Abstract: An ultrasonic flow meter, comprising a flow tube with a through-going opening for passage of a fluid between an inlet and an outlet, comprising: a flow pipe of a first material, such as metal, extending between the inlet and the outlet, a liner of a second material, such as a polymer-based material, extending along an inner surface of the flow pipe between the inlet and the outlet, a housing providing a compartment for transducers and metering electronics wherein the housing is connected to the liner, by being mounted on an interface being an integrated part of the liner.

Abstract: This invention relates to a method of reducing error in a SODAR system adapted to locate discontinuities in the atmosphere over a range extending away from an acoustic transmitter and receiver, the method comprising the steps of: measuring wind to determine either a substantially upwind direction or a substantially downwind direction relative to the transmitter; transmitting one or more forward or reverse acoustic chirps in the substantially upwind or downwind direction; receiving one or more acoustic echoes of the transmitted chirps; and processing the acoustic echoes to provide an indication of the discontinuities in the atmosphere over the range, thereby providing a wind shear profile.

Abstract: Systems and devices for airflow measurements in rooms and air delivery ducts with low-cost, low-power, accurate, calibration-free, and compact wireless airflow sensors are provided. The system uses room and duct flow sonic anemometers and processing to measure air velocities and temperatures as well as allow control over the environmental conditioning systems. The anemometers use arrays of transmitter/receivers to simultaneously measure multiple sound paths and determine velocity vectors and volumetric flow paths. By transmitting in both directions along the paths between transceivers, differential times of flight (TOF) are measured. These determine both the velocity and temperature of the air along each path.

Abstract: A method of measuring the speed of a fluid, comprising the successive steps of: causing the processor component to emit at the same emission time both a first electrical excitation signal that is applied as input to a first transducer and also a second electrical excitation signal that is applied as input to a second transducer, such that the first transducer generates a first ultrasonic signal and such that the second transducer generates a second ultrasonic signal; putting the processor component on standby; reactivating the processor component after a predetermined standby duration; causing the first ultrasonic signal to be acquired by the second transducer and then by the processor component, and causing the second ultrasonic signal to be acquired by the first transducer and then by the processor component; using a value DToF to estimate the speed of the fluid.

Abstract: An acoustic airspeed sensor system can include at least one acoustic transmitter configured to provide an acoustic pulse, a plurality of acoustic receivers including at least a first acoustic receiver, a second acoustic, receiver, and a third acoustic receiver, each positioned at a first radial distance from the at least one acoustic transmitter. The first acoustic receiver, the second acoustic receiver, and the third acoustic receiver are each configured to receive the acoustic pulse at a first time, a second time, and a third time, respectively, and output a first receiver signal, a second receiver signal, and a third receiver signal respectively. The system can include a computation unit operatively connected to the acoustic receivers and configured to generate a propagation function. The computation unit is further configured to determine true air speed based upon a receiver signals and the propagation function.

Abstract: An omnidirectional anemometer and a method for using such an anemometer to measure the airflow along a conveying path, such as a helical path through a processing chamber. The anemometer is a low-profile, omnidirectional, three-axis anemometer with minimal airflow-occluding structure. Because of its low profile, the anemometer can fit in spiral conveyors with a short tier pitch.

Abstract: A system for determining gas characteristics at high altitudes in embodiments of the present invention may have one or more of the following features: (a) a high-altitude balloon having one or more of the following features: (a) a balloon, (b) a balloonsat operably coupled to the balloon, (c) an air path chamber wherein gas at a high altitude can occupy the air path chamber, (d) a first speaker located on a substrate within the air path chamber, wherein the first speaker takes an electrical signal input and creates a first sound wave, and (e) a second speaker located on the substrate facing opposite of the first speaker located outside of the air path chamber, wherein the second speaker takes the electrical signal and creates a second sound wave.

Abstract: Apparatus and associated methods relate to determining airspeed and/or altitude based on acoustic waves caused by airflow. One of more acoustic transducers are positioned along an exterior surface of an aircraft. Each of the one or more acoustic transducers is configured to detect acoustic waves caused by the airflow. The acoustic waves detected are indicative of an airstream condition proximate the acoustic transducer, such as, for example, airspeed and/or altitude. A processor is configured to determine airspeed and/or altitude of the aircraft based, at least in part, on the acoustic waves detected.

