Equatorial Ionospheric Scintillation of BeiDou Navigation Satellite System Observed in Singapore

Ding Yu Heh, Dhimas Sentanu Murti, Eng Leong Tan, Eng Kee Poh, Keck Voon Ling, Johnson Tang

Abstract:	This paper intends to analyze the equatorial ionospheric scintillation of Beidou navigation satellite system observed in Singapore. The Beidou navigation satellite system has attracted much interest due to its more recent deployment and operation. Situated in equatorial region, Singapore is in close proximity to the equatorial ionization anomaly (EIA) region. The EIA is caused by accumulation of ionization crests around 15 to 20 degrees on either sides of geomagnetic equator, which increases the occurrence of ionospheric scintillation. To the best knowledge of the authors, such scintillation study is conducted for the first time in Singapore using the data from Beidou navigation satellite system. The data presented herein is over a one year period from January 2014 to December 2014. The Septentrio PolaRxS receiver is used as the ionospheric scintillation monitoring receiver, which is a multi-frequency, multi-constellation receiver dedicated to ionospheric monitoring. The output data provided by the receiver is in the septentrio binary format (SBF) which comprises different type of blocks data. Among the observables that can be obtained directly from SBF files are in-phase (I) and quadrature-phase (Q) channel correlator outputs, signal intensity and carrier phase, each at 50 Hz output rate. Various ionospheric scintillation parameters can then be calculated from the observables. To remove the multipath effect, only satellites with elevation angle of more than 20 degrees are considered. To study the seasonal and diurnal scintillation characteristics of Beidou satellite system, the average scintillation parameters are plotted across different months throughout the one year observation period, as well as across 24 hour period each day. It is observed that the high scintillation parameter occurs during the months of April and September, categorized as equinox months. Other months show relatively low scintillation parameter. Diurnally, most scintillation happens during local time (UTC+8) of 8 pm to 2 am, which is known as the post sunset period. To study the spatial distribution of the scintillation events, the movement paths of visible Beidou satellites are traced in a polar sky plot. Most of the satellites that are affected by scintillation are found to be towards the south of Singapore. This further reaffirms the phenomena of the EIA, which is possibly located slightly towards the south of Singapore. Some selected examples of scintillation events are plotted along with other scintillation parameters such as? ??_?, VTEC, ROT and ROTI. Results show that S4 and? ??_? generally show similar trends whereby amplitude and phase scintillations occur together. On top of that, the VTEC also shows higher fluctuations, which translate into higher ROT and ROTI. The scintillation characteristics of Beidou are further compared with that of GPS and GLONASS by plotting the scintillation parameters of different satellites system during the same period. Results show that the scintillation parameters of Beidou, GPS and GLONASS exhibit similar trends. The correlation coefficient of several scintillation parameters is calculated to further quantify the relationships among different Global Navigation Satellite System (GNSS). It is shown that the correlation coefficient is close to one, hence indicating strongly correlated scintillation parameters among different GNSS.
Published in:	Proceedings of the ION 2015 Pacific PNT Meeting April 20 - 23, 2015 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	17 - 24
Cite this article:	Heh, Ding Yu, Murti, Dhimas Sentanu, Tan, Eng Leong, Poh, Eng Kee, Ling, Keck Voon, Tang, Johnson, "Equatorial Ionospheric Scintillation of BeiDou Navigation Satellite System Observed in Singapore," Proceedings of the ION 2015 Pacific PNT Meeting, Honolulu, Hawaii, April 2015, pp. 17-24.
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