Ultrasonic Transmitters Research Articles

Design 3-D ultrasonic spatial mouse using microprocessor system

The Ultrasonic sensors can be used to accurately measure the distance to an object. These sensors normally work in transmitter/receiver pairs, and can be used for a wide variety of applications in which range analysis is required. The 3-D Ultrasonic Spatial Mouse was designed with ultrasonic sensors to measure distances in close range in three dimensions, and to output on PC the functions of a 3-D pointing device. A MOTOROLA MC68HC812A4 microcontroller was used to implement the sensor functions, and was interfaced to the PC via serial communicationswhere the screen output was rendered with OPENGL programming. Ultrasonic transmitters work by emitting high frequency signals, and the receivers capture the signals. The devices chosen for this project, Devantech SRF04 Ultrasonic Range Finders, operated at frequencies of around 40 KHz. A device was successfully implemented that sent three dimensions of data to a PC, and the position of a mouse on screen was rendered moving in a well-defined 3-D box of space. In addition, the 2-D and button capabilities of a typical mouse device were maintained.

Factors Affecting Reception Range of Ultrasonic Tags in a Georgia Estuary

AbstractUltrasonic tags are commonly used for marine biotelemetry, but little or no information exists about the in situ reception range or how different environmental variables affect the reception range of telemetry equipment. In this study, I used active tracking techniques to empirically determine three environmental effects on reception range of ultrasonic tags. Specifically, I examined the effects of (1) tag depth, (2) depth under the hydrophone, and (3) presence of snapping shrimp (Alpheidae) on the reception range of an ultrasonic transmitter (tag) in a Georgia estuary. Placing the tag in deep (8.8‐11.3 m) versus shallow (0.6‐1.5 m) water while the hydrophone was over deep water (3.4‐11.3 m) caused no significant difference in reception range. Placing the hydrophone over shallow (0.6‐2.7 m) versus deep (6.4‐9.1 m) water while the tag was in shallow (1.2‐1.8 m) water caused a significant decrease in reception range. The presence of a large aggregation of snapping shrimp between the hydrophone and the tag also caused a significant decrease in reception range. This study highlights the need for researchers to field-test equipment before conducting telemetry projects.

Reproductive interactions between fugitive farmed and wild Atlantic cod (Gadus morhua) in the field

Atlantic cod ( Gadus morhua ) are being increasingly farmed in net pens adjacent to coastal populations that are currently at historic lows. One concern is that farmed escapees enter local spawning shoals and mate with wild cod. We tested for the potential of escaped farmed cod to interact and hybridize with wild fish by examining the spatial dynamics of, and associations between, fish tagged with ultrasonic transmitters. Based on these data, we also investigated the basic mating system of cod in the field. The spawning ground was best described as a lekking arena. Wild males aggregated near the seafloor and associations between individuals were frequent. Wild females had a pelagic and dispersed distribution and rarely associated with each other. Associations between individual wild males and females were also infrequent. Farmed males rarely associated with wild fish and had core usage areas above the wild males, suggesting that they were not admitted into the spawning arena. Farmed females were over the spawning arena more frequently than wild females and often associated with wild males at the depth of the spawning arena, indicating potential mating with wild males and the possibility of courtship interference. Hence, hybridization between escaped farmed and wild cod is likely.

Dispersal of Smallmouth Bass from a Simulated Tournament Weigh‐In Site

AbstractSimulated smallmouth bass Micropterus dolomieu fishing tournaments were staged in Dale Hollow Lake, a 12,400‐ha reservoir in Tennessee, between March 2004 and February 2005 to investigate posttournament dispersal. Smallmouth bass (n = 54) were captured with conventional hook‐and‐line tackle and artificial lures, placed in live wells, and subjected to a weigh‐in procedure before being externally tagged with an ultrasonic transmitter and released. Water temperatures ranged from 7.4°C to 29.3°C (mean [SE] = 17.6°C [2.5]), fish ranged in total length from 330 to 572 mm (mean = 452 [8.3]), and no fish were dead at the weigh‐ins. Smallmouth bass dispersed rapidly away from the release site, which was located at the head of a 68‐ha embayment. After 3–5 d, survivors (n = 44) traversed an average distance of 1,475 m [213]. Most (72%) fish swam uplake and out of the 385‐ha study area after 6 d. The rapid dispersal of smallmouth bass may be relevant in systems that experience heavy tournament activity. The smallmouth bass caught and subjected to simulated tournament conditions on Dale Hollow Lake did not stockpile near the release site.

