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Data compression/MPEG1/MPEG2:
The current television standard (625 lines and 50 Hz picture
repeat frequency) provides a digital data volume of 216
MBit/s.
This would require bandwidths simply not available either ter-
restrially or via satellite. The data volume is thus reduced by
means of a data reduction system. For Europe, the internatio-
nally determined standard for data compression is MPEG-2.
MPEG-2 is an expanded version of MPEG-1
DiSEqC:
Digital Satellite Equipment Control: a digital control signal
used to control and switch DiSEqC compatible components
of the external installation via the antenna cable. An example
of how an installation consisting of DiSEqC components can
be configured is shown in (Fig. 10-1).
DVB:
Digital Video Broadcasting: A universal digital transmission
technology used to transmit pictures, graphics, sound and
text, as well as for data in every conceivable form and in
every possible, appropriate quality.
Frequency:
A physical unit of measurement, indicates the number of
oscillations per second, the unit of measurement is Hertz
(Hz)
Frequency range:
a) Satellite respectively LNC:
11 GHz range from 10,70 GHz - 11,70 GHz, 12 GHz range
from 11,70 GHz - 12,75 GHz
b) Receiver: interim frequency or 1.IF 950 tp 2150 MHz
Unit Name Oscillations per second
1 Hz 1 Hertz 1
1 kHz 1 Kilohertz 1.000
1 MHz 1 Megahertz 1.000.000
1 GHz 1 Gigahertz 1.000.000.000
Co-axial cable:
Connection cable between LNC and satellite receiver, used
to transmit the signals received and to supply power to the
LNC.
LNB/LNC (Low Noise block converter):
Reception unit located at the focal point of the parabolic dish
antenna. Converts the frequency range of the satellite to that
of the interim frequency of the digital receiver.
LOF:
Local oscillator frequency; stated in MHz or GHz; varies
depending on the LNC and the frequency range
Reception frequency of the digital receiver = Broadcasting
frequency of the satellite - LOF
22 KHz modulation:
This can be used to switch between 2 LNCs, in addition to
14/28 Volt switching. In Universal LNCs it serves to switch to
63
(Fig. 9-9)
(Fig. 9-8)
(Fig. 9-6)
(Fig. 9-7)
(Fig. 9-5)
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