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1
Mayowa, Gbalaja. "Assessment of Radio Waves Propagation Pattern from Radio Stations in Lokoja and Okene, Kogi State, Nigeria". Advanced Journal of Science, Technology and Engineering 2, n.º 1 (30 de novembro de 2022): 78–92. http://dx.doi.org/10.52589/ajste-au9cs6sp.
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Okene, Lokoja and their environs have been experiencing radio signal distortions and have been of great concern to the citizens due to bad quality signals and signal attenuation increase. This study assesses the patterns of radio wave propagation from five radio stations in Lokoja and Okene, Kogi State, Nigeria. Equipment, a field strength metre was used to measure signal strengths and quality of radio signals. Six locations in both Lokoja, Okene and the environs were selected for each radio station. The approximate distances between the transmitting and receiving antennas were determined. Thirty-five locations were measured inclusive of the five radio stations and the six selected positions. Three locations in Okene and another three locations in Lokoja were used. Thereafter, calculations of the signal wavelengths of each radio station and the free space path-loss of signals were calculated at the positions. Factors such as reflections by buildings, mountains and vegetation cover, refractions by the rivers, streams, rainfall and absorption of the human abdomen were looked into at such areas as likely causes of signal attenuation. Good locations to site FM radio stations were determined from the results. The approximate distances from the stations to establish booster stations in order to receive news adequately were also determined.
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Jin, Jionghua. "Individual Station Monitoring Using Press Tonnage Sensors for Multiple Operation Stamping Processes". Journal of Manufacturing Science and Engineering 126, n.º 1 (1 de fevereiro de 2004): 83–90. http://dx.doi.org/10.1115/1.1643749.
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In multiple operation stamping processes, a press tonnage signal measured by press tonnage sensors installed on press linkages/uprights, is the summation of die forces at all stations. Different from the current practice of using a whole cycle of press tonnage signals to monitor the compound condition of all stations, this paper proposes a new method to use the partitioned monitoring segments of press tonnage signals to monitor individual station conditions. For this purpose, a generic signal segmentation principle is proposed, and the Hotelling T2 control charts are developed with consideration of the interactions among stations. A real case study of a doorknob stamping process is provided to demonstrate analysis procedures and effectiveness of the developed methodology.
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Parshutkin, Andrey, Dmitry Levin e Aleksey Galandzovskiy. "Simulation model of radar data processing in a station network under signal-like interference". Information and Control Systems, n.º 6 (16 de janeiro de 2020): 22–31. http://dx.doi.org/10.31799/1684-8853-2019-6-22-31.
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Introduction: Radar stations, when tracking targets in a complex interference environment, form not only target marks but also false marks. A well-developed theory and technique of noise stability is not useful under signal-like interference caused by re-reflections, multi-path propagation or retransmission of the probing signals. The reliability of radar information processing under signal-like interference can be improved by joint processing of data from several spaced posts in a radar station network. Purpose: development of а simulation model which would allow you to estimate the effectiveness of radar target selection by spatial rating of its measured positions, with joint processing of the radar information obtained from two spaced radar stations. Results: We have implemented the framework of joint radar data processing for target selection in a radar station network under signal-like interference. The selection is based on using the information about the coincidence of radar target coordinates measured by spaced radar stations. A simulation model is developed to estimate the target selection probability under signal-like interference during the joint processing of data from two spaced radar stations, by analyzing the coincidence of the measured coordinates of the targets. It has been found out how the target selection probability depends on the noise interference power and the average density of false marks in the range channels of two spaced radar stations. Practical relevance: The simulation results demonstrate the possibility of increasing the range of radar target detection by network radar stations under signal-like interference, and the efficiency of using the information about coincidence of radar target coordinates measured by spaced radar stations, which is better than using only the signal features of radar target selection on the background of false marks.
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Chang, Sang-Yoon, Kyungmin Park, Jonghyun Kim e Jinoh Kim. "Flying Base Station Channel Capacity Limits: Dependent on Stationary Base Station and Independent of Positioning". Electronics 13, n.º 12 (7 de junho de 2024): 2234. http://dx.doi.org/10.3390/electronics13122234.
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Flying base stations, also known as aerial base stations, provide wireless connectivity to the user and utilize their aerial mobility to improve communication performance. Flying base stations depend on traditional stationary terrestrial base stations for connectivity, as stationary base stations act as the gateway to the backhaul/cloud via a wired connection. We introduce the flying base station channel capacity to build on the Shannon channel capacity, which quantifies the upper-bound limit of the rate at which information can be reliably transmitted using the communication channel regardless of the modulation and coding techniques used. The flying base station’s channel capacity assumes aerial mobility and ideal positioning for maximum channel capacity. Therefore, the channel capacity limit holds for any digital and signal processing technique used and for any location or positioning of the flying base station. Because of its inherent reliance on the stationary terrestrial base station, the flying base station channel capacity depends on the stationary base station’s parameters, such as its location and SNR performance to the user, in contrast to previous research, which focused on the link between the user and the flying base station without the stationary base station. For example, the beneficial region (where there is a positive flying base station capacity gain) depends on the stationary base station’s power and channel SNR in addition to the flying base station’s own transmission power and whether it has full duplex vs. half-duplex capability. We jointly study the mobility and the wireless communications of the flying base station to analyze its position, channel capacity, and beneficialness over the stationary terrestrial base station (capacity gain). As communication protocols and implementations for flying base stations undergo development for next-generation wireless networking, we focus on information-theoretical analyses and channel capacity to inform future research and development in flying base station networking.
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FABO, Peter, Pavol NEJEDLÍK, Michal KUBA, Milan ONDERKA e Dušan PODHORSKÝ. "Applicability of the ultra-high radio frequency band (UHF) for hydrometeor detection by phase difference method". Contributions to Geophysics and Geodesy 51, n.º 2 (29 de junho de 2021): 109–27. http://dx.doi.org/10.31577/congeo.2021.51.2.1.
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Hydrometeors (rain, fog and ice crystals) affect the transmission of electromagnetic signals. Previous research showed that alterations in the signal (amplitude and phase) are affected by the composition of the atmosphere, e.g. the presence of hydrometeors. The majority of hydrometeorological detecting methods are based on the attenuation of electromagnetic signals as they penetrate the atmosphere. Novel methods based on monitoring of parameters of the signal appeared in recent time. This article presents the first results from our investigation of how hydrometeors affect the phase differences in signals transmitted by BTS stations. Cell phone operators transmit electromagnetic signals in the 1 GHz frequency band. This paper describes a novel concept of how phase differences between two signals arriving at two different antennas can be used to detect hydrometeors. Although the described concept is assumed to be independent from the signal strength, the analysed signal must be detectable. The primary advantage of the proposed passive method is that the signal is almost ubiquitous and does not require demodulation. In densely populated areas, the network of BTS stations reaches a spatial density of 1 station per 1 km2 which gives excellent opportunity to use the signal for detection purposes.
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Turner, Ross J., Anya M. Reading e Matt A. King. "Separation of tectonic and local components of horizontal GPS station velocities: a case study for glacial isostatic adjustment in East Antarctica". Geophysical Journal International 222, n.º 3 (30 de maio de 2020): 1555–69. http://dx.doi.org/10.1093/gji/ggaa265.
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SUMMARY Accurate measurement of the local component of geodetic motion at GPS stations presents a challenge due to the need to separate this signal from the tectonic plate rotation. A pressing example is the observation of glacial isostatic adjustment (GIA) which constrains the Earth’s response to ice unloading, and hence, contributions of ice-covered regions such as Antarctica to global sea level rise following ice mass loss. While both vertical and horizontal motions are of interest in general, we focus on horizontal GPS velocities which typically contain a large component of plate rotation and a smaller local component primarily relating to GIA. Incomplete separation of these components introduces significant bias into estimates of GIA motion vectors. We present the results of a series of tests based on the motions of GPS stations from East Antarctica: (1) signal separation for sets of synthetic data that replicate the geometric character of non-separable, and separable, GIA-like horizontal velocities; and (2) signal separation for real GPS station data with an appraisal of uncertainties. For both synthetic and real motions, we compare results where the stations are unweighted, and where each station is areal-weighted using a metric representing the inverse of the spatial density of neighbouring stations. From the synthetic tests, we show that a GIA-like signal is recoverable from the plate rotation signal providing it has geometric variability across East Antarctica. We also show that areal-weighting has a very significant effect on the ability to recover a GIA-like signal with geometric variability, and hence on separating the plate rotation and local components. For the real data, assuming a rigid Antarctic plate, fitted plate rotation parameters compare well with other studies in the literature. We find that 25 out of 36 GPS stations examined in East Antarctica have non-zero local horizontal velocities, at the 2σ level, after signal separation. We make the code for weighted signal separation available to assist in the consistent appraisal of separated signals, and the comparison of likely uncertainty bounds, for future studies.
