Artigos de revistas: "UHF satellite communication"

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Kovář, Pavel, Pavel Puričer, Eric Benton e Jan Mikeš. "Demonstration of the Capability of 1U CubeSat for Measurement of the Energy Spectrum on LEO". Electronics 11, n.º 20 (20 de outubro de 2022): 3390. http://dx.doi.org/10.3390/electronics11203390.

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The goal of this paper is to demonstrate the capability of the 1U CubeSat to study the radiation spectra on LEO. The research was realized by the Lucky-7 mission with the primary goal of testing electronics such as a power supply, piNAV L1 GPS receiver, UHF communication system, and other subsystems in the natural space environment, and the secondary goal of testing the possibility of using 1U CubSat class satellites for scientific tasks. The satellite is equipped with a piNAV GPS receiver and piDOSE radiation detector, silicon diode radiation spectrometer, camera, and other sensors. The on-board computer enables storage of 34 h of measurements of the radiation spectrum. These measurements can be downloaded by the UHF communication system during four satellite passes over the monitoring ground station. We successfully verified all necessary instruments and their cooperation and measurement procedure. The UHF communication was identified as the most critical subsystem because of its low capacity, which slowed down the satellite operation. We needed four zenith passes to upload 34 h of measurement.

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Yadav, Viplav, Sandeep e Sanjay Sharma. "Antennas for Satellite Communication". Journal of Advance Research in Electrical & Electronics Engineering (ISSN: 2208-2395) 1, n.º 1 (31 de janeiro de 2014): 20–23. http://dx.doi.org/10.53555/nneee.v1i1.269.

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Satellite communication antenna in unvield .It also comprises of transmitting/ receiving signal section and transmission of signal to satellite . it consist of various types of antennas used in satellite communication such as UHF, L/s band ,c-band, ku-band , k-band antennas. Multibeam broadband antenna and antennas for geostationary for satellite communication is also explained in this paper . This paper mainly describes the the signal transmitting/receiving antennas for satellite communication .

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Alam, Touhidul, Muntasir M. Sheikh, Rabah W. Aldhaheri, Mandeep Singh Jit Singh, Mengu Cho, Mohammad Tariqul Islam, Khalid H. Alharbi e Md Shabiul Islam. "Lower Ultra-High Frequency Non-Deployable Omnidirectional Antenna for Nanosatellite Communication System". Nanomaterials 12, n.º 18 (10 de setembro de 2022): 3143. http://dx.doi.org/10.3390/nano12183143.

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The concept of the nanosatellite comes into play in launching miniaturized versions of satellites or regarding payloads with minimizing cost and building time. The economic affordability of nanosatellites has been promoted with a view to launching various nanosatellite missions. The communication system is one of the most important aspects of a satellite. The antenna is a key element for establishing a communication link between the earth and the nanosatellite. The antenna and solar panel of the nanosatellite are two of the most vital components that profoundly impact antenna type and design. This paper proposes a non-deployable lower ultra-high frequency (UHF) antenna, strategically mounted on the satellite body, to address the constraints of deployment complexity and solar panel integration. The antenna was fabricated and performances measured with a 1U nanosatellite structure, which achieved resonance frequency at 401 MHz frequency bands with 0.672 dBi realized gain. The overall antenna size is 0.13λ × 0.13λ × 0.006λ. The major challenges addressed by the proposed antenna are to design a nanosatellite-compatible lower UHF antenna and to ensure solar irradiance into the solar panel to minimize input power scarcity.

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Ding, Yuan Ming, Jing Jing Sun e Xue Wang. "Multipath Effect Analysis of Sea Surface in Maritime Satellite Communications". Applied Mechanics and Materials 411-414 (setembro de 2013): 803–8. http://dx.doi.org/10.4028/www.scientific.net/amm.411-414.803.

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Ultra High Frequency (UHF) band is increasingly widely used in military maritime satellite communications due to its good communication performance. When the electromagnetic wave reaches the sea surface, it is reflected. The reflected wave and direct wave enter the receiver in the form of a superimposed vector, which will inevitably produces multipath fading at the receiving end. This paper followed the general principles of modeling in multipath effects, and the UHF band multipath effects of sea surface were studied. The judgment basis was obtained which determines whether the specula reflected wave dominates in the reflected wave based on Rayleigh criterion, and then the reflection coefficient of sea surface were calculated. Finally, the power attenuation of reflected wave relative to direct wave for different wind speeds were simulated and analyzed.

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Quintana-Diaz, Gara, Torbjörn Ekman, José Miguel Lago Agra, Diego Hurtado de Mendoza, Alberto González Muíño e Fernando Aguado Agelet. "In-Orbit Measurements and Analysis of Radio Interference in the UHF Amateur Radio Band from the LUME-1 Satellite". Remote Sensing 13, n.º 16 (17 de agosto de 2021): 3252. http://dx.doi.org/10.3390/rs13163252.

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Radio interference in the uplink makes communication to satellites in the UHF amateur radio band (430–440 MHz) challenging for any satellite application. Interference measurements and characterisation can improve the robustness and reliability of the communication system design. Most published results focus on average power spectrum measurements and heatmaps. We apply a low complexity estimator on an SDR (Software-Defined Radio) to study the interference’s dispersion and temporal variation on-board a small satellite as an alternative. Measuring the Local Mean Envelope (LME) variability with different averaging window lengths enables the estimation of time variability of the interference. The coefficient of variation for the LME indicates how much the signals vary in time and the spread in magnitudes. In this article, theoretical analysis, simulations, and laboratory results were used to validate this measurement method. In-orbit measurements were performed on-board the LUME-1 satellite. Band-limited interference with pulsed temporal behaviour and a high coefficient of variation was detected over North America, Europe, and the Arctic, where space-tracking radars are located. Wide-band pulsed interference with high time variability was also detected over Europe. These measurements show why operators that use a communication system designed for Additive White Gaussian Noise (AWGN) at power levels obtained from heatmaps struggle to command their satellites.

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Bouyedda, Abdellatif, Bruno Barelaud e Laurent Gineste. "Design and Realization of an UHF Frequency Reconfigurable Antenna for Hybrid Connectivity LPWAN and LEO Satellite Networks". Sensors 21, n.º 16 (13 de agosto de 2021): 5466. http://dx.doi.org/10.3390/s21165466.

