Three is not enough - Why the U.S. specified four DBS service areas

Comparisons are presented of proposed three- and four-satellite direct satellite broadcast (DBS) systems for the contiguous U.S. (CONUS). The systems would provide 50 channels between 18-24 MHz. It is shown that a four station/four region system would provide at least as many channels as a three-area system, allow persons on the edge of one zone access to coverage from another zone, permit programming to match time zone changes, lower system costs, permit more efficient spectrum use, and have comparable terrain blockage. Using four GEO platforms is noted to allow full coverage even if one or two spacecraft malfunction. Furthermore, the cost of a home antenna is projected to be $13.50 more expensive with a three-platform system than with four platforms.