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This article highlights a customized mentoring program that successfully supported underrepresented students in science, technology, engineering, and mathematics (STEM) disciplines at a university in the northeastern part of the United States (U.S.). Because of the national and regional needs to augment underrepresented, minority, first-generation, and low-income STEM college students, this study investigated efforts to expand the number and retain such population in higher education STEM programs through a customized mentoring program based on a National Science Foundation (NSF) grant. In particular, we evaluated the necessity of strong and broad-based mentoring characteristics using assessment tools and surveys. The study was conducted with 34 participants in STEM fields. The participants’ motivation mean scores in STEM was measured at three different points in time (pre-, mid-, and end-year) and compared using descriptive statistics and repeated measures analysis of variance (ANOVA). Results obtained indicated significant improvement in mentoring characteristics such as goal orientation, resource management, and academic performance with mean scores ranging from 4.99 to 5.21. Although additional findings from the repeated measures ANOVA showed no statistically significant differences, however, the marginal mean scores suggest the customized mentoring program had some positive effect and the mentoring practices supported underrepresented groups toward successful navigation of STEM disciplines. We discuss the study limitations, implications, and future research directions.

S-parameter characterization of high-speed interconnect components is prone to numerical, modeling, and/or measurement error due, in part, to the sampled nature of the data. This is a problem in modern package design where extensive signal integrity simulations are required to validate a system’s performance. This article presents a new method of treating sampled S-parameter data where a criterion is developed to clearly state the minimum number of S-parameter frequency points required to adequately represent an analog physical system in the frequency domain. This criterion is akin to the Nyquist principle when sampling in the time domain. Based on this principle, the proper time-domain representation of S-parameters can be obtained using the inverse fast Fourier transform (IFFT). However, in order to use the IFFT, the bilinear transformation is applied to the vector fit S-parameters to place them in the z-domain. From the z-domain, the proper discrete impulse response is obtained. A lower bound, based on the discrete Heisenberg principle, is also offered to deal with frequency–time resolution of the S-parameters. The proposed method is successfully tested in the measured and simulated S-parameter data. The usefulness of this method is to accurately represent the time-domain behavior of the physical system S-parameter data, i.e., time delay causality, and, therefore, facilitates the applications of well-developed digital signal processing (DSP) techniques in S-parameter sampled data.

The plastic materials form an important constituent of connectors and printed circuit board substrates. At high data transmission rates in interconnect devices, knowledge of the plastic’s performance, such as its dielectric properties is an imperative and challenging research task for signal integrity engineers. In this paper, wideband dielectric characterization of triethylene glycol dimethacrylate ester (TrEGDMA) organic plastic material is presented using the transmission line technique with a coaxial airline in the frequency range of 1–18 GHz. The Debye models are used to analytically describe the frequency dependence of the extracted TrEGDMA dielectric properties obtained from the measured S-parameter data. A three-pole Debye model was fitted to the extracted permittivity data, where the parameters of the Debye model were obtained from a genetic algorithm. Dielectric property results coupled with its mechanical properties show that this organic plastic, which is widely used in 3-D printing, can be used as a substrate for short traces and in connector housing.

A method for extracting the effective copper surface roughness of a laminate in situ is introduced. The rough copper attenuation as a function of surface roughness is removed from the total attenuation. The residual loss is fit to coefficients, and an error is calculated based on the remaining apparent surface roughness contribution. When the error is minimized or when the apparent surface roughness contribution is nearest zero, the effective surface roughness is found, and the dielectric attenuation is isolated by subtracting the rough copper attenuation from the total attenuation. Using this value, accurate broadband permittivity values can be extracted by simply measuring the S-parameters of two stripline transmission lines. Further, the extracted dielectric electrical properties are calculated with a higher accuracy than the existing methods that neglect copper surface roughness. A supplementing method to unwrap the phase constant is also included in this work to avoid errors do to the length of the devices. Previous methods of extracting laminate material properties that consider copper surface roughness rely on cutting the sample to make a cross-section and observe the surface roughness directly. In this work, the effective surface roughness is gathered without destroying the sample.