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UHF satellite communication for Internet of Things (IoT) technology is rapidly emerging in monitoring applications as it offers the possibility of lower-costs and global coverage. At the present time, Low Power Wide Area Network (LPWAN) solutions offer low power consumption, but still suffer from white zones. In this paper, the authors propose an UHF frequency reconfigurable Antenna for hybrid connectivity LoRaWAN (at 868 MHz) and UHF satellite communication (Tx at 401 MHz and Rx at 466 MHz) with the Low Earth Orbit (LEO) Kineis constellation. The antenna is based on a meandered line structure loaded with lumped components and a PIN diode to control the antenna resonant frequencies. It resonates at 401 and 868 MHz when the PIN diode is forward-biased (ON state) and 466 MHz in reverse-biased configuration (OFF state). The antenna is designed inside the enclosure with the presence of all the parts of the connected device. The results of EM simulations and parametric studies on the values of the lumped components and the PIN diode equivalent model, which are obtained with HFSS, are presented. The antenna is prototyped and has dimensions of 78 mm × 88 mm × 1.6 mm. The paper proposes a fast and practical method to reduce time development and compensate the frequency shift between measurement and simulation.

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Humad, Yasir Ahmed Idris, e Levente Dudás. "Resonant Radar Reflector On VHF / UHF Band Based on BPSK Modulation at LEO Orbit by MRC-100 Satellite". Infocommunications journal 16, n.º 1 (2024): 26–34. http://dx.doi.org/10.36244/icj.2024.1.4.

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This paper presents a novel method for identify ing and tracking PocketQube satellites: the MRC-100 satellite is a model, and this method is based on a resonant radar reflec tor. The resonant reflector’s basic concept is that the resonant reflector uses a VHF/UHF communication subsystem antenna; there is no radiated RF signal, which means the power con sumption is only some Milliampere (mA). The continuous wave (CW) illuminator RF source is on the ground, and the onboard antenna receives the CW RF signal from the Earth. The micro controller (uC) periodically switches PIN diode forming BPSK modulated signal reflection so that another Earth station can receive the backscattered Binary Phase Shift Keying (BPSK) modulated signal. Also, it can detect the satellite if the ground station receiver can use a matched filter like a correlation re ceiver. If the ground station receiver knows the BPSK code of the satellite, it can detect it. If not, there is no way to detect the satellite. This method is similar to Radio Frequency Identifica tion (RFID) applications, but the reader is the ground station, and the tag is the satellite.

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Ramagiri, Santhosh Kumar, Arvind B. Shukla, Ramaniklal B. Bavaria, Surinder Singh e Kaushik S. Parikh. "Connector-less test setup for measurement of passive inter-modulation products at UHF band". International Journal of Microwave and Wireless Technologies 5, n.º 6 (28 de agosto de 2013): 689–98. http://dx.doi.org/10.1017/s1759078713000731.

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This paper describes the establishment of a test setup for measurement of passive inter-modulation (PIM) products generated by various device(s) under test (DUT(s)) (filters, coaxial cables etc.) at ultra high frequency (UHF) band. The paper begins with a brief discussion of an ideal PIM test setup using a quiet load. It then discusses the establishment of the setup in the absence of quiet load and demonstrates a PIM level of −192 dBc of the test setup. Finally it shows the PIM performance of a band-stop filter, a flexible cable, cascade of band-stop filter, and flexible cable, measured using the established test setup. These components are required for UHF payload of a communication satellite.

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Nguyen, Manh Thao, Fabien Ferrero e Le-Huy Trinh. "Compact UHF Circularly Polarized Multi-Band Quadrifilar Antenna for CubeSat". Sensors 23, n.º 12 (6 de junho de 2023): 5361. http://dx.doi.org/10.3390/s23125361.

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This article presents a multi-band right-hand circularly polarized antenna designed for the Cube Satellite (CubeSat). Based on a quadrifilar structure, the antenna provides circular polarization radiation suitable for satellite communication. Moreover, the antenna is designed and fabricated using two 1.6 mm thickness FR4-Epoxy boards connected by metal pins. In order to improve the robustness, a ceramic spacer is placed in the centerboard, and four screws are added at the corners to fix the antenna to the CubeSat structure. These additional parts reduce antenna damage caused by vibrations in the launch vehicle lift-off stage. The proposal has a dimension of 77 × 77 × 10 mm3 and covers the LoRa frequency bands at 868 MHz, 915 MHz, and 923 MHz. According to the measurements in the anechoic chamber, antenna gains with the values of 2.3 dBic and 1.1 dBic are obtained for the 870 MHz and 920 MHz, respectively. Finally, the antenna is integrated into a 3U CubeSat that was launched by a Soyuz launch vehicle in September 2020. The terrestrial-to-space communication link was measured, and the antenna performance was confirmed in a real-life scenario.

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Yan, Qiuying, Wei Li, Jiacheng Li, Jie Zhang, Shengyi Liu, Zhe Wang, Tong Liu, Qian Chen e Hanlin Sheng. "Real-Time Air-to-Ground Data Communication Technology of Aeroengine Health Management System with Adaptive Rate in the Whole Airspace". Mathematical Problems in Engineering 2021 (31 de julho de 2021): 1–13. http://dx.doi.org/10.1155/2021/9912574.

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To overcome the problem of data transmission of the aeroengine health management system, a multilink communication system combining ultrahigh-frequency communication link, 4G cellular mobile communication link, and BeiDou satellite communication link was proposed. This system can realize the functions such as data receiving and sending, data encryption, and resuming transfer from the break point based on multiple links. When the flight altitude is not high, the communication distance is short, so the UHF digital transmission radio communication link is adopted, which is highly efficient and stable. When the communication distance is long, the 4G cellular mobile communication link can ensure both the communication distance and the communication rate. In the area where 4G signal cannot be covered in extreme terrain environment, BeiDou satellite communication link is used for data transmission. Besides, in order to ensure the communication rate of the link, a multilink adaptive switching technology was also developed. The test verified that the system can perform adaptive switching among multiple links, realize air-ground data communication in the whole airspace, and achieve a good communication rate, which has significative value of engineering application.

