Tiernan DBR3000, Installation And Operation Manual, Page: 20 / 74

Theory of Operation
Data
Output
Data
Output
Data
Output
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Hub RF
Tx
Data
Input
Figure 1.1
Satellite Data Distribution Network
The hub or satellite transmission uplink station is the facility where the data to be transmitted is collected and
uplinked to the satellite. This facility consists of a satellite modem, an earth station, an antenna and a network
control computer. As an option, an Ethernet link can provide diagnostics and performance monitoring of receiver
sites using Telnet.
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The satellite link consists of a commercial telecommunications satellite in geosynchronous orbit above the
earth. Two radio frequency bands that are primarily used are C-band and Ku-band.
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The third major subsystem, the remote satellite receiver, includes three major components:
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A satellite antenna subsystem
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An interfacility link cable
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A satellite data receiver such as the DBR
The satellite antenna and its associated Low Noise Block (LNB) downconverter collect and convert the signal
from the satellite's native C- or Ku-band signal to L-band.
A phase lock loop (PLL) type LNB must be used for all satellite links using the QPSK modulation. Satellite links
using BPSK modulation may use the lower cost dielectric resonance oscillator (DRO) type LNB.
The L-Band signal is then sent through the interfacility link (IFL) cable to the satellite receiver. The DBR data
receiver processes this signal and outputs the data serially using RS-422.
1.3 DBR Features
The DBR:
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Accommodates both Ku- or C-band in BPSK or QPSK mode
1-6 Tiernan DBR3000