Abstract: An acoustic air data sensing system includes an acoustic transmitter, a plurality of acoustic receivers, and a skin friction sensor. The acoustic transmitter is located to transmit an acoustic signal into airflow about an exterior of a vehicle. Each of the acoustic receivers is located at a respective angle from a wind angle reference line and a respective distance from the acoustic transmitter. The skin fiction sensor is positioned in a boundary layer region of the airflow that interacts with the acoustic receivers and transmitter. Based on time of flight values of the acoustic signal from the transmitter to each of the receivers and a skin friction measurement from the skin friction sensor as inputs to a transformation matrix, the acoustic air data sensing system outputs, from the transformation matrix, the true airspeed, the relative wind angle, and the speed of sound for operational control of the vehicle.

Abstract: Methods, systems, and devices for acoustic structural reflection interference mitigation are provided in accordance with various embodiments. For example, some embodiments may provide for structural reflection interference mitigation for compact three-dimensional ultrasonic anemometers. Some embodiments include a method that may include transmitting a first acoustic signal from a first acoustic transmitter. At least a first portion of the first acoustic signal from the first acoustic transmitter may be hindered from being received at a first acoustic receiver. At least a second portion of the first acoustic signal from the first acoustic transmitter may be received at the first acoustic receiver along an acoustic propagation path. In some embodiments, the first acoustic transmitter may include a wide-beam transmitter. Some embodiments may utilize four wide-beam transducers positioned at apices of a tetrahedron.

Abstract: A method of determining flow parameters of a streaming gas in a conduit for medical applications. Longitudinal waves are generated in a transmitter connected from outside to a conduit. These waves are transmitted along two diagonal paths through the streaming medium in an upstream and a downstream direction, and received by two receivers which are located in a diagonal upstream and downstream position and on an opposite side relative to the transmitter, also connected to the conduit. A transit time value of the waves between the transmitter and each of the receivers is determined. A difference value on the basis of the determined transit time values is generated and the flow parameters are determined on the basis of the difference value. This measuring method is highly independent of the propagation velocity of the wave in the medium streaming in the conduit therefore also independent of the temperature and humidity of a gaseous medium.

Abstract: In one aspect, a microphone with closely spaced elements is used to acquire multiple signals from which a signal from a desired source is separated. The signal separation approach uses a combination of direction-of-arrival information or other information determined from variation such as phase, delay, and amplitude among the acquired signals, as well as structural information for the signal from the source of interest and/or for the interfering signals. Through this combination of information, the elements may be spaced more closely than may be effective for conventional beamforming approaches. In some examples, all the microphone elements are integrated into a single a micro-electrical-mechanical system (MEMS).

Abstract: An ultrasonic airspeed and direction sensor system comprising an ultrasonic sensor array including an elongate base member for mounting to a vehicle, such as a helicopter, so as to extend outwardly from the vehicle. A number of radially extending support members are connected to the base member. The support members carry ultrasonic transducers arranged to define at least four bidirectional ultrasonic paths between respective pairs of the transducers, the ultrasonic paths being arranged into at least three non-coplanar sets. A processing system monitors the passage of ultrasonic signals along the paths to generate corresponding time of flight data, making a weighted selection containing at least one path from each of at least three sets, and processing the time of flight data for the selected paths, proportionate to the determined weighting, to generate airspeed and direction information.

Abstract: A housing for a phased array monostatic sodar system with a transducer array that sequentially emits and receives a set of sound beams along different primary axes. The housing includes an enclosure having a plurality of sidewalls, each sidewall of the plurality of sidewalls having an inner surface, the enclosure configured to emit and receive the set of sound beams. Each inner surface of each sidewall of the plurality of sidewalls defines at least a partially elliptical cross-section configured to substantially envelop at least a portion of an angled, conical sound beam of the set of sound beams.

Abstract: A waterproof or water-resistant membrane cover for the acoustic transducer array of a sodar system. The membrane is placed over each transducer of the array. The membrane may be spaced from the array, with a structure such as a frame used to hold the membrane in place relative to the array.

Abstract: The invention relates to a probe for aerodynamic measurement of an airflow. The probe comprises a plate rotating about an axis, a transmitter for transmitting a sound wave and a receiver responsive to the sound wave, the transmitter and the receiver forming two elements which are integrally connected to the plate and are placed at separate positions on the plate, the probe furthermore comprising means for delivering information representing a time of flight of the sound wave between the two elements and a temporal variation of the information. In the case of using the probe on board a helicopter, the rotating plate is advantageously placed at the centre of the rotor of the helicopter while being integrally connected to it. This type of probe makes it possible to carry out aerodynamic measurements even at low airspeeds of the helicopter.

