Satellite Communication - Part 3 (Frequency Allocation)

Frequency Spectrum Allocation

As you can see the picture above, that the frequency spectrum that allocated in telecommunication. This post is focus only to frequency spectrum that used in satellite communication.

Intermediate Frequency (IF) Band

Mainly used in Satellite modem equipment in modulator and demodulator side.

Range of spectrum is around 70 MHz (50 MHz to 90 MHz)

L-Band

Also mainly used in Satellite modem equipment in modulator and demodulator side.

Range of spectrum is 950 MHz to 2150 MHz

C-Band

Primary used in satellite communication for frequency used communication between ground segmen and the satelllite. For this range of spectrum, Uplink frequency (from ground segment to satellite) is around 6 GHz and Downlink frequency (from satellite to ground segment) is around 4 GHz.

Ku-Band

Used in satellite communication for frequency used communication between ground segmen and the satelllite too. For this range of spectrum, Uplink frequency (from ground segment to satellite) is around 14 GHz and Downlink frequency (from satellite to ground segment) is around 12GHz.

Ka-Band

New option in satellite communication spectrum frequency. In this Frequency, Uplink frequency is 30 GHz and Downlink frequency is 28 GHz.

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Satellite Communication : Transmission Bands

A satellite link is a radio link between a transmitting earth station and receiving earth station through a communications satellite. A satellite link consists of one uplink and one downlink; the satellite electronics (i.e., the transponder) will remap the uplink frequency to the downlink frequency. The transmission channel of a satellite system is a radio channel using a direct-wave approach, operating in at specific RF bands within the overall electromagnetic spectrum as seen below : The table below shown some key of physical parameters of relevance to satellite communication, The frequency of operation is in the super high frequency (SHF) range (3-30 GHz). Regulation and practice dictate the frequency of operation, the channel bandwidth, and the bandwidth of the subchannels within the larger channel. Different frequencies are used for the uplink and for the downlink. Frequencies above about 30 MHz can pass through the ionosphere and

Satellite Communication - Part 4 (CPI)

Cross Polar Isolation (CPI) In installation and pointing/peaking antenna, Orthogonal Mode Transducer (OMT) must be set to be as precise as possible to get the best CPI value. above is picture of OMT Feed assembly include with BUC and LNB The minimum value for CPI is 30 dB (better will be good) in Linier Polarized Antennas. The reason is for our receive (Rx)-side as not to get interferenced (distrubed) by other (polarity) Down-Link users, therefore our transmit (Tx) shoild as well not interfere other users that operates at 90 deg (Orthogonal) Polarization. Note : In LH/RH Circular Polarizations, usually CPI of 27dB (=AR of 1.09) is acceptable enough. picture above is careless/miss-aligned OMT setting

Satellite Communication - Part 1

In this occasion, i want to share about Satellite communication. First, please look at the picture below, Planets of our Solar System God created Moon as our Earth satellite. In order to broading our communication, people tend to use artificial satellite for communication. Based on orbits, these are the type of satellites : Low Earth Orbit (LEO) Height : 750-2500 Km, Period : 2 - 2.5 hours Medium Earth Orbit (MEO) Height : 7500-10000 Km, Period : 4.5 - 6 hours High Earth Orbit (HEO) Height : 15000-20000 Km, Period : 11-12 hours Geo-Stationary Orbit (GSO) Height : 36000 Km, Period : 24 hours Incline Orbit Satellite (drifting > 0.1 deg. N-S and E-W) Polar (mostly very eliptical) orbit satellite "in this purpose of satellite communication, I will focus in Geo-Stationary Orbit (GSO)" If we talk about GSO, we must mention this name, Arthur C. Clarke, a Science-Fictionist, which wrote : "a Satellite

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