John R. Welch

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The gain compression (am-am), phase distortion (am-pm), and spectral regrowth of an RF amplifier may be found from measurements of the complex modulation envelope. The relationship between the distortion and spectral regrowth is explored by modeling the am-am and am-pm, and then simulating spectral regrowth from the distortion model. Comparison of(More)
Radio frequency amplifier linearity test data obtained from a network analyzer cw power sweep does not always match the amplifier's response to a digitally modulated carrier (which is the signal present in a communications system). This paper describes a DSP-based RF test technique which extracts the gain compression and phase distortion characteristics of(More)
From 2010 to 2013, the White Mountain Apache Tribe and the University of Arizona, with funding from the National Science Foundation, hosted the Western Apache Ethnography and Geographic Information Science Research Experience for Undergraduates. Designed to foster practical skills and scholarly capacities for future resource managers and anthropologists,(More)
In this paper, we describe an isolated-word recognition system which challenges the assumption that only connected word recognition can provide high-speed data entry. In previously available isolated-word recognizers, the entry rate was not only limited by the user's ability to speak words in isolation, but by the requirement to leave relatively large gaps(More)