Donald R. Hummels

A simple algorithm for generating discrete prolate spheroidal sequences

The discrete prolate spheroidal sequences are optimum waveforms in many communication and signal processing applications because they comprise the most spectral efficient set of orthogonal sequences possible. Generation of the sequences has proven to be difficult in the past due to the absence of a closed form solution. A new method of easily generating any single discrete prolate spheroidal sequence, including sequences of very long length, is presented. Also shown are some example sequences generated using the algorithm presented. >

A senior-level RF design course combining traditional lectures with an open laboratory format

In Kansas State Universitys Design of Communication Circuits course, 10 to 15 students each semester are introduced to the theory behind wireless communications hardware used in modern products such as pagers, wireless LANs, and cellular telephones. In contrast to typical senior-design courses that have separate laboratory and lecture sections, the class combines lecture and laboratory work, with the instructor managing and grading both. This allows scheduling a series of projects that can be combined at the middle and end of the semester to produce relatively sophisticated products, such as working FM broadcast transmitters and receivers. An additional feature of the course is the use of an open laboratory where students can work at any time during normal business hours to build and test their circuits. This allows a class of 10 or more to share a single copy of expensive equipment such as a spectrum or network analyzer, while providing a studio-type environment in which students can share experiences more effectively with others.

Calculation of Detection Probability for Frequency Compressive Receivers

A numerical method is described for predicting the detection probability of a frequency compressive pulse receiver. The approach is general; i.e., input pulse envelope shapes, pulse offset frequencies, and filter magnitude responses are arbitrary. The performance of the frequency compressive receiver is analyzed and compared to that of a crystal video receiver for a specific case.

Filter Selection for Receivers Using Square-Law Detection

A numerical method is described for predicting the detection probability performance of a pulse receiver which uses square-law detection. The method is useful for receivers where the ratio of RF bandwidth to video bandwidth is in the range from 2 to 40; a range where numerical results have previously been hard to obtain. A key feature of the approach is that it takes into account the actual filter transfer functions, pulse envelope shape, and pulse frequency.

Vectorcardiographic Data Compression via Walsh And Cosine Transforms

In this study the use of two-dimensional transforms for compressing human vectorcardiographic (VCG) data is investigated. The VCG signal is two-dimensional in nature, one dimension consisting of the spatial axes and the other consisting of the samples in time along a particular spatial axis. The discrete cosine transform (DCT) and the Walsh-Hadamard transform (WHT) were used. The variance criterion was employed for selecting components to be retained. The training set was formed from 225 VCG records from three different diagnostic classes. The DCT yielded compression ratios from 3:1 to 5:1, while compression ratios of around 2:1 were obtained with the WHT.

An adaptive bit time estimator

A bit time estimator which uses adaptive filtering techniques is presented. The filter weights of an adaptive linear predictor are shown to provide a reliable estimate of the bit time T of a random binary square wave contaminated with additive white Gaussian noise, with little or no a priori information. The quality of this estimator is then evaluated via the least mean square algorithm, and a comparison is made between it and a more conventional estimator based on a zero crossing detector. This comparison shows that an adaptive estimator based on a linear predictor is generally superior. >

Analysis of Detection Probability for the Acoustooptic Receiver

A numerical method is described for analyzing the performance of an acoustooptic receiver. The method provides output waveforms, probability density functions for samples of the output, and detection probabilities for output samples. The approach is general in that input pulse envelope shapes, pulse offset frequencies, and output rilter magnitude responses are arbitrary. The basic analysis is also independent of the shape of the optical beam and of the photodiode windows.

Classification of Vectorcardiograms Using Walsh And Cosine Orthogonal Transforms

In this study, the usefulness of two-dimensional transforms in classifying human vectorcardiograms is investigated. The transforms used are the Walsh-Hadamard (WHT) and the discrete cosine (DCT). Experimental results included in the paper demonstrate that about 80-85 percent correct classification may be achieved.

Transient Nonstationary Behavior of a Delay Line Discriminator

The development of numerical methods for studying the transient nonstationary behavior of a delay line discriminator is presented. Expressions are developed for the mean and the variance of the output noise process. For the cases where the output is stationary, power density spectra are found.

A short-term sequential regression algorithm

In the paper, we introduce the notion of short-term adaptive filtering via a sequential regression (SER) formulation. A corresponding short-term SER algorithm for nonrecursive filters is derived. Experimental results involving a short-term SER predictor are presented. For purposes of comparison, corresponding results using Widrows least-mean-square (LMS), and the conventional SER algorithm are also included.