The Non-Metallic Connector (NMC) was introduced several years ago. In this new iteration, the NMC has been redesigned to accomplish data transfer with an optical interface and wireless power transfer with the use of micro-inductors. To demonstrate the wireless power transfer (WPT), an NMC for a USB flash drive is proposed. The challenge for the WPT design is to understand the geometric and physical constraints inside the connector housings (form factor). Equations for optimal power transfer performance in this miniature environment are presented followed by simulations that verify the efficient WPT. Initial measurements on the proposed WPT system also validate the concept.

As data rates continue to rise, data protocols allow engineers the bandwidth and speed necessary to utilize an ever increasing video resolution and quality. The Mobile Industry Processor Interface (MIPI) D-PHY CSI-2 protocol is one such solution. The MIPI standards utilizes High Speed (HS) and Low Power modes. These modes occupy the same data lines, making oscilloscope measurements difficult to obtain because the modes are constantly switching. In addition, the amount of data sent, during HS mode, changes with each packet. Real time oscilloscopes can recognize the HS mode data and wait for single triggered measurements to create a real time eye diagram. This process is time consuming and if the PCB is not designed for signal integrity testing, the measurements involve holding a differential probe steady on the DUT, introducing human error. In this paper, we propose to use Time Domain Reflection (TDR) measurements which can be easily made on any board as they do not require capturing live data. Using differential probes, TDR measurements also capture waveforms for each data lane and obtain an eye diagram. Results show a good correlation between real time scope and TDR eye diagrams. Also, TDR software allows S-parameters to be obtained.

As the data rate of high-speed digital transmission increases, the need for high-quality power distribution within the system will continue unabated. Space constraints can sometimes dictate that both power and high-speed signals must be run together within a high-speed connector. This raises the concern that the high-speed signals could impose noise on the power pins, and that this noise could propagate onto power and ground planes and cause instability within the power distribution network (PDN). This paper uses full-wave 3-D electromagnetic modeling and circuit simulation to compute the noise transferred onto ground pins. It uses that noise as the excitation source in a subsequent full-wave analysis of a ground plane and by plotting the current density, observes the possible disruption to the PDN.

In this paper, a new and simple approach is presented to remove random jitter and intersymbol interference (ISI) effects from NRZ (Non-Return-to-Zero) signals. The method presented uses a Kalman filter to predict and remove the random jitter noise and Intersymbol Interference (ISI). Random jitter is modeled as a Gaussian distribution, with jitter effects on both rise and fall times of the signal. The Kalman filter adapts based on the provided model and predicts the exact position of the rise and fall times of the clock signal and a look-up table, combined with the Kalman filter, predicts the exact level of the signal. Random jitter and ISI simulations in MATLAB are presented and the results obtained are highly promising. The method provides a new approach to remove jitter from high-speed links without the use of clock data recovery circuits, feedforward and feedback equalizers.

A method of extracting the effective copper surface roughness of a laminate in situ is introduced. The rough copper attenuation, as a function of surface roughness, is removed from the total attenuation. The residual loss is fit to coefficients, and an error is calculated based on the remaining surface roughness contribution. When the error is minimized or when the apparent surface roughness contribution is zero, the effective surface roughness and dielectric loss contribution are found. Using this extracted dielectric loss, broadband causal laminate electrical properties are calculated with higher accuracy than existing methods that neglect copper surface roughness. The new method uses S-parameter measurements of stripline traces and does not require a cross-section of the sample.

This study deals with an electromagnetic compatibility (EMC) problem of fiber cable in disturbing electric field. Lightwaves that emerge from the output endface of the fiber are intensity modulated, phase shifted, or modulation frequency multiplied under special conditions. In this paper, theoretical investigation of the effect of interfering electric fields on the bit error rate of digital signals propagating originally in an optical fiber is presented for the EMC evaluation. Theoretical analysis and specific numerical examples show that depending on the required EMC level, the unshielded fiber may not be immune to interference of electromagnetic fields.

