Broadcasting Telecasting (Apr - Jun 1952)

of television service, since there would be no overlapping of service contours and a multiplicity of alternative services." The simple rule that the Commission applies to these two zones makes the enormous difference of 4 to 6 miles in Grade B service radius between the two zones. Four to 6 miles increase in Grade B service radii doesn't make much sense in serving the outlying areas from a relatively few large cities in Zone II. Neither does a contraction of 4 to 6 miles in service radii with 20 mile closer co-channel spacing make much sense in Zone I. Since the results of the 20 mile differential in minimum co-channel spacings between Zones I and II have no effective or practical relationship to the objectives which the Commission espouses, it seems clear that they are only a convenient "simple rule" to limit local television facilities to the 1,274 cities included in the Table. This is true unless the Commission has another basis to defend these minimum co-channel spacings. The major contention might be that engineering factors dictate the national policy of minimum spacings selected by the Commission for each zone in order to get efficient use of the spectrum assigned to television, even though the Commission has never said that this firm, fixed and final allocation plan does make efficient use of the spectrum. In its Memorandum Opinion of July 13, 1951 (FCC 51-709) it avoided any defense of this plan. Likewise, in this Report it avoids a forthright avowal that this plan makes optimum use of the channels. Instead, it couches all its discussion of "A Table of Assignments" in the abstract, that "an engineered table * * * permits a substantially more efficient use of the available spectrum" or that "an Assignment Table drawn up upon an examination of the country as a whole can confidently be expected to more closely approximate the mathematical optimum * * *." The Commission even biases its recognition that "the maximum number of staj tions which can be accommodated on any given channel" can be calculated mathematically with the hedge "once a fixed station separation has been agreed upon." As a matter of fact, this dodge of mileage separations is the Achilles heel to this allocation plan's efficiency. The arbitrary mileage separations of 155 miles and 170 miles for cochannel UHF and VHF stations, respectively, in Zone I, and 175 and 190 miles, respectively, in Zone II, are not based upon engineering principles at all. These separations are based upon a policy decision of the Commission for specific size service areas for television stations. All of the engineering for this plan is subordinate to and complementary to this non-engineering volicy decision. Therefore the arbitrary minimum co-channel separations of 170, 190 and 220 miles for VHF and 155, 175, 205 miles for UHF, respectively, have no sacrosanct engineering basis related either to optimum use of a single channel or efficient use of the spectrum — all of the channels. Fortunately, there is a mathematical and engineering basis for selecting co-channel mileage separations for any given channel in each group, i.e., VHF channels 2 to 6 (low VHF), VHF channels 7 to 13 (high VHF) and UHF channels 14 to 83. To visualize the problem of achieving maximum use of a given channel so we can calculate its maximum use, it is necessary to think of a series of dots spaced an equal distance from each other on a map of the United States. If we draw lines between the dots we will have a series of equilateral triangles overlaying the entire United States. The dots will represent assignments of a single channel. The length of the sides of each equilateral triangle will be the mileage separation between stations. Such a scheme of assigning channels will be referred to hereinafter as a "full triangular lattice." Appendices 1 through 6 are a series of charts based upon a "full triangular lattice'' of a single channel in each portion of the spectrum. Appendices 1 and 2 for 63 megacycles are valid for channels 2 to 6 (low VHF) utilizing 10 kilowatts, 100 kilowatts and infinite kilowatts of power at antenna heights of 500 feet and 1000 feet, respectively. Appendices 3 and 4 for 195 megacycles are valid for channels 7 to 13 (high VHF) utilizing 31.6 kilowatts, 316 kilowatts and infinite kilowatts of power at 500 feet and 1000 feet, respectively. Appendices 5 and 6 for 500 megacycles are valid for UHF channels 14 to 83 utilizing 100 kilowatts, 1000 kilowatts and infinite kilowatts of power at 500 feet and 1000 feet, respectively.2 These appendices, all based on the record in this proceeding, show that the minimum spacing proposed in the Third Notice, as amended and finalized in this Sixth Report and Order, is too great to produce the maximum service on any given channel in anv group: low VHF, high VHF or UHF. Appendix 1 shows that any one of the low VHF channels, 2 to 6, utilizing 100 kilowatts of power at 500 feet antenna height obtains maximum efficiency of area coverage at 140 miles co-channel separation instead of the 170 miles minimum separation finalized in this Report.3 It is significant that any one of this group of channels is as efficient in area coverage utilizing 10 kilowatts of power at 500 feet antenna height when co-channel spacing is 100 miles as it is utilizing 100 kilowatts of power at the same antenna height when minimum co-channel spacing is 170 miles. This appendix further shows that at all co-channel spacings between 100 and HO miles, every one of these channels is more efficient in channel coverage utilizing 10 kilowatts of power at 500 feet than it is utilizing 100 kilowatts at the minimum spacing of 170 miles.3 Appendix 1 also shows that if we utilized powers of infinity * at 500 feet antenna heights the maximum coverage for any one of this group of channels would still be at 140 miles co-channel separation instead of the minimum finalized in the Sixth Report. Appendix 2 shows that the maximum coverage for any one of this 2 Each of these appendices is based upon the record in those proceedings. 3 The minimum spacings for Zone I are are used because the minimum of 190 and 220 for Zones II and III respectively are less efficient yet for feasible antenna heights over most of these Zones. 