design. Modular equipment is often cheaper to maintain. If you need to only test ten modules to determine why a piece of equipment is not working, you can save a lot of money on fault analysis. If repairing the piece of equipment means throwing out the bad module and slotting in its replaceme...

There are many measurement applications in which it is not sufficient to store the measurements. It is often necessary to prove that the stored data have not been altered since the measurement was made. In a previous column [1], we discussed the general theory of one of these methods. This column gives the details. The method has two basic steps. G...

I write this having just returned home from a trip to MadaTech¿ the Israel National Museum of Science in Haifa. My family spent almost two hours in the museum, and we spent a whopping eight hours in transit. On the face of it, this had to be one of the least ¿effi cient¿ trips in recent history.

There are many data-logging applications in which measuring a signal and storing the measured values are not sufficient. Sometimes you must be able to prove that the record that you have made, and that you make use of later, has not undergone any changes since the time at which the measurement was made. This is the case in many forensic application...

People often request things that they believe are a means of achieving a particular end. As a department chair, I get many requests from students, and with the best will in the world, I cannot grant all the requests. When a request is denied, the student making the request often requests something else .

In mid-September, my family became the foster parents of one of the most advanced instrumentation and measurement systems in existence: a seeing-eye dog in training. As we learned, the majority of a seeing-eye dog¿s formal training takes place when the dog is about one year old. From the age of about two months, the dogs are given over to the care...

Matched filters are used when one would like to determine whether or not a particular, known waveform is present in a signal that has been corrupted by random noise. We show that in a sampled-data system, increasing the sampling rate only makes substantial improvements in the filter's performance up to a certain point. Sampling very quickly turns o...

Until I started helping edit the I&M magazine, I was not one to attend a conference unless it was either fairly local or located near someone with whom I was trying to collaborate. Because of the need to meet with my colleagues, I went to last year's I2MTC. While there, I gave a tutorial, presented a paper, worked with the then editor-in-chief of t...

Pulse oximetry is an optical technique for the assessment of oxygen saturation in arterial blood and is based on the different light absorption spectra for oxygenated and deoxygenated hemoglobin and on two-wavelength photoplethysmographic (PPG) measurement of arterial blood volume increase during systole. The technique requires experimental calibra...

I am writing this in mid-August during my annual summer visit to my parents in New York. In an attempt to absorb some culture and to expose my children to some culture, my family and I have been visiting some of the museums on the eastern seaboard. Yesterday, we went to the Metropolitan Museum of Art in Manhattan. It was the fi rst time my daughter...

In this column, we describe what may be the ultimate in do-it-yourself noise measurement tools. We show how you can use noise to make rather detailed measurements of the properties of a passive fi lter and how noise can be used to provide perfect encryption¿at least in principle.

It is shown that the response of piezoelectric elements to pseudorandom sequences may be correlated to the external pressure the piezoelectric element is subjected to. Thus a static force sensor was developed based on this phenomenon. This is achieved by measuring the variations of the piezoelectric sensor series resonance branch (at its first reso...

Control systems use feedback to help achieve the two goals of stabilizing a system and causing the system to perform well. Often it takes some time for the information about the system (or the state of the system) that is being "fed back" to reach the feeding information back to the controller, the problem of delays in feedback systems has, once ag...

The focus of this issue is distributed systems. We have an article concerning a safety critical network for distributed smart traffic signals, a column that deals with distributed measurement systems, and a control theory tutorial that deals with how one treats delays. (Delays are often a problem in distributed systems.) We also have an article on...

In Part I of this series of tutorials, I discussed why an instrumentation and measurement specialist must have a passable knowledge of control theory. I presented the relevant history of the subject and a brief introduction to both the advantages and the problems associated with feedback. In this part of the tutorial, I take up the mathematical end...

In this article, it describe two ways to implement a variable-Q digital filter. First, present a simple variable-Q filter and then illustrate why its frequency response is less than ideal. Next, show a trick to modify that filter, making its performance nearly ideal. As always, the choice of which filter to use is made based on the user's applicati...

Consider a cocktail party with many people attending and many conversations going on simultaneously. If we recorded the sound from somewhere in the room, we would find that we had recorded many conversations at once, and it would be very difficult to tell what was being said by any given person. The problem of taking such a recording, or several su...

Control theory is the branch of engineering that tries to answer questions like "given a system configured in a particular fashion, will the system behave reasonably?" That is, control theory deals with analyzing systems. Control theory also tries to answer the question "given a system with (negative) feedback, what can I add to my system to see to...

We often ignore the long term ethical implications of our actions.

Many applications call for the determination of the points at which a function changes values in a discontinuous fashion and require knowledge of the change in the function's value at such points. We present methods of determining the locations of discontinuities by considering the Fourier coefficients of a function. We take the Fourier coefficient...

In the late seventies, Kaiser and Hamming described a simple technique for filter sharpening that can be applied to symmetric FIR filters. We present an analogous method for producing better, "sharper," windows for use in the calculation of the discrete Fourier transform of a sequence. We present a simple method for taking a window and making the c...