A method of determining electromagnetic interference shielding effectiveness of various cases has been developed using a modeling technique where radar cross section (RCS) is used in the calculation of shielding effectiveness and a planar wave is utilized to model mode stirring in the reverberation chamber. In addition, a new shielding effectiveness equation is derived in terms of RCS. Three different test cases based on the small form-factor pluggable family are measured and compared to the simulation results based on the derived shielding effectiveness equation. The measurement and simulation results are plotted and compared to validate the proposed modeling methodology. It was found that results from the measurement and simulation are in good agreement and the simulation method is validated.

In this paper an extension to the previous work done in the Jitter modeling for high speed communication links, is presented. For the technique called “Bin Multiplication” the work was done only for NRZ systems, we derived a new general equation to find the total number of combinations for any-level system: PAM4, PAM8, etc. Moreover, the bin multiplication algorithm is developed for correlated random jitter, modeled using correlated Gaussian probability density functions (pdfs). With this approach, a more generalized and accurate jitter modeling, for PAM 4 is provided.

Differential signaling is commonly used in a large number of consumer electronics devices, including USB 3.0 channels. However, skew in differential signaling can adversely affect a channel's performance. Most of the analysis has been done on individual components of a channel; however, there is not much work done in analyzing the effect of skew on the overall system performance, from transmitter-to-receiver. The goal of this paper is to evaluate the effects of transmitter-to-receiver channel skew on channels using the Input/output Buffer Information Specification- Algorithmic Modeling Interface (IBIS-AMI) standards IBIS-AMI models. To check channel's performance, simulations are obtained at data rates from 5 to 25 Gbps.

Plastic materials form an important constituent of interconnect devices. Wideband characterization of the dielectric properties of interconnect plastics is indispensable to characterize the signal integrity performance of interconnects, which are used in a large number of consumer electronic devices. In this paper, wideband dielectric characterization of Triethylene Glycol Dimethacrylate Ester (TrEGDMA) organic plastic material is presented using transmission line technique for the frequency range of 1–17 GHz. Debye models are used to analytically describe the frequency dependency of TrEGDMA dielectric properties obtained from the measured data. These models can be utilized by commercial software packages to assign frequency dependent material properties to a solid made of TrEGDMA plastic.

This paper presents the probability distribution function (PDF) of the ratio of two random waves. This result is used to obtain the PDF of S-parameters random errors in magnitude (in decibels) and phase, which are the quantities that most engineers work with. These results are further used on the development of a Monte Carlo simulation method in order to predict the variability of frequency-domain measurements. Experiments are performed to identify and characterize frequency-domain random errors, such as instrument noise, connector repeatability, and calibration variations, in measurement systems. By comparing with real measurement data, it is shown that random-error effects can be accurately estimated by the PDF's obtained and the Monte Carlo technique.

This paper is focused on the development of a simulation method to evaluate relative humidity (RH) and temperature effects of scattering parameters on transmission systems from DC to 26 GHz. The first step in the analysis is to design a number of experiments to quantify the environmental impacts on S-parameters. Then, a method is proposed to model the RH and temperature effects on microstrip transmission lines, without the need for extensive and complex S-parameter data collection or the use of an environmental chamber. The proposed method was achieved after data analysis which included filtering, fitting, and interpolation, both in magnitude and phase of the S-parameters. The results show that the RH and temperature effects on transmission systems can be accurately modeled and predicted. This method can be applied to different printed circuit board materials, and it will be useful to engineers and manufacturers interested in predicting environmental impacts on system performance.

Differentially-routed traces on printed circuit boards typically incorporate loose in-pair coupling when compared to the coupling between the traces and the ground planes. Loose coupling facilitates in-pair skew correction without affecting the differential-mode impedance. However, practical channels combine printed circuit boards with other components that have different degrees of in-pair coupling which could affect the crosstalk among adjacent pairs. This paper examines the effects of different degrees of in-pair coupling on near end crosstalk in the absence of in-pair skew. The analysis will help printed circuit board designers to choose the desired degree of in-pair coupling to achieve targeted near end crosstalk performance.

A hash map implementation of the link analysis technique for obtaining jitter is proposed, under non-linear receiver conditions. The jitter PDF obtained from the link analysis, which typically assumes an LTI system, is passed through the I/O non-linear CMOS receiver voltage characteristics, obtaining the final jitter distribution. Simulations show promising results.

