Academic literature on the topic 'Large-array transmitters'
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Journal articles on the topic "Large-array transmitters"
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Emery, Charles D., H. C. Casey, and Stephen W. Smith. "Ultrasonic Imaging Using Optoelectronic Transmitters." Ultrasonic Imaging 20, no. 2 (1998): 113–31. http://dx.doi.org/10.1177/016173469802000203.
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Conventional ultrasound scanners utilize electronic transmitters and receivers at the scanner with a separate coaxial cable connected to each transducer element in the handle. The number of transducer elements determines the size and weight of the transducer cable assembly that connects the imaging array to the scanner. 2-D arrays that allow new imaging modalities to be introduced significantly increase the channel count making the transducer cable assembly more difficult to handle. Therefore, reducing the size and increasing the flexibility of the transducer cable assembly is a concern. Fiber optics can be used to transmit signals optically and has distinct advantages over standard coaxial cable to increase flexibility and decrease the weight of the transducer cable for large channel numbers. The use of fiber optics to connect the array and the scanner entails the use of optoelectronics such as detectors and laser diodes to send and receive signals. In transmit, optoelectronics would have to be designed to produce high-voltage wide-bandwidth pulses across the transducer element. In this paper, we describe a 48 channel ultrasound system having 16 optoelectronic transmitters and 32 conventional electronic receivers. We investigated both silicon avalanche photodiodes (APD's) and GaAs lateral photoconductive semiconductor switches (PCSS's) for producing the transmit pulses. A Siemens SI-1200 scanner and a 2.25 MHz linear array were used to compare the optoelectronic system to a conventional electronic transmit system. Transmit signal results and images in tissue mimicking phantoms of cysts and tumors are provided for comparison.
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O'Toole, A. C., K. J. Murchie, C. Pullen, et al. "Locomotory activity and depth distribution of adult great barracuda (Sphyraena barracuda) in Bahamian coastal habitats determined using acceleration and pressure biotelemetry transmitters." Marine and Freshwater Research 61, no. 12 (2010): 1446. http://dx.doi.org/10.1071/mf10046.
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Documenting free-swimming fish in their natural environment using acoustic transmitters equipped with acceleration and pressure sensors may contribute to knowledge of locomotory behaviour for a variety of aquatic species. Previously, collection of acceleration data has been limited to archival loggers, necessitating retrieval of the devices; however, recent advances in biotelemetry have allowed for acceleration data to be transmitted to a remote receiver. To illustrate the application of this technology, relative locomotory activity and depth utilisation of adult great barracuda (Sphyraena barracuda) were monitored across habitat types and diel periods using acoustic transmitters equipped with tri-axial acceleration and pressure sensors within an acoustic telemetry array (n = 53 receivers) deployed in The Bahamas. Although there were no differences in acceleration or depth use across habitats or diel periods, there was evidence of movement into shelf habitat during mid-day where they occupied depths >10 m. Given both the method of calculating the accelerometer output, and that the transmitters were unable to store and transmit large quantities of data, we suggest choosing transmitter settings with a short average delay and high transmission frequency to optimise data quality and resolution. This paper represents one of the first reports of the use of telemetered acceleration values from free-swimming fish.
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Tweneboah-Koduah, Samuel, Emmanuel Ampoma Affum, Kwame Agyemang-Prempeh Prempeh Agyekum, Sunday Adeola Ajagbe, and Matthew O. Adigun. "Performance of Cooperative Relay NOMA with Large Antenna Transmitters." Electronics 11, no. 21 (2022): 3482. http://dx.doi.org/10.3390/electronics11213482.