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Shi, Xinlei, Xiaofei Zhang e Haowei Zeng. "Direct Position Determination of Non-Circular Sources for Multiple Arrays via Weighted Euler ESPRIT Data Fusion Method". Applied Sciences 12, n.º 5 (28 de fevereiro de 2022): 2503. http://dx.doi.org/10.3390/app12052503.
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In recent years, direct position determination (DPD) with multiple arrays for non-circular (NC) signals is a hot topic to research. Conventional DPD techniques with spectral peak search methods have high computational complexity and are sensitive to the locations of the observation stations. Besides, there will be loss when the signal propagates in the air, which leads to different received signal-to-noise ratios (SNRs) for each observation station. To attack the problems mentioned above, this paper derives direct position determination of non-circular sources for multiple arrays via weighted Euler estimating signal parameters viarotational invariance techniques (ESPRIT) data fusion (NC-Euler-WESPRIT) method. Firstly, elliptic covariance information of NC signals and Euler transformation are used to extend the received signal. Secondly, ESPRIT is applied to avoid the high-dimensional spectral function search problem of each observation station. Then, we combine the information of all observation stations to construct a spectral function without complex multiplication to reduce the computational complexity. Finally, the data of each observation station is weighted to compensate for the projection error. The consequence of simulation indicates that the proposed NC-Euler-WESPRIT algorithm not only improves the estimation performance, but also greatly reduces the computational complexity compared with subspace data fusion (SDF) technology and NC-ESPRIT algorithm.
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Wei, S. S., Xiao Qing Zeng, T. Shen, Y. J. Chen e W. Y. Wang. "A Method for Correction Ranging of Train Based on RSSI". Applied Mechanics and Materials 743 (março de 2015): 484–90. http://dx.doi.org/10.4028/www.scientific.net/amm.743.484.
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In the railway operation, it's significant to obtain the distances between trains. A method based on RSSI for ranging and correction is proposed in this paper. The devices include a number of base stations installed along railways. The front train would send an active signal to the nearby base station N, when it transmits power signal to the following one. The following train also gives an active signal to its nearest base station 1 which would be enabled to gain signal from station N. The error of per meter of every section would be calculated by the known distance between base stations. The distances between trains could be corrected by the error and the loss of RSSI signal. The experiment result shows that this method is effective.
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Xi, Yanpeng, Jian Liu e Wenhao Zhao. "SATCOM Earth Station Arrays Anti-Jamming Based on MVDR Algorithm". Applied Sciences 13, n.º 14 (19 de julho de 2023): 8337. http://dx.doi.org/10.3390/app13148337.
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In modern life, a large amount of information is transmitted through satellites. The anti-jamming ability of satellite communication earth stations is the basis for ensuring the smooth flow of information. In the case that multiple small earth stations cannot communicate due to jamming, the minimum variance distortionless response (MVDR) algorithm based on reflector antenna array is proposed. Firstly, the gain expression of satellite communication earth station antenna is derived, and the mathematical model of the received signal of the reflector antenna array is established. Then, the MVDR beamforming algorithm based on the reflector antenna is proposed and applied to the satellite communication earth station reflector antenna array, and the anti-jamming capability of the reflector antenna array using this algorithm is analyzed through simulation. The simulation results show that the earth station reflector antenna array using MVDR algorithm can effectively achieve array gain of the direction of the satellite signal, suppress the jamming signals, increase the output signal to interference plus noise ratio (SINR) of the reflector antenna array, and increase the output signal to jamming plus noise ratio with the increase in the number of snapshots.
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Enice Sanyaolu, Modupe, e Sanyaolu Olufemi. "Seasonal and latitudinal variations of surface radio refractivity over Nigeria". Indonesian Journal of Electrical Engineering and Computer Science 28, n.º 3 (7 de outubro de 2022): 1548. http://dx.doi.org/10.11591/ijeecs.v28.i3.pp1548-1553.
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Refractivity is a significant challenge of radio signal propagation. As it often distorts or leads to loss of signals. The seasonal and latitudinal variations of surface refractivity at three Nigerian tropospheric Observatory stations in Nigeria, namely Port-Harcourt, Lagos, and Makurdi, are presented in this paper. Values of monthly averages of pressure, temperature, relative humidity, and water vapour from the stations were used to compute surface refractivity at each station. The results show that the values of surface refractivity increase from the arid region in the north to the coastal area in the south. There was an increase in the values of surface radio refractivity from the minimum value of about 332.83 N-units at Makurdi station to a maximum value of 386.69 N-units at Lagos station. Seasonal variations are seen to be caused by weather conditions. The values of the surface refractivity increased significantly in the wet season and reduced in the dry season. It also shows that the values of surface radio refractivity are affected by the meteorological components mentioned above. The result of this study is needed for effective planning of good signal reception in these stations.
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Li, Yingping, William Prothero, Clifford Thurber e Rhett Butler. "Observations of ambient noise and signal coherency on the Island of Hawaii for teleseismic studies". Bulletin of the Seismological Society of America 84, n.º 4 (1 de agosto de 1994): 1229–42. http://dx.doi.org/10.1785/bssa0840041229.
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Abstract Ambient seismic noise conditions at several sites on the Island of Hawaii have been studied by analyzing noise power spectral density (PSD) and signal-to-noise ratio (SNR) of teleseisms. Broadband digital waveform data used in this study were collected during Project ALOHA. Direct comparison of noise PSD and SNR of teleseisms simultaneously recorded at stations on Hawaii and at station KIP on Oahu indicates that the stations on Hawaii are quieter than station KIP on Oahu in the frequency band of 0.1 to 1 Hz, suggesting that the Island of Hawaii can provide better noise conditions than station KIP. Our interpretation of this observation is that the area and volume of Hawaii are much larger than those of Oahu and distances to the coast for the stations on Hawaii are larger than that for station KIP on Oahu. Stronger attenuation and relatively low coherency for teleseismic signals on Hawaii in frequencies of 0.4 to 1.2 Hz are attributed to the presence of partial melt in the upper mantle. Teleseismic signal coherency is very low at frequencies above 2 Hz for a small array with a radius about 2 km. The relatively high coherency of the tangential component is strongly indicative of severe scattering effects caused by the heterogeneity in structure of the active volcanic area.
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Pochernyaev, V. N., N. M. Syvkova e V. S. Povkhlib. "SPATIAL DIVERSITY SIGNAL TRANSMISSION IN DIGITAL TROPOSCATTER STATIONS". Proceedings of the O.S. Popov ОNAT 1, n.º 2 (31 de dezembro de 2020): 92–99. http://dx.doi.org/10.33243/2518-7139-2020-1-2-92-99.
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The article examines the possibility of increasing the normalized throughput of digital troposcatter stations on the way of using space-separated signal transmission. Shown is a block diagram of the transmitting path of a digital troposcatter station with space-separated signal transmission. Methods of separation at the reception of signals acting at the input of the space-time coding device of the transmission path of the microwave digital troposcatter station are analyzed. Three methods of signal addition are considered in detail: linear addition; auto selection; optimal (quasi-optimal) addition. Various variants of addition are analyzed: before the demodulator and after the demodulator. The calculation of the normalized channel capacity as a function of the signal-to-noise ratio for the case of two transmitting antennas with known and unknown channel matrices is carried out. It was found that with two transmitting antennas and an unknown channel matrix, the normalized bandwidth does not differ from the case of using one transmitting antenna. The effect of cross-polarization isolation on the normalized channel capacity is analyzed, when one transmitting antenna emits signals of horizontal polarization, and the second transmitting antenna emits signals of vertical polarization. The values of the error probability are obtained for spatially-separated signal transmission to two transmitting antennas for two laws of distribution of a random variable - Rayleigh and Rice. The Rice distribution law of a random variable, the error probability is expressed through the modified zero-order Bessel function. The calculated data are shown in the table. The calculation was carried out in two frequency ranges allowed for the use of troposcatter communication facilities and for a channel without fading and for a channel with intersymbol interference.
