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無線電科學 ~ 越來越紅的老科學~ PowerPoint PPT Presentation


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無線電科學 ~ 越來越紅的老科學~. 主講人:劉兆漢. The First Hundred Years 1865-1873 Maxwell Equation,Prediction of the existence of Radio( EM) Waves 1888 Hertz experimentally found the radio waves

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無線電科學 ~ 越來越紅的老科學~

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無線電科學~越來越紅的老科學~

主講人:劉兆漢


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  • The First Hundred Years

  • 1865-1873 Maxwell Equation,Prediction of the

  • existence of Radio( EM) Waves

  • 1888 Hertz experimentally found the radio waves

  • 1901 Marconi demonstrated Propagation of

  • Radio Waves across English Channel

  • 1907 Cross-Atlantic radio wave propagation

  • experiment, Marconi

  • 1920-1930 Appleton experimented with the idea of

  • radar, found Ionosphere


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  • 1935-1945 Invention and application of Radar

  • 1945 Discovery of NMR

  • 1947 Dawn of Radio Astronomy;

  • First idea of Cellular Phone

  • 1948 Invention Transistor

  • 1955-60 Invention of MASER and LASER

  • 1957 First Satellite(Sputnik)

  • 1964 communication and weather satellites


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大旱期 1965~1980

  • 光纖通訊

  • 數位時代


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  • 天降甘霖

  • 個人通訊

  • 行動通訊


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  • 新方向

  • 通訊

  • 遙測

  • 生物醫學應用

  • 智慧型家用


Space weather science and application

Space Weather : Science and Application


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太陽黑子


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  • Magnetic storms

Fig2.2


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  • Reconnection

Fig2.3


Activity effects in geospace

ACTIVITY EFFECTS in GEOSPACE

  • Electromagnetic Radiation: Flare X-rays and UV affect ionosphere/communications.

  • Energetic particles form shock wave, move magnetosphere, enhance radiation belts, and cause geomagnetic storms & substorms.

  • Geomagnetic storm current systems preceed elevated high energy electrons.

  • Auroral Substorm current systems and fields affect satellites directly.


Effects on satellites

EFFECTS on SATELLITES

  • Magnetopause Crossing Events (MPEs) - shock wave compresses magnetosphere inside satellite orbit altitude (5.6 Re) near noon and on flanks of magnetotail. Causes magnetically oriented satellites to lose Earth pointing.


Effects on satellites1

EFFECTS on SATELLITES

  • Navigation Satellites in outer trapping region (half-geostationary altitude) encounter fields & currents during substorms and magnetic storms - lose frequency/time standard.


Effects on surface technology

EFFECTS on Surface Technology

  • Radio communications eliminated or over amplified depending on frequency.

  • HF-DF systems disoriented.

  • Geodetic surveys interrupted.

  • Ship navigation disrupted.

  • Power system failures from induction.

  • Pipeline corrosion & bad chip production


Effects on humans

Effects on Humans

  • All ground-based effects are important for impact on humans.

  • High altitude aircraft radiation effects and all airborne technology effects are impact on humans.

  • Astronauts directly affected by high energy protons and heavier ions; September and October 1989.


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  • Aurora

  • Auroradisplays

Fig1.1


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Fig1.2


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Fig1.3


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Fig1.4


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電離層的發現


Properties of radio waves

Properties of Radio Waves

  • Amplitude

  • Phase

  • Polarization

  • Frequency


Phenomena associated with radio wave propagation

Phenomena Associated with Radio Wave Propagation

  • Line-of-Sight Propagation

  • Refraction

  • Reflection

  • Diffraction

  • Scattering

  • Absorption

  • Attenuation

  • Doppler Effect


Ground based ionosonde

Ground Based Ionosonde

  • Send radio waves from the ground to the ionosphere. The reflected signal yields information about the bottom-side of the ionosphere such as the electron density and the motion of the charged particles