Adaptive Ultrasonic Distance Measurement Technique for Handwriting Digitization Using Reconfigurable Analog Blocks

This paper proposes a low-power dynamically adaptive distance measurement technique for ultrasonic (US) pen digitizers. The technique utilizes a new clock frequency-throttling technique for a reconfigurable analog front-end in implementing a frequency-hopping scheme to minimize power dissipation. As a result, a noise-tolerant distance measurement which is not possible in conventional schemes is realized. Furthermore, the use of reconfigurable analog blocks facilitates wider bandwidth usage of the Piezo film transducers that are used for ultrasonic transmissions and receptions.

Developing an auto-tracking automated guided vehicle carrier using a wave-varied detecting method

Robots are widely used in modern industrial manufacturing, in households, in the entertainment sector, and in the security sector. In recent times, because of the increasing lifetime for old people, the concept of lifestyles of health and sustainability is prevailing. To facilitate a heavily loaded hand-carrier when aged people are travelling or working outside, an intelligent automated guided vehicle (AGV) is necessary. In this article, an intelligent and interactive AGV is developed. In order to develop the auto-tracking carrier for an AGV within an unlimited working space, a dynamic distance measuring system using the speed variation between a radio wave and an ultrasonic wave propagating in the air is adopted. The microchip PIC 18F452 is used as the control core. To facilitate the targeted functions, interactivity in conjunction with high quality sensors plays an essential role. By using a wireless transmitter (radio ray) and an ultrasonic transmitter on the user's waist angled towards the sensors at the front of the AGV, the distance between the user and the AGV can be calculated. To avoid colliding with a barrier, an ultrasonic transmitter is installed on both sides of the AGV. Subsequently, a controller based on fuzzy thinking will actuate the motor's motion enabling it to follow and dodge barriers. Consequently, a prototype AGV has been manufactured and successfully tested in the laboratory.

Focus on sensors and detectors

Focus on sensors and detectors

Hotspots within hotspots? Hammerhead shark movements around Wolf Island, Galapagos Marine Reserve

Are pelagic species such as sharks and tuna distributed homogenously or heterogeneously in the oceans? Large assemblages of these species have been observed at seamounts and offshore islands in the eastern tropical Pacific, which are considered hotspots of pelagic biodiversity. Is the species distribution uniform at these hotspots or do species aggregate at a finer spatial scale at these sites? We employed three techniques to demonstrate that the aggregations of scalloped hammerhead sharks, Sphyrna lewini, and other pelagic species were confined to the southeastern corner of Wolf Island in the Galapagos Marine Reserve. Coded ultrasonic transmitters were placed on individuals at this site and at another aggregation site at Darwin Island, separated from Wolf by 40 km, and they were detected by monitors moored at the southeastern corner of Wolf Island and rarely by monitors deployed at other sites around the island. Hammerhead sharks, carrying depth-sensing continual transmitters, were tracked for two-day periods in a vessel and shown to reside a disproportionately large fraction of their time at the southeastern corner. Visual censuses were carried out seasonally at the eight monitor sites at Wolf Island, recording the abundance of one species of tuna, four species of jacks, and a number of other species. The highest diversity and abundance of these species occurred in the southeastern corner of the island. Our results support the use of hammerhead sharks as indicator and umbrella species for pelagic hotspots on a fine scale.

Design and implementation of an embedded home surveillance system by use of multiple ultrasonic sensors

In this paper we design and implement a home surveillance system based on an embedded system with multiple ultrasonic sensor modules to enhance the system's reliability. Each ultrasonic sensor module includes a transmitter and a receiver, and the modules are placed in a line direction. Because the ultrasonic transmission will spread at a beam angle, we use multiple ultrasonic receivers to receive the ultrasonic transmission. If any intruder passes through the ultrasonic sensing area, the ultrasonic transmission will be blocked by the human body. As the receivers will not receive any transmission from the ultrasonic transmitter, the system will sense when someone is passing through the surveillance area. We use a Majority Voting Mechanism (MVM) for a group of sensors. If over half the sensors in a sensor group sense a signal blocking, the majority voting program starts the Web camera. The mathematical equation and the sensing experiment show that we improve the system's reliabilities.

