نتایج جستجو برای: scintillation
تعداد نتایج: 5620 فیلتر نتایج به سال:
The amplitude and phase scintillation indices are customarily obtained by specialised GPS Ionospheric Scintillation and TEC Monitors (GISTMs) from L1 signal recorded at the rate of 50 Hz. The scintillation indices S4 and σ8 are stored in real time from an array of high-rate scintillation receivers of the Canadian High Arctic Ionospheric Network (CHAIN). Ionospheric phase scintillation was obser...
Irregularities in the Earth's ionosphere can make the amplitude and phase of radio signals fluctuate rapidly, which is known as ionospheric scintillation. Severe ionospheric scintillation could affect the performance of the Global Navigation Satellite System (GNSS). Currently, the Multiple Phase Screen (MPS) technique is widely used in solving problems caused by weak and strong scintillations. ...
Maps of GPS phase scintillation at high latitudes have been constructed after the first two years of operation of the Canadian High Arctic Ionospheric Network (CHAIN) during the 2008–2009 solar minimum. CHAIN consists of ten dual-frequency receivers, configured to measure amplitude and phase scintillation from L1 GPS signals and ionospheric total electron content (TEC) from L1 and L2 GPS signal...
Tropospheric scintillation is caused by variations of refractive index due to turbulence. The only meteorological input parameter for two common current scintillation models by Karasawa et al. and by ITU-R is the monthly average of wet part of refractivity Nwet at ground level, which is not directly associated with turbulence. The diurnal correlation betweenNwet and scintillation variance is ve...
This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals...
The recent rapid evolution of new satellite services, including VSAT for internet access, LAN interconnection and multimedia applications, has triggered an increasing demand for bandwidth usage by satellite communications. However, these systems are susceptible to propagation effects that become significant as the frequency increases. Scintillation is the rapid signal fluctuation of the amplitu...
We examine the correspondence between high latitude ionospheric scintillation measurements made at 250 MHz with the occurrence of 10 MHz HF coherent radar backscatter, on 13 and 14 December 2002. We demonstrate that when the ionospheric intersection point of the scintillation measurements is co-located with significant HF radar backscatter, the observed scintillation, quantified by the S4 index...
Tropospheric scintillation can seriously aaect satellite links operating at Ka-band. The average bit error probability for a multiuser binary direct-sequence spread-spectrum satellite communication network operating under amplitude scintillation is evaluated. Numerical results are presented to illustrate performance comparisons of systems operating under typical scintillation statistics. As in ...
Optical wireless communication has been the subject of much research in recent years because of the increasing interest in laser satellite-ground links and urban optical wireless communication. The major sources of performance degradation have been identified as the spatial, angular, and temporal spread of the propagating beam when the propagation channel is multiscattering, resulting in reduce...
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