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LUZHANSKY, V., L. V. KARPOVA e A. POVKH. "INVESTIGATION OF SIGNAL DISTURBANCE OF THE SIGNAL AT THE INPUT OF THE MOBILE STATION RECEIVER WITH DIFFERENT CHARACTERISTICS OF BASE STATIONS IN THE CONDITIONS OF CITY BUILDING". HERALD OF KHMELNYTSKYI NATIONAL UNIVERSITY 295, n.º 2 (maio de 2021): 206–13. http://dx.doi.org/10.31891/2307-5732-2021-295-2-206-213.
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The purpose of the scientific paper is to study the effects of internal system interference caused by the movement of a mobile station in the cell of the service area, which involves the use of the same frequencies, which worsens the communication conditions. The article provides calculation formulas for determining the signal-to-noise ratio at the input of the receiver of the mobile station. Calculations, including tables and figures, for different characteristics of base stations (BS) of the mobile network are also given. The analysis of literature sources shows insufficient depth of the conducted researches in directions for improving the noise immunity of the signal under different conditions in particular: city development, terrain, interference from other base stations. The use of radio networks with moving objects makes it possible to repeatedly use the same dedicated frequency band to increase the speed of digital information transmission and economical use of the frequency range. This method has a significant disadvantage, which is the presence of mutual internal system interference between base and mobile stations that use the same frequency range. The purpose of the scientific article is to study the noise immunity of the signal at the input of the receiver of the mobile station at different characteristics of the base stations in terms of urban development
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Colalillo, Roberta. "The observation of lightning-related events with the Surface Detector of the Pierre Auger Observatory". EPJ Web of Conferences 197 (2019): 03003. http://dx.doi.org/10.1051/epjconf/201919703003.
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The Pierre Auger Observatory, designed to detect ultra-high energy cosmic rays, can be a valid instrument at the ground to study phenomena related to the atmospheric electricity. The fluorescence detector is a powerful instrument to observe ELVES thanks to its excellent time resolution, while peculiar events with a large number of triggered stations have been recorded by the surface detector. The characteristic signal of these events lasts more than 10 μs, about two orders of magnitude more than the duration of a signal produced by a cosmic muon. Moreover, each of these events has at least one station with a signal dominated by a high-frequency noise that could be related with a lightning-induced signal. Stations with a long-lasting signal are arranged in a disk shape. There are “big” events characterized by a radius of about 6 km and few “small” events with a radius of about 2-3 km. The signal, generated by a source very close to the ground, first reaches the innermost stations and then spreads outwards. In the “big” events, a lack of signal in some of the central stations was observed. Further studies and checks are in progress to understand the origin of the lack of signal and what mechanisms occurring during the lightning evolution may provide for electric fields capable of generating and accelerating particles that can produce Cherenkov light in the stations of the surface detector.
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Schwertman, Neil C. "Discovering an Optimal Property of the Mean". Mathematics Teacher 93, n.º 4 (abril de 2000): 304–11. http://dx.doi.org/10.5951/mt.93.4.0304.
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This activity introduces a mathematical idea that has several applications, which include determining the optimal location for a radio station's transmitter and determining the best locations for a fire station. Radio stations must determine the location of their transmitters so that they can broadcast the strongest possible signal and offer the broadest coverage to their listeners. The circular area covered by a transmitter at the center increases in proportion to the square of the radius. As it covers a larger area, the strength of a transmitted signal decreases proportionally to the area, or equivalently, as the square of the distance from the transmitter. To furnish the strongest overall signal to its listeners, a radio station should locate the transmitter at a site that minimizes the total of the squared distances to the communities that it serves.
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Hoole, Paul Ratnamahilan Polycarp, Lwin Maw Abdul Raheem, Ramiah Harikrishnan, Kanesan Jeevan e Samuel Ratnajeevan Herbert Hoole. "A Three-Element Handheld Mobile Communication Antenna for Desired Signal Reception and Reflected Signal Cancellation". Materials Science Forum 721 (junho de 2012): 153–58. http://dx.doi.org/10.4028/www.scientific.net/msf.721.153.
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Abstract. Space diversity, where antennas are separated in space at the receiver, is considered one of the most effective ways of eliminating unwanted signals in order to maximize the signal to noise ratio of the desired signal. Moreover it may be used to receive a signal that has gone through less fading when the direct path signal may have undergone deep fade. In this paper we use analytical electromagnetic solutions for the radiated signals to implement antenna space diversity on small handheld receiver units of mobile stations. While using the standard time difference of arrival method to obtain a first approximation of the mobile station position, the electromagnetic model is used to determine a more accurate position of the mobile station. The performance of this method with a multi-element mobile station antenna is shown to give good position estimation in the presence of various of kinds noise. A three element mobile station receiver is for the first time reported to be able simultaneously to null a deeply faded signal in the Rayleigh fading environment, and maximize the signal strength. It is shown that a three element antenna may be used to eliminate an undesired signal, while it may maximize the reception of the desired signal. The transmitter does not require a training sequence, as in the case of an equalizer, since the entire signal processing of the electromagnetic signal is done at the mobile receiver.
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Chen, Jian, Yongkun Shi, Jiaquan Sun, Jiangkuan Li e Jing Xu. "Base Station Planning Based on Region Division and Mean Shift Clustering". Mathematics 11, n.º 8 (21 de abril de 2023): 1971. http://dx.doi.org/10.3390/math11081971.
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The problem of insufficient signal coverage of 5G base stations can be solved by building new base stations in areas with weak signal coverage. However, due to construction costs and other factors, it is not possible to cover all areas. In general, areas with high traffic and weak coverage should be given priority. Although many scientists have carried out research, it is not possible to make the large-scale calculation accurately due to the lack of data support. It is necessary to search for the central point through continuous hypothesis testing, so there is a large systematic error. In addition, it is difficult to give a unique solution. In this paper, the weak signal coverage points were divided into three categories according to the number of users and traffic demand. With the lowest cost as the target, and constraints such as the distance requirement of base station construction, the proportion of the total signal coverage business, and so on, a single objective nonlinear programming model was established to solve the base station layout problem. Through traversal search, the optimal threshold of the traffic and the number of base stations was obtained, and then, a kernel function was added to the mean shift clustering algorithm. The center point of the new macro station was determined in the dense area, the location of the micro base station was determined from the scattered and abnormal areas, and finally the unique optimal planning scheme was obtained. Based on the assumptions made in this paper, the minimum total cost is 3752 when the number of macro and micro base stations were determined to be 31 and 3442 respectively, and the signal coverage rate can reach 91.43%. Compared with the existing methods, such as K-means clustering, K-medoids clustering, and simulated annealing algorithms, etc., the method proposed in this paper can achieve good economic benefits; when the traffic threshold and the number of base stations threshold are determined, the unique solution can be obtained.
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Chen, Chih Yung, e Rey Chue Hwang. "Station Deployment and Signal Filter Design for Performance Evaluation of Indoor Positioning System". Advanced Materials Research 722 (julho de 2013): 306–10. http://dx.doi.org/10.4028/www.scientific.net/amr.722.306.
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This paper investigates enhancement of fuzzy logic indoor positioning system (FLIPS) and its effect upon the wireless station deployment. The proposed scheme adopts an average filter to improve stability in transforming received signal strength (RSS) between a sensor and stations into distance. Based on the reliable distance data set, a fuzzy logic inference engine determines precise coordinates of the sensor. In order to evaluate the optimal deployment of wireless stations, this study experiments on three different size test areas within three to eight stations. Those results provide considered analysis to develope a more efficient FLIPS.
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Kumar, Ravind, Mark Stephens e Tony Weir. "Temperature trends in Fiji: a clear signal of climate change". South Pacific Journal of Natural and Applied Sciences 31, n.º 1 (2013): 27. http://dx.doi.org/10.1071/sp13002.