Performing real-time note detection of multiple audio sources, such as guitar signals, is a difficult task due to the complex nature of these signals. For instance, guitar notes are close in pitch and the harmonic overtones of each note are strongly interlaced, thus preventing standard filtering techniques. In order to accomplish note detection, a harmonic matching pursuit algorithm has been used to decompose an audio signal in terms of elementary waveforms called harmonic atoms. These atoms are derived from the standard matching pursuit algorithm, and are part of an extended and overcomplete Gabor dictionary. In this paper, the search over Gabor dictionary is optimized by using signal modeling of the guitar signal in order to pre-calculate a parameter set; therefore avoiding a costly search over the extended Gabor dictionary. The parameter set defined for the proposed algorithm includes time-location, decay rate, frequency, scale and phase, which are calculated at the onset of each note played. This optimized algorithm is demonstrated through synthesized and real guitar signal examples. Considerable computational savings of this proposed algorithm over the harmonic matching pursuit algorithm are achieved.

A fast and accurate characterization method of differential via holes is presented based on the equivalent circuit extraction technique. A 3-D model of differential via holes is created and simulated using a full wave solver and the results are compared with the equivalent circuit model using Advanced Design System software. Results presented validate the proposed approach. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.

Signal Integrity is now an integral part of the design cycles for consumer electronics devices. One of the major issues in signal integrity is passivity check and restoration of passive devices. This paper will introduce a new efficient technique of passivity restoration based on finding the local minima in the singular value vs. frequency stemming from the system matrix. The proposed new technique for passivity enforcement has the potential to restore the passivity in a real or simulated system represented by S-parameters without making significant changes in the system's original S-parameters or the systems characteristics.

This paper presents a theoretical model of the differential-mode operation of unbalanced pairs and a method for its characterization. A differential pair having temporal imbalance is characterized using S-parameter representations. Measurements in the frequency domain are performed. These measurements validate the proposed theoretical model. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1169–1174, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21549

A method to synchronize the output data in fiber optic links is proposed where the alignments for I and Q symbols are incorporated into a Kalman filter producing a received output that is corrected for polarity and phase rotations of the data symbols without any further pipelined delays post-Kalman filter.

Power line communication, abbreviated as PLC, is a communication technology that uses existing power transmission lines to carry data. It is also known by many other names such as power line carrier and broadband using power line communication. PLC is used in a wide range of applications, like home automation, Internet access and also smart grid communication. However, due to the nature of the communication link (over power lines), PCL suffers the effect of different noise components. In this paper, asynchronous noise is further analyzed in PLC systems using Orthogonal Frequency Division Multiplexing (OFDM). It is well-known that the above noise is one the critical elements to be modeled and analyzed. In this paper, the OFDM sub-carriers are modulated using BPSK, 4-QAM and 16-PSK.

Relay users play a significant role in cooperative communication system improving the overall performance by increasing reliability. First, based on code division multiple access (CDMA) techniques, we propose a network coding (NC) based CDMA cooperation, which consumes less time slots in either synchronous or asynchronous transmission. Further, NC-based cooperative system saves transmission bandwidth, in other words, we show that it reduces outage probability as compared to the traditional cooperative communication system. These results are shown considering a Nakagami-m fading channel.

In cooperative communication system, mobile users are constantly transmitting and relaying data. On the other hand, network coding has been widely investigated in communication system. In this paper, we aim to combine network coding with the conventional cooperative communication system, however, we face certain problems. The main property of cooperative system is diversity; however, when network coding operation is introduced, it violates the rules of diversity. The new signals transmitted by relays are no longer like those sent from the transmitters. In order to fix this problem, in this paper we introduce a method using a multiplier rather than the binary sum operation, which is normally used in network coding. Numerical analyses using maximum ratio combining (MRC), for performance analysis, show that the proposed method improves diversity, i.e. reliability, without deterioration of the average probability of error. Cooperative communication is widely used in consumer wireless communication.

