NAB reports (Jan-Dec 1945)

In addition to this interference from sporadic E trans¬ missions, interference from F2 transmission at 53 mega¬ cycles may be anticipated for as many as 470 hours per sunspot cycle — concentrated in a period of three years — in the case of a sunspot cycle the same as the last one; or interference may exist for as much as 2,650 hours per sunspot cycle if the next sunspot cycle is as severe as the highest on record. These figures for F2 transmission, it should be noted, assume only two stations on a channel; more than two stations on a channel would double or treble the number of hours during which F2 interference would be expected at 53 megacycles. In contrast, no F2 inter¬ ference whatever is to be anticipated above 84 megacycles. For listeners buying FM receivers in reliance on a belief that FM is an interference-free service, these figures are extremely serious. They mean, for example, that a listner tuned to a station which is carrying the program of his choice may suddenly find, either that the program to which he has been listening is being interfered with by a station hundreds or even thousands of miles away, or else that control of his receiver has been seized altogether by a distant station completely obliterating the desired program of the local station. These distant transmissions, moreover, are sporadic in nature, with the result that his enjoyment may be further destroyed by an alternation of first one program and then another as transmission vagaries decree. The effect may well be to render FM receivers useless to many listeners for substantial periods of time. It has been argued that the bulk of the interference anticipated will be found in outlying rural areas which rely upon low-intensity signals for their radio reception and that if these areas are excluded, FM service will be more than 99 percent perfect. The tables make it clear that urban as well as rural service will, be subject to substantial interference on the lower frequencies. This Commission, moreover, is under a statutory duty to make available to all the people of the United States an efficient nationwide radio service. The Commission’s duty is not fulfilled if its provision for FM service is such as to make it impossible for rural areas to enjoy satisfactory FM service. The tables and data upon which the Commission’s inter¬ ference predictions are based were set forth in full in the May 25 report and were the particular topic for the oral argument on June 22 and 23. Practically without excep¬ tion all persons appearing at the hearing stated either that they agreed with the Commission’s predictions or that in determining the best allocation for FM they were willing to assume that the predictions as to interference contained in the Commission’s report were accurate. In those cases where exception was taken, no substantiating data were offered. Indeed, the testimony at the June 22-23 argument indicated that the Commission’s predic¬ tions might understate in at least one respect the number of hours of interference to be anticipated at particular contours. The Commission’s predictions were based upon the assumption that receivers will be generally available which are capable of rejecting an undesired signal one half as strong as the desired signal Manufacturers generally appearing at the hearing were unwilling to state that their post-war receivers would meet this standard. With inferior receivers, an even greater number of hours of interference can be anticipated. The issue, accordingly, is whether the freedom from long-range interference which FM will enjoy at the higher frequencies is to be sacrificed by reason of other considerations. Various objections to assigning the higher frequencies to FM have been raised in this record. For example, it has been alleged that tropospheric interference may be worse in the vicinity of 100 megacycles than in the 50 megacycle region. The Commission in its report of May 25, 1945, specifically pointed out that there would be some difference in tropospheric propagation; but this difference would be only slight and that tropospheric interference at the higher frequencies could be eliminated by slightly increasing the geographical separation between stations. This evidence was not controverted at the oral argument on June 22 and 23, 1945, and Dr. Beverage, one of the propagation experts chiefly relied upon by persons favor¬ ing alternative No. 1, testified that tropospheric effects change slowly and that they would not be greatly different throughout the range of frequencies under consideration (Tr. 5583). The point has also been made that equipment for use in the vicinity of 100 megacycles will cost more than equipment for use in the vicinity of 50 megacycles. This will no doubt be true at least temporarily, but it seems equally clear that competition will reduce the differential substantially, and that the benefit to the public resulting from an interference-free service will more than outweigh the slight increase in initial cost for service in the 100 megacycle region. At the earlier hearings, some contended that FM might be delayed for two years or even longer if FM wer» assigned to the higher frequencies. At the time of the oral argument, June 22-23, 1945, the estimates of delay were reduced to four months. It may well be that competition will markedly reduce even this four-month estimate. More¬ over, this report makes it possible for manufacturers to begin at once their planning and design for the higher fre¬ quencies. The War Production Board has not yet au¬ thorized construction of AM, FM, or television equipment for civilian use; and some months may still elapse before manpower or materials become available in sufficient quan¬ tities for such production to begin. If so, the planning and design of equipment for the higher frequencies can be completed before civilian production of any AM, FM, and television equipment is authorized. Manufacturers, of course, are desirous of marketing FM receivers at the earliest possible moment; and the Com¬ mission, too, is concerned that FM receivers shall be free'y available to the public early enough to sunnly the immedi¬ ate post-war demand. However, the Commission has a duty to consider the long range effects of its action as well as the effects during the months immediately ahead, and it does not propose to provide an inferior FM service during the decades to come merely because of the tran¬ sitory advantages which may be urged for an inferior type of service. Earlier in these proceedings, much emphasis was placed on the presumed hardship which would result to the ap¬ proximately 400,000 persons who had purchased FM re¬ ceivers before the war. Most of these receivers are com¬ bination AM-FM and the AM part of the receiver will con¬ tinue to be used. There is now substantial agreement that the band (42-50 Me.) for which these receivers were made is wholly inadequate and unsuited to FM reception. Ac¬ cordingly, no one today argues that post-war FM should be degraded to the point necessary to accommodate these receivers. However, interim operation in the present band from 42 to 44 megacycles is being provided until such time as equipment for the higher frequencies is freely available to the public and until owners of existing receivers have had equal opportunity to adapt or convert them to the new band. In this connection, a converter was demonstrated to the Commission which would make existing FM re¬ ceivers capable of tuning to the higher frequencies and which should retail for approximately $10.00. For the foregoing reasons and upon the basis of data set forth in Section 8 of the report of May 25, 1945, the Commission is adopting alternative No. 3, with certain modifications. The allocation between 42 and 108 mega¬ cycles is as follows: Freq. Band (Me.) Proposed Allocation 42 44 Non-Government Fixed and Mobile 44 50 Television — Channel No. 1 50 54 Amateur 54 60 Television — Channel No. 2 60 66 Television — Channel No. 3 66 72 Television — Channel No. 4 72 76 Non-Government Fixed and Mobile 76 82 Television — Channel No. 5 82 88 Television — Channel No. 6 88 92 Non-Commercial Educational FM 92-106 FM 106-108 Facsimile This allocation is essentially the allocation proposed as alternative No. 3 of the earlier report, except that the non¬ government fixed and mobile services have been moved (Continued on next page) June 29, 1945-259