Commentary - planning factors redux

The concept of planning factors for the Grade A and Grade B service contours for the current analog NTSC television service, described in this paper, were also employed for the establishment of the service parameters developed by the FCC\´s Advisory Committee on Advanced Television Service (ACATS). There were, of course, several significant differences in the parameters adopted. Because of the perceived "all or nothing" nature of digital signal reception it was decided that only a single service contour would be adopted,-the noise limited contour (NLC)-roughly comparable to the Grade B contour. Also, the new DTV station service areas were designed to "replicate" the existing station\´s Grade B service with service within the NLC to be determined using the Longley-Rice propagation model. Planning factors are essential in developing a national channel allotment plan for a television service. The factors are, of course, based on location and time statistical distributions and typical home receiving systems. Reception at any specific location may vary from these assumptions, as was the case for NTSC service, which also will be true for the new DTV service.