Chair: John Shynk, University of California-Irvine, (USA)
Michael Savic, Rensselaer Polytechnic Institute (USA)
Mahesh Chugani, Rensselaer Polytechnic Institute (USA)
Keith Peabody, Rensselaer Polytechnic Institute (USA)
Atiya Husain, Rensselaer Polytechnic Institute (USA)
Ming-Hong Tang, Rensselaer Polytechnic Institute (USA)
Zlatko Macek, Rensselaer Polytechnic Institute (USA)
In this paper, we describe four new methods for detection of cholesterol plaque deposits inside arteries, using digital signal processing. These methods have been tested on a number of patients. The results obtained are presented and discussed. An ultrasonic beam is directed towards the examined artery. Signal features obtained from the Doppler signal reflected from the bloodstream contain information about the character of turbulences caused by cholesterol deposits inside the artery. These features can thus provide information about the size, shape, and position of stenosis. Features in both the time and frequency domains were utilized, such as the LPC cepstrum, the expotential time-frequency distribution, the energy waveform and the wavelet transform.
Szi-Wen Chen, The Ohio State University (USA)
Peter M. Clarkson, The Ohio State University (USA)
An investigation into the use of Prony modeling for the identification of late potentials (LPs) from signal-averaged electrocardiograms (SAECGs) is described. We develop a noninvasive method, based on the short-time Prony modeling algorithm, to extract a diagnostic feature, dubbed the Prony residual marker (PRM), from the SAECG waveform. The PRM is used as a marker for the presence of LPs and is thus used to predict the diagnostic outcome of invasive electrophysiologic study.
Peter M. Clarkson, The Ohio State University (USA)
Szi-Wen Chen, The Ohio State University (USA)
Qi Fan, The Ohio State University (USA)
We describe a modified sequential probability ratio test (SPRT) for the discrimination of ventricular fibrillation (VF) from ventricular tachycardia (VT) in measured surface electrocardiograms. The algorithm uses a novel regularity measure dubbed blanking variability (BV) applied to threshold crossings from the measured ECG. Blanking variability corresponds to the normalized rate of change of cardiac rate as the blanking interval is varied. The algorithm has been trained and tested using separate subsets drawn from the MIT-BIH malignant arrhythmia database. BV values are modeled using a truncated Gaussian distribution, and parameter values are derived by averaging over the training component of the database. In testing, the algorithm achieved an overall classification accuracy of 95%.
P.K. Gale, University of Wyoming (USA)
J.W. Pierre, University of Wyoming (USA)
Researchers have investigated the correlation between statistical differences in the aliphatic region of NMR processed blood plasma and malignant cancer. Previous efforts used nonlinear curve-fitting algorithms to indirectly estimate the nine components of interest in the methyl and methylene peaks of this region. A different method is described in this paper for directly estimating the nine components. A preprocessing algorithm is used to remove all components outside the aliphatic region. PronyUs method and Kumaresan and TuftsU modification are then run, using an order reduction algorithm to identify the compounds of interest. These methods are applied to an NMR plasma sample and the results are compared to the nonlinear curve-fitting algorithm, showing a close relationship.
Erik Lindskog, Uppsala University (SWEDEN)
Anders Ahle, Uppsala University (SWEDEN)
Mikael Sternad, Uppsala University (SWEDEN)
The purpose of this paper is to investigate the use of combined spatial and temporal equalization, in particular for short training sequences. The motivation for combining spatial and temporal equalization is the existence of multipath propagation and co-channel interference. Our main concern is to obtain good performance yet low complexity. We will suggest a low complexity algorithm utilizing a circular antenna array. Although it has inferior performance in an asymptotic sense, it turns out to be superior to the general solution for short training sequences. This conclusion is supported by simulations where a number of algorithms are evaluated for different scenarios involving co-channel interference.
Rachel E. Learned, MIT Laboratory for Information and Decision System (USA)
Stephane Mallat, MIT Laboratory for Information and Decision System (USA)
Bernhard Claus, MIT Laboratory for Information and Decision System (USA)
Alan S. Willsky, MIT Laboratory for Information and Decision System (USA)
The joint detection of all users in a multiple access (MA) communication system in which user transmissions are correlated has been shown in recent literature to enhance the system performance relative to that achieved without joint detection. Over the past several years the area of low complexity joint detectors has received much attention. This paper explains the problem of multiple access joint detection in geometrical terms. Geometric interpretation leads to the proposal of an alternating projection joint detection algorithm (APJD). Due to some similarities between our APJD and the multistage joint detector (MJD) of Varansi and Aazhang [Var:90], the MJD is also discussed. The APJD is guaranteed to converge and a proof is given. The geometric interpretation of the MA joint detection problem allows for the exploration of determining, a priori, the error probability of a joint detector and user waveform set in the absence of noise. Simulations offer empirical characterization of the error behavior of both detectors.
William S. McCormick, Wright State University (USA)
The paper presents an error sensitivity analysis of a bandwidth expansion technique in spectral analysis based on a noise-protected version of the Chinese Remainder Theorem. Necessary and sufficient conditions on remainder percent error and sampling period/time delay error are derived using various properties from number theory. The developed criteria have special relevance to real-time, wide bandwidth spectral estimation in the EW passive receiver.
Naofal Al-Dhahir, G.E. Research and Development Center
John Cioffi, Stanford University (USA)
A bandwidth-optimized and equalized multicarrier transceiver that achieves near-optimum performance at a practical complexity level is described. The equalizer used is a relatively short FIR filter whose taps and delay are set to optimize the performance of the multicarrier transceiver. Simulation results on a set of carrier-serving-area subscriber loops are also presented to demonstrate the separate and joint effects of bandwidth optimization and equalization on performance. Finally, the intriguing idea of using a pole-zero equalizer to achieve the high performance of infinite- complexity FIR equalizers at a much lower implementation cost is investigated.
Lang Tong, University of Connecticut (USA)
A scheme of joint blind signal detection and carrier recovery is developed for intersymbol interference channels. Using a blind sequence estimation scheme, the proposed approach does not require explicit channel identification. It shows robustness against timing error and carrier phase uncertainty. The efficacy of the proposed approach is demonstrated in a simulation involving frequency selective fast fading channel with substantial doppler shifts.
Mehmet V. Tazebay, New Jersey Institute of Technology (USA)
Ali N. Akansu, New Jersey Institute of Technology (USA)
In this paper, a smart Adaptive Time-Frequency (ATF) excision algorithm is proposed to perform interference suppression in spread spectrum communications. The ATF exciser has the intelligence of deciding the domain of the excision. Additionally, adaptive subband transforms are utilized for frequency domain excision in order to track the spectral variations of the incoming signal. This adaptive transform approach brings significant performance improvements in spectral resolution. Bit error rate (BER) performance of the novel ATF exciser-based direct sequence spread spectrum (DSSS) system receiver is compared with other existing transform domain-based DSSS receivers. Time localized or frequency-localized interferer types and additive white Gaussian noise (AWGN) channels are considered in this study. In all cases, the smart ATF exciser-based DSSS receiver drastically outperforms the existing competitors. Its robust performance against the variations of the interferers is verified.