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www.TELE-satellite.com
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1 -12/2012
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TELE-satellite International —
全球发行量最大的数字电视杂志
SAMSUNG
HT-DL100
DSR 9400 FTA
PS-42 P2S
D
igital satellite receivers deliver first class video yet some of this
quality is lost when viewed with a standard TV. The same can be
said for a digital audio output. It wants nothing more than to be
linkedwithaDolbySurround system thathasadigitalaudio input (opti-
cal or electrical). Why shouldn’t you simply set up a Dolby Digital Movie
Theater in your home? Samsung has put together a package for us to
test thatwoulddo the jobperfectly.
Plasma Display PS-42 P2S
At 32Kg (70 Lbs) youmight need a little help lifting the plasma display onto a
stand or installing it on the included wall mount. But this is what you get with a
107
cm (42”) picture in 16:9 format.
On the back of the display, two different video sources can be connected via
theScart jack, theRCA jacks or theS-VHS connector. In our tests these sources
wereof courseadigital satellite receiver (SamsungDSR-9400FTA)and thevideo
output of theHome TheaterHT-DL100.But a PC also has its place on this plasma
monitor (D-sub 15). A better display for the Internet or for Flight Simulator you
couldhardlyfind.Twoadditionalaudioinputsforanalogstereoarealsoprovided.
The two speakers that hang on either side of the display are connected to the
built-in amplifier (2 x 7 Watts) via a set of quick clamps. Fortunately, you don’t
have to be too concerned about this limited power output since the audio can
also be routed to the Dolby Surround system from which also comes DVD, CD
and radio tuner audio.Once you haveworked through all the different on-screen
menus, then, with a resolution of 852x480 and a contrast ratio of 700:1, it will
really feel like a movie theater.
Pleasing to the Eyes and Ears
SAMSUNG
DSR 9400 FTA,
Plasma Screen and
Home Theater System
enclosed by a contour line, modern communication satel-
lites use shaped reflector antennas. Figure 3 shows the
coverage area of JSAT-110 outlined with a 57dBW EIRP con-
tour line at the edge of coverage, corresponding to a power
flux density of –105.1 dBW/m-2.
Given that a simple paraboloidal reflector antenna would
focus the electromagnetic energy on a regular (circular
or elliptical) region on the surface of the Earth, the idea
behind a shaped reflector antenna is that by deforming the
reflector surface it is possible to adjust the antenna pattern
to fit the desired service area. This is similar to illuminat-
ing a distorted mirror to produce a distorted reflection. All
EUTELSAT HotBird satellites use a 2.3-meter dual gridded
shaped reflector antenna system. Figure 4 shows a dual
gridded shaped reflector antenna: perpendicular laser-
etched embedded grids on the Kevlar surface allow for the
use of two reflectors, one behind the other. Depending on
the polarization, either the front or back reflector can be
used for transmission or reception.
However, even the most carefully constructed surface is
not perfect: the electromagnetic energy that is incident on
the reflector is subject to diffraction, which happens pri-
marily at the edges of the reflector. The diffracted waves
may interact with the focused waves or even diverge away
from the intended coverage area. As the diffracted waves
travel away from the reflector antenna, they interfere with
each other producing arbitrary regions on Earth where the
electromagnetic energy is stronger and others where signal
is unusable. This phenomenon can be understood if you
imagine radio waves turning away from their path as the
electromagnetic energy from the feed hits the edge of the
reflector. Figure 5 shows a diffracted photograph image:
spreading of light as they pass thought the camera aper-
ture. Although diffraction decreases at higher frequencies,
it can account for out-of-footprint reception of analogue
Ku-band signals. Digital signals are more difficult to receive
because modulation schemes based on amplitude and
phase encoding are very sensitive to increases in the bit-
error-rate resulting from depolarization of electromagnetic
energy. It is very difficult to predict where a combination
of overspill and diffraction of electromagnetic energy could
allow for out-of-footprint reception. That would depend on
the area of the intended coverage region, orbital location of
the satellite and the characteristics of the satellite anten-
nas, including the shape of the reflector.
Readers may wish to program their satellite receivers
and scan for unintended programming in their area.
8
m dish in Brazil to receive ASTRA from Europe