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This paper analyses trends in temperature in Fiji, using data from more stations (10) and longer periods (52-78 years) than previous studies. All the stations analysed show a statistically significant trend in both maximum and minimum temperature, with increases ranging from 0.08 to 0.23°C per decade. More recent temperatures show a higher rate of increase, particularly in maximum temperature (0.18 to 0.69°C per decade from 1989 to 2008). This clear signal of climate change is consistent with that found in previous studies of temperatures in Fiji and other Pacific Islands. Trends in extreme values show an even stronger signal of climate change than that for mean temperatures. Our preliminary analysis of daily maxima at 6 stations indicates that for 4 of them (Suva, Labasa, Vunisea and Rotuma) there has been a tripling in the number of days per year with temperature >32°C between 1970 and 2008. The correlations between annual mean maximum (minimum) temperature and year are mostly strong: for about half the stations the correlation coefficient exceeds 60% over 50+ years. Trends do not vary systematically with location of station. At all 7 stations for which both trends are available there is no statistically significant difference between the trends in maximum and minimum temperatures.
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Wagner, Dörte, Birger Tinz e Hans von Storch. "Signal Stations: Newly Digitized Historical Climate Data of the German Bight and the Southern Baltic Sea Coast". Journal of Atmospheric and Oceanic Technology 33, n.º 12 (dezembro de 2016): 2735–41. http://dx.doi.org/10.1175/jtech-d-15-0199.1.
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AbstractAt the German Meteorological Service in Hamburg, handwritten journals of meteorological observation data of 164 signal stations exist that were digitized. These data contain long-term time series of up to 125 years for the period 1877–1999 and allow for studies of regional meteorological conditions with greatly improved spatial resolution. Wind and air pressure data of selected signal stations along the German Bight and the southern Baltic Sea coast show a spatial data homogeneity that allows for an improved description of two historical storms, in 1906 and 1913. This is the first presentation of signal station data.
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Xiang, Cai Bing, Shao Feng Bian e Ze Min Wu. "Study on Triple-Antenna KINRTK Problem Using BDS Signal". Advanced Materials Research 945-949 (junho de 2014): 2323–26. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.2323.
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Traditional kinematic baseline resolution usually needs one or more fixed reference station. In some special application, the reference stations could be in motion. In order to determine kinematic baselines in scenarios of moving reference stations and rovers, a KINRTK model is studied by using a baseline length constraint with three antenna configuration. The baseline and integer resolution method are given. A KINRTK experiment is done, using the data collected on ship enroute, the resolved baselines lengths are compared with the predetermined baselines, which show that the KINREK models baseline length errors are within 5cm, which can verify the effectiveness and accuracy of the model proposed and ambiguity resolution method.
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LUZHANSKIY, Viktor, Lesia KARPOVA e Maksym KANYUKA. "INFLUENCE OF THE TRANSMISSION RATE OF DIGITAL INFORMATION STREAMS IN VSAT-BASED SATELLITE COMMUNICATION NETWORKS WITH APPROPRIATE SIGNAL-TO-NOISE RATIOS ON THE PROBABILITY OF BIT ERROR". Herald of Khmelnytskyi National University 303, n.º 6 (dezembro de 2021): 207–15. http://dx.doi.org/10.31891/2307-5732-2021-303-6-207-215.
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Among the satellite technologies, special attention is paid to the development of satellite communication technologies based on VSAT (Very Small Aperture Terminal). Small ground station VSAT, a terminal with a very small antenna diameter (0.9 … 3.5 m), allows the use of VSAT stations antennas. This makes it possible to significantly reduce the size and cost of ground stations, the power of their transmitters and make their use widespread. VSAT equipment makes it possible to build multiservice networks that provide all modern communication services: Internet access; telephone connection; transmission of audio and video information; reservation of existing communication channels; data collection, monitoring and remote control of industrial facilities, etc. Satellite signals, especially high-frequency bands Ku and Ka, are subject to attenuation during rain, fog, clouds. But this shortcoming is easily overcome when properly designing the network, choosing the technology and location of antennas. The scientific article is devoted to the study of the influence of the speed of digital information transmission in satellite networks based on VSAT – a small satellite ground station, at the appropriate signal-to-noise ratio at the input of the receiver of the subscriber satellite station on the probability of bit error. The technical characteristics of subscriber satellite stations operating in the Ku-frequency band 11/14 GHz with an artificial satellite of the Earth in geostationary orbit are given. The dynamic range of signal power change at the input of the VSAT-based satellite ground receiver at different data rates is determined, which provides a given signal-to-noise ratio and bit error probability in the range of 10-7 – 10-4 for the required communication quality.
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Deng, Zhongliang, Buyun Jia, Shihao Tang, Xiao Fu e Jun Mo. "Fine Frequency Acquisition Scheme in Weak Signal Environment for a Communication and Navigation Fusion System". Electronics 8, n.º 8 (25 de julho de 2019): 829. http://dx.doi.org/10.3390/electronics8080829.
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A novel communication and navigation fusion system (CNFS) was developed to realized high accuracy positioning in constrained conditions. Communication and navigation fusion signal transmitted by base stations are in the same time and frequency band but are allocated different power levels. The positioning receiver of CNFS requires signal coverage of at least four base stations to realize positioning. The improvement of receiver sensitivity is an important way to expand signal coverage of base station. As an essential stage of signal processing in CNFS positioning receiver, signal acquisition requires a trade-off between improvement of acquisition frequency accuracy and reduction in computational load. A new acquisition algorithm called PMF-FC-BA-FFT method is proposed to acquire the carrier frequency accurately with lower computational load in a weak signal environment. The received signal is firstly filtered by partially matched filters (PMF) with local replica pseudorandom noise (PRN) sequences being coefficients to strip off the PRN code in the signal. Frequency compensation (FC) was performed to avoid the large attenuation in block accumulation (BA) and generate a series of signals with a small frequency offset step. Block accumulation was then executed. Finally, the acquisition detection was performed based on a series of fast Fourier transformation (FFT) outputs to obtain acquisition results with fine frequency estimation. Simulations and experimental tests results show that the proposed method can realize high accuracy frequency acquisition in a weak signal environment with fewer computational resources compared with existing acquisition methods.
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Kitchen, Frank. "THE NAPOLEONIC WAR COAST SIGNAL STATIONS". Mariner's Mirror 76, n.º 4 (janeiro de 1990): 337–44. http://dx.doi.org/10.1080/00253359.1990.10656321.
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Oktar, Osman, e Hediye Erdoğan. "Research of behaviors of continuous GNSS station by signal analysis methods". Earth Sciences Research Journal 22, n.º 1 (1 de janeiro de 2018): 19–27. http://dx.doi.org/10.15446/esrj.v22n1.62552.
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Continuously Operating Reference Station (CORS) networks consisting of multiple GNSS systems have been set up and operating in many developed countries. In Turkey, CORS-TR has been operating. The aim of CORS-TR is a fast, correct, and reliable collection of all kinds of geographic data, thus, speeding up the activities of cadastre, assuring organized urbanization, constituting the spatial infrastructure for relevant works of e-government, and monitoring plate tectonics. Therefore, in this paper, we investigated 788 days of linear and periodic of AKHR, BEYS, CIHA, KAMN, YUNA, AKSI and KNYA CORS-TR stations by linear trend analysis and Wavelet Transform in located in the Central Anatolia Region of Turkey. As a result of trend analyses of time series, it was determined that except a single station (KAMN), other stations were moving in the Southwest direction (17.78 mm/year). This finding is consistent with the region’s tectonic plate movements. In the periodical analyses, stations’ daily, monthly, seasonal, annual and even biennial movements resulting from atmospheric and hydrologic loading, climatic and other effects were revealed. Moreover, Detail (D) component, which protects the largest percentage of energy, was determined by calculating the energy spectrum. Energies of detail components are similar in horizontal, and especially D7-D8 have the highest energy. However, the components obtained the maximum energy was varied in Up coordinate time series. These results indicate that stations of CORS-TR network located in Central Anatolia were rather stable and able to be providing reliable, accurate and continuous data for national and international studies to be conducted in many fields.
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Семенова, Олена, Андрій Семенов, Андрій Луцишин e Вадим Дира. "Artificial Intelligence Techniques for Mobile Station Location Estimation". Security of Infocommunication Systems and Internet of Things, n.º 1 (30 de junho de 2023): 01006. http://dx.doi.org/10.31861/sisiot2023.1.01006.
