Abstract The equatorial zonal electric field responses to prompt penetration of eastward convection fields (PPEF) were compared at closely spaced longitudinal intervals dusk premidnight sectors during the intense geomagnetic storm 17 March 2015. At sector (Indian longitudes), a rapid uplift F layer >550 km and development plasma bubbles (EPBs) observed. These EPBs found extend up 27.13°N 25.98°S magnetic dip latitudes indicating their altitude ~1670 apex. In contrast, few degrees east in...

This paper describes the neural network (NN) application for prediction of total electron content (TEC) over Chumphon, an equatorial latitude station in Thailand. The studied period is based on available data during low-solar-activity from 2005 to 2009. single hidden layer feed-forward with a back propagation algorithm applied this work. input space NN includes day number, hour number and sunspot number. An analysis was made by comparing TEC (NN TEC), observation (GPS TEC) IRI-2007 model...

Two-dimensional ionospheric total electron content (TEC) maps have been derived from ground-based Global Navigation Satellite System (GNSS) receiver networks and applied to studies of various disturbances since the mid-1990s. For purpose monitoring researching conditions space weather phenomena, we developed TEC areas over Japan using dense GNSS network, Earth Observation NETwork (GEONET), which consists about 1300 stations is operated by Geospatial Information Authority (GSI). Currently,...

Abstract The effects of the St. Patrick's Day geomagnetic storms 2013 and 2015 in equatorial low‐latitude regions both hemispheres 100°E longitude sector is investigated compared with response Indian at 77°E. data from a chain ionosondes GPS/Global Navigation Satellite Systems receivers magnetic conjugate locations have been used. perturbation zonal electric field due to prompt penetration magnetospheric convective under shielded over shielding gives rise rapid fluctuations F 2 layer...

Abstract Dual-frequency multi-constellation (DFMC) satellite-based augmentation system (SBAS) is a new SBAS standard for aeronautical navigation systems. It supports aircraft from the enroute to approach phases via L1 and L5 frequencies (1575.42 1176.45 MHz). Although ionosphere-free (IF) combination in DFMC operation removes first-order ionospheric delays pseudorange measurement, remaining terms including satellite-clock offset errors higher-order (HOI) are still unaccounted for. The...

In this paper, we derive the average bit error probability (BEP) for common digital modulation schemes and outage of double Nakagami-m channels with MRC diversity. First, density function (PDF) moment generating (MGF) received signal maximal ratio combining (MRC) receiver diversity are computed. The derived MGF results simplified in terms a generalized hypergeometric 2F0. BEP expressions find applications existing wireless systems such as satellite mobile communication system,...

Abstract Ground‐based augmentation system (GBAS) is an important that provides the differential corrections and integrity information from reference stations to aircrafts for precision approach landing. It known nonuniform ionospheric characteristics called “ionospheric delay gradient” can cause errors in degrading accuracy safety level if they are undetected by stations. Since of ionosphere different each region, gradient observations equatorial low‐latitude regions necessary developing...

Abstract This study mainly investigates equatorial and low‐latitude ionospheric response to a great geomagnetic storm that occurred on 17 March 2015. We found there were some interesting phenomena, e.g., short‐term positive effect, daytime spread F , morning Equatorial Ionization Anomaly (EIA) in the topside ionosphere, emerged at region along longitude of about 100°E. Ground‐based ionosondes situ satellite (Swarm) utilized possible mechanisms for these phenomena. vertical downward transport...

Abstract Ionospheric irregularities can cause detrimental effects on the global navigation satellite system (GNSS) signals, often in form of rapid fluctuations both amplitude and phase. Over low-latitude regions, equatorial plasma bubble (EPB) frequently arises after sunset, leading to GNSS scintillations since signals propagate through ionospheric irregularities. The relationship between (S4 index) EPB characteristics is presented. We investigate geometrical backscatter echoes associated...

Abstract Equatorial plasma bubble (EPB) is a phenomenon characterized by depletions in ionospheric density being formed during post-sunset hours. The irregularities can lead to disruptions trans-ionospheric radio systems, navigation systems and satellite communications. Real-time detection classification of EPBs are crucial for the space weather community. Since 2020, Prachomklao radar station, very high frequency (VHF) has been installed at Chumphon station (Geographic: 10.72° N, 99.73° E...

