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Eurico Rodrigues Paula - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Characteristics of Low-Latitude GPS Amplitude Scintillation Measured During Solar Maximum Conditions and Implications for Receiver Performance
Surveys in Geophysics, 2012Co-Authors: Alison Oliveira Moraes, Fabiano Silveira Rodrigues, Waldecir João Perrella, Eurico Rodrigues PaulaAbstract:Ionospheric scintillations are fluctuations in the phase and/or amplitude of trans-ionospheric radio signals caused by electron density irregularities in the ionosphere. A better understanding of the scintillation pattern is important to make a better assessment of GPS Receiver Performance, for instance. Additionally, scintillation can be used as a tool for remote sensing of ionospheric irregularities. Therefore, the study of ionospheric scintillation has both scientific as well as technological implications. In the past few years, there has been a significant advance in the methods for analysis of scintillation and in our understanding of the impact of scintillation on GPS Receiver Performance. In this work, we revisit some of the existing methods of analysis of scintillation, propose an alternative approach, and apply these techniques in a comprehensive study of the characteristics of amplitude scintillation. This comprehensive study made use of 32 days of high-rate (50 Hz) measurements made by a GPS-based scintillation monitor located in São José dos Campos, Brazil (23.2°S, 45.9°W, −17.5° dip latitude) near the Equatorial Anomaly during high solar flux conditions. The variability of the decorrelation time (τ_0) of scintillation patterns is presented as a function of scintillation severity index ( S _4). We found that the values of τ_0 tend to decrease with the increase of S _4, confirming the results of previous studies. In addition, we found that, at least for the measurements made during this campaign, averaged values of τ_0 (for fixed S _4 index values) did not vary much as a function of local time. Our results also indicate a significant impact of τ_0 in the GPS carrier loop Performance for S _4 ≥ 0.7. An alternative way to compute the probability of cycle slip that takes into account the fading duration time is also presented. The results of this approach show a 38% probability of cycle slips during strong scintillation scenarios ( S _4 close to 1 and τ_0 near 0.2 s). Finally, we present results of an analysis of the individual amplitude fades observed in our set of measurements. This analysis suggests that users operating GPS Receivers with C / N _0 thresholds around 30 dB-Hz and above can be affected significantly by low-latitude scintillation.
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Analysis of the Characteristics of Low-Latitude GPS Amplitude Scintillation Measured During Solar Maximum Conditions and Implications for Receiver Performance
Surveys in Geophysics, 2011Co-Authors: Alison Oliveira Moraes, Waldecir João Perrella, Fabiano S. Rodrigues, Eurico Rodrigues PaulaAbstract:Ionospheric scintillations are fluctuations in the phase and/or amplitude of trans-ionospheric radio signals caused by electron density irregularities in the ionosphere. A better understanding of the scintillation pattern is important to make a better assessment of GPS Receiver Performance, for instance. Additionally, scintillation can be used as a tool for remote sensing of ionospheric irregularities. Therefore, the study of ionospheric scintillation has both scientific as well as technological implications. In the past few years, there has been a significant advance in the methods for analysis of scintillation and in our understanding of the impact of scintillation on GPS Receiver Performance. In this work, we revisit some of the existing methods of analysis of scintillation, propose an alternative approach, and apply these techniques in a comprehensive study of the characteristics of amplitude scintillation. This comprehensive study made use of 32 days of high-rate (50 Hz) measurements made by a GPS-based scintillation monitor located in Sao Jose dos Campos, Brazil (23.2°S, 45.9°W, −17.5° dip latitude) near the Equatorial Anomaly during high solar flux conditions. The variability of the decorrelation time (τ0) of scintillation patterns is presented as a function of scintillation severity index (S4). We found that the values of τ0 tend to decrease with the increase of S4, confirming the results of previous studies. In addition, we found that, at least for the measurements made during this campaign, averaged values of τ0 (for fixed S4 index values) did not vary much as a function of local time. Our results also indicate a significant impact of τ0 in the GPS carrier loop Performance for S4 ≥ 0.7. An alternative way to compute the probability of cycle slip that takes into account the fading duration time is also presented. The results of this approach show a 38% probability of cycle slips during strong scintillation scenarios (S4 close to 1 and τ0 near 0.2 s). Finally, we present results of an analysis of the individual amplitude fades observed in our set of measurements. This analysis suggests that users operating GPS Receivers with C/N0 thresholds around 30 dB-Hz and above can be affected significantly by low-latitude scintillation.
