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I mportance Of Very Low Frequency Radio Signal Data Registered By V LF -receiver System. A . Nina, V. Čadež and V. Srećković Institute of Physics, Belgrade, Serbia Astronomical Observatory , Belgrade, Serbia. Contents. Ionosphere VLF signals – “ionospheric probes”

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I mportance of very low frequency radio signal data registered by v lf receiver system

Importance Of Very Low Frequency Radio Signal DataRegistered By VLF-receiverSystem

A. Nina, V. Čadež and V. Srećković

Institute of Physics, Belgrade, Serbia

Astronomical Observatory, Belgrade, Serbia


Contents
Contents

  • Ionosphere

  • VLF signals – “ionospheric probes”

  • Importance of creating a database for studying the ionosphere and its applications in technical and scientific research such as:

    -detection of different events by VLF signals

    -ionospheric diagnostics

    -study of physical and chemical processes


Introduction
Introduction

  • Terrestrial ionosphere

  • Methods of investigation

  • Our study: low ionosphere


Vlf signals ionospheric probes
VLF signals – “ionospheric probes”

  • VLF wave propagation

  • Advantages:

    - continual emission,

    - large area involved for analyses,

    - international collaboration:

    AWESOME, AbsPAL, SAVNET, AARDDVARK

  • Belgrade VLF station


Significance of low ionospheric study
Significance of low ionospheric study

  • Science

    - detection of different pure natural and man-induced events

    - ionospheric diagnostics

    - study of physical and chemical processes

  • Telecommunications

    - radio communications,

    - planned networks of mobile communication satellites,

    - high precision applications of global navigation satellite systems, etc.

  • Explanation of application our database in scientific research and, consequently, in prediction of possible problems in the telecommunications


Importance of database
Importance of database

  • Processes in the ionosphere are:

    -very complex

    - time- and space variable

  • Experiment:

    practically impossible to exactly simulate conditions in particular cases

  • Theory:

    no real time data available for all necessary parameters needed for theoretical analyses

  • Statistics:

    requires the existence of a database that can be used to analyze the ionosphere


Detection of events

SGR 1806-20

HESSI

Detection of events

  • Sun:

    - regular variation

    - transient variations

  • Outer space

  • Earth:

    - in the atmosphere

    - in the lithosphere

    pure natural

    man-induced


Ionospheric diagnostics
Ionospheric diagnostics

  • The case considered:

    Solar flare

    February 18th, 2011

  • Recorded data:

    - GOES-15 satellite

    - Belgrade AWESOMEreceiver

    - DHO (Germany) transmitter (23.4 kHz)

  • Theoretical model:

    Wait’s model of ionosphere

  • Numerical program for simulation VLF signal propagation:

    LWPC (Long-Wave Propagation Capability)


Physical and chemical processes preliminary results
Physical and chemical processes (preliminary results)

G(t) – electron gain rate

L(t) – electron loss rate

Upper half of D region:

I - Quasi equilibrium regime

II - Photo-ionization regime

III - Recombination regime

P(t) – photo-ionization rate

R(t) – recombination rate

I(t) – radiation flux by satellite

αeff – effective recombination coefficient

Ks– coefficient (dependent on energy interval of data registered by satellite)


Conclusions
Conclusions

  • Applications of low ionospheric investigations in science and information technologies

  • Research of low ionosphere by VLF waves

  • Importance of VLF radio signal dataregistered by receiversystems


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