Abstract: The invention relates to an aerodynamic measurement probe of an airstream along a wall. The invention makes it possible notably to determine the attack of an airstream relative to an axial reference tangential to the wall. The invention is particularly useful in the aeronautical field. According to the invention, the probe comprises several emitters that can each emit a sound wave and a receiver sensitive to the different sound waves. Thus, there is forewarning of the receiver error that is common to all the measurements of travel time of a sound wave between one of the emitters and the receiver.

Abstract: An AD2CP includes at least one transducer assembly emitting sets of slanted directional acoustic beams and receiving the echoes; and electronics that processes the echoes into depth cells and computes velocity in each depth cell. The AD2CP is configured so that each beam set has a profiling catenation, at least two of which are different, and the AD2CP is configured so that the emitting, receiving and processing operate contemporaneously.

Abstract: A monostatic sodar system includes an array of essentially identical acoustic transducers. Each transducer includes a cone transducer element which generates and receives sound and a horn which guides the sound to and from the cone to a circular or hexagonal active region from which sound is emitted during a sound emission and into which sound is received during a reception of emitted sound that has been reflected by the atmosphere. Each transducer defines a generally hexagonal perimeter shape and occupying a generally hexagonal area of the array. The system includes a signal generator that generates signals that are used to drive the transducers, a phase and switching control, a receiver that receives signals from the transducers, a processor, an open-top enclosure, and a sound reflector within the enclosure.

Abstract: A housing for a phased array monostatic sodar system with a transducer array that emits and receives multiple generally conical main beams of sound along different primary axes. The housing includes one or more upwardly-directed sidewalls that define a volume between them that is open to the atmosphere at the top, to emit and receive the beams, and an upper lip at the top of at least one wall, defining a curved perimeter at the top of at least some of the volume that closely conforms to the shape of at least one main beam at the location of the lip.

Abstract: An array of transducers for a sodar system, and the operation of the array in a monostatic sodar system. The array is made up of a number of individual sound transducers. Each transducer emits sound into the atmosphere and senses emitted sound that has been reflected by the atmosphere. The transducers have a generally circular cross-sectional shape. The transducers are arranged in a generally planar, generally hexagonal grid packing arrangement.

Abstract: An AD2CP includes at least one transducer assembly emitting sets of slanted directional acoustic beams and receiving the echoes; and electronics that processes the echoes into depth cells and computes velocity in each depth cell. The AD2CP is configured so that each beam set has a profiling catenation, at least two of which are different, and the AD2CP is configured so that the emitting, receiving and processing operate contemporaneously.

Abstract: A system and method for measuring velocity in a fluid medium utilizing a transducer are disclosed. In one aspect, the method comprises transmitting an acoustic signal comprising N (where N is integer and N>1) pings for each of a plurality of beams, receiving echoes from each ping, obtaining a velocity estimate for each of the N pings based on echoes of the ping, and calculating a velocity based on the sum of the N velocity estimates such that the velocity is substantially free from error caused by cross-coupling between the beams.

Abstract: A monostatic sodar system (10) for atmospheric sounding includes a processor and display unit (12) that generates a set of acoustic chirps for transmission by transmitter 20. Discontinuities (22, 24 and 26) result in echoes (28, 30 and 32) being returned to a receiver (38) of system (10). Receiver (38) outputs extracted echo signals on line to the processor (12) for analysis. Detector (36) implements a Fourier domain matched-filter to extract echo signals from noise. By using a set of multiple chirps of increasing length with increasing intervals between them, substantially any feasible range can be accommodated using send-then-listen techniques with the benefit of high s/n performance.

Abstract: A monstatic sodar system using long chirps and send-while-listening techniques employs transmitter-receiver pairs (Tw, Rw; Tv, Rv; Te, Re) that have coincident main lobes (Twm, Rwm; Tvm, Rvm; Tem, Rem). The system uses digital time domain matched filters and frequency modulated or digitally modulated (eg, BPSK) chirps. Digital frequency domain matched filtering may also be used. The matched filters generate sample streams indicative of the phase and amplitude of echo signals returned from the atmosphere after the transmission of a chirp into the atmosphere.

Abstract: The invention relates to an aerodynamic measurement probe of an airstream along a wall. The invention makes it possible notably to determine the attack of an airstream relative to an axial reference tangential to the wall. The invention is particularly useful in the aeronautical field. According to the invention, the probe comprises several emitters that can each emit a sound wave and a receiver sensitive to the different sound waves. Thus, there is forewarning of the receiver error that is common to all the measurements of travel time of a sound wave between one of the emitters and the receiver.

