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Graduation Project developed at Cape Peninsula University of Technology in 2004 entitled: "Satellite Communication - Weather Satellite Image Download System", a low-cost system for communicating with satellites weather, which consists of an FM receiver and a PC, enabling receiving signals propagated through space, decoding the signals and displaying the captured images of the planet and its atmosphere.
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Claudemir StenicoClaudemir Stenico
Mr. Miles B. JacobsMr. Miles B. Jacobs
Department ofDepartment of
Electrical EngineeringElectrical Engineering
Employed a simplified data process system Employed a simplified data process system with reduced complexities, low cost with reduced complexities, low cost satellite image reception and analysis satellite image reception and analysis facility.facility.
Weather satellitesWeather satellites
To acquire information and receive To acquire information and receive data data from from weather satellite weather satellite and and to obtain pictures from to obtain pictures from available satellites orbiting South Africa, using:available satellites orbiting South Africa, using:
• FT-847 (Yaesu) FT-847 (Yaesu) • PC (input soundcard)PC (input soundcard)• WXSAT - WXTOIMG (program to process wav files) WXSAT - WXTOIMG (program to process wav files)
AimsAimsAimsAims
144.986 = 1695 MHz (UHF)144.986 = 1695 MHz (UHF)
Polar-orbiters satellites - the IF bandwidth must be wide enough Polar-orbiters satellites - the IF bandwidth must be wide enough to pass the entire signal waveform.to pass the entire signal waveform.
At least 40 - 50KHz At least 40 - 50KHz
FT-847 – 30 KHz (max)FT-847 – 30 KHz (max)
YAESU – FT-847YAESU – FT-847
BandwidthBandwidth
The bandwidth requirement is influenced by The bandwidth requirement is influenced by two factors: the satellite transmitter deviation two factors: the satellite transmitter deviation and the Doppler effect. and the Doppler effect.
NOAA platforms have a signal deviation of NOAA platforms have a signal deviation of about 17 KHz. Adding a Doppler shift of +- about 17 KHz. Adding a Doppler shift of +- 4,5 KHz at the time of closest approach.4,5 KHz at the time of closest approach.
ResultsResults From geostationary satellites From geostationary satellites
central Africa (VIS)central Africa (VIS)
Decoding through the SoftwareDecoding through the Software
WXSATWXSAT
Set up Set up interfaceinterface
1 channel1 channel 2 channels2 channels
Decoding through the SoftwareDecoding through the Software
South America (IR)South America (IR)
Flow signal diagram
Due to the large amount of data, the lowest standard sampling frequency that fulfils the Nyquist criteria the soundcard must have fixed sampling frequency (11025 kHz)
Decoding aspects Decoding aspects
1 channel1 channel 2 channels2 channels
Eastern Africa Eastern Africa (VIS)(VIS)
Wxtoimg
Interface
Decoder Software
Meteosat operations are affected for the two eclipse periods each year when the satellite undergoes an eclipse of the sun by 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!!!Eclipse!!!
METEOSAT 7METEOSAT 7
An eclipse of the sun An eclipse of the sun occurs when the satellite occurs when the satellite passes into the conical passes into the conical shadow region of the shadow region of the earth or of the moon.earth or of the moon.
(2004, 20 Oct).(2004, 20 Oct).
Colour enhanced for the GlobeColour enhanced for the Globe
Southern HemisphereSouthern Hemisphere
South AfricaSouth Africa
The futureThe future
During ten years (2000-During ten years (2000-2009), there will be a 2009), there will be a transition of the present transition of the present low-resolution satellite low-resolution satellite service called APT and service called APT and WEFAX to LRPT & WEFAX to LRPT & LRTI, a digital system. LRTI, a digital system.
Everything must still be Everything must still be improved.improved.
Thank you!!Thank you!! Questions??Questions??