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The potential of the Non-Orthogonal Multiple Access (NOMA) approach for wireless communications in the fifth generation (5G) and beyond can not be underestimated. This is because users with favorable channel conditions can serve as relays to improve system performance by employing Successive Interference Cancellation (SIC). Lately, the combination of NOMA and the cooperative relay has attracted the interest of researchers. The analysis of cooperative relay NOMA (CR-NOMA) with a massive multiple-input multiple-output (mMIMO) system is mainly based on theoretical channel models such as the correlated-based stochastic channel model (CBSM) even though the geometric-based stochastic channel model (GBSM) has been found to provide better, practical and realistic channel properties. This, in our view, is due to computational challenges. Again, the performance of CR-NOMA systems using the GBSM channel model with large antenna transmitters and network coding schemes has attracted little attention in academia. Therefore, the need to study mMIMO CR-NOMA that considers channel properties such as path-loss, delay profile and tilt angle has become vital. Furthermore, the co-existing of large antenna transmitters with coding schemes needs further investigation. In this paper, we study the performance of a two-stage mMIMO CR-NOMA network where the transmitter is represented as a uniform rectangular array (URA) or cylindrical array (CA). The communication channel from the transmitter (TX) to the user equipment (UE) through a relay station (RS) is modeled with a 3GPP’s three-dimensional (3D) GBSM mMIMO channel model. To improve the analytical tractability of 3D GBSM, we defined the antenna element location vectors using the physical dimension of the antenna array and incorporated them into the 3D channel model. Bit-error rates, achievable rates and outage probabilities (OP) are examined using amplify-and-forward (AF) and decode-and-forward (DF) coding schemes. Results obtained show with fixed power allocation and SNR of 20 dB, far or weak users can attain a high achievable rate using DF and URA. Again, from the results, the combination of AF and CA presents better outage probabilities. Finally, the results indicate that the performance difference between CBSM and GBSM is marginal, even though the proposed 3D GBSM channel model has a higher degree of random parameters and computational complexities.
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Shirai, Toshimichi, Tomoaki Oyama, Hiroshi Imai, and Shinsuke Abe. "Search for Extraterrestrial Intelligence at 22 GHz with the Very Large Array." Symposium - International Astronomical Union 213 (2004): 423–28. http://dx.doi.org/10.1017/s0074180900193647.
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We have conducted a direct Search for Extraterrestrial Intelligence at the Water Maser frequency, 22.235 GHz, using the Very Large Array. The targets were 13 solar-type stars that were known to host exoplanetary systems. In all cases, the RMS limits of the flux density, 20 mJy (5σ), were sufficient to rule out any omnidirectional transmitters of the same power as terrestrial radars (5 × 1012 W). We discuss the significance of this non-detection.
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Kurdzo, James M., Boon Leng Cheong, Robert D. Palmer, Guifu Zhang, and John B. Meier. "A Pulse Compression Waveform for Improved-Sensitivity Weather Radar Observations." Journal of Atmospheric and Oceanic Technology 31, no. 12 (2014): 2713–31. http://dx.doi.org/10.1175/jtech-d-13-00021.1.
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Abstract The progression of phased array weather observations, research, and planning over the past decade has led to significant advances in development efforts for future weather radar technologies. However, numerous challenges still remain for large-scale deployment. The eventual goal for phased array weather radar technology includes the use of active arrays, where each element would have its own transmit/receive module. This would lead to significant advantages; however, such a design must be capable of utilizing low-power, solid-state transmitters at each element in order to keep costs down. To provide acceptable sensitivity, as well as the range resolution needed for weather observations, pulse compression strategies are required. Pulse compression has been used for decades in military applications, but it has yet to be applied on a broad scale to weather radar, partly because of concerns regarding sensitivity loss caused by pulse windowing. A robust optimization technique for pulse compression waveforms with minimalistic windowing using a genetic algorithm is presented. A continuous nonlinear frequency-modulated waveform that takes into account transmitter distortion is shown, both in theory and in practical use scenarios. Measured pulses and weather observations from the Advanced Radar Research Center’s dual-polarized PX-1000 transportable radar, which utilizes dual 100-W solid-state transmitters, are presented. Both stratiform and convective scenarios, as well as dual-polarization observations, are shown, demonstrating significant improvement in sensitivity over previous pulse compression methods.
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Plotkin, A., and E. Paperno. "3-D magnetic tracking of a single subminiature coil with a large 2-D array of uniaxial transmitters." IEEE Transactions on Magnetics 39, no. 5 (2003): 3295–97. http://dx.doi.org/10.1109/tmag.2003.816750.
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Lamoral Coines, Adrián, and Víctor P. Gil Jiménez. "CCSDS 131.2-B-1 Transmitter Design on FPGA with Adaptive Coding and Modulation Schemes for Satellite Communications." Electronics 10, no. 20 (2021): 2476. http://dx.doi.org/10.3390/electronics10202476.
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Satellite communications are a well-established research area in which the main innovation of last decade has been the use of multi-carrier modulations and more robust channel coding techniques. However, in recent years, novel advanced signal processing has started being developed for these communications due to the increase in the signal processing capacity of transmitters and receivers. Although signal processing capabilities are increasing, they are still constrained by large limitations because these techniques need to be implemented in real hardware, thus making complexity a matter of critical importance. Therefore, this paper presents the design and implementation of a transmitter with adaptable coding and modulation on a field-programmable-gate-array (FPGA). The main motivation came from the standard CCSDS 131.2-B-1 which recommends that such a novel transmitter which has to date not been implemented in a real system The system was modeled by MATLAB with the purpose of being programmed in VHDL following the AXI-stream protocol between components. Behavioral simulation results were obtained in VIVADO and compared with MATLAB for verification purposes. The transmitter logical circuit was synthesized in a FPGA Zynq Ultrascale RFSoC ZU28DR, showing low resource consumption and correct functioning, leading us to conclude that the deployment of new communication systems in state-of-the-art hardware in satellite communications is justified.