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Modern wireless communication systems require positioning functions, which provide are automatic location estimation of stations within a network. However, when new networks are implemented, much higher accuracy is required when determining geographical coordinates of a mobile station to develop of services related to the station location. To solve the problem of mobile station positioning, its geographical coordinates are calculated, coordinates of the closest base stations being known. The paper proposes to use a genetic neuro-fuzzy controller for improving the effectiveness of positioning a mobile station. Positioning methods providing usage of artificial intelligence methods are based on measurements of levels for signals from the closets access points or base stations, their coordinates are known. The proposed localization method is based on values of received signal strength indicator – RSSI. At the same time, the RSSI method has a disadvantage – low accuracy, which is proposed to be increased by applying methods of artificial intelligence – fuzzy logic, neural networks, genetic algorithms. Therefore, the objective of this paper is to elaborate an optimized method for determining location of a mobile station. In compliance with the suggested method, RSSI values and ToA values enter the genetic neuro-fuzzy controller, after corresponding processing, the distance from the mobile station to the base station appears at its output.
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Zhang, Shane, Lili Feng e Michael H. Ritzwoller. "Three-station interferometry and tomography: coda versus direct waves". Geophysical Journal International 221, n.º 1 (28 de janeiro de 2020): 521–41. http://dx.doi.org/10.1093/gji/ggaa046.
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SUMMARY Traditional two-station ambient noise interferometry estimates the Green’s function between a pair of synchronously deployed seismic stations. Three-station interferometry considers records observed three stations at a time, where two of the stations are considered receiver–stations and the third is a source–station. Cross-correlations between records at the source–station with each of the receiver–stations are correlated or convolved again to estimate the Green’s function between the receiver–stations, which may be deployed asynchronously. We use data from the EarthScope USArray in the western United States to compare Rayleigh wave dispersion obtained from two-station and three-station interferometry. Three three-station interferometric methods are distinguished by the data segment utilized (coda-wave or direct-wave) and whether the source–stations are constrained to lie in stationary phase zones approximately inline with the receiver–stations. The primary finding is that the three-station direct wave methods perform considerably better than the three-station coda-wave method and two-station ambient noise interferometry for obtaining surface wave dispersion measurements in terms of signal-to-noise ratio, bandwidth, and the number of measurements obtained, but possess small biases relative to two-station interferometry. We present a ray-theoretic correction method that largely removes the bias below 40 s period and reduces it at longer periods. Three-station direct-wave interferometry provides substantial value for imaging the crust and uppermost mantle, and its ability to bridge asynchronously deployed stations may impact the design of seismic networks in the future.
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Abancó, C., M. Hürlimann e J. Moya. "Analysis of the ground vibration generated by debris flows and other torrential processes at the Rebaixader monitoring site (Central Pyrenees, Spain)". Natural Hazards and Earth System Sciences 14, n.º 4 (17 de abril de 2014): 929–43. http://dx.doi.org/10.5194/nhess-14-929-2014.
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Abstract. Monitoring of debris flows using ground vibration sensors has increased in the last two decades. However, the correct interpretation of the signals still presents ambiguity. In the Rebaixader monitoring site (Central Pyrenees, Spain) two different ground vibration stations are installed. At the first station the ground velocity signal is transformed into an impulses-per-second signal (low frequency, 1 Hz). The analysis of the data recorded at this station show that the shape of the impulses signal is one of the key parameters to describe the evolution of the event. At the second station the ground velocity signal is directly recorded at high frequency (250 Hz). The results achieved at this station show that the differences in time series and spectral analysis are helpful to describe the temporal evolution of the events. In addition, some general outcomes were obtained: the attenuation of the signal with the distance has been identified as linear to exponential; and the assembly of the geophones to the terrain has an important effect on the amplification of the signal. All these results highlight that the definition of ground vibration thresholds for debris-flow detection or warning purposes is a difficult task; and that influence of site-specific conditions is notable.
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Bao, Zhenyu, Shanshan Yong, Xin’an Wang, Chao Yang, Jinhan Xie e Chunjiu He. "Seismic Reflection Analysis of AETA Electromagnetic Signals". Applied Sciences 11, n.º 13 (24 de junho de 2021): 5869. http://dx.doi.org/10.3390/app11135869.
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Acoustic and electromagnetics to artificial intelligence (AETA) is a system used to predict seismic events through monitoring of electromagnetic and geoacoustic signals. It is widely deployed in the Sichuan–Yunnan region (22° N–34° N, 98° E–107° E) of China. Generally, the electromagnetic signals of AETA stations near the epicenter have abnormal disturbances before an earthquake. When a significant decrease or increase in the signal is observed, it is difficult to quantify this change using only visual observation and confirm that it is related to an upcoming large earthquake. Considering that the AETA data comprise a typical time series, current work has analyzed the anomalism of AETA electromagnetic signals using the long short-term memory (LSTM) autoencoder method to prove that the electromagnetic anomaly of the AETA station can be regarded as an earthquake precursor. The results show that there are 2–4% anomalous points and some outliers exceeding 0.7 (after normalization) in the AETA stations within 200 km of the epicenter of the Jiuzaigou earthquake (M. 7.0) and the Yibin earthquake (M. 6.0) half a month before the earthquakes. Therefore, the AETA electromagnetic disturbance signal can be used as an earthquake precursor and for further earthquake prediction.
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Cho, Seong-Yun. "Simultaneous LTE Signal Propagation Modelling and Base Station Positioning Based on Multiple Virtual Locations". Sensors 22, n.º 15 (8 de agosto de 2022): 5917. http://dx.doi.org/10.3390/s22155917.
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In the Long Term Evolution (LTE) system, the Signal Propagation Model (SPM) and the location information of the base stations are required for positioning a smartphone. To this end, this paper proposes a technique for estimating the SPM and the location of the base station at the same time using location-based Reference Signal Received Power (RSRP) information acquired in a limited area. In the proposed technique, multiple Virtual Locations (VLs) for a base station are set within the service area. Signal propagation modelling is performed based on the assumptions that a base station is in each VL and the RSRP measurements are obtained from the corresponding base station. The residuals between the outputs of the estimated SPM and the RSRP measurements are then calculated. The VL with the minimum sum of the squared residuals is determined as the location of the base station. At the same time, the SPM estimated based on the corresponding VL is selected as the SPM of the base station. As a result of the experiment in Seoul, it was confirmed that the positions of seven base stations were estimated with an average accuracy of 40.2 m.
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Pedersen, Helle A., Nicolas Leroy, Dimitri Zigone, Martin Vallée, Adam T. Ringler e David C. Wilson. "Using Component Ratios to Detect Metadata and Instrument Problems of Seismic Stations: Examples from 18 Yr of GEOSCOPE Data". Seismological Research Letters 91, n.º 1 (20 de novembro de 2019): 272–86. http://dx.doi.org/10.1785/0220190180.
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Abstract Replacement or deterioration of seismic instruments and the evolution of the installation conditions and sites can alter the seismic signal in very subtle ways; therefore, it is notoriously difficult to monitor the signal quality of permanent seismic stations. We present a simple way to characterize and monitor signal quality, using energy ratios between each pair of the three components, as a complement to existing methods. To calculate stable daily energy ratios over a large frequency range (0.01–5 Hz), we use the daily median energy ratio over all 5 min windows within the day. The method is applied to all GEOSCOPE stations, for continuous BH channel data collected since 2001. We show applications to identify past gain problems (stations ROCAM and CRZF), to provide feedback after field interventions at remote sites (Antarctic station DRV), and to shed light on complex instrument problems (stations ECH and KIP). Our results show that component energy ratios have excellent time resolution and that they are visually simple for identification of problems. They can be used both for ongoing continuous monitoring of the signal quality, or as a tool to identify past problems. The Python code to produce the results in this work and the Python code for daily monitoring used by GEOSCOPE are available (see Data and Resources).
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Oluwole, Ayodele Sunday, Olumayowa Ojo e Olaitan Akinsanmi. "Received signal evaluation for Ultra High Frequency (UHF)terrestrial television; Case of Ekiti State, Nigeria". Dutse Journal of Pure and Applied Sciences 10, n.º 1a (27 de abril de 2024): 177–90. http://dx.doi.org/10.4314/dujopas.v10i1a.20.