A portable three-dimensional vision coordinate measuring system capable of determining the six degrees of freedom (6DoF) is proposed in this paper. This cost-efficient test equipment is intended for use in manufacturing and assembly processes, such as the alignment process of aircraft stations. The three-dimensional vision coordinate measuring system is a low cost line-of-sight (LOS) system. It is capable of measuring large objects in the field, and has reduced setup times, as compared to other test measuring systems. Whereas conventional coordinate measurement systems provide three dimensional measurements in a Cartesian coordinate system, the system proposed in this paper is capable of determining yaw, pitch, and roll with respect to a camera. The three-dimensional vision coordinate measuring system consists of light-emitting diode (LED) planar target, a high resolution camera, and a laptop computer. The equations of the three-dimensional vision coordinate measuring system are derived from analytical geometry and the perspective of three collinear points. This paper explores techniques to measure the 6DoF of a LED planar target in monocular image. Experiments confirming the validity of the three-dimensional vision coordinate measuring system are included in this paper.

This paper proposes an improved pre-equalization approach for the transmitter in the new high speed communication IEEE 802.3ba 40G/100G Ethernet standards. It is noted that the new 64b/66b encoder, for the above standards, causes a shift in the signal's power spectral density. Preliminary results show that the power shift is not uniform. Depending of the bit rate, in some cases the encoder shifts the spectrum from the low frequency to the high frequency region of the spectrum; at other bit rates is the opposite. This problem is compounded by the attenuation of the signal caused by the frequency response of a typical physical channel. In this paper, a transmitter pre-equalizer is proposed that compensates for this spectrum shift. In addition, this approach is aimed at emerging high speed data standards which are transmitting at 25 Giga bits per second (Gbps) on a single trace using the 64b/66b encoder. Based on our previous experience, a receiver equalizer will be proposed to enhance the performance legacy backplanes so that they can work up to the 25 Gbps speeds.

In this paper, the authors propose an alternative methodology of modeling jitter for high speed communication links through a technique called "Direct Computation of Probabilities". Jitter modeling cannot be expressed through ordinary means for linear time invariant (LTI) systems as timing distortions (jitter) are comprised of numerous components that are neither linear or timeinvariant or even wide-sense stationary. Therefore, special algorithms have been developed to merge and transform these two sets of data, i.e. timing distortion and signal amplitude values, into a set of probability distributions, which are then compared to the output of other analysis techniques such as link analysis and peak distortion analysis.

With the emergence of new high-speed data standards, such as the IEEE 802.3ba, the clock rate on individual channels can go up to 10 Gbps creating the need for highly efficient encoding schemes. One such scheme is the 64b/66b. An undesired effect of using encoding schemes is the spreading of signal power to higher harmonics, thereby requiring greater bandwidth to transmit the signal. A clear understanding of the exact effect of the encoding scheme on the PSD of the transmitted data will help in better understanding the bandwidth requirements associated with these encoding schemes. This will prevent over budgeting of the channel requirements and allow for more exact specifications to be developed. This paper analyzes the change in the power spectral density of random data when encoded using 64b/66b scheme. A comparison to similar effects caused by using 8b/10b is presented for reference. The results show consistent variations in PSD which allow us to characterize the encoding scheme.

As high-speed data applications, such as USB 3.0, are coming down to the consumer electronic world, there is a need of accurate methods to characterize channel behavior. This paper investigates further S-parameter phase errors when de-embedding a device under test (DUT) from onboard structures. A fixture model containing a DUT is constructed enabling the determination of the de-embedding solutions. From these solutions, new equations for DUT S-parameter phase sensitivity are developed. The improved method enables accurate de-embedding of the phase of high-speed connectors used in consumer electronics hardware.

With new high speed data standards, such as USB 3.0, data rate has increased up to 5 Gbps (a 10-fold increase from USB 2.0) creating new challenges for a design engineer. Amid these speeds, issues like crosstalk, signal integrity and bit-error rates are coming to the forefront of the design cycle, especially for consumer electronics-related devices. Therefore, there is a need of accurate methods to characterize device behavior at high frequencies. For instance, S-parameter characterization of high speed interconnect components by full wave field solvers, macromodels and physical measurement are prone to numerical, modeling, and measurement error. This error can lead to non-physical results such as passivity violations. This is a major problem in modern package design where extensive signal integrity simulations are required to validate a systems performance and passivity violations can cause such simulations to fail completely. This paper presents a new method for restoring passivity to non-passive S-parameter data by using singular value decomposition. Simulations show promising results although the method is limited to passivity violations of 1dB.