Abstract: A bi-static sodar system and method are used to measure and monitor the wake vortices of aircraft in the flight path of an airport runway. A loudspeaker (16) is arranged on one side of the flight path (12) and transmits a series of acoustic pulses to illuminate portion of the flight path. Multiple microphones (18, 20 and 22) are arranged on the opposite side of the flight path (12) so as to receive direct signals from the loudspeaker (16) and forward-scattered echo signals from an echo source (26) within the illuminated portion of the flight path. The microphones (18, 20 and 22) are arranged at different distances from the loudspeaker so that the time intervals between the receipt of the direct and echo signals from each pulse will vary because of the different locations of the microphones. This variation is used to assist in identifying the location and other characteristics of the echo signals and in generating an output indicative of a wake vortex (28).

Abstract: A system and method for measuring velocity in a fluid medium utilizing a measuring system are disclosed, wherein the measuring system comprises a transducer. In one aspect, the method comprises transmitting a first set of one or more signals of a bandwidth substantially broader than the bandwidth of the measuring system, receiving echoes from the first set of signals, obtaining a first velocity estimate based at least in part on the echoes from the first set of signals, transmitting a second set of one or more signals of a bandwidth, substantially equal to, or narrower than the bandwidth of the measuring system, receiving echoes from the second set of signals, obtaining two or more possible velocity estimates based at least in part on the echoes from the second set of signals, and selecting one of the possible velocity estimates based on the first velocity estimate.

Abstract: A bi-static sodar system and method are used to measure and monitor the wake vortices of aircraft in the flight path of an airport runway. A loudspeaker (16) is arranged on one side of the flight path (12) and transmits a series of acoustic pulses to illuminate portion of the flight path. Multiple microphones (18, 20 and 22) are arranged on the opposite side of the flight path (12) so as to receive direct signals from the loudspeaker (16) and forward-scattered echo signals from an echo source (26) within the illuminated portion of the flight path. The microphones (18, 20 and 22) are arranged at different distances from the loudspeaker so that the time intervals between the receipt of the direct and echo signals from each pulse will vary because of the different locations of the microphones. This variation is used to assist in identifying the location and other characteristics of the echo signals and in generating an output indicative of a wake vortex (28).

Abstract: A method for measuring channel flow discharge comprising the steps of: locating a platform carrying a fluid flow measurement device at a plurality of stations at spaced locations across a channel; determining the velocity of the platform at each station by averaging the differences between the position of the platform at a first time (t) and the position of the platform at a second time equal to the first time plus a position averaging interval (PI) for a plurality of different first times; obtaining current flow vs. depth profiles at each station by adjusting current velocity as measured by the current flow measuring device for the platform velocity; determining the flow discharge at each station.

Abstract: A system and method for correcting wind speed and direction data collected by a sodar or lidar apparatus for the orientation and/or position of the apparatus. There are sensors mounted to the sodar or lidar apparatus that detect the orientation and position of the apparatus. Software is used to adjust in situ the calculations of wind speeds and directions in three dimensions for deviations from some nominal orientation. Software and data structures can be used to cause the inclusion of the orientation and position of the system with the collected data.

Abstract: A waterproof or water-resistant membrane cover for the acoustic transducer array of a sodar system. The membrane is placed over each transducer of the array. The membrane may be spaced from the array, with a structure such as a frame used to hold the membrane in place relative to the array.

Abstract: An AD2CP includes at least one transducer assembly emitting sets of slanted directional acoustic beams and receiving the echoes; and electronics that processes the echoes into depth cells and computes velocity in each depth cell. The AD2CP is configured so that each beam set has a profiling catenation, at least two of which are different, and the AD2CP is configured so that the emitting, receiving and processing operate contemporaneously.

Abstract: A system and method for measuring velocity in a fluid medium utilizing a transducer are disclosed. In one aspect, the method comprises transmitting an acoustic signal comprising N (where N is integer and N>1) pings for each of a plurality of beams, receiving echoes from each ping, obtaining a velocity estimate for each of the N pings based on echoes of the ping, and calculating a velocity based on the sum of the N velocity estimates such that the velocity is substantially free from error caused by cross-coupling between the beams.

