Large Dish Satellite TV

DETAILS: ELEMENTS OF THE LARGE DISH SYSTEM

THE ANTENNA REFLECTOR DISH

The size of the dish and its adjustments are very important because the signals coming from the ordinary communications satellites are weak compared to the signals used in small dish satellite TV. However, with the proper adjustments and components it is possible to reproduce a flawless analog picture and digital stereo sound.

If the next program to be received is carried by a different satellite the actuator must be able to move the antenna accurately to the new position where the program can be received. It is very important that the dish is accurately aimed to get the strongest possible signal.

The majority of actuators are of the DC electric motor/screw jack type with a ball joint or "acme" type thread arrangement which changes the direction of motion so that actuator provides linear (straight line push or pull) motion to the dish. The push or pull is exerted at a point several inches off center from the dish pivot point so the dish is easily moved.

The actuator extends or retracts as needed to position the dish. After the proper position is reached the dish is held stationary until it is must be moved to point the dish at another satellite.

The signals from the downlink transponders are polarized either vertically or horizontally and the feedhorn must have a means to discern between these two. Most feedhorns are equipped to do this by means of a movable probe controlled by a small electric motor. Others manage this electronically.

The Low Noise Amplifier amplifies the signals gathered by the feedhorn. It is called "low noise" because it is designed to amplify the desired signals while injecting very little self induced noise. The quality of a LNA is expressed in degrees Kelvin which is a measure of self induced noise. In the early 1980's the best LNA's available were rated at 120°K. Now (1999) it is common to see "K" figures of 20° or 17°. The lower the "K" figure the better the LNA (and the better the TV picture).

The shielding and dielectric insulation are necessary to minimize the loss and pickup. Purchasing high quality coax is worth the extra cost because of the increase in signal quality and strength.

When programs which have not been scrambled are received the descrambler is not activated so the program material is processed unchanged into TV picture and sound elements by the receiver.

The signal is descrambled, if needed, by the descrambler and is then returned to the receiver circuits.

The receiver then converts the video and sound elements to signals which can be processed by the video monitor or TV and sound systems into picture and sound.

DETAILS: ADVANTAGES OF THE LARGE DISH SYSTEM

LESS EXPENSIVE PROGRAMMING

These channels include (1) the "NASA CONTRACT CHANNEL" which broadcasts all space shuttle flights from start to finish, (2) BET Jazz, a 24 hour all jazz channel and (3) several more shopping channels. The list goes on: (4) Religious programming, (5) wild feeds (network broadcasting which will run at a later date or time on the commercial TV networks), (6) the Knowledge Channel, (7) several channels of interest to persons who understand languages other than English (Spanish, German, French, Arabic, Japanese, etc.), etc. Most of these are free channels which are not scrambled.

(8) Several "Adult" (for pay) channels are available on large dish antenna systems in most states for those who like that sort of thing. They must have a large following judging from the number of channels available. There are at present six(6) X, XX, and XXX channels.

Add to these the Playboy Channel which plays mostly material rated R(MA) and usually called "hard R" which is intended for mature audiences because of strong sexual content. The Playboy Channel is available in all states since the program material is not as sexually explicit as on the X (XX) (XXX) rated channels.

It is not intended to imply that "Adult" channels are greatly to be desired. That's up to the individual TV viewer, but many more are available on large dish satellite TV than on the small dish systems.

With the small satellite dishes your only choice of programs are the ones tailored to the special hardware they are using. The small dish systems cannot pick up programming from any satellites other than the special designated high power ones. If you decide you want to change program providers you are stuck with an antenna and receiver which cannot receive programming from any other source than the one it was designed for. If you bought the hardware, tough luck. If you rent the hardware as on Primestar®, it will have to be changed out and new equipment installed before you can make a change.

Cable TV systems use receiving equipment similar to that of a large dish system to obtain TV programming. Then they use additional equipment to put the signals on their cable, provide for customer options such as tier considerations, premium services, etc.

Add to these factors many miles of cable and many repeater amplifiers, poles or underground cable runs, and connections to get the signals to the customers.

All this extra equipment is subject to failure or malfunction. In addition, surge damage from lightning and power failures anywhere in the system are elements which can cause system-wide outages.

Small dish satellite (DBS) systems operate in the KU band at extremely high frequencies. The wavelengths at these frequencies are so short that raindrops and other forms of precipitation can actually block portions of the signal causing outages.

DBS systems are also dependent on the processing center equipment which receives the same signals that a large dish system receives, processes them, and rebroadcasts them through an uplink antenna to a special DBS satellite. The TV signals are then rebroadcast once more from the DBS satellite to the small dish receivers. More equipment equals more probability for failures.

A large dish system is operational as long as electrical power is available. It is not dependent on power availability at a cable headend, cable strung for miles, repeaters, cable amplifiers, etc.

Neither is large dish satellite TV reception subject to rain outages, processing center equipment problems, etc.

With a large dish system, TV signals are received from several different satellites. If one satellite experiences a failure, as has happened on several different occasions, it does not mean a complete blackout of TV reception as it could if a DBS satellite fails. Even with available backup equipment in place, such a failure of a DBS satellite could cause a signal blackout for several minutes or hours.

There are many channels available which are not carried on cable except in the largest markets. Some are privately or group owned such as Dr. Gene Scott's network. Others are publicly owned like the NASA Select Channel. Some of the privately or group owned channels, like Dr. Scott's, are dedicated to religious programs. Others are promotional channels for various purposes. The NASA channel is dedicated to space exploration and science.

There are "wild feeds" and "backhaul feeds" where one can actually see some of the production work behind various network TV programs or see an episode of a favorite "soap" days before its actual broadcast.

Sometimes it is possible to see a football game or other sports event from its origination point before commercials and other network segments are added.

In short, owning a large dish system places one on the leading edge of this new technology of space exploration, satellite communications, and entertainment.

This power carries with it a sense of freedom in being able to choose from all the many TV channels which are available from satellite sources. No longer must one be dependent on someone else's idea of what programming to make available and what to pass over. With a large dish system you really have many more choices than with either the small dish systems or cable!

DETAILS: DISADVANTAGES

HIGH INITIAL COST

The antenna dish mounting pole should either be concreted in a hole about two feet deep or mounted on a special pedestal with heavy weights to hold it in place. Antennas can be mounted on roof tops or on a pole attached to the side of a house, but precautions must be taken to be sure the mount is strong enough for severe weather.

It had been considered the right of any person who had the equipment to receive any signal transmitted by wireless means to receive and use that signal. According to the FCC and the courts that was still the case when private satellite antenna systems were first developed and sold. The privately owned satellite antenna systems were at that time definitely legal.

Not only are satellite antenna systems legal. They are developing into a very large market area for the very cable TV program providers who fought so hard to hold them back just a few years ago. The small dish systems have a place in the scheme of things for the average TV fan who wants an alternative to cable or lives where cable is not available.

For the technologically minded TV gourmet the large dish system is the way to go.

Another problem was in setting the polarity properly. On the older systems the operator had to make the adjustment by skillfully operating a toggle switch device which rotated the feed horn probe. The person operating the system usually made this adjustment while watching the TV picture. Personal judgement as to what constituted a good enough picture could be another headache.

Now there are new microprocessor controlled receivers called IRD's which make both of these jobs much simpler. Both of these adjustments, satellite position for each satellite and polarity adjustments (sometimes called skew) are programmed into the receiver memory. Integrated Receiver Descramblers have a receiver, an actuator control, and a descrambler all built into one unit.

For large dish antenna users with older systems there are stand alone descramblers and stand alone actuator controls.