Abstract: Embodiments of the present invention provide estimates of soil moisture by measuring the change in electrical conductivity near the surface of the earth using surface-propagated electromagnetic fields. A method is provided for estimating near-surface soil moisture, including measuring signals from an electromagnetic ground wave propagating between one or more receiving element locations, determining a transfer characteristic proportional to an average electrical conductivity between pairs of locations; and determining estimated soil moisture in one or more regions derived from analyzing the determined electrical conductivity between pairs of locations and a predetermined regional relationship between electrical conductivity and soil moisture.

Abstract: A lightning detection system provides an estimated location of a lightning stroke. The system includes sensors, and an analyzer. Each sensor provides messages having sensor identification, an amplitude responsive to the lightning stroke, and a time of detecting the lightning stroke. The analyzer applies time corrections and amplitude corrections to improve the accuracy of determining the location of the lightning stroke. Time adjustments and amplitude adjustments for the time and amplitude corrections are recalled from a matrix accessed according to a suggested or estimated location. The matrix may be organized by coordinates of longitude and latitude.

Abstract: Embodiments of the present invention provide estimates of soil moisture by measuring the change in electrical conductivity near the surface of the earth using surface-propagated electromagnetic fields. A method is provided for estimating near-surface soil moisture, including measuring signals from an electromagnetic ground wave propagating between one or more receiving element locations, determining a transfer characteristic proportional to an average electrical conductivity between pairs of locations; and determining estimated soil moisture in one or more regions derived from analyzing the determined electrical conductivity between pairs of locations and a predetermined regional relationship between electrical conductivity and soil moisture.

Abstract: A lightning detection system provides an estimated location of a lightning stroke. The system includes sensors, and an analyzer. Each sensor provides messages having sensor identification, an amplitude responsive to the lightning stroke, and a time of detecting the lightning stroke. The analyzer applies time corrections and amplitude corrections to improve the accuracy of determining the location of the lightning stroke. Time adjustments and amplitude adjustments for the time and amplitude corrections are recalled from a matrix accessed according to a suggested or estimated location. The matrix may be organized by coordinates of longitude and latitude.

Abstract: A lightning detection system provides an estimated location of a lightning stroke. The system includes sensors, and an analyzer. Each sensor provides messages having sensor identification, an amplitude responsive to the lightning stroke, and a time of detecting the lightning stroke. The analyzer applies time corrections and amplitude corrections to improve the accuracy of determining the location of the lightning stroke. Time adjustments and amplitude adjustments for the time and amplitude corrections are recalled from a matrix accessed according to a suggested or estimated location. The matrix may be organized by coordinates of longitude and latitude.

Abstract: A lightning detection and data acquisition system. A plurality of remote programmable sensor is utilized to detect cloud to ground and IC lightning strikes. Analog representations of the lightning strikes are converted to digital signals. The digital signals are classified according to user changeable criteria. The classified digital signals are compressed and optionally decimated. The compressed information is transmitted to a central location where it is decompressed and used to correlate the location, magnitude, and travel path of the detected lightning strikes.

Abstract: A lightning detection and data acquisition system. A plurality of remote programmable sensor is utilized to detect cloud to ground and IC lightning strikes. Analog representations of the lightning strikes are converted to digital signals. The digital signals are classified according to user changeable criteria. The classified digital signals are compressed and optionally decimated. The compressed information is transmitted to a central location where it is decompressed and used to correlate the location, magnitude, and travel path of the detected lightning strikes.

Abstract: A lightning detection and data acquisition system. A plurality of remote programmable sensor is utilized to detect cloud to ground and IC lightning strikes. Analog representations of the lightning strikes are converted to digital signals. The digital signals are classified according to user changeable criteria. The classified digital signals are compressed and optionally decimated. The compressed information is transmitted to a central location where it is decompressed and used to correlate the location, magnitude, and travel path of the detected lightning strikes.

Abstract: A lightning detection and data acquisition system. A plurality of remote programmable sensor is utilized to detect cloud to ground and IC lightning strikes. Analog representations of the lightning strikes are converted to digital signals. The digital signals are classified according to user changeable criteria. The classified digital signals are compressed and optionally decimated. The compressed information is transmitted to a central location where it is decompressed and used to correlate the location, magnitude, and travel path of the detected lightning strikes.

Abstract: A power line fault locating system employing combinations of conducted electrical transient signals recorded at specific points in the power delivery network, radiated electromagnetic signals produced by the air-gap arc preceeding the fault current or by the lightning discharge causing the fault, and knowledge of the power line path associated therewith. The arrival time of conducted transient signals produced by the fault are detected with microsecond accuracy through use of a fault recording sensor (FRS). The low level electromagnetic radiation (VHF/UHF) caused by arcing associated with power line faults is detected at at least one arc detection sensor (ADS) located at some distance from the power line. The ADS senses the time of arrival of the radiated signal associated with the fault.

Abstract: Efficient cancellation of AC power line interference from a signal received by electronic instruments, such as biomedical monitors, is obtained by efficiently estimating the magnitude and phase of the noise signal from the contaminated input signal in a digital signal processor. Each interfering noise component of known frequency is represented as a sinusoid composed of cosine and sine components having estimated amplitude parameters. These amplitude parameters are recalculated at discrete points in time in the digital signal processor to carry out substantially a Fourier integration on the input signal at the known frequency f.sub.0 of the interfering signal, with the integration being updated to the last sample. The integration can be carried out to allow the estimates to adapt to time varying amplitudes and/or phases of the interfering signals. Cancellation of the estimated noise sinusoid from the input signal results in an output signal substantially uncontaminated by the noise.

Abstract: An omnidirectional lightning ranging, identification and protection system having circuits that produce no false alarms or failures to alarm, responsive to cloud to ground and cloud discharges, capable of differentiating between cloud to ground and cloud discharges insensitive to background noise, autonomous with respect to power and communications conductors for operating reliably in the presence of nearby lightning discharges, requiring no field calibration, that provides local and remote lightning rate and range data, and that provides mechanisms for automatically signalling and disconnecting electrical equipment for the purpose of lightning protection. The system has circuits that are responsive to the electric field changes produced by lightning discharges in the frequency range between 2 khz and about 200 khz and to time coincident optical radiation in the 6000 to 9000 angstroms wavelength range.

Abstract: A hearing aid system utilizes digital signal processing to correct for the hearing deficit of a particular user and to maximize the intelligibility of the desired audio signal relative to noise. An analog signal from a microphone is converted to digital data which is operated on by a digital signal processor, with the output of the digital signal processor being converted back to an analog signal which is amplified and provided to the user. The digital signal processor includes a time varying spectral filter having filter coefficients which can be varied on a quasi-real time basis to spectrally shape the signal to match the hearing deficit of the user and to accommodate ambient signal and noise levels. The coefficients of the spectral filter are determined by estimating the energy in several frequency bands within the frequency range of the input signal, and using those energy estimates to calculate desired gains for the frequency bands and corresponding spectral filter coefficients.

Abstract: A hearing aid system utilizing digital signal processing is programmable to fit the hearing deficit of a particular use and adaptive to the sound environment to maximize the intelligibility of the desired audio signal relative to noise. An analog signal picked from a microphone is amplified, filtered and converted to digital data. A digital signal processor preferably performs spectral shaping on the data to match the user's preference and performs a non-linear adaptive amplification function on the digital data. The amplification gain function may include several piecewise linear sections, including a first section providing expansion up to a first knee point, a second section providing linear amplification from the first knee point to a second knee point, and a third section providing compression for signals above the second knee to reduce the effort of over range signals and minimize loudness discomfort to the user.