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This paper presents the evaluation of the received signal for UHF channel 41, (transmitting frequency of 631.25 MHz) and Star-times (transmitting frequency of 618 MHz). Using a Digital Field Strength Meter, the signal strength from the two UHF Transmitting Stations was measured throughout the state along two routes. The elevation, geographic coordinates, and line of sight of the various data points from the base stations were determined using a global positioning system (GPS) receiver. Regression analysis and correlation were used in the signal assessment process. Analysis of the data collected from the field measurements indicated that as line of sight increases signal strength reduces along all the routes for Ekiti Television (EKTV) and Star-times except along Route B for Star-times. Line of Sight and Elevation have a strong negative connection in almost all routes except along route A for star-times. Elevation and Signal strength correlation indicated negatively very high except for that along route B for EKTV and route A for Star-times. Regression analysis revealed that variance in Line of Sight and Elevation accounted for high significant changes in signal strength for EKTV and consistently very high changes for Star-times. Generally, it was observed that distance from the base station, topography/elevation, power of the transmitter, nature of signal (Digital/Analog) as shown for regression analysis and other factors affected the quality of service of the propagated signal. Terrestrial Television stations should ensure they transmit with the standard parameters. To improve service quality, the transition from analog to digital should be accelerated in Nigeria such that most stations transmit via the standard Digital method of transmission.
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Chen, Ta-Cheng, Sheng-Chuan Wang e Wen-Cheng Tseng. "Using a Hybrid Evolutionary Algorithm for Solving Signal Transmission Station Location and Allocation Problem with Different Regional Communication Quality Restriction". International Journal of Engineering and Technology Innovation 10, n.º 3 (1 de julho de 2020): 165–78. http://dx.doi.org/10.46604/ijeti.2020.5054.
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This study aims to investigate the signal transmission station location-allocation problems with the various restricted regional constraints. In each constraint, the types of signal transmission stations and the corresponding numbers and locations are to be decided at the same time. Inappropriate set up of stations is not only causing the unnecessary cost but also making the poor service quality. In this study, we proposed a hybrid evolutionary approach integrating the immune algorithm with particle swarm optimization (IAPSO) to solve this problem where each of the regions is with different maximum failure rate restrictions. We compared the performance of the proposed method with commercial optimization software LINGO®. According to the experimental results, solutions obtained by our IAPSO are better than or as well as the best solutions obtained by LINGO®. It is expected that our research can provide the telecommunication enterprise the optimal/near-optimal strategies for the setup of signal transmission stations.
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Wu, Zhi Qiang, e Jun Fang Zhao. "The Design of Plate Mills Hydraulic Lubricating and Monitoring System". Advanced Materials Research 1006-1007 (agosto de 2014): 643–49. http://dx.doi.org/10.4028/www.scientific.net/amr.1006-1007.643.
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Plate mills hydraulic system is made up of several hydraulic stations, lubrication stations and grease stations, these hydraulic stations and lubrication stations are distributed around the mills. Each hydraulic station possesses qualities of successive long working time, high reliability and signal complexity, and it can satisfy diverse demands of high grade pressure or temperature control, etc. This paper is based on these demands, assembling control missions of hydraulic and lubricating stations. Several PLC S7-300 were chosen to match the need of controlling mills hydraulic and lubricating system for a certain plate factory, and the HMI monitoring system for mill hydraulic and lubricating stations was developed by WINCC, which achieved central control and monitoring the hydraulic and lubricating system of plate mills.
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Jiang, Jinzhong, Runhai Yang, Bin Wang, Ya Xiang, Weidong Pang, Jun Yang, Xiaobin Li e Beng Ye. "Assessing Short‐Term Clock Errors and Drifts of Temporary Seismic Networks Using the Active Airgun Source in Binchuan, Yunnan". Seismological Research Letters 90, n.º 6 (2 de outubro de 2019): 2165–74. http://dx.doi.org/10.1785/0220190098.
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ABSTRACT We conducted a short‐term airgun experiment at the Binchuan Fixed Airgun Signal Transmission Station from 14 to 20 February 2017, and two different types of seismometers (Güralp CMG‐40T and QS05A) recorded 62 airgun shots triggered under the same conditions. However, we observed significant clock errors and drifts in seismic data recorded by four QS05A seismometers. To assess the short‐term clock errors and drifts for seismometers, we propose a new method that measures the P‐wave arrival‐time differences between airgun signals recorded at a station pair, using the matched filter method. We find ∼1.0 s absolute clock errors for two Güralp CMG‐40T stations (CKT2 and 53261) and one QS05A station (STA05), as well as ∼0.5 s timing leaps for four QS05A stations (STA19, STA21, STA31, and STA33) during the experiment. Furthermore, all the QS05A seismometers exhibit clock drifts with similar linear trends. Additionally, we use teleseismic waveforms to verify the absolute clock errors for stations CKT2, 53261, and STA05. After double‐checking several possible factors, we determine the hardware failure or malfunctioning that may cause clock errors for the two types of seismometers.
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Chen, Wen-Tzu, e Chen-Hsun Ho. "Spectrum monitoring with unmanned aerial vehicle carrying a receiver based on the core technology of cognitive radio – A software-defined radio design". Journal of Unmanned Vehicle Systems 5, n.º 1 (1 de março de 2017): 1–12. http://dx.doi.org/10.1139/juvs-2016-0011.
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In this paper, we design and make a prototype of an aerial spectrum monitoring system that consists of a ground control station and a four-rotor unmanned aerial vehicle (UAV). This UAV carries a software-defined radio (SDR) receiver to perform spectrum monitoring tasks, including signal strength, frequency occupancy, and signal analysis. A light and low-cost SDR-based dongle consisting of RTL2832U chip and R820T tuner is employed as the monitoring receiver. A global positioning system and an electronic compass system are built on board to report the UAV’s position and direction. The open-source development platform GNU Radio is employed to design the radio monitoring system through the use of software-defined blocks. The proposed aerial monitoring system can detect radio signals in the frequency range of 25–1700 MHz that in practice covers the FM and DVB bands. With the prototype monitoring system, we have performed a few measurement tasks, including signal strength, waterfall display, and demodulation for identifying FM stations. Our proposed aerial monitoring system is more cost-effective than land-vehicle monitoring stations because of its much more flexible implementation.
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Zhou, Hui, Yunlong Shen, Ming Chen, Jun Cheng e Yuting Zeng. "A ROF Access Network for Simultaneous Generation and Transmission Multiband Signals Based on Frequency Octupling and FWM Techniques". Advances in Condensed Matter Physics 2018 (2 de setembro de 2018): 1–9. http://dx.doi.org/10.1155/2018/9409583.
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We report a radio-over-fiber (ROF) access network with multiple high-repetive frequency mm-wave signals generation utilizing a dual-parallel Mach-Zehnder modulator (DP-MZM) and an semiconductor optical amplifier (SOA) for multiple base stations (BSs). In the scheme, at the central station (CS), signal and pump with frequency interval of 8fRF are generated by properly adjusting the parameters of the DP-MZM. After FWM in a SOA, new converted optical signals are obtained. Two tones of the optical signals are selected by using tunable optical filter (TOF), which are then sent into a photodiode (PD) to generate multiple mm-wave signals with different frequencies (8fRF, 16fRF, and 24fRF) for different BSs. Based on the proposed scheme, the mm-wave signals with frequencies of 20, 40, and 60 GHz carrying 2.5 Gb/s signal by a 2.5GHz RF signal have been generated by numerical simulation. Simulation results show that the proposed ROF system architecture with multiple-frequency millimeter-wave signals generation serving multiple BSs can work well. This scheme can raise the capacity of ROF system, reduce the requirement of the repetitive frequency of the driven RF signal, and support multiple mm-wave wireless access for BSs.
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Wolff, A. M., D. M. Akos e S. Lo. "Potential radio frequency interference with the GPS L5 band for radio occultation measurements". Atmospheric Measurement Techniques Discussions 7, n.º 5 (7 de maio de 2014): 4529–50. http://dx.doi.org/10.5194/amtd-7-4529-2014.
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Abstract. New Radio Occultation (RO) receivers are planned to utilize the newly implemented Global Positioning System (GPS) L5 signal centered at 1176.45 MHz. Since there are currently no operational GPS L5 receivers used for space-based RO applications, the interference environment is unclear. Distance Measuring Equipment (DME) and Tactical Air Navigation (TACAN) stations share the same frequency band as the GPS L5 signal. DME/TACAN signals have been identified to be a means of interference for any GPS L5 receiver. This study focuses on implementing a Systems Tools Kit (STK) simulation to gain insight into the power received by a RO satellite in Low Earth Orbit (LEO) from a DME/TACAN transmission. In order to confirm the validity of utilizing STK for communication purposes, a theoretical scenario was recreated as a simulation and the results were confirmed. Once the method was validated, STK was used to output a received power level aboard a RO satellite from a DME/TACAN station as well as a tool to predict the number of interfering DME/TACAN stations at any point in time. Taking a conservative approach, the signal power received was much greater than the typical power level received by a RO satellite from a GPS satellite transmission. This relatively high received power along with a high number of interfering DME/TACAN stations as an RO satellite passes over North America or Western Europe indicate that DME/TACAN interference may conflict with RO receivers.