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Rechisky, Erin L., David W. Welch, Aswea D. Porter, Melinda C. Jacobs, and Adrian Ladouceur. "Experimental measurement of hydrosystem-induced delayed mortality in juvenile Snake River spring Chinook salmon (Oncorhynchus tshawytscha) using a large-scale acoustic array." Canadian Journal of Fisheries and Aquatic Sciences 66, no. 7 (2009): 1019–24. http://dx.doi.org/10.1139/f09-078.
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Out-migrating Snake River salmon smolts must pass eight major hydro dams before reaching the Pacific Ocean. Direct mortality at the dams is generally low; however, the cumulative stress caused by dam passage is hypothesized to result in delayed mortality, which occurs beyond the impounded section of the river. We tested the delayed mortality hypothesis by comparing in-river and early ocean survival of hatchery-origin spring Chinook salmon ( Oncorhynchus tshawytscha ) from the Snake River to a mid-Columbia River population that passes through only four dams and has higher smolt to adult return rates. Smolts >140 mm fork length were implanted with acoustic transmitters and tracked with the Pacific Ocean Shelf Tracking (POST) array to as far as Alaska. There was no detectable difference in survivorship to the first ocean detection line, 274 km beyond the final dam (SSnake = 29% ± 4%, SYakima = 28% ± 5%), indicating that the survival disparity observed in adult return rates may develop later in the marine life history phase. Our study is the first to estimate survival in the coastal ocean and demonstrates the utility of a large-scale array in testing previously intractable hypotheses.
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Klinard, Natalie V., Aaron T. Fisk, Steven T. Kessel, Edmund A. Halfyard, and Scott F. Colborne. "Habitat use and small-scale residence patterns of sympatric sunfish species in a large temperate river." Canadian Journal of Fisheries and Aquatic Sciences 75, no. 7 (2018): 1059–69. http://dx.doi.org/10.1139/cjfas-2017-0125.
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Bluegill (Lepomis macrochirus) and pumpkinseed (Lepomis gibbosus) sunfish function as a trophic link between invertebrates and piscivores in temperate freshwater food webs, but little is known about their movement in large-scale riverine ecosystems. To address this, pumpkinseed and bluegill were implanted with acoustic transmitters and monitored for 5 months (June to November 2015) within a 0.39 km2 acoustic array in the Detroit River. Residence index analysis revealed site fidelity of sunfish to the side of the river they were tagged and a lack of movement across a shipping channel. Bluegill were more active at night and pumpkinseed more active during daylight hours, possibly partitioning resources on a temporal basis, unlike in smaller lakes where the species partition the littoral and pelagic habitats. Pumpkinseed presence was positively correlated with water temperature and level, whereas bluegill presence was not related to any environmental parameters examined. This study demonstrates that anthropogenic alterations (e.g., channelization) influence the movement and distribution of fishes and that fish behaviour in a large river ecosystem can differ from smaller temperate lakes.
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Starr, Richard M., Victoria O'Connell, Stephen Ralston, and Laurence Breaker. "Use of Acoustic Tags to Estimate Natural Mortality, Spillover, and Movements of Lingcod (Ophiodon elongatus) in a Marine Reserve." Marine Technology Society Journal 39, no. 1 (2005): 19–30. http://dx.doi.org/10.4031/002533205787521677.
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Advances in electronic telemetry systems have led to fish tagging studies that are sufficiently long to provide estimates of natural mortality of many marine fishes. We used acoustic transmitters and an array of recording receivers to estimate natural mortality, residence times, and rates of movements of lingcod (Ophiodon elongatus) in a marine reserve in southeast Alaska. We surgically implanted acoustic tags in a total of 83 lingcod in December 1999 and July 2000, and distributed recording monitors with receiving ranges of at least 800 m throughout the reserve. The receivers were anchored on the seafloor in locations that resulted in overlapping receiving ranges, and thus created an array of receivers that completely encompassed an 8 km2 reserve. In this way, we were able to estimate natural mortality rates and track movements of tagged lingcod into and out of the reserve from December 1999 through October 2001. Acoustic tag results indicated that most of the tagged fish frequently left the reserve, but were only absent for short time periods. Tagged fish showed a high degree of site fidelity. The large number of signals received from tagged fish enabled us to generate models that provided a way to predict the effects of marine reserves on yield and eggs per recruit for a cohort of female lingcod.
