Broadcasting (July - Dec 1936)

AT OPENING GUN— At left Chief Engineer Craven opens the hearings; at press table, the genial G. Franklin Wisner, FCC press chief, at his "knitting". At right is group of Westinghouse and ex-Westinghouse executives: Walter C. Evans, manager of broadcasting for West inghouse; C. W. Horn, NBC development and research director; George; S. Law, Westinghouse counsel; Horace L. Lohnes, Washington attorney? S. D. Gregory, assistant manager of broadcasting for Westinghouse ji Frank B. Falknor, CBS western division chief engineer. Chamber's Case for CLEAR CHANNELS CONTINUING the Clear Channel Group presentation during the afternoon session Oct. 6, Joseph A. Chambers, consulting engineer and former chief engineer of WLW, presented a detailed technical case in favor of superpower and clear channels. Utilizing slides and photographic charts, together with recordings of station signals to prove his points, Mr. Chambers consumed some four hours for his technical presentation. In consonance with the preceding speakers, Mr. Chambers advocated an evolutionary change rather than a widespread reallocation, urging progressive modifications of the present structure. Mr. Chambers brought out that under existing allocations there are 195 local station assignments, 206 unlimited regional station assignments, nine assignments of unlimited high powered regionals, 51 assignments on so-called clear channels and 148 limited time assignments. Would Eliminate Daytimes AS FOR limited time and daytime assignments on clear channels, he advocated that they be eliminated because of the impairment to daytime reception they cause upon the dominant stations on the clear channels. As power increases, daytime service increases and that translates itself into better rural coverage, he said. Mr. Chambers praised the present system of allocations, that is, the classification of clear, high power, regional and local stations. He said this diversification of allocations is necessary to provide adequate coverage for all types of listeners. He emphasized again that the majority of rural and small town listeners are almost entirely dependent upon clear channel station service. Ultimately, he said, ultra high frequencies mav become available for local broadcast service and synchronization methods on regional and local channels may tend to improve service of its stations. Clear channels should be kept clear for future expansion and such clear channels as now are duplicated should be reclassified and placed in other categories, he said. Mr. Chambers pointed to numerous field surveys to prove his contention that only with clear chan nels can the rural listener receive adequate service. He recommended more stringent regulation of stations to prevent over-modulation interference, that is, interference which breaks through on adjacent channels in terms of harmonics. No Adjacent Interference HE RECOMMENDED an 85% modulation, which he said would eliminate over-modulation harmonics. By way of discrediting arguments that superpower tends to blanket out reception of stations on adjacent channels, or for that matter any other stations, Mr. Chambers played a series of recordings of programs of stations on both sides of the 500 kw. WLW. These essayed to show that stations like WOR, WGN, WEAF, WMAQ and others on neighboring channels, each with 50,000 watts power, came in with excellent signal strength at a location only 41/* miles away from the WLW transmitter. Exhibiting additional charts and graphs, Mr. Chambers said these showed that if two 50,000-watt stations on opposite coasts were duplicated on the same channel without directional antennas, the secondary service would be non-existent. Actually, he said, each station would cover only about 85 miles from its transmitter. With directional antennas and the use of one lower powered station on such channels, he said, there would be some secondary coverage but none that compares with the coverage of a station even with nominal power when it operates exclusively on a clear channel. Directional antennas, he said, also would help to increase the secondary service of the dominant station but would not enable wide coverage of the character expected from clear channels. As for daytime stations operating on clear channels, Mr. Chambers recommended a rearrangement of assignments to prevent interference and a ban on the licensing of any future daytime stations on such waves. Instead of these daytime stations signing off at local sunset, he said, they should really sign off at sunset at a pointijl half way between the duplicated?! stations, thus insuring better prop-SI agation for the dominant station!! Chambers' Cross-Examination WHEN Mr. Chambers resumed his protracted technical testimony a1 the Oct. 7 session, he was subjectec to a grilling cross-examination bj Comdr. Craven, the questioning being aimed at breaking down th( theory that clear channels are es sential to afford rural coverag< and that there can be no duplica tion on them. Mr. Chambers delved into radic theory by estimating coverage oi stations not only of 500,000 watts at particular locations but also oi 5,000,000 watts. He indicated thai the latter type station could pro vide effective service over the enl tire country, adding that it was!' entirely possible to build such sta-j tions. A station on the easterrj coast using a directional antenng} with 500,000 watts, he said, coukfl do an acceptable service job ovei| most of the territorial area of thq United States. Recalling the outcries against" superpower virtually from the be ginning of commercial broadcast* ing, Mr. Chambers brought ouflj that all of them proved groundless! and that instead of any deterioration of service the result was im'l proved service particularly for th< less fortunate rural listener. In be i half of the Clear Channel Group Mr. Chambers favored a horizon tal increase in power for regiona j stations, declaring these increase: should be encouraged. He said tha the only problem of interference i; that it might occur on adjacen t channels and that the solution la? in improved receivers of sufficien' selectivity. "To procure the maximum us< on clear channels we should us< j • the highest power possible," hi said. He advocated 50 kw. as th< minimum with no maximum. Even if all of the clear channel: used superpower, Mr. Chamber: said under Comdr. Craven's cross i examination, satisfactory servic< could not be provided everywhere in the country. Superpower's National Coverage RESPONDING to a Craven inl quiry as to whether all rural lis. teners could get as many as 2< of the clear channels if all 30 o those now on the air were oper ating with superpower, Mr. Cham bers said he doubted it because o the distance factors involved. Re ducing the figure to 15 of the 30 Mr. Chambers said that sucl might be possible during bes night conditions but certainl; SUMMARY OF CLEAR CHANNEL VIEWS HERE are technical recommendations of the Clear Channel Group as presented to the FCC allocation hearing by Joseph A. Chambers, chief technical witness: 1. That there be no radical reallocation, in view of the necessity for retaining all the present classes of stations. 2. That the field intensity ratios for common and adjacent channel interference limitations be changed as regards the adjacentchannel figures, and be unchanged as regards the same-channel figures, as follows: Same channel, 20 to 1; 10 kc. frequency difference, 0.1 to 1; 20 kc. frequency difference, 0.01 to 1; 30 kc. frequency difference 0.001 to 1. That interference with 40 kc. separation between stations is sufficiently low to be ignored in the signal ratio and separation tables. 3. That present empirical values of signal strengths required for various grades of service be maintained for regulatory purposes. 4. That mileage separation tables, if continued in use, give way in all cases to field measurement data or otherwise known conditions. 5. That the present value of "blanketing" signal be changed from 125 millivolts to 1 volt or more. 6. That no allocation plan be set up based only on geographical conditions. 7. That there is no objection, from the point of view of the Clear Channel Group, to a horizontal or other increase in night power to 5 KW by Regional stations. 8. That daytime duplication of Clear Channel assignments is not objectionable if the present specified 1000 miles separation is maintained, and providing the duplicating station signs off at the hour of sunset one-half way between the longitudes of the two stations. 9. That the present 30 clear channels remain clear, with such change of regulations as may be required to authorize operation with a minimum power of 50 kw. and an unlimited maximum power, where proper showing is made. 10. That no change in the status of the 10 duplicated channels, now classed as Clear Channels, appears necessary other than a change in nomenclature. Page 54 • October 15, 1936 BROADCASTING • Broadcast Advertising