Abstract: A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

Abstract: A method and apparatus of determining the analyte concentration of a test sample is described. A temperature gradient is introduced into the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. The modulation of the temperature gradient is controlled by a surface temperature modulation. A transfer function is determined that relates the surface temperature modulation to the modulation of the measured infrared radiation. Reference and analytical signals are detected. In the presence of the selected analyte, phase and magnitude differences in the transfer function are detected. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the sample.

Abstract: A method and apparatus of determining the analyte concentration of a test sample is described. A temperature gradient is introduced into the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. The modulation of the temperature gradient is controlled by a surface temperature modulation. A transfer function is determined that relates the surface temperature modulation to the modulation of the measured infrared radiation. Reference and analytical signals are detected. In the presence of the selected analyte, phase and magnitude differences in the transfer function are detected. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the sample.

Abstract: A device and method for determining analyte concentrations within a material sample are provided. A modulating temperature gradient is induced in the sample and resultant, emitted infrared radiation is measured at selected analyte absorbance peaks and reference wavelengths. The modulating temperature gradient is controlled by a surface temperature modulation. One embodiment provides a transfer function relating the surface temperature modulation to a modulation of the measured infrared radiation. Phase and magnitude differences in the transfer function are detected in the presence of the sought-after analyte. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the material sample. Another embodiment provides a method for transforming thermal phase spectra to absorption spectra for consistent determination of analyte concentration within the sample.

Abstract: A device and method for determining analyte concentrations within a material sample are provided. A modulating temperature gradient is induced in the sample and resultant, emitted infrared radiation is measured at selected analyte absorbance peaks and reference wavelengths. The modulating temperature gradient is controlled by a surface temperature modulation. One embodiment provides a transfer function relating the surface temperature modulation to a modulation of the measured infrared radiation. Phase and magnitude differences in the transfer function are detected in the presence of the sought-after analyte. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the material sample. Another embodiment provides a method for transforming thermal phase spectra to absorption spectra for consistent determination of analyte concentration within the sample.

Abstract: A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

Abstract: A device and method for determining analyte concentrations within a material sample are provided. A modulating temperature gradient is induced in the sample and resultant, emitted infrared radiation is measured at selected analyte absorbance peaks and reference wavelengths. The modulating temperature gradient is controlled by a surface temperature modulation. One embodiment provides a transfer function relating the surface temperature modulation to a modulation of the measured infrared radiation. Phase and magnitude differences in the transfer function are detected in the presence of the sought-after analyte. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the material sample. Another embodiment provides a method for transforming thermal phase spectra to absorption spectra for consistent determination of analyte concentration within the sample.

Abstract: A method and apparatus of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. The modulation of the temperature gradient is controlled by a surface temperature modulation. A transfer function is determined that relates the surface temperature modulation to the modulation of the measured infrared radiation. Reference and analytical signals are detected. In the presence of the selected analyte, phase and magnitude differences in the transfer function are detected. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample.

Abstract: A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

Abstract: A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

Abstract: A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

Abstract: A decoder capable of decoding audio signals encoded using analog noise reduction techniques, particularly Dolby SR, is implemented by means of digital signal processing. The typical decoding paradigm used by analog Dolby SR decoders is modified to overcome the problems caused by delay which is introduced by the digital implementation. A gain factor is factored out of the feedback transfer function and is placed in the forward signal path of each stage of the digital decoder. A single control circuit can then be used to generate coefficients which define transfer functions of each filter stage of the signal path. Linear interpolation techniques are used to limit the number of coefficient entries necessary to emulate the transfer function of an analog Dolby SR decoder. The digital decoder structure can be inverted to produce a digital encoder which is capable of implementing any noise reduction standard desired, including Dolby SR.

Abstract: Impedance to fluid flow in a fluid delivery line is measured. Two techniques are used depending on the flow rate selected. For high flow rates, the pump is controlled to vary the flow rate and the change in pressure is divided by the change in flow to directly determine the resistance. For low flow rates, a processor controls the pump to pump flow quantities in accordance with a pseudo-random binary code. The resulting pressure signal sensed at the conduit is decoded in accordance with that code. Pressures received during code periods of no flow are subtracted from pressures received during code periods of flow. Pressure offset is also removed and a least squares estimation approach is used with a linear prediction model to determine impedance. The coefficients determined in the model are used to calculate the resistance to fluid flow of the system. A quality supervisor monitors the resistance determination process and controls the display of resistance depending on the quality determined.

Abstract: A Doppler velocity spectrum produced by radial projection in a two-dimensional Fourier frequency domain is processed to suppress alias spectral terms. The projected spectrum is divided into windows using an iterative algorithm which centers the spectral mean. The window containing data samples which maximizes a weighted score based upon the width and maximal value of samples within the window is used to determine which window contains true spectral components. Spectral components in other windows are then suppressed.

Abstract: Apparatus for mapping moving objects by determining the cross-correlation function between two digitally sampled ultrasound A-line signals comprises a plurality of fractional step delay (FSD) digital interpolation filters which estimate the value of one of said input signals at intervals between said samples and a plurality of one-bit correlation circuits each of which determines the correlation between the first signal and the output of one of said interpolation filters.

Abstract: A circuit for determining the cross-correlation function between two digitally sampled signals comprises a plurality of fractional step delay (FSD) digital interpolation filters which estimate the value of one of said input signals at intervals between said samples and a plurality of correlation circuits each of which determines the correlation between the first signal and the output of one of said interpolation filters.

Abstract: An ultrasound attenuation scanner measures the local attenuation of tissues from pulse echo A-line data. An adaptive filter with a transfer function which is the inverse of the tissue undergoing examination operates on the complex envelope of the RF signal.

Abstract: Apparatus and methods for remote identification of tissue types model the scattering of ultrasound energy from living tissue as an autoregressive or autoregressive moving average random process. Autoregressive or autoregressive moving average models of candidate tissue types are generated from pulse-echo data that is known to come from that particular tissue type. Kalman prediction error filters are used for each candidate tissue type to generate estimates of the probability that an unknown pulse echo signal belongs to the class generated by that tissue type. Unknown pulse-echo signals are filtered in a specific Kalman filter to test the hypothesis that the unknown signal belongs to the class associated with that particular Kalman filter.

Abstract: An ultrasound transducer having an annular acoustic aperture is utilized in combination with an echo-ultrasound imaging system having an FM detector. The off-axis transfer function characteristics of the annular transducer substantially improve the lateral resolution of the imaging system as compared with prior art systems which utilized round or rectangular transducer apertures.

Abstract: Flow regulating apparatus comprises a turbulent-flow valve with a fluid supply connected at the upstream side thereof. A fixed pressure bias is applied to the fluid upstream of the valve whereby the mass flow rate of fluid through the valve is directly proportional to the pressure differential across the apparatus when these variations are within a selected pressure range. Such flow regulation may be used in a system for introducing a metered amount of liquid fuel into an air stream to provide a combustible air-fuel mixture having a substantially constant air-to-fuel ratio. With this system air is passed through a constricted zone to increase its velocity to sonic, and the area of the constricted zone is varied in correlation with operating demands imposed upon the engine for which the mixture is produced.