|
|
 |
Knowledge Is Key
For Intelligent Decisions
Satellite Logic is a leading,
authoritative source of information in
the Satellite Industry. Located in the
heart of the Silicon Valley, Satellite
Logic provides one of the most
valuable and comprehensive
knowledge bases on the Satellite
market! This is a primary Worldwide
information center which enables our
clients to analyze, evaluate, inquire
and select their best tailored
solutions. Our company sets the
industry standards for targeted
buying leads, reflecting a dramatic
advance over traditional marketing
solutions.
|
|
|
 |
Satellite radio receivers are the component that connects between
the satellite broadcast and the listeners. In other words, the
component that connects your ears to the satellites. They are
present of course in each satellite radio and consist the main
difference between the conventional AM FM radios and the new,
innovative satellite radios.
Unlike the conventional radio systems which can receive clear signal
over 65km, on satellite radios the range typically extends beyond
30,000km. Over such distances, satellite radio signals are received
with complete clarity and fidelity and apart from the remarkable
absence of interfering static.
Satellite radio infrastructure necessarily includes broadcast studios,
from where signals are transmitted to the satellites. Such studios are
invariably acoustically isolated rooms, because the 90db dynamic
range (compared with the 40db-50db values for FM) of the digital
satellite radio, implies that the softest background noise can
constitute an unwanted interference signal. Consequently, one
primary objective of studio design in this case is to reduce
transmission loss or SPL - the intensity of an audio signal as it
propagates through a physical acoustic barrier. This is achieved with
the use of a wall that is simultaneously massive and highly damped.
In the broadcast studio, the satellite signal is first recorded on a
storage medium, using a special format. Then it is encoded at a high
rate in order to preserve quality without having to sacrifice drive
space efficiency requirements. During the encoding process, each
format is sent to an encoder which converts the analog to digital,
and produces a real-time digital stream of 0s and 1s. Signals from
the various encoders are forwarded to a multiplexer, which typically
has the ability to multiplex 80 channels, including classical opera,
sports and disco music channels, among several others. The
multiplexed signals constitute the massive digital stream that is
transmitted to a satellite modem device, where it modulates a
radiofrequency carrier.
Today there are three main satellite radio providers - XM, Sirius and
WorldSpace. The broadcasting satellites are fed by radio ground
stations and they, in turn, retransmit to radio receivers located on
Earth. Because the signals are scrambled, satellite radio receivers
are programmed to unscramble received digital audio signals
containing up to 100 channels and including such information about
the broadcast as song title, name of artist and music genre, which
items of information are displayed by the receiver. In urban locations,
where obstacles such as high-rise buildings block satellite signals,
the XM broadcast network is supplemented by ground-based
repeater stations, each of which is equipped with a proprietary chip
set.
XM Radio and Sirius don't make their own receivers, they use various
manufacturers such as Delphi, Pioneer, and Audiovox make receivers.
Unfortunately, these receivers are not compatible with both services,
so that you'll need to choose an XM compatible receiver or Sirius
compatible receiver depending on the service you subscribed to.
There's no reason why receivers could not pick up both sets of
signals, but there's probably no commercial reason to make such a
receiver. Almost no-one would choose to subscribe to both services,
and it is unlikely that either radio service would actively cooperate
with receiver manufacturers. Some car manufacturers have a satellite
receiver available with their cars, either included as standard or
offered as an option. Choosing this option means that you'll have to
accept the manufacturer's choice of the service provider, which may
or may not be the service you'd choose yourself.
At present the differences between the receivers aren't too
significant. When choosing a receiver, there are several things to
consider, like look and feel, unit size and display. Usually listeners
prefer a unit that is attractive and easy to use, especially if used it
while driving. A display that is sufficiently bright and easy to read is
also an important consideration. Displays with three or more lines are
able to show your more data at the same time.
Also, you'd probably choose a receiver with a layout you can
intuitively understand, and buttons that are easy to find and push.
You don't want to take your eyes off the road while driving and hunt
around a tiny control console to find the button you need.
The unit's size is of high importance either. Although these units are
small, they still do take up an appreciable amount of dashboard
space, especially if they need extra space for a mounting cradle. In
general, the smaller the unit, the easier it can be installed.
Although the smaller the unit, the better, the display is the other way
around. The larger the display, the easier it is to read what is shown
on the display, and the more information that can be displayed. So
your challenge is to choose a small unit with a large display. Get a
small unit with a large proportion of the panel used by the display,
this is probably the best compromise between overall size and
display size.
Make sure you can dim the display sufficiently for night driving. Some
units allow you to change the color of the display lighting, and most
units allow you to change the brightness and contrast, but at least
one popular model remains way too bright, even on its dimmest
setting, for night driving.
Finally, be sure to cost out and compare the total system you need,
not just the simple receiver unit by itself. If there's some other
special need you have, make sure the unit you choose can handle
that, too.
|
|
|
|