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Lad, Rupesh, Pritesh Chhajed, Lokeshsingh Bai, Shyam Dahiwal, Sukhada Saoji, Vaibhav Rekhate, Pushkar Chaudhari et al. "Design and Performance Evaluation of Two-Unit YAGI-UDA Array for UHF Satellite Communication". International Journal of Wireless & Mobile Networks 6, n.º 5 (31 de outubro de 2014): 145–52. http://dx.doi.org/10.5121/ijwmn.2014.6512.

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J, Gowri, Indu Nair e Hari Hara Priyadharshini. "THE CONSTRUCTION AND PERFORMANCE ENHANCEMENTS OF ULTRA HIGH-FREQUENCY RANGE FOR THE INDOOR AND OUTDOOR ANTENNAS IN BUILT-IN COMMUNICATION NETWORKS". ICTACT Journal on Microelectronics 8, n.º 1 (1 de abril de 2022): 1307–12. http://dx.doi.org/10.21917/ijme.2022.0225.

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Digital terrestrial television is a good budget alternative to satellite TV. Its main advantages are excellent image and sound quality and no subscription fees. There is a set-top box (receiver) and antenna for digital TV in smart homes, and a great picture on any TV is guaranteed. The accurate picture is achieved due to a different quality signal transmission system than analogue TV. The digital signal is not subject to interference and interference and depends very little on the distance to the transmitter. The proposed antenna design provides enhancements to the Ultra High Frequency (UHF) range for indoor and outdoor antennas. There are indoor and outdoor antennas for the home and Dutch, respectively, where the antenna is installed. They are divided into active and passive depending on the presence of a built-in signal amplifier operating from the network. If the cable is long, the signal attenuation will be strong, which is very important for receiving meter waves unlike UHF, for which the length of the wire is also important, but not so much.

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Rastinasab, Vahid, e Victor Hu. "Simulation and Verification Two YAGI-UDI VHF/UHF and S-Band Satellite Dish Antenna for LEO Nanosatellites Communication". International Journal of Wireless & Mobile Networks 11, n.º 03 (29 de junho de 2019): 33–42. http://dx.doi.org/10.5121/ijwmn.2019.11303.

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Pearson, Christie, Lucy Lush e Luciano A. González. "Intravaginal Devices and GNSS Collars with Satellite Communication to Detect Calving Events in Extensive Beef Production in Northern Australia". Remote Sensing 12, n.º 23 (3 de dezembro de 2020): 3963. http://dx.doi.org/10.3390/rs12233963.

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Observing calves at birth may help to identify risk factors for, and reduce, calf loss in extensive beef systems. The objectives of this study were to: (1) evaluate two commercial satellite birth alert systems to enable the observation of newborn calves and (2) assess behavioral changes of cows around calving. Vaginal Implant Transmitters (VIT) paired with Global Navigation Satellite System (GNSS) collars were worn by 20 cows in Trial 1 and 10 cows in Trial 2 to identify birthing events. The VIT and GNSS collars contained a temperature sensor, accelerometer, and very high frequency (VHF) to communicate with a handheld tracker, and ultra-high frequency (UHF) for communication between the VIT and GNSS collar, which had two-way communication using Iridium satellites. A change (Brand 1) or drop (Brand 2) in temperature of more than 3 °C and inactivity triggered the VIT to communicate an expelled alert to the collar, which transmitted the birth alert information via Iridium (device ID, date, time and geolocation of the GNSS collar at expulsion). Cows and calves were tracked in the paddock following a birth alert to assess their health and status. Overall, true birth alerts occurred in only 27.6% of devices. Cows remained active on the day of calving travelling 5.54 ± 4.11 and 5.00 ± 2.80 km/day compared to 6.45 ± 2.79 and 6.12 ± 2.30 km/d on days when calving did not occur for Trial 1 and 2, respectively (mean ± SD). Average activity of the accelerometer X- and Y-axis on calving day was reduced by 15%–20% compared to other days in Trial 1 (p < 0.05) but not in Trial 2 (p > 0.05). Results suggest that these two birth alert systems are not suitable for use in extensive systems and the further development of the technology is required. Cows in the current trials remained active on the day of, and after, calving, indicating that a faster, real-time alert system and communication protocol would be required to achieve the aim of finding newborn calves.

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Kared, Trusha, Helga Silaghi, Matthias Rudolph, Andrei Silaghi e Ulrich L. Rohde. "Design of a Fixed IF Down-Conversion Double-Balanced Mixer for UHF Band Applications". Sensors 25, n.º 3 (21 de janeiro de 2025): 608. https://doi.org/10.3390/s25030608.

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This paper presents a new SiGe HBT-based high dynamic range double-balanced down-conversion differential mixer. Operating within the 0.5 GHz to 1.8 GHz range, the suggested mixer is appropriate for a variety of applications, such as cellular base stations, satellite communication (SATCOM), and military radar. The down-conversion mixer is made up of a single-ended to a differential-balanced radiofrequency (RF) stage, a dual feedback linearization for the RF stage, a local oscillator (LO) balun, LO mixing cores, and a fixed intermediate frequency (IF)-tuned circuit connected between two outputs to serve as a load at 145 MHz. Compared to earlier research in the literature, the measured SSB noise figure is approximately 7 dB ± 0.4 dB, and the measured conversion gain is approximately 12 dB ± 1 dB for a full band of operation. The mixer achieves a good return loss of over 8 dB for an RF and LO port in the desired band and a measured return loss of over 18 dB at 145 MHz and IF frequency. Furthermore, the design achieved an RF-to-IF isolation of greater than 35 dB, LO feedthrough, and an LO leakage isolation of better than 50 dB. Lastly, the measured third-order intercept point was found to be +4.7 dBm, and the 1 dB compression point was approximately −8 dBm. These results demonstrate good linearity performance.

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Jain, Abhinav, e Rana Pratap Yadav. "Design and development of rigid coaxial line based variable stub tuner". Frequenz 75, n.º 5-6 (22 de fevereiro de 2021): 153–58. http://dx.doi.org/10.1515/freq-2020-0085.