Nondestructive evaluation of the depth of surface-breaking cracks in concrete pipes

Surface-breaking cracks affect the material and structural properties of concrete pipes. Therefore, the nondestructive evaluation of the crack depth is important to assess the serviceability of these pipes, which are commonly used in underground infrastructure and trenchless installations (micro-tunneling). This paper presents theoretical, numerical and experimental results for the depth evaluation of surface-breaking cracks. The wall of a concrete pipe is represented as a plate in the numerical and the analytical studies. In the experiments, an ultrasonic piezoelectric transmitter is used as a source. The propagation of the ultrasonic pulse is analyzed using the wavelet transform. A newly proposed wavelet transmission coefficient (WTC) is measured using an equal spacing configuration for the crack depth evaluation in concrete pipes and concrete plates. The results from laboratory and in situ tests show good potential for the practical application of the WTC for the depth evaluation of surface-breaking cracks.

A Comparison of Seasonal Movement Patterns of Yellow Perch in Simple and Complex Lake Basins

AbstractDetermining the seasonal movement patterns of fish can provide insight into their spawning behaviors, predator–prey interactions, and habitat preferences. To investigate the seasonal movement patterns of adult yellow perch and how they are affected by lake habitat characteristics, we attached ultrasonic transmitters to two length‐groups (210–235 and 250–280 mm total length) of yellow perch from populations inhabiting two temperate lakes differing in habitat diversity and basin morphology. In the simple lake, yellow perch distributions differed between seasons, mean depth and distance from shore being greatest during the summer. The observed seasonal differences were similar between the two length‐groups. In the complex lake, yellow perch depth varied seasonally, the fish occupying deeper waters during the fall and shallower ones during the summer; however, the distance from shore was consistent among seasons. During the spring, males inhabited areas closer to shore than females in the complex lake, whereas the spatial distributions did not differ between sexes in the simple basin. Yellow perch from both lakes displayed similar seasonal variation in activity, movement rates being highest during the fall and lowest during the summer. Movement rates in the simple lake, however, were higher than those in the complex lake during all three seasons, which suggests that the effectiveness of passive sampling gears may vary in response to habitat complexity. These results reveal several seasonal differences in yellow perch habitat use, distribution, and activity in relation to basin complexity that may provide insight for managers considering sampling plans for individual lake types.

Shape Recognition and Position and Posture Measurement of an Object Based on Ultrasonic Pressure Distributions

Ultrasonic sensors are often utilized to perceive the outside world. In this paper, we propose the construction of an object identification system that utilizes the ultrasonic waves reflected from a measured object. This identification system also detects the position and posture of an object. The system consists of an ultrasonic sensor array and a neural network. The ultrasonic sensor array is made up of plural ultrasonic transmitters and receivers that are arranged on the same plane. The receiver outputs the peak values of ultrasonic sound pressure waves. Their values are input into the neural network, which identifies the shape of the object and detects its position and posture. We have designed and built a prototype system and carried out numerous experiments using objects with primitive shapes or transparent bottles (PET bottles). The experimental results showed almost perfect shape identification and a measurement accuracy of up to one-half of one wavelength of the ultrasonic wave.

New Methodology for Source Characterization in Pulse Velocity Testing

Abstract The pulse velocity test (PVT) is an ASTM standard for the measurement of compressional wave velocities in geomaterials. The PVT is based only on the first arrival of the wave. Full-waveform analysis can be used to measure the variation in geomaterial properties with frequency but requires the dynamic characteristics of the transducers. This paper presents a new methodology for the dynamic characterization of ultrasonic transmitters based on experimental and numerical results. Different types of excitation pulses (input signals) are used, and their theoretical Fourier spectra are computed. The methodology is demonstrated using a piezoelectric accelerometer to measure the frequency response function of an ultrasonic transmitter (UT) (50 kHz). The complex exponential method is used to extract the dynamic properties of the transmitter from transient time signals. Experimental results show that this methodology can be used for the dynamic characterization of ultrasonic transmitters. Results from finite element numerical simulations of wave propagation agree with laboratory results.

Phase boundary characterization in liquids by acoustic waves

Precise inline process analysis, as an instrument for securing product qualities and enhanced process efficiency, nowadays often requires not only a temporal but also a spatial investigation of relevant physical process parameters. From the variety of available methods that allow for a tempo-spatial medium analysis, the ultrasonic-based tomographic approach and its direct application for inline monitoring of liquid systems is discussed in the present contribution. As an application example, the localization and characterization of an a priori unknown multiphase layer system has been performed by means of a simple ultrasonic transmitter–receiver arrangement. The data acquisition is based on the ultrasonic waves that are transmitted through the medium under test. Those signals represent the input of the tomographic process imaging. Using a linear model describing the homogeneous wave propagation and a fast estimation algorithm running on a normal PC, the extraction of information regarding layer thicknesses, materials and boundary properties has been performed in real time. The corresponding results are verified by simulations and semi-numeric studies and are additionally confirmed by first experimental tests.