This study presents the diurnal and seasonal variations of slab thickness at equatorial magnetic latitudes in Thailand during 2004–2006, corresponding to declining part low solar activity. The GPS-derived total electron content (TEC) maximum density F-region (NmF2) are used compute (τ) Chumphon station (10.72°N, 99.37°E), located near equator. results show that large peaks exist pre-sunrise hours all three seasons when compared with other latitudes. value occurs peak F2 region is lowest...

Abstract. We present the results of a comparative study spread-F signatures over five low-latitude sites: Chiangmai (CGM; 18.8° N, 98.9° E, mag. Lat. 8.8° N), Thailand; Tanjungsari (TNJ; 6.9° S, 107.6° 16.9° S), Indonesia; Palmas (PAL; 10.2° 311.8° 0.9° S) and São José Dos Campos (SJC; 23.2° 314.1° 14.0° Brazil; Tucumán (TUC; 26.9° 294.6° 16.8° Argentina. The investigation was based on simultaneous ionograms recorded by an FMCW (frequency-modulated continuous-wave) at CGM, IPS-71 (digital...

The readback signal of patterned media storage (PMS) is corrupted by a two-dimensional interference consisting inter-symbol (ISI) and inter-track (ITI). In this paper, we apply the turbo equalization to mitigate ITI effects. codeword outer code divided then written on three separate tracks. After first iteration, bit estimates from provide partial for branch metric computation in soft-output viterbi algorithm (SOVA) detectors. Unlike previous works, number states channel trellis due ISI only...

Combined scintillation and terrestrial fadings occur in mobile satellite communication channels as the signal passes through ionosphere lower atmosphere. This results a product fading channel, which negatively affects performance of system. The challenge is to evaluate system, terms average bit error probability (BEP). In this paper, use moment generating function, we derive expressions for BEP an upper bound M-ary phase-shift keying (M-PSK) modulation with maximal-ratio combining (MRC)...

Abstract Ionospheric nighttime enhancements are manifested in an increase of the electron density at nighttime. This paper studies latitudinal variation specific local time postmidnight enhancement peaks using ionosondes distributed low latitudes. To obtain parameters ionosphere, we manually extracted ionograms recorded by ionosondes. Cases show that there significant variations observed peaks. Results lower geomagnetic latitude, earlier peak occurred northern hemisphere. Additionally,...

Abstract An ionogram image serves as a valuable data for examining the ionospheric bottom side characteristics and variabilities. Spread-F is indicated or identified by plasma irregularity in region. Diffused echo images particularly pose challenges efficient interpretation required further applications. automatic classification of spread-F presented this study. Ionogram are automatically classified using preprocessing techniques to improve performance. In study, designed two machine...

Abstract Using the HF Doppler sounders at middle and low latitudes (Prague, Czech Republic; Tucuman, Argentina; Zhongli, Republic of China, Sugadaira, Japan), we observed electric fields geomagnetic sudden commencement (SC) propagating near-instantaneously (within 10 s) over globe. We found that preliminary impulse (PI) main (MI) SC are in opposite direction to each other PI MI directed from dusk dawn dusk, respectively, manifesting nature curl-free potential field. further onset peak field...

Abstract The predictability of the nighttime equatorial spread-F (ESF) occurrences is essential to ionospheric disturbance warning system. In this work, we propose ESF forecasting models using two deep learning techniques: artificial neural network (ANN) and long short-term memory (LSTM). ANN LSTM are trained with ionogram data from equinoctial months in 2008 2018 at Chumphon station (CPN), Thailand near magnetic equator, where onset typically occurs, they tested 2019. These especially new...

Abstract This study estimates the scale sizes of plasma density irregularities and longitudinal width associated with equatorial bubbles (EPBs) in low-latitude regions. By analyzing amplitude scintillation S 4 indices total electron content (TEC) measured from low earth orbit (LEO) satellite’s beacon signals 400 MHz Global Navigation Satellite System (GNSS) L1/E1 1575.42 MHz, recorded by receivers at KMITL station Bangkok, Thailand (geographic; 13.73° N, 100.77°E, magnetic: 7.26°N), we...

Rain attenuation is a major factor to degrade the system performance in frequency above 10 GHz. This paper presents statistical analysis of rainfall rate and rain data on satellite ground propagation path. By measuring 12.7-GHz beacon signal from JCSAT continuously. Yearly cumulative distribution functions were then compared predicted models. The Crane Global model for zone H provides overestimated values measured ones. For G, global close ITU-R model; both are smaller than ones