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Abstract This paper presents a novel design of rigid coaxial line based variable stub tuner. It incorporates controlled drive for the movement of shorting ring along the length of the stub inside the coaxial line. The ring is housed inside stub through linear slot over the coaxial conductor. Inbuilt slot at outer conductor of coaxial line introduces undesirable discontinuity which deteriorates the performance of the stub. It needs to be compensated to get the desirable performance of tuner. The effect of discontinuity has been analyzed using circuit modelling and compensated in design itself for the desired performance. The compensated tuner has been fabricated and tested where test results are found as return loss better than 25 dB and Voltage Standing Wave Ratio (VSWR) in between 1.1 and 1.9 in the frequency range of 80–850 MHz. The presented work is useful for the development of high power stub tuner in the range of High Frequency (HF), Very High Frequency (VHF) and Ultra High Frequency (UHF) which is an interest of wide spread applications in areas of communication, defence, satellite, radar, tokamak etc.

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Alam, Touhidul, Mohammad Tariqul Islam, Md Amanath Ullah e Mengu Cho. "A Solar Panel-Integrated Modified Planner Inverted F Antenna for Low Earth Orbit Remote Sensing Nanosatellite Communication System". Sensors 18, n.º 8 (31 de julho de 2018): 2480. http://dx.doi.org/10.3390/s18082480.

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One of the most efficient methods to observe the impact of geographical, environmental, and geological changes is remote sensing. Nowadays, nanosatellites are being used to observe climate change using remote sensing technology. Communication between a remote sensing nanosatellite and Earth significantly depends upon antenna systems. Body-mounted solar panels are the main source of satellite operating power unless deployable solar panels are used. Lower ultra-high frequency (UHF) nanosatellite antenna design is a crucial challenge due to the physical size constraint and the need for solar panel integration. Moreover, nanosatellite space missions are vulnerable because of antenna and solar panel deployment complexity. This paper proposes a solar panel-integrated modified planner inverted F antenna (PIFA) to mitigate these crucial limitations. The antenna consists of a slotted rectangular radiating patch with coaxial probe feeding and a rectangular ground plane. The proposed antenna has achieved a −10 dB impedance bandwidth of 6.0 MHz (447.5 MHz–453.5 MHz) with a small-sized (80 mm× 90 mm× 0.5 mm) radiating element. In addition, the antenna achieved a maximum realized gain of 0.6 dB and a total efficiency of 67.45% with the nanosatellite structure and a solar panel. The challenges addressed by the proposed antenna are to ensure solar panel placement between the radiating element and the ground plane, and provide approximately 55% open space to allow solar irradiance into the solar panel.

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White, Jim. "Use of, and limits to telecommunications supporting Spill Response in the Arctic". International Oil Spill Conference Proceedings 2014, n.º 1 (1 de maio de 2014): 281407. http://dx.doi.org/10.7901/2169-3358-2014-1-281407.1.

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The ability to exchange critical information across a broad spectrum of users is the success of a response. Communicating on the North Slope of Alaska is a technical challenge. One of the most critical elements supporting any Contingency Response is telecommunications (telecom). Telecom, as an issue rears its head after almost every exercise or real world response situation. It never seems to matter what type of event the response is supporting, the location of the response or weather that is occurring. Telecom continues to come up as a 'lessons learned'. Recent technological advances (Last 15–20 Years) have resolved some older, yet lingering issues, (e.g. SATCOM, Fiber Optics, Digitization, and the Internet). That said, trying to communicate over an area covering tens-of-thousands of square miles in some of the harshest, most remote regions on the planet is at the very least - demanding. Technically, in many regions, telecom issues can be fairly easy to resolve. In the Arctic, several factors as well as weather play a major part in our ability to respond to an incident. Many areas are not accessible on a road system. Ice roads provide seasonal, temporary access. When ice roads are not available then various aircraft can be utilized. Some sites may only be accessible via specialized vehicles treading lightly on the tundra or that displace the tons of equipment over a broad area for frozen pond, lake and river crossings, minimizing environmental impact. To meet the challenge of Spill Response on the North Slope of Alaska, Alaska Clean Seas and its member companies have developed and employ a network of Very High Frequency (VHF), Ultra-High Frequency (UHF), Cellular, Microwave, and SATellite COMmunications (SATCOM) Systems. A recent Federal Communications Commission directive to reduce bandwidth usage forced the modernization of Alaska's Oil Spill Response Network. The nationwide requirement enables the same number of users to occupy half the frequency spectrum. Alaska is unique in that the entire State's Oil Spill Response Network shares the same frequencies and compatible equipment. This enables the cooperatives to seamlessly support each another. One of the obvious reasons that telecom becomes an issue is non-standardized exchange of ideas, recommendations, or commands. User unfamiliarity with telecom devices (radios, speaker microphones) also contributes to communication barriers. Use of jargon, ten codes and often cultural references can inhibit needed messages from being received as expected. This can easily be improved through Incident Command System training

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Galgon, T. L., e W. D. Jemison. "Mobile antenna characterization and optimization for uhf satellite communications". Journal of the Franklin Institute 336, n.º 1 (janeiro de 1999): 65–76. http://dx.doi.org/10.1016/s0016-0032(98)00015-5.

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Novak, Markus H., e John L. Volakis. "Ultrawideband Antennas for Multiband Satellite Communications at UHF–Ku Frequencies". IEEE Transactions on Antennas and Propagation 63, n.º 4 (abril de 2015): 1334–41. http://dx.doi.org/10.1109/tap.2015.2390616.

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Kestilä, A., T. Tikka, P. Peitso, J. Rantanen, A. Näsilä, K. Nordling, H. Saari et al. "Aalto-1 nanosatellite – technical description and mission objectives". Geoscientific Instrumentation, Methods and Data Systems Discussions 2, n.º 2 (26 de novembro de 2012): 925–51. http://dx.doi.org/10.5194/gid-2-925-2012.