Book chapters on the topic "Large-array transmitters"
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Ranglack, Dustin H., Glenn E. Plumb, and Luke R. Rogers. "American Bison (Bison bison): A Rangeland Wildlife Continuum." In Rangeland Wildlife Ecology and Conservation. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-34037-6_23.
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AbstractAmerican bison (Bison bison) are the largest extant land animal in North America and have an important history and contemporary role in modern conservation. Bison historically had the widest continental distribution of all native ungulates but now only function as wildlife under natural selection on < 1.2% of the original range. Bison as rangeland wildlife occur on an array of exclusive and overlapping governance jurisdictions (e.g., Federal, State, Provincial, County, and Tribes and First Nations), private not-for-profit conservation lands enterprises, zoo and education enterprises, and for-profit commodity production. The historical and prevailing relationships within and between these higher order sectors are very complex and often conflicting, yet each sector has invested tremendous effort and public and private resources to increase the total abundance of bison to present levels. Despite long-term public investment in wild bison conservation, the private sector has far out-stripped wild bison, resulting in a potentially divergent evolution trajectory towards species domestication. The primary ecosystem function of plains bison on rangelands is contributing to plant community heterogeneity through patchily distributed grazing events that create mosaics of grazing pressure. Additionally, bison exhibit a myriad of other roles in their environment through direct and indirect interactions. Perhaps more than with other rangeland wildlife species, genetics play an outsized role in current bison population management given historical bottlenecks and intentional cross breeding of bison and cattle. However, moving forward the interplay between population size, isolation, and genetic diversity is more important. Along the continuum of bison management there exist a wide variety of rangeland management techniques. However, as a wildlife species, the rangeland management practices associated with bison have generally focused on disturbance ecology with a more recent push to understand the impacts of bison grazing at scale. The question of scale is important given that every bison is behind a barrier, thus restricting their impacts on rangeland ecology and processes. Bison and cattle are considered by many to be potential competitors, due to large overlaps in diet and body size, and much research has focused on the ecological equivalence of the two species. While this is still not without controversy, bison and cattle are not incompatible when properly managed. Chronic infection of wild bison populations with diseases that can be transmitted to livestock and humans is an important factor affecting potential recovery of bison outside existing reserve boundaries. Climate change may represent the next major challenge to bison, as it is expected to directly affect bison through decreased forage and water availability and increased thermal stress. These threats, combined with the differences in bison management practices between sectors have led some to classify bison as moderately vulnerable to climate change, recommending the creation of a ‘bison coalition’ that could seek climate change adaptation solutions through shared stewardship. While much of the continental historical range is no longer available for bison restoration, there are exciting conservation opportunities that are finding voice through the vision of “Shared Stewardship” that embraces innovative collaboration to work together across jurisdictions and sectors to successfully address the scale, complexity, and ecological and cultural significance of wild bison.
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"Advances in Fish Tagging and Marking Technology." In Advances in Fish Tagging and Marking Technology, edited by Chris T. Walsh, vars V. Reinfelds, Ron J. West, Charles A. Gray, and Dylan E. van der Meulen. American Fisheries Society, 2012. http://dx.doi.org/10.47886/9781934874271.ch17.
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<i>Abstract</i>.—Movement patterns of two co-occurring catadromous fishes, estuary perch <i>Macquaria colonorum </i>and Australian bass <i>Macquaria novemaculeata</i>, were investigated in a large tidal river in southeastern Australia. Nineteen estuary perch and seventeen Australian bass were captured as mature adults from the Shoalhaven River, surgically implanted with electronic transmitters and released. Forty-nine Vemco (VR2W) acoustic receivers were strategically placed throughout the river from the Tallowa Dam wall downstream to the sea (a distance of 75 km). Between September 2007 and February 2008, a total of 800,263 detection events were recorded with most fish detected in the middle (estuary perch) to upper (Australian bass) estuarine reaches of the river. Both species made extensive use of the estuary, with no estuary perch and only three Australian bass entering the freshwater, indicating that the freshwater residency phase of these catadromous fishes may not be obligatory. The data also suggests that estuary perch and Australian bass exhibit high site fidelity, which, along with their large scale movements may be influenced by factors such as river discharge and prey availability. This large freshwater-estuarine telemetry array combined with critical abiotic information (river discharge and salinity) has and will provide a greater understanding of catadromous fish movement, particularly in relation to habitat utilization and environmental flows.