Alison Oliveira Moraes - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Characteristics of Low-Latitude GPS Amplitude Scintillation Measured During Solar Maximum Conditions and Implications for Receiver Performance
Surveys in Geophysics, 2012Co-Authors: Alison Oliveira Moraes, Fabiano Silveira Rodrigues, Waldecir João Perrella, Eurico Rodrigues PaulaAbstract:Ionospheric scintillations are fluctuations in the phase and/or amplitude of trans-ionospheric radio signals caused by electron density irregularities in the ionosphere. A better understanding of the scintillation pattern is important to make a better assessment of GPS Receiver Performance, for instance. Additionally, scintillation can be used as a tool for remote sensing of ionospheric irregularities. Therefore, the study of ionospheric scintillation has both scientific as well as technological implications. In the past few years, there has been a significant advance in the methods for analysis of scintillation and in our understanding of the impact of scintillation on GPS Receiver Performance. In this work, we revisit some of the existing methods of analysis of scintillation, propose an alternative approach, and apply these techniques in a comprehensive study of the characteristics of amplitude scintillation. This comprehensive study made use of 32 days of high-rate (50 Hz) measurements made by a GPS-based scintillation monitor located in São José dos Campos, Brazil (23.2°S, 45.9°W, −17.5° dip latitude) near the Equatorial Anomaly during high solar flux conditions. The variability of the decorrelation time (τ_0) of scintillation patterns is presented as a function of scintillation severity index ( S _4). We found that the values of τ_0 tend to decrease with the increase of S _4, confirming the results of previous studies. In addition, we found that, at least for the measurements made during this campaign, averaged values of τ_0 (for fixed S _4 index values) did not vary much as a function of local time. Our results also indicate a significant impact of τ_0 in the GPS carrier loop Performance for S _4 ≥ 0.7. An alternative way to compute the probability of cycle slip that takes into account the fading duration time is also presented. The results of this approach show a 38% probability of cycle slips during strong scintillation scenarios ( S _4 close to 1 and τ_0 near 0.2 s). Finally, we present results of an analysis of the individual amplitude fades observed in our set of measurements. This analysis suggests that users operating GPS Receivers with C / N _0 thresholds around 30 dB-Hz and above can be affected significantly by low-latitude scintillation.
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Analysis of the Characteristics of Low-Latitude GPS Amplitude Scintillation Measured During Solar Maximum Conditions and Implications for Receiver Performance
Surveys in Geophysics, 2011Co-Authors: Alison Oliveira Moraes, Waldecir João Perrella, Fabiano S. Rodrigues, Eurico Rodrigues PaulaAbstract:Ionospheric scintillations are fluctuations in the phase and/or amplitude of trans-ionospheric radio signals caused by electron density irregularities in the ionosphere. A better understanding of the scintillation pattern is important to make a better assessment of GPS Receiver Performance, for instance. Additionally, scintillation can be used as a tool for remote sensing of ionospheric irregularities. Therefore, the study of ionospheric scintillation has both scientific as well as technological implications. In the past few years, there has been a significant advance in the methods for analysis of scintillation and in our understanding of the impact of scintillation on GPS Receiver Performance. In this work, we revisit some of the existing methods of analysis of scintillation, propose an alternative approach, and apply these techniques in a comprehensive study of the characteristics of amplitude scintillation. This comprehensive study made use of 32 days of high-rate (50 Hz) measurements made by a GPS-based scintillation monitor located in Sao Jose dos Campos, Brazil (23.2°S, 45.9°W, −17.5° dip latitude) near the Equatorial Anomaly during high solar flux conditions. The variability of the decorrelation time (τ0) of scintillation patterns is presented as a function of scintillation severity index (S4). We found that the values of τ0 tend to decrease with the increase of S4, confirming the results of previous studies. In addition, we found that, at least for the measurements made during this campaign, averaged values of τ0 (for fixed S4 index values) did not vary much as a function of local time. Our results also indicate a significant impact of τ0 in the GPS carrier loop Performance for S4 ≥ 0.7. An alternative way to compute the probability of cycle slip that takes into account the fading duration time is also presented. The results of this approach show a 38% probability of cycle slips during strong scintillation scenarios (S4 close to 1 and τ0 near 0.2 s). Finally, we present results of an analysis of the individual amplitude fades observed in our set of measurements. This analysis suggests that users operating GPS Receivers with C/N0 thresholds around 30 dB-Hz and above can be affected significantly by low-latitude scintillation.