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Abstract. This work presents the outline and so far completed design of the Aalto-1 science mission. Aalto-1 is a multi-payload remote sensing nanosatellite, built almost entirely by students. The satellite aims for a 500–900 km sun-synchronous orbit, and includes an accurate attitude dynamics and control unit, a UHF/VHF housekeeping and S-band data links, and a GPS unit for positioning (radio positioning and NORAD TLE's are planned to be used as backups). It has three specific payloads: a spectral imager based on piezo-actuated Fabry–Perot interferometry, designed and built by The Technical Research Center of Finland (VTT); a miniaturized radiation monitor (RADMON) jointly designed and built by Universities of Helsinki and Turku ; and an electrostatic plasma brake designed and built by the Finnish Meteorological Institute (FMI), derived from the concept of the e-sail, also originating from FMI. Two phases are important for the payloads, the technology demonstration and the science phase. Emphasis is placed on technological demonstration of the spectral imager and RADMON, and suitable targets have already been chosen to be completed during that phase, while the plasma brake will start operation in the latter part of the science phase. The technology demonstration will be over in relatively short time, while the science phase is planned to last two years. The science phase is divided into two smaller phases: the science observations phase, during which only the spectral imager and RADMON will be operated for 6–12 months, and the plasma brake demonstration phase, which is dedicated to the plasma brake experiment for at least a year. These smaller phases are necessary due to the drastically different power, communication and attitude requirements of the payloads. The spectral imager will be by far the most demanding instrument on board, as it requires most of the downlink bandwidth, has a high peak power and attitude performance. It will acquire images in a series up to at least 20 spectral bands within the 500–900 nm spectral range, forming the desired spectral data cube product. Shortly before an image is acquired, the parallel visual spectrum camera will take a broader picture for comparison. Also stereoscopic imaging is planned. The amount of data collected by the spectral imager is adjustable, and ranges anywhere from 10 to 500 MB. The RADMON will be on 80% of an orbit period in average and together with housekeeping data will gather around 2 MB of data in 24 h. An operational limitation is formed due to the S-band downlink capability of 29–49 MB per 24 h for a 500 900 km orbit altitude, as only one ground station is planned to be available to the satellite. This will limit both type and quantity of spectral imager images taken during the science phase. The plasma brake will in turn be on within an angle of 20° over the poles for efficient use of the Earth's magnetic field and ionosphere during its spin-up and operation.

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Kestilä, A., T. Tikka, P. Peitso, J. Rantanen, A. Näsilä, K. Nordling, H. Saari et al. "Aalto-1 nanosatellite – technical description and mission objectives". Geoscientific Instrumentation, Methods and Data Systems 2, n.º 1 (21 de fevereiro de 2013): 121–30. http://dx.doi.org/10.5194/gi-2-121-2013.

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Abstract. This work presents the outline and so far completed design of the Aalto-1 science mission. Aalto-1 is a multi-payload remote-sensing nanosatellite, built almost entirely by students. The satellite aims for a 500–900 km sun-synchronous orbit and includes an accurate attitude dynamics and control unit, a UHF/VHF housekeeping and S-band data links, and a GPS unit for positioning (radio positioning and NORAD TLE's are planned to be used as backup). It has three specific payloads: a spectral imager based on piezo-actuated Fabry–Perot interferometry, designed and built by The Technical Research Centre of Finland (VTT); a miniaturised radiation monitor (RADMON) jointly designed and built by Universities of Helsinki and Turku; and an electrostatic plasma brake designed and built by the Finnish Meteorological Institute (FMI), derived from the concept of the e-sail, also originating from FMI. Two phases are important for the payloads, the technology demonstration and the science phase. The emphasis is placed on technological demonstration of the spectral imager and RADMON, and suitable targets have already been chosen to be completed during that phase, while the plasma brake will start operation in the latter part of the science phase. The technology demonstration will be over in a relatively short time, while the science phase is planned to last two years. The science phase is divided into two smaller phases: the science observations phase, during which only the spectral imager and RADMON will be operated for 6–12 months and the plasma brake demonstration phase, which is dedicated to the plasma brake experiment for at least a year. These smaller phases are necessary due to the drastically different power, communication and attitude requirements of the payloads. The spectral imager will be by far the most demanding instrument on board, as it requires most of the downlink bandwidth, has a high peak power and attitude performance. It will acquire images in a series up to at least 20 spectral bands within the 500–900 nm spectral range, forming the desired spectral data cube product. Shortly before an image is acquired, the parallel visual spectrum camera will take a broader picture for comparison. Also stereoscopic imaging is planned. The amount of data collected by the spectral imager is adjustable, and ranges anywhere from 10 to 500 MB. The RADMON will be on 80% of an orbit period on average and together with housekeeping data will gather around 2 MB of data in 24 h. An operational limitation is formed due to the S-band downlink capability of 29–49 MB per 24 h for a 500 900 km orbit altitude, as only one ground station is planned to be available for the satellite. This will limit both type and quantity of spectral imager images taken during the science phase. The plasma brake will in turn be within an angle of 20° over the poles for efficient use of the Earth's magnetic field and ionosphere during its spin-up and operation.

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Sekine, K., Y. Dooi, A. Iso, H. Funaki e I. Takei. "UHF band high-efficiency linear power amplifier for mobile communication satellites". Electronics Letters 26, n.º 7 (1990): 441. http://dx.doi.org/10.1049/el:19900286.

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Chae, Bong-Geon, Heon-Woo Ha, Su-Eun Jang e Hyun-Ung Oh. "Development of Cube Satellite's Communication System Using Commercial UHF Half-Duplex Antenna". Journal of the Korean Society for Aeronautical & Space Sciences 42, n.º 6 (1 de junho de 2014): 522–28. http://dx.doi.org/10.5139/jksas.2014.42.6.522.

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Pérez V., Gustavo, e Stefany Marrugo Ll. "Design methodology of a militar messaging system". Ciencia y tecnología de buques 4, n.º 8 (24 de janeiro de 2011): 61. http://dx.doi.org/10.25043/19098642.46.

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The paper describes the design methodology of a military messaging system. The system’s design is characterized by its coherence among security, transmission medium, and design protocol, which allow added value in the strategic operations center. The system allows using a selected data base for subsequent applications of operations research tools and simulation. The system was designed with a low bandwidth communications network (HF / VHF / UHF and satellite phone calls) as the transmission media. The messaging system security is based on a public key cryptographic system. The paper also shows some of the test results of the system’s functionality.