Abstract: In an exemplary implementation of a method and system for determining the direction of fluid flow, one or more sound transducers are positioned in proximity to a conduit, each such sound transducer generating a signal representative of a selected characteristic of acoustic waves emanating from the conduit. Such signals are collected and analyzed to determine a threshold value for the selected characteristic (e.g., frequency) indicative of a change in the direction of fluid flow through the conduit. Based on whether subsequent measurements of the selected characteristic (e.g., frequency) are above or below the threshold value, the direction of fluid flow can be predicted and/or a change in the operational state of a component associated with the conduit can be identified.

Abstract: Two SODAR systems (12a and 12r) for detecting and characterizing vortices (16) shed from landing or departing aircraft (14) as at an airport (10) are positioned so that one, the active system (12a) is located beneath the likely vortices (16) and the other, the reference system (12r) is located away from the vortices but in the same ambient environment. Thus, where a wind duct or thermal inversion (18) is present, both SODAR systems will detect echoes (22 and 28) generated thereby, whereas only the active system (12a) will detect echoes (24) from wake vortices (16). By differencing the outputs of the reference and active systems, better vortex identification and discrimination is achieved. Only one SODAR system need be used where sufficiently normal conditions prevail between aircraft activity, since readings taken in the absence of aircraft can be used as reference data for subtraction from ‘active’ data recorded during the presence of aircraft.

Abstract: A system estimates flow parameters associated with a fluid flow encountering a bluff body. The system includes multiple sensors distributed on a surface of a bluff body. The system further includes input circuitry and a sensor processing unit. The input circuitry receives a signal from each of the multiple sensors. The sensor processing unit determines noise levels associated with each of the multiple sensors due to the fluid flow encountering the bluff body. The sensor processing unit further assigns weights to each of the multiple sensors based on the determined noise levels and estimates the fluid flow direction based on the assigned weights.

Abstract: Wind indicator apparatus for indicating air flow comprising: a direction pointer, including a vane member, for providing a visible indication of air flow direction; pivoting means including a fixed portion for coupling to a sailing craft and a pivotable portion able to pivot with respect to said fixed portion and with which said direction pointer is entrained for movement therewith; and a counterbalance extending from said pivotable portion of said pivoting means and arranged to move therewith, the mass of the counterbalance being disposed so as to maintain the direction pointer in a substantially level position.

Abstract: An acoustic system has an acoustic sensor and a processing circuit. The acoustic sensor includes a base, a microphone having a microphone diaphragm supported by the base, and a hot-wire anemometer having a set of hot-wire extending members supported by the base. The set of hot-wire extending members defines a plane which is substantially parallel to the microphone diaphragm. The processing circuit receives a sound and wind pressure signal from the microphone and a wind velocity signal from the hot-wire anemometer, and provides an output signal based on the sound and wind pressure signal from the microphone and the wind velocity signal from the hot-wire anemometer (e.g., accurate sound with wind noise removed). The configuration of the hot-wire extending members defining a plane which is substantially parallel to the microphone diaphragm can be easily implemented in a MEMS device making the configuration suitable for miniaturized applications.

Abstract: The present invention is directed to a radio-acoustic sounding system for providing wind measurements at altitudes of 100 meters or less. Wind measurements are obtained by transmitting a pulse of audio frequency energy through one or more volumes corresponding to the coverage area of one or more radio frequency transceivers. The frequency of the audio pulse is selected to have a wavelength that is one-half the wavelength of the electromagnetic energy transmitted by the antenna or antennas. By monitoring a return radio frequency signal at selected times following the transmission of the audio pulse, wind data is obtained at selected altitudes. Wind speed and direction can be obtained by observing the Doppler frequency shift of return radio frequency signals, or by observing the amplitude of the return radio frequency signals.

Abstract: An apparatus for non-intrusively sensing fluid flow within a pipe is provided. The apparatus includes a first sensing array for sensing acoustic signals traveling at the speed of sound through fluid flow within the pipe, a second sensing array for sensing local pressure variations traveling with the fluid flow, and a housing attached to the pipe for enclosing the sensing arrays. The first sensing array includes a plurality of first optical pressure sensors and the second sensing array includes a plurality of second optical pressure sensors.

Abstract: Apparatus (50) for deploying an object to an underwater target position, the apparatus being provided with a beacon to transmit acoustic rays, a plurality of thrusters (56(i), i=1, 2, . . . I, I being an integer) to control positioning of the apparatus with respect to the underwater target position, and a sound velocity meter to measure velocity of sound in a fluid surrounding the apparatus.

