Satellite TV Distribution and Headend Equipment
Satellite TV Distribution: An Overview
Individual vs. Collective Systems
Individual Distribution (FI):
This system distributes all satellite channels to each user via a satellite receiver (IRD). It allows users to select the channels they want to watch.
Collective Distribution (FI):
This system uses shared components like headend amplifiers and multiswitches to distribute signals to multiple users. It’s more cost-effective for larger communities.
Types of Collective Distribution:
- Single Polarity Distribution: Distributes signals from a single satellite or polarity.
- Multi-Polarity Distribution: Distributes signals from two or more satellites or polarities.
Components of a Single Polarity Distribution System:
- Amplifiers: Boost signal strength.
- Splitters: Divide the signal into multiple paths.
- Line Amplifiers: Compensate for signal loss in long cable runs.
- Combiners: Combine signals from different sources.
- Drifters: Shift the frequency of a channel.
Components of a Multi-Polarity Distribution System:
- FI Processors: Manage and manipulate satellite channels.
- Amplifiers: Boost signal strength.
- Switched Splitters (H/V): Route signals based on polarity.
- H/V Switches: Select between horizontal and vertical polarity signals.
- Splitters: Divide the signal into multiple paths.
Using a Single Cable for MATV and Satellite Signals
A single drop cable can be used to distribute both MATV and satellite signals. This requires the use of processors and filters to manage the different frequencies.
FI Processors: Optimizing Bandwidth
FI processors allow you to maximize bandwidth usage by converting satellite channels from one frequency to another within the same band. This enables you to select and manage the channels you want to distribute.
Key Features of FI Processors:
- Agility: Ability to adapt to various satellite channels.
- LNB Powering: Ability to power the LNB directly.
- Low Phase Noise: Ensures high-quality digital TV reception.
- Conversion Flexibility: Ability to convert channels without limitations.
- Low Spurious Emissions: Prevents interference with other signals.
Choosing the Right FI Processor:
Consider factors like input and output frequency range, channel bandwidth, noise figure, input level, LNB power, conversion limitations, phase noise, and spurious emissions.
Understanding Key Terms
- Spurious: Signals that are unwanted or degenerate in nature.
- Galibo (Gauge): A template used to define the maximum dimensions of an object.
- Agile: Refers to a device that can be tuned or adjusted on-site.
Amplifiers: Boosting Signal Strength
Key Amplifier Features:
- Frequency Range: Should cover the satellite IF band (950-2150 MHz).
- Noise Figure: Measures the amount of noise added by the amplifier.
- Equalization (EQ): Compensates for signal loss at different frequencies.
- Maximum Output Voltage: Determines the amplifier’s ability to handle multiple channels.
Types of Amplifiers:
- Broadband Amplifiers: Amplify both terrestrial and satellite signals.
- Dual Satellite Amplifiers: Feature separate amplifiers for each satellite band.
- Equalizer Amplifiers: Include equalization for terrestrial channels and amplification for the satellite IF band.
- Satellite Band Amplifiers: Amplify only the satellite IF band.
Other Essential Components
Combiners:
Combine terrestrial and satellite TV signals onto a single cable.
Switched Splitters (M/V):
Mix and distribute terrestrial TV signals and signals with vertical and horizontal polarity.
H/V Switches:
Select between horizontal and vertical polarity signals.
Transmodulation: Converting Signal Formats
Pooled Transmodulation Facilities:
Use headend receivers to demodulate satellite channels and distribute them as analog signals, eliminating the need for individual receivers in each home.
Types of Transmodulators:
- QPSK-QAM Transmodulators: Convert QPSK satellite signals to QAM for efficient spectrum usage.
- Analog-Analog (FM-PAL) Transmodulators: Demodulate and remodulate analog signals.
- Digital-Analog (QPSK-PAL) Transmodulators: Demodulate digital QPSK signals and convert them to analog PAL.
Designing TV Reception Facilities
Amplifier Selection:
Choose amplifiers based on output voltage, noise figure, configuration options, and signal loss characteristics.
Terrestrial TV Reception:
Consider using broadband amplifiers or specialized amplifiers for terrestrial signals.