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Ciężkowski, Maciej, Piotr Jankowski-Mihułowicz e Kacper Skrobacz. "RFID-Based Localization System for Monitoring the Dispersal of Oak Acorns". Electronics 13, n.º 3 (30 de janeiro de 2024): 567. http://dx.doi.org/10.3390/electronics13030567.

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Radio techniques are widely used in wildlife tracking. Currently, the most common tracking methods include radio tracking (operating on Very high frequency (VHF) and Ultra high frequency (UHF)), satellite tracking (e.g., Argos satellite Doppler-based positioning system), and Global Navigation Satellite System (GNSS) tracking. One of the radio tracking systems is the Radio-Frequency Identification (RFID) system, characterized by small dimensions and a long operational period due to energy-efficient features. The advantages of RFID make it possible to apply this technique to track oak acorns in the process of zoochoric dispersal. In our study, we explored the potential applications of RFID systems for monitoring the dispersal of oak acorns. We developed a tracking system based on a semi-passive RFID tag, which we tested under laboratory and quasi-realistic conditions. The obtained results confirm the feasibility of using our system in radio tracking small objects such as oak acorns.

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Caton, R. G., W. J. McNeil, K. M. Groves e S. Basu. "GPS proxy model for real-time UHF satellite communications scintillation maps from the Scintillation Network Decision Aid (SCINDA)". Radio Science 39, n.º 1 (16 de janeiro de 2004): n/a. http://dx.doi.org/10.1029/2002rs002821.

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Kim, Tae-hun, Chan-ho Han e Kil-houm Park. "DTV Essential Hidden Area Decoder for DTV Broadcasting". Electronics 12, n.º 17 (30 de agosto de 2023): 3666. http://dx.doi.org/10.3390/electronics12173666.

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Terrestrial, satellite, and internet High Definition (HD) and Ultra High Definition (UHD) broadcasting have experienced notable advancements in recent years, yet the potential within the DTV Essential Hidden Area (DEHA) in each frame remains largely untapped. This study focuses on exploring and harnessing the capabilities of the DEHA via the introduction of a DEHA decoder. Through experimental analysis, the proposed decoder effectively reveals previously unnoticed DEHA in diverse HDTV broadcasting systems. By incorporating overlaid three-digit values, DEHA text, a 16 × 15 checked board pattern, and a QR code, the decoder enables the easy identification and extraction of the embedded DEHA service. Furthermore, the research investigates the potential of utilizing the embedded DEHA for transmitting program-related metadata, encompassing technical information, specific camera details, and post-production technologies. Leveraging a checked pattern block image, a seamless and efficient transfer mechanism within the embedded DEHA is established. The utilization of the embedded DEHA holds promising opportunities for enhancing DTV service, leveraging its inherent synchronization advantages within video content. Moreover, compliance with established broadcasting standards, such as ATSC, ISDB, and DVB, ensures compatibility and interoperability. This study emphasizes the significance of the DEHA in terrestrial, satellite, and internet broadcasting, unveiling new possibilities for innovation and improvement in the industry.

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ISLAM, SABA, Prof Dr Shaker Mahmood Mayo, Prof Dr M. Atiq Ur Rahman, Urooj Afzal e Maria Ali. "Determination and Mitigation of Urban Heat Island (UHI) In Lahore (A comparative Study of Landsat 8&9)". Vol 4 Issue 2 4, n.º 2 (26 de junho de 2022): 526–51. http://dx.doi.org/10.33411/ijist/2022040221.

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The term "Urban Heat Island" (UHI) refers to a city or metropolitan area that is significantly warmer than its surroundings. Heatwaves are one of the most visible hazards associated with UHI, that intensified exponentially over the last two decades. The overall approach of the study is initially based on a review of the literature and qualitative studies. The findings were applied to the case study to obtain empirical shreds of evidence. The study investigated the spatiotemporal urbanization trends and their impacts on UHI in Lahore, Pakistan, using multiple datasets. By identifying thermal drivers and simulating the spatial pattern, the direct relationship between development patterns and thermal properties can be visualized. To identify hot spots multi-temporal Landsat TM/OLI satellite images were processed using GIS and remote sensing techniques. It also investigates urban green spaces using spectral indices like the Normalized Difference Vegetation Index (NDVI). The findings indicate that Lahore's urbanization trend is intensifying in both existing and newly proposed zones which increases the pressure on land use planning. The negative correlation between Land Surface Temperature (LST) and NDVI confirms urban sprawl at the expense of green spaces, reshaping and aggregating the UHI profile of Lahore. These methodologies were combined to create UHI mitigation strategies that may aid communication among various stakeholders, including those in academia, development authorities, planners, and practitioners of the built environment. LST calculation by Landsat 9 proved efficient in comparison to Landsat 8 which may be due to improvement in spatial and spectral domain in architectural design Landsat series.

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Chitambara Rao, K., M. Lakshmun, D. Nataraj, G. Vinutna Ujwala e K. S. Chakradha. "A Circularly Polarized Antenna for UHF Satellite Communication Applications". Journal of Communications, outubro de 2023, 643–57. http://dx.doi.org/10.12720/jcm.18.10.643-657.

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There is a tremendous demand for antennas with very broad bandwidth and gain so that one antenna can cover the entire frequency range of the satellite communication applications, which are rapidly expanding with the current technology for diverse platforms. Helical antennas are ideal for these applications due to their distinctive qualities such as circular polarization, wide bandwidth, excellent gain, and low-profile conformability. For transmitting and receiving applications, which comprise frequency ranges of 240MHz to 270MHz and 290MHz to 320MHz, respectively. A new design of circularly polarized double-wire helical antenna employing the butterfly approach has been created in this study. An antenna was designed, simulated, analyzed, and fabricated before being experimentally measured for important parameters such as axial ratio, gain, 3dB beamwidth, and voltage standing wave ratio.

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Alam, Touhidul, Ali F. Almutairi, Md Samsuzzaman, Mengu Cho e Mohammad Tariqul Islam. "Metamaterial array based meander line planar antenna for cube satellite communication". Scientific Reports 11, n.º 1 (8 de julho de 2021). http://dx.doi.org/10.1038/s41598-021-93537-6.

