scholarly journals Markov Chain‐based Stochastic Modeling of Deep Signal Fading: Availability Assessment of Dual‐frequency GNSS‐based Aviation under Ionospheric Scintillation

Space Weather ◽  
2021 ◽  
Author(s):  
Andrew K. Sun ◽  
Hyeyeon Chang ◽  
Sam Pullen ◽  
Hyosub Kil ◽  
Jiwon Seo ◽  
...  
2018 ◽  
Vol 26 (01) ◽  
pp. 87-106 ◽  
Author(s):  
T. MIHIRI M. DE SILVA ◽  
SOPHIA R.-J. JANG

We construct models of continuous-time Markov chain (CTMC) and Itô stochastic differential equations of population interactions based on a deterministic system of two phytoplankton and one zooplankton populations. The mechanisms of mutual interference among the predator zooplankton and the avoidance of toxin-producing phytoplankton (TPP) by zooplankton are incorporated. Sudden population extinctions occur in the stochastic models that cannot be captured in the deterministic systems. In addition, the effect of periodic toxin production by TPP is lessened when the birth and death of the populations are modeled randomly.


2020 ◽  
Author(s):  
Mohammad Ali Goudarzi

<p>In order to enable our new PPP processing engine and online service to work in full multi-GNSS mode, and provide high quality precise GNSS orbit and clock (POD) products to IGS and international geodetic community, Canadian Geodetic Survey (known as EMR) has started to modernize his POD system. The new system is based on GipsyX and in-house software development and will replace our current POD system in near future. When become operational, the new POD system will produce multi-GNSS precise orbit and clock corrections with ambiguity resolution along with wide-lane and phase biases using zero-differenced, dual-frequency, ionosphere-free phase and code observations in RINEX 2 and 3 formats estimated in combined solution. The new system also benefits from advanced features such as removing observations affected by ionospheric scintillation and ground stations affected by earthquake as well as real-time monitoring of estimated position time-series of ground stations, among others.</p>


Navigation ◽  
2016 ◽  
Vol 63 (4) ◽  
pp. 405-413 ◽  
Author(s):  
Takeshi Fujiwara ◽  
Toshiaki Tsujii

2015 ◽  
Vol 73 (1) ◽  
Author(s):  
Emad F. Aon ◽  
A. R. Othman ◽  
Y. H. Ho ◽  
R. Q. Shaddad

Wireless signals propagated along global positioning system (GPS) channel are affected by ionospheric electron density irregularities such that GPS signals may experience amplitude and phase fluctuations. The global navigation satellite system (GNSS), ionospheric scintillation, and total electron content (TEC) monitor (GISTM) receiver has been installed at UTeM, Malaysia (2.3139°N, 102.3183°E) for monitoring ionospheric scintillation at several frequencies. In this paper, the GPS ionospheric scintillations are concerned for the dual frequency L1 (fL1 = 1.57542 GHz) and L2C (fL2= 1.2276 GHz).  Ionospheric scintillation data has been collected during solar maximum cycle 2013-2014 for six months October 2013–March 2014. Solar activities significantly impact the ionospheric GPS scintillation, especially in the equatorial region where Malaysia is located. The GPS link is analyzed to investigate how the scintillation increases during the solar maximum cycle. When the sun flux is maximum, the total of electrons is increased in the ionospheric layer and the scintillation values gradually become high. The ionospheric amplitude/phase scintillation, carrier-to-noise (C/No) ratio, and availability of GPS satellites are reported in the proposed experimental GPS model. Consequently, for Malaysia, typical threshold received C/No ratio is 43 dB-Hz, implying that C/No ratio should be greater than 43 dB-Hz to receive good signals at the GPS receiver.


Radio Science ◽  
2009 ◽  
Vol 44 (1) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jiwon Seo ◽  
Todd Walter ◽  
Tsung-Yu Chiou ◽  
Per Enge

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