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Hansen, Roger A., Frode Ringdal e Paul G. Richards. "The stability of rms Lg measurements and their potential for accurate estimation of the yields of Soviet underground nuclear explosions". Bulletin of the Seismological Society of America 80, n.º 6B (1 de dezembro de 1990): 2106–26. http://dx.doi.org/10.1785/bssa08006b2106.
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Abstract Data on underground nuclear explosions have recently become available from modern digital seismic stations installed within the Soviet Union and China. Observations of root mean square (rms) Lg-wave signals for Soviet underground nuclear explosions at the Shagan River Test Site in East Kazakhstan show that the relative amplitudes of the rms signals at stations in Norway, the USSR, and China are very similar for different explosions, the standard deviation of the differences being only about 0.03 in logarithmic units (i.e., magnitude units). This is consistent with earlier observations comparing NORSAR and Graefenberg array data, and the observed scatter is significantly lower than has been reported for Lg data from Nevada Test Site explosions. In view of the excellent correspondence found by Nuttli (1986) and Patton (1988) for Lg versus yield at Nevada, this indicates that rms Lg has a potential for yield estimation with very high accuracy at Shagan River. Our study has shown that: (a) selected stations in the USSR and China, situated at regional distances, provide a much improved signal-to-noise ratio of the Lg phase for events at Shagan River, as compared to NORSAR array data; (b) the scaling of rms Lg amplitudes between different-sized events recorded at the same single station site appears to be consistent with that of NORSAR, indicating a remarkable degree of precision in single station measurements of Lg signal; (c) rms Lg amplitude measurements for the best of these stations may be made at 1.5 to 2.0 magnitude units lower than at NORSAR or Graefenberg, allowing a much lower threshold for Lg-based yield determination; and (d) the P-wave detection capabilities of these single stations do not match those of the NORESS and ARCESS arrays; thus, teleseismic signals continue to be important for detection of small nuclear explosions. Our conclusion is that Lg signals appear to provide an excellent basis for supplying estimates of the yields of nuclear explosions even down to below 1 kt when such signals are recorded at high-quality, digital in-country seismic stations, and when calibrated by access to independent (nonseismic) yield information for a few nuclear explosions at the test sites of interest. In the context of monitoring a low-yield threshold test ban treaty, it will, in addition, be important to take into consideration various environmental conditions in the testing area, such as the possible presence of cavities, and to devise appropriate procedures for on-site observations in this regard.
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Zhang, Zhaohui, Jing Li e Qian Liu. "Modified Least Squares Algorithm for Three-Dimensional Target Location Based on Wireless Communication Base Stations". Complexity 2020 (2 de setembro de 2020): 1–10. http://dx.doi.org/10.1155/2020/5879415.
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The observed values of time of arrival (TOA) for the radio signals between the target and the wireless communication base stations are mainly affected by signal non-line-of-sight (NLOS) propagation in target location. TOA with NLOS makes a lot of signal noises and propagation delays, that is, location errors. For the first time, this paper focuses on the problem of modifying the Z-axis location coordinates in three-dimensional (3D) target location. A novel algorithm is proposed by establishing the modified least squares 3D location model for the accurate target location. Meanwhile, an optimal base station selection strategy is proposed by using the spectral clustering algorithm, which is based on the spatial distribution of the base stations. Compared with the existing algorithms, the proposed algorithm in this paper has better performance on the accurate target 3D location in real scenes, which has a high value of practical application. The simulations illustrate that the location error of the proposed algorithm is smaller than those of other existing algorithms based on the same simulation data and conditions.
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Al-Anbagi, Haidar N., e Ivo Vertat. "Cooperative Reception of Multiple Satellite Downlinks". Sensors 22, n.º 8 (8 de abril de 2022): 2856. http://dx.doi.org/10.3390/s22082856.
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Popular small satellites host individual sensors or sensor networks in space but require ground stations with directional antennas on rotators to download sensors’ data. Such ground stations can establish a single downlink communication with only one satellite at a time with high vulnerability to system outages when experiencing severe channel impairments or steering engine failures. To contribute to the area of improving the reception quality of small satellites signals, this paper presents a simple receive diversity scheme with proposed processing algorithms to virtually combine satellite downlink streams collected from multiple omnidirectional receivers. These algorithms process multiple received versions of the same signal from multiple geographically separated receiving sites to be combined in one virtual ground station. This virtual ground station helps detect the intended signal more reliably based only on a network of simple and cooperating software-defined radio receivers with omnidirectional antennas. The suggested receive diversity combining techniques can provide significant system performance improvement if compared to the performance of each individual receiving site. In addition, the probability of system outages is decreased even if one or more sites experience severe impairment consequences. Simulation results showed that the bit error rate (BER) of the combined stream is lower than the BER of the best quality receiving site if considered alone. Moreover, virtual ground stations with cooperative omnidirectional reception at geographically separated receivers also allow data to be received from multiple satellites in the same frequency band simultaneously, as software-defined receivers can digitize a wider portion of the frequency band. This can be a significant conceptual advantage as the number of small satellites transmitting data grows, and it is reasonable to avoid the corresponding necessary increase in the number of fully equipped ground stations with rotators.
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Enoch, Sharmini, Ifiok Otung, Naeem Azeemi e M. A. Habli. "Performance Evaluation of Angular Separation on Cell Site Diversity Gain". GIS Business 14, n.º 6 (5 de dezembro de 2019): 717–27. http://dx.doi.org/10.26643/gis.v14i6.15127.
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There have been remarkable advancements in the field of broadband wireless access (BFWA) technologies. These technologies operate in microwave frequencies where rain attenuation is the most important factor leading to signal impairments. The use of cell site diversity (CSD) can help in overcoming the signal fading. During the event of rain, when the signal level falls below a particular threshold, the subscriber station switches to another base station in the coverage area. The CSD gain bears strong correlation with the angular separation between the various base stations. This paper analyses the effects of CSD gain on angular separation.
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Liang, Mingliang, Wenxuan Li, Jie Ji, Zhenxi Zhou, Yihang Zhao, Huiru Zhao e Sen Guo. "Evaluating the Comprehensive Performance of 5G Base Station: A Hybrid MCDM Model Based on Bayesian Best-Worst Method and DQ-GRA Technique". Mathematical Problems in Engineering 2022 (31 de janeiro de 2022): 1–15. http://dx.doi.org/10.1155/2022/4038369.
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In recent years, 5G technology has rapidly developed, which is widely used in medical, transportation, energy, and other fields. As the core equipment of the 5G network, 5G base stations provide wireless coverage and realize wireless signal transmission between wired communication networks and wireless terminals. However, as the scale of 5G base stations gradually increases, problems such as poor user experience and insufficient coverage area frequently occur. Hence, it is necessary to evaluate the comprehensive performance of 5G base stations, so as to clarify the problems existing in the construction of base stations. First, the performance evaluation index system is constructed from the perspectives of operational performance, financial performance, environmental impact, and social influence. Then, a novel hybrid multicriteria decision-making (MCDM) model based on the Bayesian best-worst method (BBWM) and difference-quotient gray relational analysis (DQ-GRA) technique is adopted. Finally, sixteen 5G base stations are taken as examples for analysis. The result shows that the signal coverage area and per capita input cost are the most important indicators greatly affecting the overall performance of the 5G base station. Compared with the two other MCDM models, the proposed hybrid MCDM model has good applicability and effectiveness for performance evaluation of 5G base stations.
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Fen, Cao, Yang Xuhai, Li Zhigang, Chen Liang e Feng Chugang. "Signal Biases Calibration for Precise Orbit Determination of the Chinese Area Positioning System using SLR and C-Band Transfer Ranging Observations". Journal of Navigation 69, n.º 6 (19 de abril de 2016): 1234–46. http://dx.doi.org/10.1017/s0373463316000205.