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AbstractThis research article presents a design and performance analysis of a metamaterial inspired ultra-high frequency (UHF) compact planar patch antenna for the CubeSat communication system that could be smoothly integrated with commercially available 2U Cube Satellite structure and onboard subsystem. The proposed antenna consists of two layers, one is two different width meander line antenna patch with partial ground plane and another layer is 3 × 2 near-zero-indexed metamaterial (NZIM) metamaterial array structure with ground plane. The NZIM array layer has been utilized to minimize the coupling effect with Cube Satellite structure and improve the frequency stability with enhanced antenna gain and efficiency. The fabricated antenna can operate within the lower UHF frequency band of 443.5–455 MHz. with an average peak gain of 2.5 dB. The designed antenna impedance stability characteristic has been explored after integration with the 2U Cube Satellite body layout. Besides, the antenna communication performance has been verified using 2U Cube Satellite free space path loss investigation. Small antenna volume with trade-off between the antenna size and performance are the key advantages of the proposed design, as the antenna occupies only 80 × 40 × 3.35 mm3 space of the 2U Cube Satellite body structure and the geometrical parameters can be designed to provide the best performance between 449 and 468.5 MHz.

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Пастух, А. С., e Е. Е. Девяткин. "METHODS FOR DETERMINATING THE THROUGHPUT OF DIRECT-TO-DEVICE HYBRID SATELLITE SYSTEMS PROVIDING 5G/6G SERVICES". Электросвязь, n.º 12(49) (25 de dezembro de 2023). http://dx.doi.org/10.34832/elsv.2023.49.12.006.

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В работе приведены методы определения пропускной способности гибридных спутниковых систем связи для предоставления услуг прямого доступа direct-to-device 5G/6G на абонентские терминалы типа смартфона. Приведены общие подходы моделирования радиолиний гибридных спутниковых сетей (ГСС) с учетом адаптивной модуляции и кодирования и дан пример определения пропускной способности восходящего и нисходящего каналов ГСС в полосе частот UHF диапазона. The paper presents methods for determining the throughput of hybrid satellite communication systems to provide direct-to-device 5G/6G services using smartphones. General approaches to simulating hybrid satellite systems (HSS) radio links are described taking into account adaptive modulation and coding, and an example simulation is done that determines the throughput of the uplink and downlink HSS channels in the satellite network that operates in the UHF frequency band.

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Suwarjo, Minto. "RANCANGAN AWAL SISTEM KOMUNIKASI SATELIT IMAGE PROCESSING LAPAN-TUBSAT". Jurnal Teknologi Dirgantara 1, n.º 2 (4 de novembro de 2010). http://dx.doi.org/10.30536/j.jtd.2003.v1.a782.

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The LAPAN-TUBSAT is a joint reseaverd between LAPAN and TECHNICAL UNIVERSITY OF BERLIN for image processing application. The satellite will be built in with half-duplex transmission system, with uplink frequency is uHF-band 435.075 Mhz in minimum data rate 1200 pbs, while the downlink frequency is S-band 2.2 GHz use data rate 38400 bps. The uplink frequency will functioned for command and donwlink frequencies for telemetry data and image data. The main communication payload consists of transmitter and antenna s-band, tranceiver and antenna UHF-band, two cameras with resolution 50 mm and 1000 mm with PAL standard, data and video multiplexes, on borad data handling and power control unit. The ground station consists of TT and C operates in UHF-band and ground receiver processing operates in S-band frequency. The minimum image signal quality received is 45 dB for BER 10.

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Ferreira, A. A., R. A. Borges, L. R. Reis, C. Borries e D. Vasylyev. "Investigation of Ionospheric Effects in the Planning of the AlfaCrux UHF Satellite Communication System". IEEE Access, 2022, 1. http://dx.doi.org/10.1109/access.2022.3183152.

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Seigi, Bernadus Kbato, Yohanes Calvinus e Tjandra Susila. "Simulasi Antena Cross Yagi Pada Komunikasi Satelit Menggunakan Perangkat Lunak Mmana-Gal". Jetri : Jurnal Ilmiah Teknik Elektro, 14 de agosto de 2021, 1–16. http://dx.doi.org/10.25105/jetri.v19i1.8795.

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In this era, the role of telecommunications facilities is very important because of that we needed several components of good telecommunications support equipment. One of the most important components in telecommunications is the antenna to be used in the transmitter as well as receiver transmission system. The most widely used antenna is the Yagi antenna. In communication, especially satellite communication also uses Yagi antenna type Cross Yagi. This Cross Yagi Antenna uses different frequencies to distinguish the uplink and downlink processes. when the uplink uses the VHF frequency and the downlink uses the UHF frequency. This simulation is done to find out the changes that occur if there is a rounding of the size made during manufacture. Rounding on the antenna is done because at the time of manufacture it is not possible for someone to measure and cut the components precisely according to calculations. The test results indicate a change that occurs from the radiation pattern where the UHF antenna radiation pattern becomes leaner. In the Gain for UHF antennas it also changes where it becomes larger, while for beamwidth there is a calculation error wherein the simulation cannot designate 3 dB.Saat era ini peranan sarana telekomunikasi sangatlah penting sehingga diperlukan beberapa komponen alat pendukung telekomunikasi yang baik. Salah satu komponen yang sangat penting dalam telekomunikasi adalah antena yang digunakan pada sistem transmisi pemancar maupun transmisi penerima. Antena yang paling banyak digunakan adalah antena Yagi. Pada komunikasi khususnya komuniksi satelit juga menggunakan antena Yagi bertipe Cross Yagi. Antena Cross Yagi ini menggunakan frekuensi yang berbeda untuk membedakan proses uplink dan downlink . saat uplink menggunakan frekuensi VHF dan downlink menggunakan frekuensi UHF. Simulasi ini di lakukan untuk mencari tahu perubahan yang terjadi jika adanya pembulatan ukuran yang dilakukan saat pembuatan. Pembulatan pada antena dilakukan karena pada saat pembuatan tidak memungkinkan untuk seseorang mengukur dan memotong komponen dengan tepat sesuai perhitungan. Hasil pengujian menunjukkan adanya perubahan yang terjadi dari pola radiasi dimana pada antena UHF pola radiasi menjadi lebih ramping. Pada Gain untuk antena UHF juga berubah dimana menjadi lebih besar, sedangkan untuk beamwidth mengalami kesalahan perhitungan dimana pada simulasi tidak dapat menunjuk 3 dB.

