scholarly journals Diurnal and seasonal amplitude and phase variations of the radio signals of RSDN-20 transmitters and the intensity of radio noise (11.9 kHz) registered in Yakutsk during 2009-2017

2021 ◽  
pp. 122-136
Author(s):  
А.А. Корсаков ◽  
В.И. Козлов ◽  
Е.А. Павлов
Keyword(s):  
Seasonal Variations ◽  
Phase Delay ◽  
Propagation Path ◽  
Radio Noise ◽  
Night Time ◽  
Radio System ◽  
Radio Signals ◽  
Delay Increase ◽  
Phase Variations ◽  
Seasonal And Interannual Variations

В работе проводится анализ суточных, сезонных и межгодовых вариаций интенсивности радиошума, а также амплитуды и фазы сигналов радиотехнической системы дальней навигации РСДН-20 по данным регистрации на частоте 11.904 кГц в г. Якутске в периоды нарастания, максимума и спада в 24-м цикле солнечной активности (2009-2017 годы). Наиболее ярко выражены сезонные дневные вариации амплитуды. Зарегистрировано увеличение фазовой задержки радиосигнала от дня к ночи, что характерно для увеличения эффективной высоты волновода Земля – ионосфера. Наблюдаемое уменьшение фазовой задержки в ночное зимнее время на радиотрассе малой протяженности Хабаровск-Якутск возможно объясняется интерференцией мод высших порядков. Наблюдается асимметрия дневных сезонных вариаций амплитуды ОНЧ радиосигналов (11.904 кГц). Амплитуда сигнала в период осеннего равноденствия ближе к летнему солнцестоянию, а амплитуда весеннего равноденствия — к зимнему солнцестоянию. В дневные часы сезонные вариации амплитуды и фазы относительно стабильны год от года. В периоды нарастания, максимума и спада в 24-м цикле солнечной активности отмечены большие изменения амплитуды ОНЧ-сигнала, зарегистрированные зимой, по сравнению с летом. На фоне повышения солнечной активности в зимний период ночью регистрируется повышение фазовой задержки на радиотрассе меньшей протяженности Хабаровск-Якутск (1400 км) на 23 ± 6°. The daily, seasonal and interannual variations of the radio noise intensity, the amplitude and phase of signals from the long-range navigation radio system RSDN-20 are analyzed based on the registration at a frequency of 11.904 kHz in Yakutsk during increase, maximum and decrease periods in the 24th solar cycle activity (2009-2017). The most pronounced seasonal daytime amplitude variations. The signal phase delay increase from day to night was recorded, which is characteristic of an increase in the effective height of the Earthionosphere waveguide. The observed phase delay decrease in the winter night time on the short radio propagation path Khabarovsk-Yakutsk can be explained by the interference of higher-order modes. There is an asymmetry of the daytime seasonal variations of the amplitude of VLF radio signals (11.904 kHz). During daytime, seasonal variations in amplitude and phase are relatively stable from year to year. Against the background of an increase in solar activity in winter, at night, the phase delay increase is recorded by 23 ± 6°on a shorter radio path Khabarovsk-Yakutsk (1400 km).

Adaptation of model parameters of VLF radio signals phase variations on the Novosibirsk-Yakutsk propagation path

2014 ◽  
Author(s):  
Alexey A. Korsakov ◽  
Vladimir I. Kozlov ◽  
Viktor A. Mullayarov ◽  
Rustam R. Karimov
Keyword(s):  
Propagation Path ◽  
Model Parameters ◽  
Radio Signals ◽  
Phase Variations

Secure Intelligent Radio for Trains (SIRT)

2017 ◽  
Author(s):  
K. R. Damindra S. Bandara ◽  
Satish Kolli ◽  
Duminda Wijesekara
Keyword(s):  
Critical Infrastructure ◽  
Adaptive Modulation ◽  
Radio Spectrum ◽  
Spectrum Management ◽  
Worker Safety ◽  
Radio Noise ◽  
Radio Communication ◽  
Radio System ◽  
Cognitive Engine ◽  
Prototype Development