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"Challenges for Diadromous Fishes in a Dynamic Global Environment." In Challenges for Diadromous Fishes in a Dynamic Global Environment, edited by John F. Kocik, James P. Hawkes, Timothy F. Sheehan, Paul A. Music, and Kenneth F. Beland. American Fisheries Society, 2009. http://dx.doi.org/10.47886/9781934874080.ch19.
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<em>Abstract</em>.-Understanding estuarine and early marine ecology of Atlantic salmon <em>Salmo salar </em>smolts within the relatively large and spatially dynamic environments of eastern Maine is challenging. Using ultrasonic transmitters and a large network of fixed receivers, we monitored natural smolt migration in the Narraguagus River, Narraguagus Bay, and coastal environment of the western Gulf of Maine. Our 30-km-long study area began in the lower river and extended 8 km downstream to head-of-tide, 7 km through the estuary, then fanned out seaward 15 km into the western gulf along the interface with Maine Coastal Current. From 1997 to 2004, we increased sampling network density in the estuary and expanded marine arrays further into the Gulf of Maine. We designed receiver networks to monitor all smolt exit routes and were able to (1) estimate smolt survival to the Gulf of Maine, (2) map primary migration paths, and (3) document emigration timing. Survival ranged from 36% to 47% to our outer receiver array. Median migration rates were 0.7 km/h in the estuary to middle bay and 1.0 km/h in the outer bay. Smolts generally traveled with the tides and upon entering saltwater most commonly used the western 6 km of a 23-km-wide embayment. These are among the first quantitative data to estimate survival during early marine migration of wild Atlantic salmon smolts. A Cormack- Jolly-Seber model estimated site efficiency and smolt survival simultaneously, providing a useful methodology and information benchmarks for other studies to better understand emigration dynamics and to help identify mortality factors at sea.
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Ilango, Parthiban, V. Sudha, and Hassan Pakarzadeh. "Lattice-Aided Delay Phase Precoding for 6G THz Massive MIMO." In 5G and Fiber Optics Security Technologies for Smart Grid Cyber Defense. IGI Global, 2024. http://dx.doi.org/10.4018/979-8-3693-2786-9.ch018.
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The future 6G wireless technology promotes applications like three-dimensional (3D) communication, extended virtual reality, digital twins, autonomous driven vehicles, etc. Such applications require tens of GHz bandwidth, such large bandwidth is promoted by Terahertz communication system. To compensate the effect of attenuation and to increase the coverage massive MIMO with traditional hybrid precoder is considered. The conventional hybrid precoder suffers from beam split effect, where the transmitted beams are oriented towards different direction leads to loss of array gain. To circumvent the array gain loss and to focus the orientation of all transmitted beams toward a particular direction a delay phase precoder (DPP) is considered. In delay phase precoding, the selected precoder is not redundant therefore consumes more power. To reduce the power consumption two lattice aided DPP namely: Boosted LLL aided DPP and Boosted KZ aided DPP were proposed. The performance in terms of array gain and data rate were plotted. The computational complexity analysis was also performed.
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Wong, Yue Chim Richard. "The High Cost of Regulating Development." In Fixing Inequality in Hong Kong. Hong Kong University Press, 2017. http://dx.doi.org/10.5790/hongkong/9789888390625.003.0025.
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Housing prices have risen in the United States and Hong Kong mostly because of the high regulation costs of development. In each of the developed countries, a very large array of complex regulations has made development difficult and effectively prevented housing supply from responding to demand. The problem is not market competition, but government regulations that prevent markets from functioning properly. The rising ratio of capital to income is almost entirely due to the rise of housing. What begins initially as inequality in housing wealth gets transmitted into the next generation and is transformed into other forms of inequality, in particular inequality in opportunities, with other distributional consequences.
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"Quasi-Newton Cross-Correlation and Constant Modulus Adaptive Algorithm for Space-Ti1ne Blind Equalization." In Mathematics in Signal Processing V, edited by Yuhui Luo and Jonathon Chambers. Oxford University PressOxford, 2002. http://dx.doi.org/10.1093/oso/9780198507345.003.0004.
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Abstract In a multiuser wireless communication system, it may be assumed that the base-band digital signals originating from d spatially separated sources are transmitted through multiple linear channels and captured by an array of AI antennas, representative of a multiple input multiple output (Mll\IO) model. Due to the potentional large delay spread introduced by multipath propagation and the presence of co-channel system users, the received signals are corrupted not only by inter symbol interference (ISI) but also by inter user interference (IUI). In this context, the objective for a blind space-time equalizer is to jointly combat ISI and IUI without recourse to exploit training sequences. A. schematic illustration is shown in Fig. 1.
