Satellite Technology n Assoc. Prof Dr Syed Idris Syed Hassan n School of Electrical and Electronic Eng n Universiti Sains Malaysia n Seri Iskandar, Perak

Concept Transponder Earth station (site A) Earth station(site B) IRRADIUM downlink uplink downlink uplink

Applications n Communication (truncking call) n Teleconference n Telemedicine n TV Broadcasting n Data communication n Telemetry(TEC, remote sensing etc) n Weather telecast n Navigation n GPS n Security/Calamity monitoring n Standard Time n military

Type of Satellites n LEO -Low Earth orbital ,000Km (90min to 12hrs orbiting the earth) n MEO - Medium Earth Orbital 16, ,000 Km ( hrs orbiting the earth) n GEO - Geosynchronous Earth Orbital - 36,000 Km ( The satellite appears to be stationary over one point on earth)

Look angle (Elevation) El

continue n Le = Earth station Latitude n le = Earth station longitude n Ls = Satellite latitude ( = 0 for GEO) n ls = Satellite longitude n rs = Satellite orbital radius ( ~ 36,000 km for GEO) n re = earth radius = 6370 km For GEO satellite

Looking angle(azimuth) n Consider for GEO only N S ES Sat E W 

continue n If Earth station is in the North Latitude, the azimuth will be as follow (refer to N) the azimuth will be as follow (refer to N)

continue n If the Earth station is in the South latitude, the azimuth will be (refer to N)

Example

Link budget Noise Power Budget for 54 MHz channel Boltzmann’s Constant= dBW/K/Hz Receiving system noise temp.= 28.5 dBK Receiving system noise temp.= 28.5 dBK Ku- Band ‘s channel bandwidth= 77.3 dB Ku- Band ‘s channel bandwidth= 77.3 dB Receiving noise level dB For C/N about 10 dB to allow rain and other fading the signal level should be dB For C/N about 10 dB to allow rain and other fading the signal level should be dB

continue

continue In decibel

Continue n Parabolic antenna diameter

Continue n MEASAT

continue n JCSAT

continue n Superbird C

Teleconference System Teleconference System LNA/HPATransceiver QPSK mod & demod CODEC 1.536Mbps TVmonitor IDU ODU

Data communication LNA/HPATransceiver QPSK mod & demod 1.536Mbps PC Router&Transciever IDUODU

Other factors need to consider n Antenna n Rain attenuation n Beam Footprint n Mismatch losses n Misalignment n Scintillation ~for low elevation n troposphere/atmosphere n Bit error rate

Rain attenuation 1% 0.1% 0.01% % of time exceedance mm/hr rain rate

Continue n For TV and broadcasting usually the reliability is not very critical, so 99% is okay and this equivalent to 1% of exceedance of time n For data other digital com the reliability of 99.99% is probably chosen and this is equivalent to 0.01% of exceedance of time.

continue For 99.99% reliability, the attenuation is calculated as where a and b are constants relied on frequency R 0.01 rain rate at 0.01% of exceedance of time L path is slant path where signal passed the rain

Slant path L path Rainheight~3km