Waldecir João Perrella - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Characteristics of Low-Latitude GPS Amplitude Scintillation Measured During Solar Maximum Conditions and Implications for Receiver Performance
Surveys in Geophysics, 2012Co-Authors: Alison Oliveira Moraes, Fabiano Silveira Rodrigues, Waldecir João Perrella, Eurico Rodrigues PaulaAbstract:Ionospheric scintillations are fluctuations in the phase and/or amplitude of trans-ionospheric radio signals caused by electron density irregularities in the ionosphere. A better understanding of the scintillation pattern is important to make a better assessment of GPS Receiver Performance, for instance. Additionally, scintillation can be used as a tool for remote sensing of ionospheric irregularities. Therefore, the study of ionospheric scintillation has both scientific as well as technological implications. In the past few years, there has been a significant advance in the methods for analysis of scintillation and in our understanding of the impact of scintillation on GPS Receiver Performance. In this work, we revisit some of the existing methods of analysis of scintillation, propose an alternative approach, and apply these techniques in a comprehensive study of the characteristics of amplitude scintillation. This comprehensive study made use of 32 days of high-rate (50 Hz) measurements made by a GPS-based scintillation monitor located in São José dos Campos, Brazil (23.2°S, 45.9°W, −17.5° dip latitude) near the Equatorial Anomaly during high solar flux conditions. The variability of the decorrelation time (τ_0) of scintillation patterns is presented as a function of scintillation severity index ( S _4). We found that the values of τ_0 tend to decrease with the increase of S _4, confirming the results of previous studies. In addition, we found that, at least for the measurements made during this campaign, averaged values of τ_0 (for fixed S _4 index values) did not vary much as a function of local time. Our results also indicate a significant impact of τ_0 in the GPS carrier loop Performance for S _4 ≥ 0.7. An alternative way to compute the probability of cycle slip that takes into account the fading duration time is also presented. The results of this approach show a 38% probability of cycle slips during strong scintillation scenarios ( S _4 close to 1 and τ_0 near 0.2 s). Finally, we present results of an analysis of the individual amplitude fades observed in our set of measurements. This analysis suggests that users operating GPS Receivers with C / N _0 thresholds around 30 dB-Hz and above can be affected significantly by low-latitude scintillation.
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Analysis of the Characteristics of Low-Latitude GPS Amplitude Scintillation Measured During Solar Maximum Conditions and Implications for Receiver Performance
Surveys in Geophysics, 2011Co-Authors: Alison Oliveira Moraes, Waldecir João Perrella, Fabiano S. Rodrigues, Eurico Rodrigues PaulaAbstract:Ionospheric scintillations are fluctuations in the phase and/or amplitude of trans-ionospheric radio signals caused by electron density irregularities in the ionosphere. A better understanding of the scintillation pattern is important to make a better assessment of GPS Receiver Performance, for instance. Additionally, scintillation can be used as a tool for remote sensing of ionospheric irregularities. Therefore, the study of ionospheric scintillation has both scientific as well as technological implications. In the past few years, there has been a significant advance in the methods for analysis of scintillation and in our understanding of the impact of scintillation on GPS Receiver Performance. In this work, we revisit some of the existing methods of analysis of scintillation, propose an alternative approach, and apply these techniques in a comprehensive study of the characteristics of amplitude scintillation. This comprehensive study made use of 32 days of high-rate (50 Hz) measurements made by a GPS-based scintillation monitor located in Sao Jose dos Campos, Brazil (23.2°S, 45.9°W, −17.5° dip latitude) near the Equatorial Anomaly during high solar flux conditions. The variability of the decorrelation time (τ0) of scintillation patterns is presented as a function of scintillation severity index (S4). We found that the values of τ0 tend to decrease with the increase of S4, confirming the results of previous studies. In addition, we found that, at least for the measurements made during this campaign, averaged values of τ0 (for fixed S4 index values) did not vary much as a function of local time. Our results also indicate a significant impact of τ0 in the GPS carrier loop Performance for S4 ≥ 0.7. An alternative way to compute the probability of cycle slip that takes into account the fading duration time is also presented. The results of this approach show a 38% probability of cycle slips during strong scintillation scenarios (S4 close to 1 and τ0 near 0.2 s). Finally, we present results of an analysis of the individual amplitude fades observed in our set of measurements. This analysis suggests that users operating GPS Receivers with C/N0 thresholds around 30 dB-Hz and above can be affected significantly by low-latitude scintillation.
