1. COMMUNAL SATELLITE TV
In general terms, two Categories of
DISTRIBUTION NETWORKS
can be implemented:
RF. DISTRIBUTION (Radio Frequency)
IF. DISTRIBUTION (Intermediate Frequency)
2. Network Types
Two different ways of distribution in accordance with the used
frequency band:
Terrestrial Channels Reception
RF. Type
IF-PAL Transmodulation (SAT- Analogue)
QPSK-PAL Transmodulation (SAT - Digital)
QSPK to QAM Transmodulation
Distribution
Categories
IF. Type
Satellite IF/IF conversion (Freq. & Polarity)
DiSEqC control distribution (Multi-switcher)
3. RF. DISTRIBUTION
Advantages
All channels available at every outlet
The Looping between outlets is
allowed
Distribution network simplicity
Less cabels are required
Inconveniences
Limited frequency band
Limited number of channels
The terrestrial channels
reception quality is not good all
times.
H/E
5. Distribution Network/RF.
Practical Considerations Headend installation
*The most important element, always present in a communal
installation, is the amplification system.
*Head-end amplifier selection Inter-modulation and crossmodulation
Any interfering signal 47 dB below the video carrier will not affect to
the signal’s quality
*The amplifier output level at witch the interfering signal
reach the level above is called the maximum output level When using
broadband amplifiers the maximum output level is decreased as long
as the number of channels increases. Also it is very important to
perform a very good channel equalisation.
6. IF. Distribution System
Multible Cable Distribution Network System
Possible multiple-cable distribution layouts:
Stand alone multi-switchers (Villas)
Cascaded multi switchers (Buildings)
Tapped Star multi switchers
7. IF. Distribution System
Advantages
High number of channels can be
distributed
Implementation flexibility
Possibility of several
configurations
MSW
Inconveniences
MSW
MSW
4,8,12 or 16 coaxial
cables can be dropped
H/E
No through outlets
Wires consumption is very high.
Complicated installation
MSW
MSW
8. IF. Distribution System
SWITCHED STAR
Advantages
Easy installation in new buildings
All channels are available
Inconveniences
There must be a direct cable for
each outlet.
Cables drops of different length
are necessary.
To feed two outlets it is necessary
to use two separate cables
It is not possible to use
through outlets
Multi
Switch
