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More than 50% of normal ears generate spontaneous otoacoustic emissions, which are sinusoidal tones originating in the cochlea. These faint sounds with levels typically at 10 dB to -30 dB are usually not recognized by the subjects who have them, but can be recorded by sensitive microphones in the ear canal. The clinical significance of having or not having(More)
Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment(More)
—We report on the characterization of blackbody target reflections as part of the recent progress on the development of brightness temperature standards for microwave remote sensing at the National Institute of Standards and Technology. The very low reflections from the blackbody targets used in airborne or satellite remote sensing systems present(More)
1. ABSTRACT Accurate characterization of the brightness temperature (T_B) of black-body targets used for calibrating microwave remote-sensing radiometers includes many inputs: antenna pattern and loss, target temperature, target emissivity, mechanical alignment, and radiometric T_B measurements calibrated against physical standards. Here we describe(More)
—The NIST Noise Project has developed the theoretical formalism and experimental methods for performing accurate noise-temperature measurements on a wafer. This report summarizes the theoretical formulation and describes the design, methods, and results of tests performed to verify our ability to measure on-wafer noise temperature. Several different(More)
has developed the capability to measure noise parameters on a wafer in the 1–12.4-GHz range. We describe the measurement method and the uncertainty analysis and present results of measurements on a highly reflective transistor. Typical standard uncertainties are within the range of 20–25 K in T min , which is the minimum transistor noise temperature, and(More)
—We report our recent progress toward the development of microwave brightness-temperature (BT) standards. As one of the crucial parameters, the target illumination efficiency (IE) was traditionally determined from the relative antenna pattern. We propose a measurement technique to extract the target IE solely by the use of passive radiometric measurements(More)
We report precision measurements of the effective input noise temperature of a cryogenic (liquid-helium temperature) monolithic-microwave integrated-circuit amplifier at the amplifier reference planes within the cryostat. A method is given for characterizing and removing the effect of the transmission lines between the amplifier reference planes and the(More)