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Satellite TV Primer
Remember BUDs? Those were great. So great I have three
them! Maybe you've got an old BUD, or Primestar dish, or Super Dish and
you're wondering if there's anything you can do with it. The analog
receivers originally used with BUDs are (nearly) worthless today,
Primestar receivers are worthless,
and Dish Network no longer uses the 105° FSS orbital location, but
what about the antennas themselves, is there anything you can still do
with those? Fortunately, there is.
Types of Antennas and Bands
First you have to know what kind of dish you have. There
two common bands used for satellite broadcasting, C-band from 3.7-4.2
GHz and Ku-band from 11.7-12.2 GHz. C-band antennas, coloquially
referred to as BUD, big-ugly-dishes, etc... are usually 2M in diameter
or larger. Most common C-band dishes are prime focus antennas, with a
reflector made from fiberglass or aluminum mesh. Motorized dishes were
used to receive programming from more than one satellite by using an
linear electric jack powered by the receiver to physically move the
dish. Such dishes are mounted on a polar mount, which is aligned
exactly with the earth's poles. C-band antennas made from 1988 onwards
are usually also capable of receiving Ku band if fitted with the proper
type of feed.
Ku band antennas are usually relatively small - 1M
antennas are common, but they can be larger. These are made of
fiberglass for higher end models or pressed steel for the cheaper ones.
Ku band antennas are usually offset
prime focus antennas, which are more efficient for smaller
diameter reflectors because the feedhorn and LNB aren't in the signal
path. The smallest size generally considered acceptable is 75cm for a
round dish. Primestar and Super Dish antennas are both examples of
excellent Ku band antennas; for advice on adapting those for other
purposes, see my articles on the subject.
Uses for Old Receivers
So, if you can't use the old receivers, what can you
Well, I never said all of the old receivers were useless. The
subscription channels may be gone, but the old analog and Digicipher
receivers are still useful for bringing in feeds - news staions, radio
stations and others send each other video and audio over both C and Ku
band in these formats. Sometimes it takes a while to find them, though,
since by definition a feed isn't broadcasting all the time.
The most common type of new receiver is the DVB
is an international standard for digital
video broadcasting used extensively all
over the world for satellite broadcasting, and most of the world (ex;
everywhere but the US) for terrestrial and cable transmission.
DVB-S uses MPEG II video encoding, MPEG I layer 2 audio coding, and
QPSK (2 bits per symbol) modulation. The newer DVB-S2 specification
uses MPEG IV video and audio coding and (usually) 8PSK (3 bits ber
New DVB receivers cost between $60 or so for basic
the way up to about $300 for super fancy models with all the fruit.
DVRs, HD, SD, stuff with integrated terrestrial tuners, internet
streaming, wifi, are all great features you can get with these
receivers. The best part is that they work with pretty much all
existing C and Ku band equipment.
DVB programs can be unencrypted "free-to-air", or
with one of a variety of encryption algorithms: Nagravision (used with
Dish Network), Cryptoworks, Iredto, Betacrypt, and Conax CAS. The best
encryption for DVB streams is BISS, which is a free, open, standardized
system not owned by any particular company. The worst is PowerVu, which
is proprietary, obscenely expensive, and the exclusive property of
Scientific Atlanta, which doesn't technically exist anymore.
Because everyone involved with the US pay-TV industry is
retarded and evil PowerVu is the dominant form
of encryption used here. As far as I know, there aren't any IRDs meant
for consumer use that use PowerVu, although you could buy a commercial
receiver like the D9223, but I don't think there's any way to get it
authorized right now. For this reason I and many others are actively
lobbying for the retirement of the ugly mess that is PowerVu for good
in favor of anything else.
The better DVB receivers have a PCMCIA slot, called a
Common Interface that allows the receiver to accept a CAM (conditional
access module) to be used for whatever encryption system you need.
These aren't much use in US yet (see; retarded, evil) but are used
extensively around the world for pay-TV service.
Adapting "polarotor" type feedhorns for use with modern
Unfortunately, most new receivers don't have provisions
dealing with the 5V servo motors used on older C-band feedhorns for
switching between polarities - which means as is you'll only be getting
half of the transponders available on any particular satellite. There
are a number of ways around this. The easiest is probably to replace
your old feed with a 13/18V switched dual polarity C-band LNBF like the
DMS International BSC-421. The highest performance option requires two
LNBs: get an ortho-mode-transducer or dual feed which has two LNB
ports, one for each polarization and combine them with a regular old
multiswitch. A third, and possibly the coolest option is to track down
an automatic polarizer, which takes the 13/18V your receiver uses to
select polarity and moves the servo motor accordingly.
Adapting positioner motors to modern receivers
Modern receivers can't power the older motorized dishes
their own, but you can get a little device like the V-box which takes
the digital commands issued by your receiver and moves the actuator on
your dish accordingly. Most receivers will let you program in the
position of dozens of satellites, and will move the dish to the right
satellite automatically when you change channels.
Combining multiple dishes onto one cable
There are a two different options for remotely switching
between different antennas. A 22kHz "tone burst" switch has two inputs
and one output: the output is connected to one input normally and
switches to the other input when your receiver sends a 22kHz tone down
the line. If you have more than two different feeds, you can use a
DiSEqC switch, which can have up to 16 inputs.
Receiving multiple satellites with a single dish
If you don't have a motor, but you'd still like to
programming from more than one satellite you can get a multi LNB
bracket. These wild looking assortments of clamps, brackets and tubes
allow you to mount extra LNBFs over your dish's reflector in various
positions. This is a good option for two to five satellites that are
all within 20° or so of each other, but impractical for larger
Keep in mind that your antenna's reflector is a mirror,
position of the LNBFs will be backwards from their position in the sky.
For example, the lowest satellite on the left will be picked up by the
highest LNBF on the right side of the dish. The larger the dish, the
greater the spacing between the LNBFs will be.