Receiver Is The Brains In Satellite Dish System

September 21, 1985|By Jonathan Takiff, KNT News Service

While the hulking backyard dish is the most obvious part of a satellite TV system, the receiver is certainly a more critical component. In fact, the smart money says it's best to select the receiver first, then match it to a compatible dish and accessories.

Really more of a tuner -- since it doesn't have built-in amplification -- a satellite receiver works something like a radio, with a variable setting knob or a set of pushbutton controls to tune in a satellite signal.

Normally, a communications satellite beams down two signals on each of 12 transponders, for a total of 24 channels. A transponder sends two channels simultanously by transmitting them at different polarities -- meaning that the signal waves move in different planes so they don't interfere with each other. On less expensive satellite receivers, the ones with the click-stop or continuous knob tuning, there's also a button for manually selecting either ''positive'' polarity or ''negative'' polarity.

On the newer, more sophisticated microprocessor-controlled receivers with multiple channel pre-sets, the polarity of the signal is pre-programmed once into the receiver's memory.

Automatic frequency control is another nicety you find in pushbutton models. This circuit keeps the satellite receiver from drifting off the exact frequency, an ongoing concern when you're trying to track a five-to-nine-watt signal emanating from 22,000-plus miles in space.

Better still is an AFC that's switchable, so you can shut it off and manually fine-tune the signal with the assistance of a signal-strength meter -- a ''must have'' feature, according to satellite TV afficiandos.

The better receivers also have stereo sound reception capability. Stereo satellite sound comes in two flavors -- discrete and matrix. A switch selects one type or the other, and an audio fine-tuning knob sharpens the reception. Here, too, the smartest microprocessor-controlled receivers can be programmed to pre-select the right stereo mode when you call up a specific channel. And the AFC audio circuit will be switchable, with a wide-narrow band setting -- so that you can tune in the more densely packed radio services (like classical superstation WFMT) carried on some satellite transponders.

The ultimate in a ''user-friendly'' receiver has a built-in dish control that sends a signal through the coaxial cable to the motor on the dish mount, telling it to move the dish to whichever satellite is selected.

Wireless remote control of all the above features certainly is nice to have, too, especially if the satellite receiver isn't located near your easy chair.

A decoder loop, found in some of the very latest models, allows you to readily install the descrambler device that M-A-Com will market for HBO, Showtime-Movie Channel and possibly other channels. The loop doesn't sacrifice the receiver's ability to access other non-scrambled stations by remote control.

If you're planning on a satellite system installation that's hooked up to more than one TV, look for a receiver that works with a ''block downconverter.'' That's a device that simultaneously delivers 12 or 24 satellite channels through the line, instead of just one channel at a time (the norm on most systems.)

Orlando Sentinel Articles