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www.TELE-satellite.com —
06-07-08/2012 —
TELE-satellite International —
全球发行量最大的数字电视杂志
able to really receive satellites between
the Hispasat 30 degrees west (azimuth
42.1 degrees west) and the Panam-Sat
45 degrees east (azimuth 32.9 degrees
east). Between these positions there are
approximately 20 satellites transmitting
more than 1500 free-to-air channels.
Next we have to perform all additional
calculations, even though not all might
be needed, depending on the make and
model of the antenna:
Inclination of the rotating axis towards
the north:
φ = 48,1 degrees against the horizon-
tal line
γ = 90 - φ = 90 – 48,1 = 41,9 against
the vertical line
Once all calculations are finished we
have to look for a suitable spot to install
the antenna. While perfect reception is
the number one focus we nonetheless
have to take into account other factors
such as a robust support for the antenna
mast (making it windproof and earth-
ing it) and any restrictions or limitations
that exist at the location. Of course all
regulations by local authorities must be
adhered to as well.
We recommend contracting a special-
ised company for installing the antenna
mast. This way you can make sure (i.e.
they must make sure) the mast can take
high wind loads and is protected against
damage from lightning. Authorised busi-
nesses can also be expected to know
local regulations and are responsible for
not breaking any rules.
Now that all queries are solved the next
step is buying the technical equipment. If
you’re not the tech-savvy kind feel free
to ask a specialist for assistance.
As far as assembly is concerned you
start out with the antenna support and
with adjusting the antenna according to
the calculated values with the help of the
existing marking on the support. Next,
the support is attached to the antenna
mast and the antenna itself with the
LNB is attached to the support. You then
need to connect a monitor or TV to the
antenna before you start rotating the
antenna until signals from a southern
satellite can be received. We recommend
Hotbird at 13 degrees east, as it almost
exactly (only 0.9 degrees deviation) cor-
responds to the geographic longitude of
Munich. To make sure you’re hooking to
the correct satellite it is paramount to
select a channel from that particular sat-
ellite. The following channel, for exam-
ple, can be used for Hotbird:
ZDF digital 11,054 GHz vertical
Symbol rate 27 500
SID 8011
Video PID 570
Audio PID 571
PCR PID 570
Please make a point in setting all
required parameters, as the same chan-
nel with the same name is also broad-
cast from ASTRA. Also make sure that
the marking for south on the antenna
support is adjusted precisely while the
complete construction is rotated on the
mast.
Once you can confirm reception of
Hotbird all that is left to do is tighten
the fixing screws before you can rotate
the antenna for the first time to its limit
stops, and check if the motor works sat-
isfactorily using a soft stop mechanism
that is available with most receiver types
and prevents the antenna from striking
any obstacle that might be in its way.
In case a satellite close to the limit
stops cannot be received or comes in
only weakly you can slightly bend the
antenna up or down to find out which of
the two scenarios shown in figure 10 you
are faced with. It is now that a less than
perfect installation of the antenna mast
shows its unwelcome consequences:
Fig. 10
a: The rotation axis is not enough to
the north
b: The rotations axis is too much to
the north
c: The mast leans towards the east
d: The mast leans towards the west
Mishaps like these can be rectified by
readjusting elevation and inclination of
the rotation axis – but always starting
from a southern direction.
Addendum
Compilation
λ = geographic longitude
φ = geographic latitude
ε = elevation towards south
δ = declination
ω = reception angle from the south
maximum no. of satellite positions
(azimuth):
towards west: λ - ω
towards east: λ + ω
inclination of the rotation axis towards
north:
against the horizontal level: φ
against the vertical level: γ = 90 – φ
radius of the earth = 6,371 km
orbit of the satellites = 42,160 km
Technical terms
Equator
(Latin)
:
balancer
Azimuth
(Arab)
:
angle between the meridian
of the location of observation and the vertical
circle of a heavenly body
Declination
(Latin)
:
deviation
DiSEqC
(acronym)
:
Digital Satellite Equipment
Control. Transmission of data via the antenna
cable by way of impulse controls using the 22
kHz tone. Developed by Philips and offering
almost endless options. Even return channels
can be implemented for more complex control
set-ups.
Elevation
(Latin)
:
heightening, increase
Geodetic system
(Gea = Greek: earth)
:
system
of imaginary lines covering the earth.
Horizon
(Greek)
:
skyline, horizontal level
Kepler:
Natural scientist 1571 – 1630. Kepler's
laws of planetary motion:
1. The
of every
is an
with the
sun at a
2. A
joining a planet and the sun sweeps out
equal areas during equal intervals of time.
3. The
of the
of a planet
is directly
to the
of the
of its orbit.
LNB
: Low Noise Block Converter (converter
positioned in the focal point of the parabolic
antenna and using an oscillator to convert the
satellite frequencies into 950 to 2150 MHz,
which then are transmitted to the receiver via
the antenna cable)
Meridian
(Latin)
:
length, longitudinal circle.
(0-meridian: longitudinal circle from the north
pole via Greenwich near London to the south
pole. Generally acknowledged as the zero
meridian since 1884).
Monitor
(Latin)
:
device for observing images,
video screen.
Polar
(Greek)
:
pivotal point; polar mount:
mounted in a pole-to-pole direction.
Polarisation
(Latin)
:
direction (of waves).
Satellite
(Latin)
:
companion.
Greek characters that have been used:
λ Lambda δ Delta
ω Omega π Pi
γ Gamma ε Epsilon μ My
φ Phi
Literature:
Prof. Dr. Hans Heinrich Voigt,
Göttingen university observatory „ Abriss der
Astronomie“ ("Abstract of Astronomy")