American Railroads are planning to complete implementing their Positive Train Control (PTC) systems by 2020. Safety objectives of PTC are to avoid inter-train collisions, train derailments and ensuring railroad worker safety. Under published specifications of I-ETMS (the PTC system developed by Class I freight railroads), the on-board PTC controller communicates with two networks; namely, the Signaling network and the Wayside Interface Unit network to gather navigational information such as the positions of other trains, the status of critical infrastructure (such as switches) and any hazardous conditions that may affect the train path. By design, PTC systems are predicated on having a reliable radio network operating in reserved radio spectrum, although the PTC system itself is designed to be a real-time fail safe distributed control systems. Secure Intelligent Radio for Trains (SIRT) is an intelligent radio that is customized to train operations with the aim of improving the reliability and security of the radio communication network. SIRT has two tiers. The upper tier has the Master Cognitive Engine (MCE) which communicates with other SIRT nodes to obtain signaling and wayside device information. To do so, the MCE communicates with cognitive engines at the lower tier of SIRT; namely the Cryptographic Cognitive Engine (CCE) (that provide cryptographic security and threat detection) and the Spectrum Management Cognitive Engine (SCE) (that uses spectrum monitoring, frequency hopping and adaptive modulation to ensure the reliability of the radio communication medium). We presented the architecture and the prototype development of the CCE in [1]. This paper presents the design of the MCE and the SCE. We are currently developing a prototype of the SCE and the MCE and testing the performance of our cognitive radio system under varying radio noise conditions. Our experiments show that SIRT dynamically switches modulation schemes in response to radio noise and switches channels in response to channel jamming.

scholarly journals Seasonal and Inter Annual Variation of Sea Surface Temperature in the Indonesian Waters

2016 ◽  
Vol 30 (2) ◽  
pp. 120
Author(s):  
Martono Martono
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Seasonal Variations ◽  
Sea Surface ◽  
Positive Anomaly ◽  
Interannual Variations ◽  
Arafura Sea ◽  
Timor Sea ◽  
Anomaly Analysis ◽  
Seasonal And Interannual Variations

Sea surface temperature plays an important role in air-sea interactions. This research was conducted to understand seasonal and interannual variations of sea surface temperature in the Indonesian waters. The data used in this research was daily sea surface temperature in 1986 to 2015 which was obtained from the Physical Oceanography Distributed Active Archive Center - National Aeronautics and Space Administration. Method used in this study was the anomaly analysis. The result showed that the seasonal and interannual variations of sea surface temperature in the Indonesian waters varied. Seasonal variations of SST in the Makasar Strait, Sulawesi Sea, and Halmahera Sea were low. High seasonal variations of sea surface temperature occurred in the southern waters of Java, Timor Sea, Arafura Sea, and Banda Sea, which were allegedly due to the upwelling process. In addition, interannual variation of sea surface temperature in the Indonesian waters fluctuated. From 1986 to 2000, it showed a negative anomaly dominant. Meanwhile, from 2001 to 2015, it showed a positive anomaly dominant. The effect of Indian Ocean Dipole on the fluctuation of sea surface temperature in the Indonesian waters was stronger than ENSO. Within the last 30 years, the sea surface temperature in the Indonesian water indicated a rising trend. The highest sea surface temperature rise occurred in the Halmahera Sea that reached 0.66 OC/30 years and the lowest was in the Timor Sea of 0.36 OC/30 years.

scholarly journals Observations of Pc 3-4 and Pi 2 geomagnetic pulsations in the low-latitude ionosphere

1999 ◽  
Vol 17 (11) ◽  
pp. 1397-1410 ◽  
Author(s):  
R. A. Marshall ◽  
F. W. Menk
Keyword(s):  
Resonance Frequency ◽  
Field Line ◽  
Night Time ◽  
Field Line Resonance ◽  
Radio Science ◽  
Ionospheric Physics ◽  
Line Resonance ◽  
Frequency Independent ◽  
Radio Signals ◽  
Magnetic Pulsations

