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Technology of satellite television
Direct broadcast via satellite
Television receive-only
Early history of satellite television
Beginning of the satellite TV industry
TVRO/C-band satellite era
1990s to present of satellite television
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Video on demand
Reception equipment of satellite television
Technical details of satellite television



Television receive-only


Television receive-only (TVRO) is a term used chiefly in North America to refer to the reception of satellite television from FSS-type satellites, generally on C-band analog; free-to-air and unconnected to a commercial DBS provider. TVRO was the main means of consumer satellite reception in the United States and Canada until the mid-1990s with the arrival of direct-broadcast satellite television services such as PrimeStar, USSB, Bell TV, DirecTV, Dish Network, Sky TV that transmit Ku signals. While these services are at least theoretically based on open standards (DVB-S, MPEG-2, MPEG-4), the majority of services are encrypted and require proprietary decoder hardware. TVRO systems relied on feeds being transmitted unencrypted and using open standards, which heavily contrasts to DBS systems in the region.

TVRO systems were originally marketed in the late 1970s. On October 18, 1979, the FCC began allowing people to have home satellite earth stations without a federal government license. The dishes were nearly 20 feet (6.1 m) in diameter, were remote controlled, and could only pick up HBO signals from one of two satellites.

The dishes worked by receiving a low-power C-Band (3.74.2 GHz) frequency-modulated analog signal directly from the original distribution satellite the same signal received by cable television headends. Because analog channels took up an entire transponder on the satellite, and each satellite had a fixed number of transponders, dishes were usually equipped with a modified polar mount and actuator to sweep the dish across the horizon to receive channels from multiple satellites. Switching between horizontal and vertical polarization was accomplished by a small electric servo motor that moved a probe inside the feedhorn throat at the command of the receiver (commonly called a "polarotor" setup). Higher-end receivers did this transparently, switching polarization and moving the dish automatically as the user changed channels.

Originally, all channels could be received in the clear (ITC) and free of charge. In October 1984, the U.S. Congress passed the Cable Communications Act of 1984, which gave those using dishes the right to see signals for free unless they were scrambled, and required those who did scramble to make their signals available for a fee. Since cable channels could prevent reception by big dishes, other companies had an incentive to offer competition.

TVRO systems were most popular in rural areas, beyond the broadcast range of most local television stations. The mountainous terrain of West Virginia, for example, makes reception of over-the-air television broadcasts (especially in the higher UHF frequencies) very difficult. From the late 1970s to the early 1990s DBS systems were not available, and cable television systems of the time only carried a few channels, resulting in a boom in sales of systems in the area, which led to the systems being termed the "West Virginia state flower". The term was regional, known mostly to those living in West Virginia and surrounding areas. Another reason was the large sizes of the dishes. The first satellite systems consisted of "BUDs" twelve to sixteen feet in diameter. They became much more popular in the mid-1980s when dish sizes decreased to about six to ten feet, but have always been a source of much consternation (even local zoning disputes) due to their perception as an eyesore. Neighborhoods with restrictive covenants usually still prohibit this size of dish, except where such restrictions are illegal. Support for systems dried up when strong encryption was introduced around 1994. Many long-disconnected dishes still occupy their original spot.

The dishes themselves can be modified to receive free-to-air and DBS signals. The stock LNBs fitted to typical BUDs will usually need to be replaced with one of a lower noise temperature to receive digital broadcasts. With a suitable replacement LNB (provided there is no warping of the reflector) a BUD can be used to receive free-to-air (FTA) and DBS signals. Several companies market LNBs, LNBFs, and adaptor collars for big-dish systems. For receiving FTA signals the replacement should be capable of dual C/Ku reception with linear polarization, for DBS it will need a high band Ku LNBF using circular polarization. Older mesh dishes with perforations larger than 5mm are inefficient at Ku frequencies, because the smaller wavelengths will pass through them. Solid fiberglass dishes usually contain metal mesh with large-diameter perforations as a reflector and are usually unsuitable for anything other than C band.