Papers by Michael D Godfrey
A Second-Generation Analog Wavelet Chip for Speech Compression
Abstract: This paper describes the theory and implementation in CMOS technology of a circuit whic... more Abstract: This paper describes the theory and implementation in CMOS technology of a circuit which performs analog wavelet decompositions of a one-dimensional (eg, sound) input. The circuit is based on the Analog VLSI techniques described by Carver Mead in ...
An analog wavelet transform chip
IEEE International Conference on Neural Networks
Prediction for Non-Stationary Stochastic Processes -II
ABSTRACT A method is presented for extrapolation of time-series which contain time-varying fre- q... more ABSTRACT A method is presented for extrapolation of time-series which contain time-varying fre- quency components. The time-series is complex-demodulated at a set of frequencies. The resulting time-frequency time-series are assumed to be time-dependent such that the amplitude and phase change relatively slowly with time. This change is taken into account in the extrapolation. This model of a non-stationary time-series was first expressed by Wald in 1936(9, 10) as part of his research concerning the seasonal variation of economic time-series. It is also closely related to Gabor's time-frequency analysis in his 1946 paper(3).
An Analog Wavelet Chip for Speech Compression
This paper describes the theory and implementation in CMOS technology of a circuit which performs... more This paper describes the theory and implementation in CMOS technology of a circuit which performs analog wavelet decompositions of a one-dimensional (e.g., sound) input. The circuit is based on the Analog VLSI techniques described by Carver Mead in Analog VLSI and Neural Systems 1]. The analog wavelet outputs are the output of a logarithmically scaled set of bandpass lters; each band is sampled at a rate proportional to the Nyquist rate of the highest frequency content of that band. The result is a matrix of discrete points describing the input signal as a function of both frequency and time. The lter function of each band is gaussian shaped in order to best resolve the uncertainty relation between time and frequency at each sampled point. This chip has been designed by Tim Edwards under the direction of Michael Godfrey, and fabricated by Zilog Corporation of Campbell, California. Zilog provided the funding for this project. 1 Overview This paper describes the Analog Wavelet Transfo...
Cartographic Computing Technology
Cartographica: The International Journal for Geographic Information and Geovisualization, 1982
196 A Non-linear Analysis of Seasonal Variation A Non-linear Analysis of Seasonal Variation
Note: The first reference in the paper is given as a Research Memorandum. This was subsequently
Machine-independent organic software tools (MINT)
Transactions of the IRE Professional Group on Information Theory, 1953
This later version incorporated a number of typographical corrections, but the Appendices from th... more This later version incorporated a number of typographical corrections, but the Appendices from the first version were not included. Instead this paper provides references to the Appendices in the previous paper. In order to make this version self-contained, I have included the Appendices. A number of typographical errors, particularly in the equations, have been corrected. It would appear from the publication dates that Gabor had about three years to think about and review the Phil. Mag. paper. But, this is not the case. The IEEE Transactions of February 1953 was, in fact, devoted to the papers and discussion from the Symposium on Information Theory, London, September 1950. However, there is one substantive change in the IEEE paper: the next to last paragraph before the References (pg.1177) from the Phil. Mag. paper was removed. This paragraph first argues that "we can show at once that a light-amplifier for the reception of weak-light signals is impossible." However, this was intended to refer to light waves and accurate measurement of amplitude and phase. The final sentence of the paragraph is: "This example demonstrates that what we see are always photons, not waves."
Modern techniques of power spectrum estimation
IEEE Transactions on Audio and Electroacoustics, 1967
Naval Research Logistics Quarterly, 1965
Machine-independent organic software tools (MINT). Rev. 2nd ed
A Spectrum Analysis of Seasonal Adjustment
Naval Research Logistics Quarterly, 1964
<title>An ultralow-noise high-speed CMOS linescan sensor for scientific and industrial applications</title>
Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications V, 2004
Low-noise readout using active reset for CMOS APS
SPIE Proceedings, 2000
Journal of VLSI Signal Processing, 1994
Operating System Considerations for Statistical Computing
Applied Statistics, 1971
This paper presents a survey of the main components of computer operating systems, indicates some... more This paper presents a survey of the main components of computer operating systems, indicates some of the requirements of statistical computing and discusses how some needs of statistical computing might be better met. A main conclusion of the paper is that, since the processing of user programs through the computing system is itself a statistical computing task, if the operating system can effectively perform this function while using only facilities which are also available to the user then the operating system may be useful for other statistical processing tasks.
An Exploratory Study of the Bi-Spectrum of Economic Time Series
Applied Statistics, 1965
The main motivation of the analysis presented here is to investigate certain non-linear propertie... more The main motivation of the analysis presented here is to investigate certain non-linear properties of the mechanism which may be supposed to generate a time series. I investigate specifically quadratic terms in the generating model. For a wide-sense stationary process the spectrum describes the linear mechanism. For a third moment stationary process the bi-spectrum describes the quadratic terms in the mechanism. I will discuss the derivation of the bi-spectrum. The interpretation of the bi-spectrum in terms of certain non-linear transformations will also be discussed. As I have chosen to compute bi-spectra by means of complexdemodulation, there will be a major digression into the computation and analysis of complex-demodulates. For background information concerning the estimation of spectra the reader is referred to Blackman and Tukey (1959). Analysis of certain non-linear systems is discussed in Wiener (1958), while the statistical theory of higher order spectra (polyspectra) is treated in Brillinger (1964). An extremely interesting application of the bispectrum is given in Hasselman et al. (1963).
CMOS device modeling for subthreshold circuits
IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing, 1992
Simple models of MOS device behavior that covers the subthreshold regime and the transition to ab... more Simple models of MOS device behavior that covers the subthreshold regime and the transition to above threshold are explored. A formulation that appears to provide results as good as process variation permits and that is well-suited to efficient computation is proposed. The exponential dependence of source-drain current on gate voltage in subthreshold implies that current values may be very sensitive to variation in parameter values (particularly those that appear in exponents). This problem is investigated, particularly with respect to threshold voltage, I0, and κ
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Papers by Michael D Godfrey