Abstract. Day-time Pc 3–4 (~5–60 mHz) and night-time Pi 2 (~5–20 mHz) ULF waves propagating down through the ionosphere can cause oscillations in the Doppler shift of HF radio transmissions that are correlated with the magnetic pulsations recorded on the ground. In order to examine properties of these correlated signals, we conducted a joint HF Doppler/magnetometer experiment for two six-month intervals at a location near L = 1.8. The magnetic pulsations were best correlated with ionospheric oscillations from near the F region peak. The Doppler oscillations were in phase at two different altitudes, and their amplitude increased in proportion to the radio sounding frequency. The same results were obtained for the O- and X-mode radio signals. A surprising finding was a constant phase difference between the pulsations in the ionosphere and on the ground for all frequencies below the local field line resonance frequency, independent of season or local time. These observations have been compared with theoretical predictions of the amplitude and phase of ionospheric Doppler oscillations driven by downgoing Alfvén mode waves. Our results agree with these predictions at or very near the field line resonance frequency but not at other frequencies. We conclude that the majority of the observations, which are for pulsations below the resonant frequency, are associated with downgoing fast mode waves, and models of the wave-ionosphere interaction need to be modified accordingly.Key words. Ionosphere (ionosphere irregularities) · Magnetospheric physics (magnetosphere-ionosphere interactions) · Radio science (ionospheric physics)

scholarly journals Anomalies in VLF radio signals prior the Abruzzo earthquake (<i>M</i>=6.3) on 6 April 2009

2009 ◽  
Vol 9 (5) ◽  
pp. 1727-1732 ◽  
Author(s):  
A. Rozhnoi ◽  
M. Solovieva ◽  
O. Molchanov ◽  
K. Schwingenschuh ◽  
M. Boudjada ◽  
...  
Keyword(s):  
Great Britain ◽  
The Other ◽  
Time Signal ◽  
Night Time ◽  
Epicentral Area ◽  
Radio Signals ◽  
Propagation Paths

Abstract. The VLF/LF radio signals method for studying preseimic activity is applied to the Abruzzo earthquake (M=6.3, 6 April 2009). The data collected by three receivers located in Moscow (Russia), Graz (Austria) and Bari (Italy) at about 3000 km, 1000 km and 500 km from the epicenter were used. The signals received from the Sardinia (20.27 kHz) and the Sicily (45.9 kHz) transmitters, both located in Italy, were compared with those received from the Iceland (37.5 kHz), the Great Britain (19.58 kHz) and the Germany (23.4 kHz) transmitters. The propagation paths of the two Italian transmitters cross the epicentral area (seismic paths) unlike the paths of the other three signals (control paths). Using two different analyses, that are the study of the night-time signal and the research of shifts in the evening terminator times, clear anomalies were revealed 2–8 days before the occurrence of the Abruzzo earthquake in the seismic paths, while no anomalies have been found in the control paths.

scholarly journals SIGNAL RECOGNITION SYSTEM MACHINE LEARNING ALGORITHM

2020 ◽  
pp. 053-059
Author(s):  
D. E. SCHUMACHER ◽  
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Software Defined Radio ◽  
Learning Algorithm ◽  
Recognition System ◽  
Digital Information ◽  
Signal Recognition ◽  
Radio System ◽  
The Neural Network ◽  
Radio Signals

The article provides a comparative analysis of processing algorithms for digital information methods of machine learning. A research system for recognizing radio signals based on an artificial neural network as part of a software-defined radio system (SDR). The neural network was designed in the MatLab program, simulation signals were generated, and an algorithm for training the neural network was developed.

scholarly journals Ionospheric Absorption Studies Based on Cosmic Noise Data at 28·6 MHz at Bangalore

1967 ◽  
Vol 20 (4) ◽  
pp. 455 ◽  
Author(s):  
M Krishnamurthi ◽  
SBS Subrahmanya Sarma
Keyword(s):  
Local Time ◽  
Seasonal Variations ◽  
Noise Intensity ◽  
Cosmic Radio ◽  
Narrow Beam ◽  
Radio Noise ◽  
Ionospheric Absorption ◽  
Absorption Studies ◽  
Noise Data ◽  
Cosmic Noise

Using a. fa.irly narrow beam antenna (10��5 by 16��5), cosmic radio noise at 28�6 MHz has been continuously recorded during the years 1962-64. The data between midnight and 06 hr local time were used to determine the "unabsorbed cosmic noise intensity" for different sidereal times. Based on this, the total ionospheric absorption at this frequency was computed for the rest of the day. Diurnal and seasonal variations are discussed.

Sign in / Sign up

Export Citation Format

Share Document