Embedded Piezo-Transducer in Concrete for Property Diagnosis

In this study, new ultrasonic transducers with piezo patches as transmitting and sensing element were fabricated and used as embedded ultrasonic transducers for concrete property diagnosis. The ultrasonic transmitter was designed and manufactured to generate both longitudinal and transverse wave simultaneously according to the polarization and electric field direction. The current research focused on the velocity measurement of the longitudinal and transverse waves. Young's modulus and Poisson's ratio of concrete could be calculated using the measured wave velocity. The Young's modulus and Poisson's ratio obtained by test results of newly developed embedded transducers were compared with the values obtained from impact test for same batch of concrete and good agreement was observed. The advantages of this method were that it could generate both longitudinal and transverse wave and had a stable coupling between concrete matrix and ultrasonic transducers. This method showed a good potential for application in concrete health monitoring.

Overwinter survival of stocked age-0 lake sturgeon

Summary Knowledge of age-specific survivorship is critical when developing management prescriptions for imperiled species such as the lake sturgeon (Acipenser fulvescens). Management has focused on population restoration through hatchery supplementation, largely in the absence of data about relationships between hatchery rearing conditions, size/age at release, and estimates of overwinter survival for stocked age-0 lake sturgeon. Young of the year lake sturgeon were reared from egg to age 3 months in two separate hatchery environments: a streamside hatchery on the natal Upper Black River, Michigan, and a traditional hatchery environment. From age 3 to 6 months all fish were reared in the traditional hatchery. Fish (n = 20) originating from each rearing environment were surgically implanted with ultrasonic transmitters at 6 months of age (mean total length: 31.4 cm; mean weight: 106.4 g) and released into Black Lake in December 2005. Tracking using manual and automated hydrophones was conducted during April and May 2006 to estimate overwinter survival and to test for differences in survival of fish reared in different hatchery environments. Eighteen fish (45%) were detected, 16 (40%) of which survived the winter (range of distance traveled between observations of surviving fish was 0.09–0.55 km). The remaining fish were not detected. No significant differences in survival were documented due to rearing environment or size at release. This study represents the first quantified estimate of overwinter survival for stocked age-0 lake sturgeon. The minimum estimate of 40% survival through the first winter is encouraging for hatchery programs, and will aid in the development of management prescriptions for this species.

Measurement of the speed and attenuation of the Biot slow wave using a large ultrasonic transmitter

Two compressional wave modes, a fast P1 and a slow P2, propagate through fluid‐saturated porous and permeable media. This contribution focuses on new experimental tests of existing theories describing wave propagation in such media. Updated observations of this P2 mode are obtained through a water‐loaded, porous sintered glass bead plate with a novel pair of ultrasonic transducers consisting of a large transmitter and a near‐point receiver. The properties of the porous plate are measured in independent laboratory experiments. Waveforms are acquired as a function of the angle of incidence over the range from −50° to +50° with respect to the normal. The porous plate is fully characterized, and the physical properties are used to calculate the wave speeds and attenuations of the P1, the P2, and the shear S waves. Comparisons of theory and observation are further facilitated by numerically modeling the observed waveforms. This modeling method incorporates the frequency and angle of incidence‐dependent reflectivity, transmissivity, and transducer edge effects; the modeled waveforms match well those observed. Taken together, this study provides further support for existing poroelastic bulk wave propagation and boundary condition theory. However, observed transmitted P1 and S mode amplitudes could not be adequately described unless the attenuation of the medium's frame was also included. The observed P2 amplitudes could be explained without any knowledge of the solid frame attenuation.

