Space-time dependences of propagation parameters of decameter radio waves at high latitudes

1981 ◽  
Vol 24 (9) ◽  
pp. 729-733
Author(s):  
D. V. Blagoveshchenskii
Keyword(s):  
Space Time ◽  
High Latitudes ◽  
Radio Waves ◽  
Decameter Radio ◽  
Propagation Parameters

Deviation of decameter radio waves from the great circle path at high latitudes

1991 ◽  
Vol 34 (2) ◽  
pp. 102-105
Author(s):  
N. F. Blagoveshchenskaya ◽  
A. N. Baranets ◽  
T. D. Borisova ◽  
V. A. Bubnov
Keyword(s):  
Great Circle ◽  
High Latitudes ◽  
Radio Waves ◽  
Decameter Radio ◽  
Great Circle Path

scholarly journals NCREASING IMMUNITY OF DECAMETER RADIO CHANNEL TRANSMISSIONS UNDER UNINTENDED INTERFERENCE

T-Comm ◽  
2021 ◽  
Vol 15 (6) ◽  
pp. 4-9
Author(s):  
Sergey V. Dvornikov ◽  
◽  
Evgeniy V. Markov ◽  
Adjan A. Manoshi ◽  
◽  
...  
Keyword(s):  
Fading Channels ◽  
Rayleigh Fading ◽  
Noise Immunity ◽  
Radio Channel ◽  
Radio Waves ◽  
Radio Communication ◽  
Radio Channels ◽  
Shift Keying ◽  
Decameter Radio ◽  
Significant Length

The transmission of messages is a complex process, which is largely determined by the properties of the radio channel used. Decameter radio channels are the most difficult for organizing communication, since the ionospheric propagation of radio waves is associated with their significant attenuation, due to the significant length of the paths, as well as the presence of Rayleigh fading in the channel. However, the possibility of transmitting information over long distances without serious resource costs stimulates further research to improve the reliability of decameter radio communication. In this paper, we investigate the possibility of increasing the noise immunity of frequency-shift keying transmissions of decameter radio channels in conditions of unintentional interference due to the use of broadband signals. An analytical expression of the dependence of the probability of a bit error on the level of the ratio of the peak signal power to the peak interference power is considered; a graph of this dependence is presented. It is shown that the plot is consistent with the overall noise immunity estimate for Rayleigh fading channels using double FSK signals. The rationality of methods for obtaining the required reception quality in decameter radio channels is analyzed. It is shown that the most rational direction for increasing the noise immunity of FM-2 transmissions in decameter radio channels with Rayleigh fading in conditions of unintended interference is the use of broadband signals. In this case, for expansion, it is advisable to choose a value kf = 7, which makes it possible to increase the noise immunity by 9 dB. The conclusions are illustrated by graphs.

scholarly journals An analysis of anomalous propagation parameters and its effect on the intensity of clutter in weather radars

MAUSAM ◽  
2021 ◽  
Vol 71 (1) ◽  
pp. 11-20
Author(s):  
BIBRAJ R ◽  
KANNAN B. ARUL MALAR ◽  
RAO K. RAMACHANDRA ◽  
SAIKRISHNAN K. C.
Keyword(s):  
Refractive Index ◽  
Electromagnetic Waves ◽  
Inversion Layer ◽  
Weather Radar ◽  
Temperature Inversion ◽  
Radiosonde Data ◽  
Radio Waves ◽  
Radar Images ◽  
Propagation Parameters ◽  
Anomalous Propagation

Weather radar is used by forecasters for identifying storms and estimating its corresponding precipitation. Anomalous propagation of the radar beam may lead to misinterpretation of the weather events and associated errors in precipitation estimates. As the weather radar transmits electromagnetic waves, it is affected by the refractive index of the atmosphere which depends on the temperature, pressure and water vapor content. It is important to understand the refractive index of the atmosphere and how it affects the beam propagation of the radar to interpret the echoes better. Meteorological conditions causing anomalous propagation is well described in literature by Battan (1973), Doviak and Zrnik (2006) and Rinehart (2001). The vertical refractivity gradient (VRG) affects the propagation of radio waves in the atmosphere (Gossard, 1977). These anomalous propagation cause clutter to be displayed in the radar images. The intensity of the clutter was differentiated into various groups by the amount of clutter present in the radar image. Refractivity parameters at various heights and the height of the temperature inversion layer were calculated using radiosonde observational data at the Visakhapatnam (VSK) station. The observed values from the radiosonde data were compared with the intensity groups and it was found that three parameters were influential in determining the intensity of the clutter which is the presence of the temperature inversion layer above the radar, the VRG of the temperature inversion layer above the radar and the VRG from the radar to a height of 1 km from sea level.

Пространственно-временное кодирование в системах MISO

2020 ◽  
Author(s):  
M.A. Bykhovskiy
Keyword(s):  
Noise Immunity ◽  
Signal Transmission ◽  
Base Station ◽  
Space Time ◽  
Radio Waves ◽  
Space Time Codes ◽  
The One ◽  
Error Probabilities

The analysis of noise immunity of MISO systems withKantennas at the base station (BS) and Space-Time Codes (STC) is performed. This system, as compared to STC systems, selects just one of K antennas for signal transmission the one whose radiation during radio waves broadcasting along the route BSuser station has the least attenuation. Formulas allowing to calculate error probabilities at the reception of multiposition signals with QAM and the various number of transmitting antennas at BSs both in STC systems and in the new MISO system are obtained. Выполнен анализ помехоустойчивости систем MISO с K антеннами на базовой станции (БС) и пространственно-временными кодами (ПВК). Дано описание и выполнен анализ помехоустойчивости новой, более простой в реализации, системы MISO, также имеющей K антенн на БС. В ней, в отличие от систем с ПВК, для передачи сигналов выбирается лишь одна из K антенн, излучение которой при распространении радиоволн на трассе от БС к абонентской станции (АС) ослабляется в наименьшей степени. Получены формулы, позволяющие вычислить вероятности ошибки при приеме многопозиционных сигналов с квадратурно-амплитудной модуляцией при разном числе передающих антенн на БС как в системах с ПВК, так и в новой системе MISO. Показано, что при одном и том же количестве передающих антенн на БС новая система MISO по сравнению с системой с ПВК обеспечивает энергетический выигрыш, составляющий 2 дБ. С увеличением количества передающих антенн K этот выигрыш увеличивается.

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