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Ndongo, Hervé Abena, Tieudjo Daniel, and Bitjoka Laurent. "Securing Digital Photography Images by Encryption-Watermarking CFA (Color Filter Array) Images." In Global Perspectives on the Applications of Computer Vision in Cybersecurity. IGI Global, 2024. http://dx.doi.org/10.4018/978-1-6684-8127-1.ch009.
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Research in image processing of digital color photography is in full expansion, especially on CFA (color filter array) images. These raw CFA images are very important for image analysis because they have not undergone any processing (interpolation, demosaicking, etc.) that would alter their reliability. The chapter presents three robust hybrid algorithms combining chaotic encryption and blind watermarking techniques of CFA images based on the quaternionic wavelet transform (QWT) to propose solutions related to the problems of confidentiality, security, authenticity of these images transmitted over digital networks, the size of some CFA images, and the large amount of data to be transferred in a non-secure environment where resources in terms of throughput and bandwidth are quite limited. The three hybrid algorithms were implemented simultaneously and successively.
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Surya Jyothi, M., S. Sai Prasanna, K. L. V. Prasad, and Sanjeev Kumar. "Microstrip Antenna for 5G Millimetre-Wave Applications." In Advances in Transdisciplinary Engineering. IOS Press, 2023. http://dx.doi.org/10.3233/atde221323.
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In this paper, a single element antenna is presented for 5G millimeter wave (mm Wave) applications and using single element can be made for MIMO, array of antenna. The bandwidth value of the presented antenna is 11.1 GHz (from 25.1 GHz to 36.2 GHz) and overall size is only 11.5 × 12.5 mm2. It shows that very good candidate for 5G applications. Future wireless communications services require high data rates as technology is progressing. Multi-input multi-output (MIMO) technology for emerging and future wireless communications systems is seen as a fundamental requirement. Technologies like data rate improvements, transmission speed, channel capacity and throughput increase the performance of wireless communication systems substantially. On the side of the transmitter and the receiver, MIMO antennas are several. The design of effective MIMO antennas with a high rate of data and large capacity presents various obstacles.
Conference papers on the topic "Large-array transmitters"
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Brihuega, Alberto, Lauri Anttila, Mahmoud Abdelaziz, and Mikko Valkama. "Digital Predistortion in Large-Array Digital Beamforming Transmitters." In 2018 52nd Asilomar Conference on Signals, Systems, and Computers. IEEE, 2018. http://dx.doi.org/10.1109/acssc.2018.8645137.
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Rupakula, Bhaskara, Abdurrahman H. Aljuhani, and Gabriel M. Rebeiz. "Linearity and Efficiency Improvements in Phased-Array Transmitters with Large Number of Elements and Complex Modulation." In 2018 IEEE/MTT-S International Microwave Symposium - IMS 2018. IEEE, 2018. http://dx.doi.org/10.1109/mwsym.2018.8439860.
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Sun, Liusheng, Babar Hussain, Xianbo Li, Guang Zhu, and C. Patrick Yue. "A Micro-LED Driver with Bandwidth Expansion for Visible Light Communications." In JSAP-OSA Joint Symposia. Optica Publishing Group, 2017. http://dx.doi.org/10.1364/jsap.2017.6p_a410_5.
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Visible light communication (VLC) using LEDs has generated strong research interest recently [1, 2]. Many existing LEDs in display applications can be employed as transmitters for the further deployment of VLC. The first active matrix LED (AMLED) micro-display with an embedded VLC transmitter was reported in [2], with a 5-Mb/s modulation bit rate. This paper presents an AMLED system, consisting of a proposed CMOS pixel driver and a flip-chip bonded blue gallium nitride (GaN) micro-LED (μLED) array with 36×64 pixels of 40×40 μm2, for simultaneous display and VLC applications. Measurement results show that the proposed pixel driver can achieve a 20-Mb/s bit rate at 10 cm, which is four times as large as the 5-Mb/s modulation bit rate in [2].
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Eriksen, Torkild, Ulf-Peter Hoppe, Eivind V. Thrane, and Tom A. Blix. "A Rayleigh lidar on rockets for studies of the middle atmosphere." In The European Conference on Lasers and Electro-Optics. Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cmi6.