4 Infinite power cannot be achieved. For the purpose of this dissent the term means powers elevated as high as are practically obtaintable. group of channels is obtained at co-channel spacings of 155 miles when 100 kilowatts of power is utilized at 1000 foot antenna heights. It also shows that the efficiency is as great at 145 miles co-channel spacing as at the 170 miles3 minimum finalized in the Sixth Report and Order. It further shows that if powers of infinity were utilized at 1000 feet antenna heights the maximum coverage would be as efficient at 137 mile co-channel spacing as it is at 155 miles utilizing the maximum power authorized in the Sixth Report and Order. It is significant that if 10 kilowatts of power is utilized at the same antenna height, the maximum coverage would be obtained at 145 miles and is equally as efficient at 140 miles as at 150 miles. Appendix 3 shows that any one of the group of VHF channels 7 to 13 utilizing 316 kilowatts of power at 500 foot antenna height obtains maximum efficiency of area coverage at 135 miles co-channel separation instead of 170 miles minimum separation finalized in this Report. It shows that any one of this group of channels is as efficient in area coverage utilizing 31.6 kilowatts of power at 500 foot antenna heights when co-channel spacing is 110 miles as it is when 316 kilowatts of power at the same height is utilized with the minimum co-channel spacing of 170 miles.3 If the maximum power is utilized at the same height for any one of this group of channels they are equally efficient at 90 and 170 miles co-channel spacing. Appendix 4 shows the efficiency of any channel in the same group utilizing the same designated powers at 1000 foot antenna heights. The maximum channel efficiency at this height utilizing maximum power of 316 kw occurs at 155 miles co-channel spacing; and it is equally as efficient at 130 miles as at the minimum of 170 miles3 co-channel spacing provided for in the Sixth Report and Order. The maximum efficiency of one of this group of channels utilizing 31.6 kilowatts occurs equally from 140 to 150 miles spacing. If infinite power is utilized the maximum efficiency is at the co-channel spacing of 155 miles. Appendices 5 and 6 show that the channel efficiency of each of the UHF channels is less sensitive to station spacing than either VHF channels 2 to 6 or 7 to 13. Appendix 5 shows that using 1000 kilowatts of power the maximum efficiency of a UHF channel occurs at 115 miles instead of 155 miles as finalized in the Sixth Report. This is the only group whose channels each increase in efficiency from 100 to 265 miles co-channel spacing utilizing antenna heights of 500 feet and infinite power. When 100 kilowatts at 500 feet are used the maximum efficiency of a UHF channel occurs at 100 miles cochannel spacing. Appendix 6 shows that a UHF channel utilizing 1000 kilowatts at 1000 feet antenna height reaches its maximum efficiency at 130 miles co-channel spacing; utilizing infinite power at the same height it approaches a flat curve of maximum efficiency at around 250 miles co-channel spacing. When 100 kilowatts is used at the same height the maximum efficiency decreases at all distances beyond 100 miles cochannel spacing. These appendices show that the Commission has not selected minimum co-channel spacings in its general rules and standards that obtain maximum coverage efficiency of Zone I if any power is utilized at 500 feet and 1000 feet antenna heights. This inefficient minimum spacing holds true for large areas in Zone II which have the same population and concentration of city characteristics as Zone I as will be more fully discussed in connection with the actual assignments employed in the Table of Assignments hereafter. While the Commission represents that it can be confidently expected that an assignment Table drawn upon the examination of the country as a whole will more closely approximate the mathematical optimum, the minimum spacings in the general rules and standards certainly ignore principles involved in obtaining that mathematical optimum. The VHF assignments actually employed in the Table of Assignments are even less efficient mathematically in Zone I particularly and in the parts of Zone II indicated. The UHF assignments are admittedly incomplete and a sample statistical analysis cannot be made ; but such a complete analysis can be made of the VHF assignments. Appendices 7 through 18 are maps of all VHF assignments in the Table of Assignments. They are revealing, if not shocking, in their lack of adherence to the minimum spacings proposed in any zone. They are offensive, if not arbitrary and capricious, because the Commission will not permit a change in the Table until enough construction permits are granted to freeze this inefficient firm, fixed and final allocation plan forever. Now let us examine the actual co-channel spacings employed in this firm, fixed and final allocation plan for VHF channels. Appendices 19 and 20 are analyses of VHF assignments, as shown on the assignment maps, (Appendices 7 through 18). Appendix 19 shows that the median co-channel separation is 280 miles for all VHF channels assigned to cities throughout the nation. Appendix 20 shows that in Zone I the median cochannel separation is 250 miles for channels 2 through 6. There is no reason to believe that the separations employed in channels 2 through 6 are different than channels 7 through 13 in Zone I. If any section of the country is picked other than Zone I it is likely that the median co-channel separation will be within 20 miles of the 280 mile median for the entire nation. Approximately % of 1% of all VHF assignments are less than 175 miles. In Zone I only 4% of station separations are 170 miles or less and only 8% are 180 miles or less. In the entire country only 7% of all the co-channel separations are 195 miles or less. It is apparent that the Commission has constructed this Table of Assignments without regard to the minimum co-channel spacings of 170 miles in Zone I, 190 miles in Zone II and 220 miles in Zone III for all VHF channels. It is also quite apparent that in selecting these minimum co-channel spacings the Commission has not had ROADCASTING • Telecasting April 14, 1952 Part II Final TV Report • Page 173