Human Face Classification Using Ultrasonic Sonar Imaging

In this paper, human face classification using ultrasonic sonar imaging is investigated. On the basis of Freedman's “image pulse” model, the scattering centers model is employed to simplify the complex geometry of the human face into a series of scattering centers. A chirp signal is utilized to detect the human face for its high range resolution and large signal-to-noise ratio. Ultrasonic sonar images, also named high-resolution range profiles, are obtained by demodulating the echoes with a reference chirp signal. Features directly related to the geometry of the human face are extracted from ultrasonic sonar images and verified in the experiments designed with different configurations of transmitter–receiver (TR) pairs. Experimental results indicate that the improved feature extraction method can achieve a high recognition rate of over 99% in the case of ultrasonic transmitters angled at 45° above and orthogonal to the face, and this method improves the performance of ultrasonic face recognition compared with our previous result.

Evaluation of fast-acquisition GPS in stationary tests and fine-scale tracking of green turtles

Fastloc GPS (FGPS) is a variant of Global Positioning System (GPS) technology that offers important new utility for investigating fine-scale movements of marine animals like green turtles that surface too briefly for effective use of standard GPS. I report here on the accuracy and efficiency of this novel technology, compare it with two alternative methods, namely boat-based ultrasonic tracking and Argos Platform Transmitter Terminals (PTTs), and provide new data on the vagility and habitat selection of green turtles in shallow coastal foraging habitat. I used a combined FGPS receiver and PTT transmitter (Sirtrack, Havelock North, New Zealand) mounted together with an ultrasonic transmitter and time-depth recorder in a tether-attached housing that allowed automatic detachment and subsequent retrieval of the equipment without the requirement to recapture turtles. With this equipment I conducted short deployments (4.5 to 16.8 d) on 3 free-living adult-size green turtles in coastal foraging habitat in Queensland, Australia. In addition, stationary tests in air and afloat were conducted at the same site. FGPS location error (mean ± SD) increased as the number of satellites used in each computation decreased, from 26 m ± 19.2 (8 satellites) to 172 m ± 317.5 (4 satellites). During live tracking the frequency of FGPS locations greatly exceeded Argos PTT, such that screened data comprised about 50 times more FGPS locations despite a much tighter screening threshold for FGPS (250 m) than for Argos PTT (1000 m). FGPS locations showed the three study turtles used modest short-term activity ranges with Minimum Convex Polygon area mean ± SD 662 ha ± 293.9. They all remained within < 4.7 km of their capture–release locations and favoured shallow water, with 86% of locations at charted depths ≤ 3 m and the deepest location at 5.9 m. Fine-scale movements of each turtle varied from day to day with respect to tortuosity and areas traversed. Statistically significant day–night differences were evident in average rates of movement (greater by day) and in habitat selection, where diurnal locations had greater seagrass density while nocturnal locations featured deeper bathymetry. Individual turtles revisited some of their centres of activity (identified from 50% fixed kernel utilisation distributions) on multiple occasions but none of the study turtles travelled consistently between the same day–night pair of sites as has been reported elsewhere. Such disparity and the day-to-day variation in movements revealed by these short-term findings highlight the need for detailed tracking over longer periods at multiple locations. Fastloc GPS technology proved an effective new tool for this area of research.

A self-contained system for observing and quantifying the behavior of Atlantic cod, Gadus morhua, in an offshore aquaculture cage

A self-contained data collection system is described that was used to investigate the behavior of Atlantic cod ( Gadus morhua) in an offshore net pen (Sea Station 3000) located 13 km off the coast of New Hampshire, USA. The entire system was housed inside a modified U.S. Coast Guard (USCG) navigational buoy that was retrofitted for this purpose. Power was provided by a combination of eight 12 V batteries, two solar panels and a wind generator. The behavior of the population of cod as a whole, during daylight hours, was monitored using four waterproof cameras connected to a four channel digital video recorder. The behavior of 4–12 individual fish implanted with ultrasonic transmitters was continuously recorded, during each of four study periods, using a HTI model 291 ultrasonic telemetry system. Laboratory studies showed no influence of transmitter implantation on swimming or feeding behavior. Transmitters were programmed to “ping” at intervals between 1.7 and 3.3 s and they typically lasted for about one month. The system successfully detected and plotted 84.9 ± 6.0% of transmissions, resulting in an average of 1283.4 ± 252.5 positional fixes for each animal, during each hour of the study. This preliminary evaluation of cod behavior in a net pen demonstrated that they are diurnally active and have a tendency to mill about, rather than school. Cod predominately used the lower half of the cage, except when rising to the feeding area during periods when feed was delivered. The system that was developed proved to be ideal for investigating the behavior of fish within a net pen, and it can be used by both inshore and offshore farms to gather behavioral data that can lead to improvements in the efficiency of aquaculture operations.