Abstract: Methods and apparatus for atmospheric sounding using acoustic chirps are disclosed, the transmitted and echo chirps being compared in a mixer that yields frequency sums and differences. Preferably, the mixing is performed as a complex multiplication in the Fourier domain. In one system (1) a signal generator (5) such as a PC sound card drives a loudspeaker (3) that serves as a transmitter and echo pulses are detedcted by a microphone (4) that serves as a receiver. Chirps transmitted by the loudspeaker (3) travel by different paths (7a and 7b) due to reflection from TILS or thermal inversion layers (2a and 2b) at different altitudes. The transmitted and echo chirp signals are compared in a mixer (6) from which various outputs (8 and 9) can be generated. One output (8) might be the magnitude of the difference between the transmitted and echo chirp tones, instant by instant, which is indicative of the altitudes of the respective TILs.

Abstract: An improved acoustic Doppler flow measurement system which employs multiple acoustic frequencies to acquire multiple independent backscatter data from the flow channel, combining the data to enable survey measurement of channel flow properties beyond what can be achieved with either a single frequency system or multiple independent single frequency systems. The system is installed on small moving channel survey boats, remotely measuring vertical profiles of river currents, achieving accurate surveys of channel flow velocity structure and bottom topography, enabling accurate (approximately 1% resolution) survey measurement of channel flow discharge. Significant synergistic improvements are realized from both physical and functional integrations of the multi-frequency operational capability into a single integrated flow survey system. Use of phased array transducer techniques further reduces flow disturbance and transducer size, enabling use on even smaller survey boats.

Abstract: An acoustic system has an acoustic sensor and a processing circuit. The acoustic sensor includes a base, a microphone having a microphone diaphragm supported by the base, and a hot-wire anemometer having a set of hot-wire extending members supported by the base. The set of hot-wire extending members defines a plane which is substantially parallel to the microphone diaphragm. The processing circuit receives a sound and wind pressure signal from the microphone and a wind velocity signal from the hot-wire anemometer, and provides an output signal based on the sound and wind pressure signal from the microphone and the wind velocity signal from the hot-wire anemometer (e.g., accurate sound with wind noise removed). The configuration of the hot-wire extending members defining a plane which is substantially parallel to the microphone diaphragm can be easily implemented in a MEMS device making the configuration suitable for miniaturized applications.

Abstract: An air data sensor for an aircraft has a flush mounted plate at the outside surface of the aircraft and a housing for the sensor within the aircraft below the plate. A plurality of holes in the plate provide air flow to a pressure sensor in the housing. To prevent water from reaching the sensor, a trap chamber is provided below the holes. Various contorted air flow paths are disclosed. The tube to the pressure sensor may be heated.

Abstract: An apparatus for measuring a fluid flow velocity vector including a signal generator for generating an oscillating electrical signal, an acoustic transmitter for generating an acoustic signal proportional to the oscillating electrical signal; and at least three acoustic receivers for receiving the acoustic signal and generating electrical signals which are phase shifted by the influence of the fluid flow, and a signal processor for receiving and processing the oscillating electrical signal and the electrical signals generated by the at least three acoustic receivers to determine time delays for each acoustical receiver caused by the influence of the fluid flow which are processed to determine the fluid flow velocity vector components.

Abstract: A hyper-sound detection and ranging system for remote wind measurements that provides all three orthogonal components of a three dimensional wind field on a single transmission pulse utilizing simultaneous beams of acoustic waves. The present invention measures atmospheric wind by transmitting a broad beam acoustic pulse to illuminate a zone of the atmosphere, and then measuring the Doppler shifts in the backscatter signals arrived at the system from various directions along the broad beam projection utilizing simultaneous receiving beams of narrow beamwidth. The simultaneous receiving beams are obtained by means of a hybrid of analog and digital beamforming technologies that enables simultaneous formation of a programmable number of beams in any direction within the designed fields-of-view.

Abstract: An improved acoustic Doppler flow measurement system which employs multiple acoustic frequencies to acquire multiple independent backscatter data from the flow channel, combining the data to enable survey measurement of channel flow properties beyond what can be achieved with either a single frequency system or multiple independent single frequency systems. The system is installed on small moving channel survey boats, remotely measuring vertical profiles of river currents, achieving accurate surveys of channel flow velocity structure and bottom topography, enabling accurate (approximately 1% resolution) survey measurement of channel flow discharge. Significant synergistic improvements are realized from both physical and functional integrations of the multi-frequency operational capability into a single integrated flow survey system. Use of phased array transducer techniques further reduces flow disturbance and transducer size, enabling use on even smaller survey boats.