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  • SPUTNIK, 1957


Satellite radio beacon experiment

Satellite Radio Beacon Experiment

  • Radio beacon signal is sent from the satellite and received on the ground

  • From the polarization of the received signal one can deduce the Total Electron Content (TEC) of the ionosphere which is the integrated electron density in the ionosphere along the ray tube of the radio wave from the satellite to the ground


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  • EquatorialBubble


Scintillation

Scintillation

  • Plasma instabilities

  • Ionosphere density irregularities

  • Scattering of radio waves

  • Scintillation


Qp diffraction pattern at the beginning of an intense scintillation patch west wall

QP diffraction pattern at the beginning of an intense scintillation patch (West Wall)


Correlation analysis in small scale

Correlation Analysis insmallscale

D=216m

dt=1.62s

D/dt=133m/s


Computerized ionospheric tomography

Computerized Ionospheric Tomography

  • J.R.Austen, S.J.Franke and C.H.Liu, 1988,

  • Radio Sci. V.23, 299-307.

  • The idea of ionospheric tomography was first proposed and proven.

  • Opened the new field of CIT

  • Affordable. Robust technique for ionospheric probing


Atmospheric radars

ATMOSPHERIC RADARS

  • Weather Radar

  • Doppler Radar and Polarization Radar

  • Mesosphere-Stratosphere-Troposphere Radar


Mst radar

MST RADAR

  • Jicamaca Radar in Peru, 1973

  • SOUSY Radar, Germany, 1974

  • MU Radar, Japan, 1984

  • Chung Li Radar, 1986


To study atmospheric wave and instability

To study atmospheric wave and instability


Tropopause and wave like structures

Tropopause and wave-like structures


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Colour coded-Power spectrum during (a) clear air, (b) Clear air with stratiform rain and (c) clear air with convective rain


Gps radio occultation

GPS Radio Occultation

  • GPS/MET project, UCAR/JPL, 1995 -96

  • Tom Yunck

  • NASA Earth Observation System (EOS) Program, proposal submission in 1988,phase I study in 1989 – 1990

  • ROCSAT/COSMIC (Constellation Of Satellites for Meteorology Ionosphere and Climate), 1998 --


The gps occultation geometry

The GPS Occultation Geometry

Forward Propagation

Abel Inversion


Obtaining temperature and pressure from refractivity

Obtaining Temperature and Pressure From Refractivity


Gps met sounding comparison

GPS/MET sounding comparison

Dry GPS/MET

Dry GPS/MET


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中華衛星三號COSMIC計畫


Cosmic observational requirements

COSMIC Observational Requirements

Measurement Parameter

Requirement

Number of occultations

>3000 soundings/day

Distribution

Global

L1/L2 phase measurement

<1 mm

GPS phase sampling rate

0.1 –50 Hz

GPS vertical range neutral atmosphere

surface –60 km (50Hz sampling)

GPS vertical range ionosphere

90 – 800 km (10Hz sampling)

TBB (Tri-Band Beacon) phase measurement

< 32 mm @ 150 MHz (ground receiver)

TBB sampling rate

> 50 Hz (ground receiver)

TIP (Tiny Ionosphere Photometer) measurement

< 10% (uncertainty in photon count)

TIP footprint

125 x 25 km (at 300 km height of F2 layer)

TIP resolution

0.1 – 10 sec averaging

Magnetometer

10 nT precision, 500 nT accuracy

COSMIC Observational Requirements


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  • 6 LEO satellites provide 2500~3000 measurements daily.

  • It will offer up to about 100 soundings in a regional model domain for a 6-h assimilation time window.


Rocsat 3 formosat 3 cosmic mission

ROCSAT-3 (FORMOSAT-3)/COSMICMission

  • The mission offers a unique opportunity for Taiwan to be an international leader in the application of a revolutionary remote sensing technique that will have tremendous impact on atmosphere and ionosphere sciences and meteorological applications.

  • Comments by International COSMIC Science Review Team, December, 2005


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結束

謝謝!


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