satellite_communication.pdf

7/29/2019 satellite_communication.pdf

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Claudemir Stenico

Mr. Miles B. Jacobs

Department of

Electrical Engineering


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Employed a simplified data process system

with reduced complexities, low cost

satellite image reception and analysisfacility.

Weather satellites


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To acquire information and receive data from

weather satellite and to obtain pictures from

available satellites orbiting South Africa, using:

FT-847 (Yaesu)

PC (input soundcard)

WXSAT - WXTOIMG (program to process wav files)

AimsAims


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144.986 = 1695 MHz (UHF)

Polar-orbiters satellites - the IF bandwidth must be

wide enough to pass the entire signal waveform.

At least 40 - 50KHz

FT-847 30 KHz (max)

YAESU FT-847


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Bandwidth

The bandwidth requirement is influenced bytwo factors: the satellite transmitter deviation

and the Doppler effect.

NOAA platforms have a signal deviation ofabout 17 KHz. Adding a Doppler shift of +-

4,5 KHz at the time of closest approach.


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ResultsFrom geostationary satellitescentral Africa (VIS)


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Decoding through the Software

WXSAT

Set up

interface


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1 channel2 channels

Decoding through the Software

South America (IR)


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Flow signal diagram

Due to the large amount of data, the loweststandard sampling frequency that fulfils theNyquist criteria the soundcard must have fixed

sampling frequency (11025 kHz)


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Decoding aspects

1 channel 2 channels

Eastern Africa (VIS)


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Wxtoimg

Interface

Decoder Software


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Meteosat operations are affected for the two eclipse periods

each year when the satellite undergoes an eclipse of the sunby the Earth. The two periods occur at the equinoxes.

During the actual eclipse, certain satellite functions,including earth imaging and all dissemination services are

interrupted in order to save power.

Eclipse!!!


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METEOSAT 7

An eclipse of the sun

occurs when the satellite

passes into the conical

shadow region of the

earth or of the moon.

(2004, 20 Oct).


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Colour enhanced for the Globe


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Southern Hemisphere

South Africa


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The future

During ten years (2000-

2009), there will be a

transition of the present

low-resolution satellite

service called APT andWEFAX to LRPT &

LRTI, a digital system.

Everything must still beimproved.


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Thank you!! Questions??

Documents

satellite_communication.pdf