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Two new rocket-borne Rayleigh lidar experiments were developed at the Norwegian Defence Research Establishment and launched from Andøya Rocket Range in October 97 and January 98. The aim of the experiments were to measure the neutral atmosphere number density and to study the dynamics of the middle atmosphere. A simulation programme for calculation of Rayleigh-scattered signal, background level and noise was used to investigate the performance of the instrument. Various configurations of transmitters and receivers were evaluated. For the transmitter, laser diode arrays and solid state lasers were considered. The diode arrays were found suitable and two types of high power diode arrays were tested in the laboratory. A 20 bar array assembled using the bars-in-grooves technology was selected. It was operated in QCW mode with a pulse length of 450 μs, a pulse repetition rate of 135 Hz and an average optical power of 62 W at 805 ± 5 nm. It required a power supply giving 65 A at 42 V, active water cooling and a collimating lens. For the receiver, diodes and PMTs were considered. A large-area detector able to process photon rates of 106to 1010 s-1 was essential. An APD was selected due to the better quantum efficiency compared to the PMTs at 805 nm. It had a gain of 200 at 2.4 kV, and was cooled to -20°C to reduce the dark current to 1.5 nA and the rms-noise to 40 pA.
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Lin, Bin, and Victor Giurgiutiu. "PVDF and PZT Piezoelectric Wafer Active Sensors for Structural Health Monitoring." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80400.
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Piezoelectric wafer active sensors (PWAS) used in structural health monitoring (SHM) applications are able to detect structural damage using Lamb waves. PWAS are small, lightweight, unobtrusive and inexpensive. PWAS achieve direct transduction between electric and elastic wave energies. PWAS are essential elements in the Lamb-wave SHM with pitch-catch, pulse-echo, phased array system and electromechanical impedance methods. PWAS are charge mode sensors and they can be used as both transmitters and receivers. A model of PWAS is shown in this paper. In vibration, impact detections applications, the PWAS response is strong due to the large dynamic change of strain. In pitch-catch, pulse-echo and phased array applications, PWAS are used to generate and receive Lamb waves and the PWAS response is small. A charge amplifier for PWAS applications is introduced in this paper. PWAS are normally made of piezoceramic Lead Zirconate Titanate (PZT). The structural integrity tests require attachment of PWAS to the material surface and there are critical applications where the rigid piezoceramic wafers cannot conform to curved surfaces. As alternative one can use flexible piezopolymer such as polyvinylidene fluoride (PVDF); such PVDF-PWAS have been studied in this paper. PVDF-PWAS were mounted on a cantilever beam for the free vibration test and on a long rod for the longitudinal impact test. The experimental results of the PZT-PWAS and PVDF-PWAS have been compared with the conventional strain gauge. The theoretical and experimental results in this study gave the basic demonstration of the piezoelectricity of PZT-PWAS and PVDF-PWAS.
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Goldberg, L., M. M. Howerton, A. S. Greenblatt, and W. K. Burns. "High-power optical transmitter for optical communication." In Integrated Photonics Research. Optica Publishing Group, 1990. http://dx.doi.org/10.1364/ipr.1990.wd5.
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Many optical communication systems, such as those based on free-space propagation, require significantly higher diffraction-limited transmitter power than is available from single-stripe laser diodes. An attractive solution is to use a high-power coupled stripe laser-diode array or broad stripe laser that is externally injection locked to achieve a diffraction-limited far-field emission.1 To encode the transmitted information, we could use direct array current modulation, but this requires large drive currents and is limited by relatively low modulation bandwidth of the array. One alternative is to frequency modulate the master laser for FSK transmission.2 Recent advances in optical damage-resistant waveguides3 permit the use of another approach, described here and shown in Fig. 1, where the information is first encoded as phase modulation on the master laser signal by using a LiTaO3 proton-exchanged waveguide phase modulator. Modulated output is then used to injection lock a coupled stripe array. When the phase-modulation spectral sidebands in the injected signal are within the locking bandwidth, the phase-modulated signal is amplified and transmitted by the injection-locked laser without suppression of the modulation index.4
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Daudlin, Stuart, Sunwoo Lee, Devesh Kilwani, et al. "Ultra-dense 3D integrated 5.3 Tb/s/mm2 80 micro-disk modulator transmitter." In Optical Fiber Communication Conference. Optica Publishing Group, 2023. http://dx.doi.org/10.1364/ofc.2023.m3i.1.
Full textAbstract:
A large-scale array of 80 micro-disk modulators is densely bonded to an electronic chip and driven at 10 Gb/s/modulator for an unprecedented 5.3 Tb/s/mm2 bandwidth density and 50 fJ/bit energy consumption.