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Sarkar, Sayan, e Bhaskar Gupta. "A Triple-band Slotted Patch Antenna with Metasurface Loading for UHF-RFID, Satellite Communication and 5G Applications". IEEE Access, 2024, 1. https://doi.org/10.1109/access.2024.3522916.

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"Estimation and Correction of Sampling Time Offsets in Tiadcs using Optimization Algorithm". International Journal of Innovative Technology and Exploring Engineering 9, n.º 4 (10 de fevereiro de 2020): 1217–22. http://dx.doi.org/10.35940/ijitee.d1523.029420.

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In recent communication technologies, very high sampling rates are required for rf signals particularly for signals coming under ultra high frequency (UHF), super high frequency (SHF) and extremely high frequency (EHF) ranges. The applications include global positioning system (GPS), satellite communication, radar, radio astronomy, 5G mobile phones etc. Such high sampling rates can be accomplished with time-interleaved analog to digital converters (TIADCs). However, sampling time offsets existing in TIADCs produce non-uniform samples. This poses a drawback in the reconstruction of the signal. The current paper addresses this drawback and offers a solution for improved signal reconstruction by estimation and correction of the offsets. A modified differential evolution (MDE) algorithm, which is an optimization algorithm, is used for estimating the sampling time offsets and the estimated offsets are used for correction. The estimation algorithm is implemented on an FPGA board and correction is implemented using MATLAB. The power consumption of FPGA for implementation is 57mW. IO utilization is 27% for 4-channel TIADCs and 13% for 2-channel TIADCs. The algorithm estimated the sampling time offsets precisely. For estimation the algorithm uses a sinusoidal signal as a test signal. Correction is performed with sinusoidal and speech signals as inputs for TIADCs. Performance metrics used for evaluating the algorithm are SNR (signal to noise ratio), SNDR (signal to noise and distortion ratio), SFDR (spurious-free dynamic range) and PSNR (peak signal to noise ratio). A noteworthy improvement is observed in the above mentioned parameters. Results are compared with the existing state of the art algorithms and superiority of the proposed algorithm is verified.

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Elgee, Peter K., Joshua C. Hill, Kermit-James E. LeBlanc, Gabriel D. Ko, Paul D. Kunz, David H. Meyer e Kevin C. Cox. "Satellite radio detection via dual-microwave Rydberg spectroscopy". Applied Physics Letters 123, n.º 8 (21 de agosto de 2023). http://dx.doi.org/10.1063/5.0158150.

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Rydberg electric field sensors exploit the large number of Rydberg resonances to provide sensitivity over a broad range of the electromagnetic spectrum. However, due to the difficulty of accessing resonant Rydberg states at ultra-high frequency (UHF) and below, ubiquitous bands in the world's current wireless communications infrastructure, they currently fall, short in sensitivity in this range. We present a resonant Rydberg electric field sensor operating in the UHF band using a dual-optical dual-microwave spectroscopy scheme. Adding an additional microwave photon allows us to access transitions between Rydberg states with higher angular momentum (L=3→4), which have lower resonant frequencies than transitions typically used in Rydberg sensors. We discuss the applicability of this type of sensor across the UHF band and below and measure the resonant sensitivity of our system at 2.3 GHz to be 70(5) μV m−1 Hz−1∕2, 57 times better than the measured sensitivity with a far off-resonant probing scheme at this frequency. We also show the effectiveness of this sensing scheme by measuring Sirius XM satellite radio (2.320–2.345 GHz) received outside the laboratory and rebroadcast onto the atoms.

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Ding, Yuanming, Jingjing Sun e Xue Wang. "Sea Surface Reflection and Power Attenuation Analysis of Radio Wave in UHF Satellite Communications". TELKOMNIKA Indonesian Journal of Electrical Engineering 12, n.º 4 (1 de abril de 2014). http://dx.doi.org/10.11591/telkomnika.v12i4.4787.

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Mascarenhas-Junior, Paulo Braga, Jozelia Maria Sousa Correia e Pedro Ivo Simões. "Tracking crocodylia: a review of telemetry studies on movements and spatial use". Animal Biotelemetry 11, n.º 1 (17 de maio de 2023). http://dx.doi.org/10.1186/s40317-023-00333-2.

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AbstractCrocodylians are top predators that play key ecological roles in aquatic ecosystems. As in other groups of large predators, crocodylian populations are often impacted by habitat loss, habitat degradation or direct exploitation for commercial purposes or subsistence. Hence, understanding their spatiotemporal ecology can provide valuable information for conservation planning. We reviewed the published scientific literature on telemetry-tracking in crocodylians, combining the terms “telemetry”, “track” or “tag” and variations; “VHF”, “UHF”, “satellite”, “GPS”, “radio”, “acoustic” or “transmitters”; and “caiman”, “alligator”, “crocodile”, “gharial” or “Crocodylia”. Publications retrieved by our search were carefully reviewed for information on study length, geographic location, sample size, taxonomy, and telemetry technology used. We identified 72 research articles in indexed journals and 110 reports available from the IUCN’s Crocodile Specialist Group, published between 1970 and 2022. Publications included 23 of the 27-living described crocodylian species. We identified strong geographic and taxonomic biases, with most articles proceeding from the USA (21.2%) and Australia (14%), with Alligator mississipiensis and Crocodylus porosus as the main target species in studies conducted in these countries, respectively. Despite representing 22% of IUCN’s reports, Gavialis gangeticus was referred in a single indexed research article. VHF telemetry was the prevalent tracking method, followed by GPS and acoustic transmitters. Studies using VHF devices had generally shorter in length when compared to alternative technologies. Transmitter weight represented less than 2% of the body mass of the carrying individual in all studies. Although attachment site of transmitters was notified in all research papers, few described anaesthetic or clinical procedures during attachment (33%). Our review highlights the need to encourage publication of crocodylian telemetry studies in non-English speaking countries in Asia, Africa, and Latin America, where many endemic species are threatened. We also highlight the need of detailed information on methods and results to facilitate the choice and implementation of appropriate protocols in future telemetry-tracking studies.

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