Satellite Terminology

TDMA:

TDMA technology, which stands for Time Division Multiple Access. Time Division Multiple Access or TDMA is a method used to enable multiple earth stations or VSAT terminals to transmit intermittently on the same frequency, but with the timing of their transmissions so arranged that the bursts do not overlay when they arrive at the satellite but arrive in sequence and thus are all successfully received by the teleport hub modem burst demodulator.

SCPC:

SCPC stands for Single Channel Per Carrier. SCPC is a form of satellite transmission where each channel is transmitted on a dedicated single carrier.Single channel per carrier (SCPC) refers to using a single signal at a given frequency and bandwidth. In an SCPC system, satellite bandwidth is dedicated to a single source.

Carrier –in-Carrier:

Both carriers are in a directly looped back transponder, i.e. both earth station sites are in the same beam.  Each site must be able to see its own transmit carrier, as well as the received carrier from the other site. It works best with two carriers of the same size. i.e. similar bandwidth in each direction.

DVB-S2 Technology:

DVB-S2 CCM (Constant Coding and Modulation)

A DVB-S2 CCM Uplink Signal Must be dimensioned according to the smallest receiving station  and highest possible signal fading, to ensure adequate signal availability in all receiving stations.

DVB-S2 ACM (Adaptive Coding and Modulation)

In Adaptive coding & modulation mode, the modulation parameters of the baseband frames can vary over time, according to instantaneous receiving condition of site where the frame will be received.

DVB-S2 VCM (Variable Coding and Modulation)

Variable coding and Modulation is a mode of operation that allows different modulation parameters to be applied to the different DVB-S2 Stream of a Multistream Signal.

C Band:  

The uplink frequencies ranged from 5.9 to 6.4 GHz. The downlink frequencies ranged from 3.7 to 4.2 GHz. The EIRP is limited to a level so that there is no interference from the satellite with the terrestrial system. Also, the locations of the uplink earth-stations need to be restricted to prevent interference with terrestrial microwave communication systems.

 

Ku-band:

 

The downlink frequencies are 11.7 to 12.7 GHz, and the uplink frequencies are 14.0 to 14.5 GHz.

The Ku-band frequency region allows increased EIRP levels from the satellite and significantly smaller earth-station antennas for the same gain and beamwidth as the C-band antennas. Also, Ku-band uplinks can operate from any location and can be highly mobile.

 

 

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