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Lu, Liangjun, Weihan Xu, Yuyao Guo, Chuxin Liu, Jianping Chen, and Linjie Zhou. "Large-Scale Optical Phased Array Based on a Multi-Layer Silicon-Nitride-on-Silicon Photonic Platform." In Optical Fiber Communication Conference. Optica Publishing Group, 2024. http://dx.doi.org/10.1364/ofc.2024.m4b.1.
Full textAbstract:
We review our recent progress on a chip-scale LiDAR transmitter on a multi-layer Si3N4-on-Si photonic platform. Experimental results show the high optical power budget of the chip and the feasibility for FMCW ranging.
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Wakelin, Suzanne, Kelvin K. Chau, Matthew W. Derstine, James S. Wong, and John Cloonan. "Implementation of Hybrid Micro-Optical Beam Combining Unit (MOBCU) with Smart Pixel Transmitter Array." In Optics in Computing. Optica Publishing Group, 1997. http://dx.doi.org/10.1364/oc.1997.ofa.4.
Full textAbstract:
Combining the parallelism and connectivity of optics with electronics in smart pixel systems requires the development of robust and reliable optical systems. This is an important issue as the solutions to many applications must be implemented in harsh or variable environments. In addition, the combination of electronic boards that are relatively placement insensitive with optical systems that demand accurate positioning to obtain high performance, requires methods by which these demands can be fulfilled. Most bulk optical imaging systems utilizing custom and off-the-shelf optics and optomechanics can provide some solutions to optical interconnections in laboratory experiments and subsystem demonstrations. However, there are optical and size limitations to classical imaging techniques that can be overcome with the use of hybrid bulk and micro optic imaging. Use of large arrays of microlenses is an effective method of interconnecting large dilute arrays of smart pixels. The micro channel technique for 4-f imaging of focal spot arrays and device planes establishes a single optical path for each channel in the array. This type of one-to-one imaging may be usefully implemented in various imaging systems. In particular, relaying optical data from chips mounted on electronic boards. In addition to simple one to one imaging, arrays of focal spots originating from different sources must be combined together. For example, signal inputs incident a smart pixel array must be combined with the clock array that is used to read the state of the devices. We have investigated and developed passive and active alignment techniques applied to the construction of these hybrid optical components and have fabricated hybrid micro-channel beam combining units that have been integrated into a smart pixel transmitter array subsystem demonstration [1].
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Mons, Ishan, Andrea Mansfeld, Océane Boulais, Vinod Veedu, Stefan Mrozewski, and Hani Elshahawi. "Distributed Real-Time Plume Monitoring for Deep Sea Mineral Extraction." In Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/32074-ms.
Full textAbstract:
Abstract In the emerging industry of deep-sea mining for minerals and deposits (e.g., polymetallic nodules for nickel, cobalt, copper, and manganese), more data is required to understand the effects of sediment plume generation and predict the distribution of disturbed sediments. There are two main sources of plume generation, the first being at the active mining site where the "collector" directly removes the top layer of the sea floor. The other is the "midwater plume" consisting of unwanted sediment that was collected during extraction that is pumped back into the aphotic zone. The vast majority of plume generation is caused by the collector, causing detrimental and long-lasting impacts on sea floor ecosystems due to the lack of wave activity or strong currents at the sea floor. Therefore, it is crucial to invest in the infrastructure to support the study and constant monitoring over a large area of the sea floor where plume generation is present. Due to the limited number of usable channels and power requirements, current subsea wireless communications technologies are not well suited to instrumenting the large areas of the sea floor needed to monitor plume migration. The scope of this effort is to transition experimental demonstrations of high-bandwidth, full-duplex scalable underwater laser communications to the sea floor in an open ocean environment. Specifically tackling challenges associated with the dynamic nature of the subsea world, including but not limited to, deployment logistics, sustainability, and range. The goal is to enable the internet of underwater things for deep sea industries by broadening the capabilities of subsea communications. By using high-precision laser transmitters, many of the challenges facing current subsea optical systems can be circumvented, such as power consumption, interference, and bandwidth limitations. This approach lends itself to wireless interlinking multi-node networks, in series or parallel, facilitating the implementation of a wide array of sensor types. This interlinking allows all the data gathered from the network to be processed through a single hardline uplink to the surface, lowering the complexity required for near real-time data processing. Additionally, the laser control systems produce metadata that can be used to help characterize the water column between the nodes. Combining data from various sensors such as turbidity, temperature, and current velocity with metadata such as beam attenuation and deflection can produce a high-resolution model of sea floor conditions around an active mining zone. The resulting near real-time model can be used to optimize location and flow rate of the mining operation to minimize and quantify the environmental impact.