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In C-Band transfer measuring systems, the Precise Orbit Determination (POD) precision of Geostationary Earth Orbit (GEO) satellites is limited by signal biases such as the station delay biases, transponder delay biases, the ionospheric delay model bias, etc. In order to improve the POD precision, the signal biases of the Chinese Area Positioning System (CAPS) are calibrated using Satellite Laser Ranging (SLR) and C-Band Transfer Ranging (CBTR) observations. Since the Changchun SLR site and C-Band station are close to each other, the signal biases of the Changchun C-Band station are calibrated using the co-location comparison method. Then the signal biases of the other two CAPS C-Band stations, located in Linton and Kashi, are calibrated using the combined POD method, with the signal biases of the Changchun C-Band station being fixed. After the signal biases are calibrated, the RMS of the line-of-sight residuals of the Changchun SLR observations decrease by 0·4 m, with the percentage improvement being 75·19%.
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Ivanova, Aleksandra A., e Sergei F. Shakhnov. "METHOD OF AUTOMATIC TRANSMISSION OF THE INTEGRITY BREACH SIGNALS OF THE RIVER LOCAL DIFFERENTIAL SUBSYSTEM". T-Comm 15, n.º 4 (2021): 42–48. http://dx.doi.org/10.36724/2072-8735-2021-15-4-42-48.
Texto completo da fonteResumo:
The integrity of the navigation system is one of the important factors affecting the safety of navigation. Currently, on the inland waterways of Russia, alerts on the integrity of the GLONASS global navigation satellite system (GNSS) are transmitted through river local differential subsystems (LDSS), which include one or more reference stations. Industrial interference from industrial zones and power lines, mutual interference from neighboring reference stations and, especially, the inhomogeneity of the underlying surface affect the range of the reference stations, which leads to the integrity breach of the differential field and transmission of unreliable corrective information to the navigator. However, the navigator is not notified of the incorrect operation of the reference stations. As a result, inaccurate corrective information leads to errors in calculating the vessel position, which reduces the level of navigation safety. A method for the automatic transmission of notifications about the LDSS integrity breach from a remote control and management station (RCMS) to the ship is presented in the paper. The structure of the message transmitting the notification signal has been formed. Criteria characterizing the quality of the differential correction signal are presented. Possible combinations of such criteria, which determine the performance of the differential mode of the reference station, are identified. Each combination of criteria is juxtaposed the corresponding notification texts displayed on the monitors of the LDSS operators and on the navigator’s display. A scheme for the automatic transmission of an alarm message from a remote control point through the RCMS, the regional command and control center, the vessel traffic control center and base stations of the automatic identification system (AIS) to ship transponders has been developed. As a result, the developed method for transmitting the alarm message containing combinations of quality criteria for the differential correction signal allows to automatically inform the navigator about the reliability of the corrective information transmitted by one or another reference station.
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Guo, Qinmeng, Shanshan Yong e Xin’an Wang. "Statistical Analysis of the Relationship between AETA Electromagnetic Anomalies and Local Earthquakes". Entropy 23, n.º 4 (30 de março de 2021): 411. http://dx.doi.org/10.3390/e23040411.
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To verify the relationship between AETA (Acoustic and Electromagnetics to Artificial Intelligence (AI)) electromagnetic anomalies and local earthquakes, we have performed statistical studies on the electromagnetic data observed at AETA station. To ensure the accuracy of statistical results, 20 AETA stations with few data missing and abundant local earthquake events were selected as research objects. A modified PCA method was used to obtain the sequence representing the signal anomaly. Statistical results of superposed epoch analysis have indicated that 80% of AETA stations have significant relationship between electromagnetic anomalies and local earthquakes. These anomalies are more likely to appear before the earthquakes rather than after them. Further, we used Molchan’s error diagram to evaluate the electromagnetic signal anomalies at stations with significant relationships. All area skill scores are greater than 0. The above results have indicated that AETA electromagnetic anomalies contain precursory information and have the potential to improve local earthquake forecasting.
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Li, Hai Xia, e Jie Hui Zeng. "Remote Control Stepper Motor Based on the GPRS". Applied Mechanics and Materials 496-500 (janeiro de 2014): 1603–8. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.1603.
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This design uses GPRS wireless communication technology to achieve remote control of the stepper motor. The system design the software of upper machine by the VC++ based on the TCP/IP protocol. The wireless module SIM300 transfers data to the primary station by its GPRS function. Then the primary station converters the input into differential signal and send commands to slave stations via RS485 and Modbusprotocol. According to the commands, slave stations output the corresponding control signal to the stepper motor. Stepper motor has some protection function when working, such as: acceleration and deceleration and down limit , emergency stop , over-temperature .The result of experiments verifies that the aim of design GPRS-based remote control of stepper motor is realized. It is possible to improve largely both in real-time performance and reliability by using the GPRS wireless technology, it promotes the industrial monitoring and control system more intelligent and informed.
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Nikolajevs, A., e K. Prūsis. "The LOFAR Long-Baseline Calibrator Survey Classification". Latvian Journal of Physics and Technical Sciences 57, n.º 1-2 (1 de abril de 2020): 34–40. http://dx.doi.org/10.2478/lpts-2020-0005.
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AbstractData manipulation of the LOFAR Long-Baseline Calibrator Survey (LBCS) and the Westerbork Northern Sky Survey (WENSS) catalogues are carried out in the present study. The aim of the study is to make calibrator classification statistics plots and estimations for further observations and upcoming stations. First, mean flux densities of LBCS calibrators against declination and observed station baseline length to the tied core station are plotted and the classified sources are marked. Second, we provide the designation – naming it the success rate – for the number of sources with the correlated signal against all the LBCS catalogue sources. Third, there is a trend in mean peak flux densities between stations – longer the baseline, higher mean peak flux density. Finally, estimations for upcoming and recent stations are made and some results are not encouraging.
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Novikova, Tatyana, Svetlana Evdokimova e Roman Medvedev. "Computer-aided design of the location of wireless cellular base stations". Modeling of systems and processes 16, n.º 4 (18 de dezembro de 2023): 61–70. http://dx.doi.org/10.12737/2219-0767-2023-16-4-61-70.
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The planning of wireless base stations is a multi-purpose task of optimizing combinations, and the main goals of optimization include cost reduction, increased coverage and quality preservation. The paper pays attention to the consideration of the coverage radius, the quality of signal transmission and two types of signal interference. To implement the tasks set for the location of the base station, the following algorithms were used: PMET-PSO and PPSO-GA, which became the basis for the module for solving problems of designing the location of base stations in the proposed automated design system. Using the C/S architecture and 3D CAD based on ACIS and Google Earth, based on an in-depth analysis of the actual requirements for the base station, a CAD for the location of wireless cellular base stations is proposed. The main technical modules of the system are the technology of rapid modeling involving objects in the planning of base stations, the technology of multi-purpose modeling and solving problems of planning base stations and the technology of distributed joint integration of program modules. The technology for solving planning problems uses the PMET-PSO and PPSO-GA algorithms. Both algorithms compensate for the disadvantages of their original algorithms (MET-PSO and PSO-GA) and retain their respective advantages: time - PMET-PSO, and if the user does not care about time and wants to get the optimal possible solution, then the PPSO-GA algorithm. Both algorithms combine memory computing with good parallelism, which plays a crucial role in solving multi-purpose optimization problems.
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Saini, Hemraj, L. K. Sharma, T. C. Panda e H. N. Pratihari. "Extended Cell Planning for Capacity Expansion and Power Optimization by Using MEMETIC Algorithm". International Journal of Wireless Networks and Broadband Technologies 2, n.º 2 (abril de 2012): 36–46. http://dx.doi.org/10.4018/ijwnbt.2012040103.
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In the current era of cellular world, cell planning plays an important role to achieve better performance of the cellular network. Capacity expansion and cost optimization of a newly activated base station by placing it at an optimized location is one of the primary objectives of the current manuscript. The locations of the new as well as the existing base stations are directly correlated to the required capacity demand and the power of the received signal at the base station which becomes the sensitive parameter for the cell planning. Therefore, cell planning is to be modeled to optimize the location of the base stations in the form of a linear programming problem. Further, the MEMETIC algorithm has to be used for the optimization of the multi-objectives of the scenario. The simulated results show that there is a significant enhancement in the capacity of the base stations (1% to 5%) as compared with the orientation of base stations achieved by random deployment.