EARTH SEGMENT Rizvi College of Engineering Earth segment

EARTH SEGMENT

Rizvi College of Engineering Earth segment �Introduction �Receive-Only Home TV Systems �Outdoor Unit �Indoor Unit for Analog (FM) TV �Master Antenna TV System �Community Antenna TV System �Transmit-Receive Earth Stations Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Satellite Segments A satellite communications system can be broadly classified into 2 segments: � Space Segment: includes the sat. And ground facilities (TT&CCommand) tracking, telemetry & �Earth Segment: consists of the transmit and receive earth stations. Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Receive-Only Home TV systems �Planned broadcasting directly to home TV receivers (Direct Broadcast Satellite (DBS service). �Early, C-band (4 GHz), currently the Ku band: (12 GHz) �Large antennas (3 m diameter) were used with the C-band while smaller (<1 m diameter) are currently used with the Ku Band. Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Outdoor Unit • Consists of a receiving antenna feeding directly into a LNA/converter combination. • A parabolic reflector is generally used with the receiving horn mounted at the focus. Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Outdoor Unit • 12. 2 -12. 7 GHz 500 MHz 32 TV/FM with 24 MHz each. • A polarizer may be switched from the indoor unit for polarization interleaving (LHC/RHC or H/V polarization) Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Outdoor Unit • The horn feeds into the Low Noise Block (LNB) that contains an LNA+Converter. • LNB provides gain for the broadband 4/12 GHz signal then converts it to a lower frequency range so that a low -cost coaxial cable can be used as feeder to the indoor unit (950 -1450 MHz) Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Indoor Unit for analog FM/TV • 12. 2 -12. 7 GHz 500 MHz 32 TV/FM with 24 MHz each. • The selected channel is down-converted to an IF frequency (70 MHz) where the most gain is achieved Satellite Communication & (FM system rather than VSB). Prof. Nayna Dahatonde Networks

Rizvi College of Engineering Master Antenna TV System �A master antenna TV (MATV) system is used to provide reception of DBS TV/FM channels to a small group of users �It consists of a single outdoor unit (antenna and LNA/C) feeding a number of indoor units Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Master Antenna TV System Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Community Antenna TV System Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Community Antenna TV System �Instead of having a separate receiver for each user, all the carriers are demodulated in a common receiver-filter system �The channels are then combined into a standard multiplexed signal for transmission over cable to the subscribers Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Transmit-Receive Earth Stations �In some situations, a transmit-only station is required �For example, �in relaying TV signals to the remote TV receive-only stations � Transmit-receive stations provide both functions �Transmit-Receive ES provide TX/RX functions that are required for telecommunications traffic generally including network TV. Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Transmit-Receive Earth Stations Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Transmit-Receive Earth stations • Interconnection equipment is required for interconnecting the satellite station and terrestrial network. • MUX required for TX where a kind of reformatting is maintained. Here, Parallel IF stages are used. Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Transmit-Receive Earth stations • Next, Modulators are used for TX function • QPSK/QAM for digital and FM for analog systems • The Upconvertor is implemented to upconvert the IF (70 MHZ) to RF (6, 14 GHz) Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Transmit-Receive Earth stations • Next, carriers are combined and the resulting wideband signal is amplified and is fed to the antenna through the Diplexer, which allows simultaneous TX/RX operations • The ES antenna functions both TX and RX modes Satellite Communication & but at different frequencies (4/6, 12/14 GHz) Prof. Nayna Dahatonde Networks

Rizvi College of Engineering Traffic � Traffic can be broadly classified as �heavy route, �medium route, and �thin route. � In a thin-route circuit, a transponder channel (36 MHz) may be occupied by a number of single carriers, each associated with its own voice circuit. � This mode of operation is known as single carrier per channel (SCPC) � Antenna sizes range from 3. 6 m (11. 8 ft) for transportable stations up to 30 m (98. 4 ft) for a main terminal. Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Medium route �A medium-route circuit also provides multiple access, either on the basis of �frequency-division multiple access (FDMA) or �time-division multiple access (TDMA) �Antenna sizes range from 30 m (89. 4 ft) for a main station to 10 m (32. 8 ft) for a remote station. Satellite Communication & Networks Prof. Nayna Dahatonde

Rizvi College of Engineering Heavy route �In a 6/4 -GHz heavy-route system, �each satellite channel (bandwidth 36 MHz) is capable of carrying over 960 one-way voice circuits simultaneously or �a single-color analog TV signal with associated audio �Thus the transponder channel for a heavy- route circuit carries one large-bandwidth signal which may be TV or multiplexed telephony. �The antenna diameter for a heavy-route circuit is at least 30 m (98. 4 ft). Satellite Communication & Networks Prof. Nayna Dahatonde