Jens Rheinländer - One of the best experts on this subject based on the ideXlab platform.
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Advancing Tube Receiver Performance by Using Corrugated Tubes
Energy Procedia, 2015Co-Authors: Ralf Uhlig, Birgit Gobereit, Jens RheinländerAbstract:Abstract Direct introduction of solar energy into a Brayton cycle using Solar Tower systems enables a highly efficient conversion of the solar energy, especially so when combined cycles are used. One key component of such a solar gas turbine system is the Receiver. High and inhomogeneous heat fluxes pose the main challenge for the design of such Receivers. One possible design of the Receiver uses directly irradiated metallic tubes arranged in an insulated cavity. The paper presents the results of a study comparing thermo hydraulic absorber tube layouts with varying absorber tube dimensions and number of parallel tubes. The more parallel tubes are used the lower is the velocity of the fluid flow and in the same way the heat transfer coefficient is reduced. This leads to higher wall temperatures and therefore to a lower Receiver efficiency. Using corrugated tubes instead of smooth tubes gives the possibility to increase the heat transfer coefficient.A thermo hydraulic test bench was developed in order to analyze the influence of different structures of corrugated tubes on heat transfer capability and pressure drop. The geometry of helicallyribbed tubes was optimized using CFD modelling. Design goal was a high heat transfer coefficient without exceeding the allowed pressure drop of the turbine. The resultingconfigurations were used to improve a tubular Receiver based on the SOLUGAS Receiver design. A thermal FEM model was used to analyze the temperature field and the efficiency of the different Receiver designs. Solar radiation, convection to fluid, radiation exchange, convective and conductive losses were considered in the model. It was found that the Receiver efficiency of about 0.719 (at design point) could be increased up to 0.835 by using more parallel absorber tubes than needed to fulfill the pressure drop limit.
Hiroyuki Morikawa - One of the best experts on this subject based on the ideXlab platform.
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evaluation of lora Receiver Performance under co technology interference
Consumer Communications and Networking Conference, 2018Co-Authors: Guibing Zhu, Chunhao Liao, Makoto Suzuki, Yoshiaki Narusue, Hiroyuki MorikawaAbstract:LoRa networks achieve a remarkably wide coverage as compared to that of the conventional wireless systems by employing the chirp spread spectrum (CSS). However, single-hop LoRa networks have limited penetration in indoor environments and cannot efficiently utilize the multiple-access dimensions arising from different spreading factors (SF) because the star topology is typically used for LoRa. On the other hand, a multi-hop LoRa network has the potential to realize extensive network coverage by utilizing packet relaying and improving the network capacity by utilizing different SFs. We evaluated the LoRa Receiver Performance under co-technology interference via simulation and experiments to realize these potentials. The results show that LoRa can survive interference from time-synchronized packets transmitted by multiple transmitters with an identical SF. Furthermore, we examined the orthogonality between different SFs by evaluating the required signal-to-interference ratio (SIR). Finally, we demonstrated the possibility of employing different SFs to construct the pipeline in a multi-hop relay network to increase network efficiency.
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CCNC - Evaluation of LoRa Receiver Performance under co-technology interference
2018 15th IEEE Annual Consumer Communications & Networking Conference (CCNC), 2018Co-Authors: Guibing Zhu, Chunhao Liao, Makoto Suzuki, Yoshiaki Narusue, Hiroyuki MorikawaAbstract:LoRa networks achieve a remarkably wide coverage as compared to that of the conventional wireless systems by employing the chirp spread spectrum (CSS). However, single-hop LoRa networks have limited penetration in indoor environments and cannot efficiently utilize the multiple-access dimensions arising from different spreading factors (SF) because the star topology is typically used for LoRa. On the other hand, a multi-hop LoRa network has the potential to realize extensive network coverage by utilizing packet relaying and improving the network capacity by utilizing different SFs. We evaluated the LoRa Receiver Performance under co-technology interference via simulation and experiments to realize these potentials. The results show that LoRa can survive interference from time-synchronized packets transmitted by multiple transmitters with an identical SF. Furthermore, we examined the orthogonality between different SFs by evaluating the required signal-to-interference ratio (SIR). Finally, we demonstrated the possibility of employing different SFs to construct the pipeline in a multi-hop relay network to increase network efficiency.