Nanosecond discontinuities are a concern in separable-interface connectors. Speculation about their causes includes the structural movement between perfectly clean and flat contact surfaces and/or surface irregularities and presence of surface films. Both of these scenarios are considered here in the context of high-speed transmission (i.e. greater than 1 Gbit/s) in backplane connectors. Because such connectors have gold-to-gold mating surfaces, oxide-related discontinuities such as may occur with tin, silver, or aluminum interfaces are not considered. This paper considers the propagation speed of a stress wave to show the unlikelihood of nanosecond discontinuities arising due only to macroscopic structural shock and vibration. Thus, contact physics and the presence of contact imperfections, are required to cause nanosecond-level intermittences. Assuming that a discontinuity of one or several nanoseconds does occur, the short duration of the event permits only a minute separation between the two contact surfaces. This effect is equivalent to and modeled as the insertion of a very large series capacitor between the two conductors. At high frequencies, such a capacitor would behave quite similarly to a short circuit. Circuit simulations of a communication link and the resultant insertion loss and eye patterns show that these discontinuities do not disrupt high-speed data transmission.

The phase error problem in de-embedding is examined for board structures and devices under test (DUT). The main feature of this paper is the comparison between the S-parameter data for the embedded DUT and the data for a judiciously chosen reference situation. It is important to note that de-embedding the phase is essential in the design of high-speed connectors in consumer electronics hardware, especially in providing "swappable" models for high-end microprocessor-based applications.

In this paper, an adaptive equalization technique of a multi-gigabit channel using duobinary signaling is proposed. Both the receiver and transmitter are equalized and implemented using ADS. The results show that the duobinary signaling performs better than NRZ at half of the bandwidth. The algorithm was tested in a Tyco XAUI-FR4 backplane.

In this paper, a new adaptive equalization technique of a multi-Gigabit channel is proposed. This approach calculates the voltages probability density functions of the received signal; and based on the spread of the PDF curves, weights of FIR filters are updated. The algorithm was tested in a Tyco XAUI-FR4 backplane.

This paper presents an automatic region of interest (ROI) generation algorithm for images, where the information provided by the wavelets decomposition is re-used to automatically cluster pixels according to their energy values. The clusters are found using the K-means algorithm and then classified as belonging to the ROI depending of their entropy. Results show the benefits of the algorithm.

Performing real time note detection of multiple audio sources is a difficult task due to the complex nature of audio signals. Typically notes are close in pitch and the harmonic overtones of each note are strongly interlaced, thus preventing standard filtering techniques. In this paper, we develop signal-optimized harmonic atom matching pursuit algorithm, which will be used to decompose an audio signal in terms of elementary waveforms called harmonic atoms. Matching pursuit is an iterative algorithm that correlates the signal against a dictionary set of Gabor atoms and searches for the atoms that exhibit the highest level of correlation. The resulting matched atoms allow for accurate and efficient detection of a single note or multiple notes played simultaneously. In this paper prior knowledge of the signal is used to calculate a parameter set to avoid a costly research over the complete dictionary. The parameter set defined for our proposed algorithm includes time-location, decay rate, frequency, scale and phase, which are calculated at the onset of each note played. The onset (transient) is detected by using a fourth order digital difference then an appropriate interval and optimal window atom is selected. This optimized algorithm is demonstrated through synthesized analysis example. The application of this algorithm in multi-source audio signal can also be demonstrated.

This paper presents the calculation of the differential impedance, the velocity of propagation, and the worst-case near-end crosstalk coefficient of the cross sections of transmission lines by using a computer-aided design tool. The cross sections embedded in this tool are commonly seen in electrical connector design, but not in printed circuit board design due to their different fabrication processes. Several designs are studied and the important results are presented. Some charts that illustrate the relationship between the electrical parameters and the geometries of the transmission lines are shown, which allow the designers to perform a quick initial design.