Abstract: A method for detecting a phase difference between first and second input signals is provided. The method includes modulating a duty cycle of first and second intermediate signals from a first duty cycle based on the phase difference between the first and second input signals. The method further includes creating a differential output signal based on the modulated duty cycles of the first and second intermediate signals that is related to the phase difference between the first and second input signals.
Abstract: The volume of fluid flow within a vessel (VE) is measured by an ultrasound system. Ultrasound waves backscattered from the fluid within the vessel generate data from which velocity values representing components of velocity (Vx and Vy) of the fluid flow in the scan plane (IP) are calculated. Grayscale data is correlated and the rate of decorrelation (D) of the data is calculated. The volume flow of the fluid (F) is estimated in response to the velocity signals and the rate of decorrelation (D).
Type:
Grant
Filed:
January 31, 2000
Date of Patent:
March 18, 2003
Assignees:
GE Medical Systems Global Technology Company, LLC, The Regents of the University of Michigan
Inventors:
Jonathan M. Rubin, Jeffrey Brian Fowlkes, Theresa Ann Tuthill, Anne Lindsey Hall
Abstract: A drive system is taught for controlling the modal content of any number of drive signals used to excite any number of drives on a vibrating conduit such as is found in a Coriolis mass flowmeter or a vibrating tube densimeter. One or more motion signals are obtained from one or more spatially distinct feedback sensors. The motion signals are preferably filtered using a multi-channel modal filter to decompose the motion signals, each of which contain modal content at a plurality of vibration modes, into n single degree of freedom modal response signals. Each modal response signal corresponds to one of the vibration modes at which the vibrating conduit is excited. The n modal response signals are input to a drive channel having a separate processing channel for each of the n modal response signals.
Type:
Grant
Filed:
February 25, 1998
Date of Patent:
March 19, 2002
Assignee:
Micro Motion, Inc.
Inventors:
Timothy J. Cunningham, Stuart J. Shelley
Abstract: A flow rate measuring apparatus capable of accurately measuring a flow rate of fluctuating fluid. A mode setting circuit selectively sets any one of a plurality of predetermined transmission modes different in transmission timing. The mode setting circuit sets any one of a first transmission mode which permits an ultrasonic wave to be transmitted at a predetermined timing for every period of a flow waveform of exhaust gas, a second transmission mode which permits an ultrasonic wave to be transmitted at a timing shifted by a predetermined time for every period of the flow waveform of the exhaust gas and a third transmission mode which permits an ultrasonic wave to be transmitted at predetermined intervals.
Type:
Application
Filed:
January 24, 2001
Publication date:
July 26, 2001
Applicant:
NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY
Abstract: Measuring the propagation time of a sound signal between two spaced-apart transducers disposed in a fluid flow involves determining the zero-crossing of the signal. Each received sound signal is sampled and digitized, then for each period of the sampled and digitized signal the maximum amplitudes P− and P+ of the two lobes of the period under examination are determined. The ratio of the amplitudes are compared to an ideal amplitude ratio between the maximum amplitudes Pi− and Pi+ of two lobes of a first ideal characteristic period. The first zero-crossing of the characteristic oscillations of the signal is determined. And, as a function of the result of the comparison relative to a threshold value Gs, the period under examination is accepted or ignored as a characteristic period. The zero-crossing thereof is determined or not determined between the two lobes of the characteristic period.
Abstract: Methods, devices and system for measuring the speed of the watercraft relative to the water through which it travels. An embodiment comprises two streamlined fins configured to extend at least partially below the waterline. The fins are oriented parallel to the water flow so that as the watercraft moves, the water flows in between the fins in a smooth unobstructed motion. One piezoelectric transducer is mounted in each fin so that the acoustic signal path between the transducers is a straight line. The transducers are offset upstream and downstream so that water flow between the fins can significantly affect the acoustic signal travel time between the upstream and downstream sensors.
Abstract: A method for measuring a fluid flow rate between two points of a fluid flow according to which a measurement of the respective propagation times of two acoustic signals transmitted in opposite directions is combined with a measurement of acoustic phase shifts respectively induced in each signal. Each received signal is sampled and digitized and the corresponding acoustic phase shift is determined by synchronous detection. During successive iterations, a programmable phase shift dependent on the value of the acoustic phase shift obtained by synchronous detection in the previous iteration is determined for each iteration, so that the result of the synchronous detection step in the current iteration is as close as possible to zero, and the acoustic phase shift is therefore substantially the same as the last programmable phase shift.
Abstract: A method of determining a characteristic of a fluid involves measuring a sonic transit time (102), along a non-perpendicular path, through the fluid. The sonic transit time is used to determine a speed of sound in the fluid (104). A measured flow rate (106) is determined from the sonic transit time. A friction factor (108) is calculated using the speed of sound and the measured flow rate. Next, a velocity profile (110) is determined using the friction factor. Finally, an adjusted flow rate is calculated (112) using the velocity profile.