Broadcasting (July - Dec 1936)

Coverage surveys conducted by ntBC in 1933 of more than 100 : t a t i o n s, declaring it was the argest undertaking of its kind iver attempted. This survey is being kept up to date, and is used .long with a fan mail analysis. Part of this information, he exjlained, was made available hrough the publication of NBC Network Aireas. Each station, he continued, was ; urveyed individually and in each ,:ase its own par rating is determined. He said: "This survey we are conducting is a continuous jrocess. We have a staff which 'aries between 30 and 35 people o take care of this work, which is .'candled in New York, Chicago and San Francisco. "These measurements took many nonths, and after all the informaion had been assembled we compared the signal field strength concur maps with our letter surveys, .fhere was general agreement beween the two results, and in those ases where there were any marked jifferences we found we could determine the reasons for the devia:ions. In some cases it was traceible to interference from some other station on the same channel, 1>r from an adjacent channel and sometimes even to man-made static." Jansky Proposes 590 Kc. POWER EXPERIMENT A PROPOSAL that the FCC authorize the three stations now on the 590 kc. regional channel to operate with power of 5,000 watts or more at night on a special experimental baMr. Jansky sjs was macje in :a statement presented to the FCC Oct. 20 by C. M. Jansky Jr., consulting radio engineer of Washington. Pointing out that WOW, Omaha, has been operating with 5,000 watts day and night with no appreciable interference to the other stations, he said that the logical conclusion from all technical evidence which has been gathered is that power assignments of 1,000 watts at night on this channel are too low for efficient service. The present nighttime assignments on (590 kc, are WEEI, Boston, with : 1,000 watts; KHQ, Spokane, with 17000 watts, and WOW, with 1,000 ;watts and 4,000 additional on a special basis. "Power assignments at each of i;he stations of at least 5,000 watts at night are fully justified and it lis quite possible that even higher powers are desirable if the maxi. jmum service on this channel is to be obtained," Mr. Jansky testified. .. 'Therefore, that the fullest capabilities of 590 kc. may be developed and that there may be adequate engineering study of all the factors affecting the operation of .regional broadcast stations at the We never did like TWO rate cards. Effective Nov. 1st ONE card does the trick at 1000 Watts 17 d"~^7 J % Missoula 1260 Kc. ■» 1 9 » \W Montana Affiliated with the Columbia Broadcasting System lower end of the broadcast spectrum the following are proposed: Six Steps Suggested 1. That the 590 kc. channel be removed from the regular regional classification and be made a special experimental channel under the provisions described below ; 2. There shall be no set upper limit of power to be used by the stations on 590 kc, save as may be specified for given periods of time by the Commission after consideration of the joint applications of these stations for such powers as field study will substantiate ; 3. Following the transmitter location and antenna changes now being made on this channel application will be made for such power assignment as it appears can be used with the greatest benefit ; 4. If the Commission sees fit to grant the power assignment requested on an experimental basis, then using these assignments engineering studies will be made to determine the coverage areas obtained and also the limitation each station imposes upon the other ; 5. At the time application for specific power assignments is made there will also be submitted to the Commission a research program involving the study of nighttime transmission phenomena on the channel as affected by both time and distance with the" view of supplying to the Commission data of value in determining those power assignments on this channel and other low frequency regional assignments of similar characteristics which will make for the most efficient use of the channels in question. 6. It is respectfully requested that during the proposed experiments to determine the maximum power which is necessary at the present stations on 590 kc. to deliver the most efficient service, no other broadcast stations be assigned to this channel. Neglecting Some Factors PRELIMINARY to his recommendations, Mr. Jansky asserted that in engineering regulation too much emphasis has been placed upon certain factors of minor import ance while others have been neglected. Power and distance have been given too much emphasis, he declared, because they are easy to define and understand, while altogether too little consideration has been given to such complex factors as antenna efficiency, frequency, attenuation, etc. For example, he said, two stations of the same power and the same efficiency may easily have primary service areas whose radii vary from one another by a factor of over 8 to 1, and the areas served may well vary over a ratio of 64 to 1. Such factors as frequency assignment at the lower or higher end of the band, attenuation characteristics of the territory the signal must travel over, radiation characteristics or efficiency of the antenna system, and the power in use at the transmitter must be taken into account, he said. Discussing the regional power limitation of 1,000 watts, Mr. Jansky said that in some instances, because of the characteristics of the various assignments, power of 1,000 watts may be too high for the legitimate purposes of the stations involved. In other instances 1,000 watts or even 5,000 watts may prove to be too low for efficient service. WOW with 5,000 watts has a primary day and night coverage in excess of 150 miles, Mr. Jansky testified. The average radius of the primary day coverage of KHQ with 5,000 watts is in excess of 100 miles, and at night with 1,000 watts it is greater than 75 miles. Primary day and night coverage areas of WEEI, while not so large as those of WOW and KHQ, are large compared with other stations in the same general area regardless of power, he said. The primary daytime service areas of the three stations, Mr. Jansky contended, are larger than for most clear channel stations. The reason, he added, is the fact that the 590 kc. frequency is near the lower end of the broadcast spectrum. Asks Higher Power on HIGHER FREQUENCIES THE NEED for higher power on higher frequencies, to procure service comparable to that of stations on lower frequencies, was emphasized by Dr. Herbert L. Wilson, consulting radio engineer of New York, Oct. 19 in a statement filed with the FCC. Differences in attenuation on the various frequencies, he said, make such a differential in power desirable. Basing his recommendations on a series of measurements made in New York City and other points, Dr. Wilson said that more power is required at the higher than at the lower end of the band. By using 1,000 watts on 550 kc. as a basis, he said, a station has a signal equal to that of 16,000 watts on the higher frequency, taking into account the attenuation in metropolitan areas and the difference between 550 and 1500 kc. "In other words," he said, "the broadcaster at the higher end of the broadcast band cannot hope to render the same field intensity KG IK BUTTE* MONTANA JOSEPH Mc.6ILL.VRA WALTER. BIDDlCK CO. NEW YORK-CHICAGO ' PACIFIC COAST • id: ;t .1 IOOO Watts KIRO SEATTLE, WASHINGTON 7IO KC KIRO LOOSE says: "You cart t afford to overlook results KIRO/ now celebrating its first anniversary, is carrying more business than any other independent station in the Pacific Northwest. NATIONAL REPRESENTATIVES . NEW YORK CHICAGO Detroit John Blair & Co. sanfranosco BROADCASTING • Broadcast Advertising November 1, 1936 • Page 67