Broadcasting (Oct 1931-Dec 1932)

Dual Operation Test Shows Results Engineer Claims Greater Coverage and Loss of "Squeal" Through 4-Station Common Frequency Experiment T. A. M. Craven BY T. A. M. CRAVEN IN MARCH, 1931, four independent radio stations ventured forth on what may be the beginning of a new era in broadcasting. This venture is so well advanced on the road to success that today is an opportune time to take note of the results accomplished by these four pioneers. The most important phase of this new thought in broadcasting is the complete acceptance on the part of the individual managements of the four stations of the underlying necessity for cooperative action in place of the usual non-cooperative fever which is the bugbear of so many radio stations of today. Having accepted this principle of cooperation, the next phase of importance was the application of engineering principles to increase coverage and quality of service. The four stations engaged in this pioneering work are WHP, Harrisburg, Pa.; WOKO, Albany, N. Y.; WHEC, Rochester, N. Y., and WCAH, Columbus, 0., all subscribers to CBS programs. WBAK, the state police station at Harrisburg, Pa., cooperated handsomely in assisting in this advance of science. The distance in miles between the four stations is as follows: WHP WCAH WHEC WOKO WHP 330 mi. 216 mi. 240 mi. WCAH 330 mi. 370 mi. B3(l mi. WHEC 215 mi. 370 mi. 205 mi. WOKO 240 mi. 630 mi. 205 mi. OBJECT OF EXPERIMENT THESE distances vary from onethird to one-half of that which is considered standard. The object of the experiment was to determine whether this below standard geographical separation between stations operating simultaneouly on the same frequency could be maintained without detriment to the service of each. These stations are licensed for 500 watts operation with the exception of WHP, which is licensed for 1,000 watts in the daytime and 500 watts at night. WOKO of Albany, N. Y., and WHEC of Rochester, N. Y., formerly operated on 1440 kc. with a time-sharing arrangement at night. Their service was subjected to severe interference from stations on the same channel. This interference, combined with the time-sharing feature, was an unsatisfactory condition from both an economic standpoint and from the point of view of service rendered the public. WHP of Harrisburg, and WCAH of Columbus, formerly operated on 1430 kc. with a time-sharing arrangement. In addition, WHP shared time with WBAK, also of Harrisburg. This condition was unsatisfactory from an economic standpoint to all of the stations involved. These four stations now operate simultaneously on 1430 kc. This means that each has full time, except that WHP still shares with WBAK, the other station on the same channel in the same city. WBAK uses the transmitter of WHP during the experiment. Observations made during the past summer show that within the normal protected service area of these stations mutual radio interference is of such a slight degree as to make service entirely acceptable and saleable. In fact, the interference between the four stations is much less than that created by stations on adjacent channels. This is a remarkable situation, differing greatly from the conditions usually resulting from the heterodyne "squeals" one so frequently encounters between regional and local stations separated at greater distances than those of the four pioneer stations. "SQUEAL" DOOMED THE HETERODYNE "squeal" is now doomed. In its place we will have a "flutter," but this "flutter" will occur at greater distances from the station than the former "squeal." In other words, the coverage will be increased. This is especially true when stations broadcast the same program, such as those used at chain stations. #, # Control Panel Used in 4-Station Common Frequency Experiment Thus, so far, the four stations are enjoying more time and experiencing less interference and hence can render an improved service to the public with an increased economic return. All of this is accomplished in a very simple and inexpensive manner within each of the stations. No extra land wires are required to connect the stations. Considering the returns which will accrue to the stations, the capital invested is remarkably small. In a few words, the equipment required at each station is merely a frequency control unit capable of being tuned and maintaining the station frequency with more than the usual degree of accuracy. In addition, there is required an accurate frequency checking device independent of the control unit. At one of the stations this frequency checking device should be of extra accuracy and so fitted that this station can check the frequeny of the other three stations, and thus permit the maintenance of a near "zero beat" relation. Such a relation means that the stations are using exactly the same frequency instead of slightly differing frequencies such as is usually the case with broadcasting stations licensed for the same channel. The important features of the equipment are the capability of tuning to within a few cycles, the maintenance of this tuning to a constant value under changeable conditions, and the ability to check the "zero beat" relation. MADE IN WASHINGTON THE EQUIPMENT used by the four stations was specially designed and manufactured by the Radio Research Company, Inc., of Washington, D. C, which specializes in practical applications of high precision work. A significant feature of the four station experiment is that all of the new equipment is required by the new orders of the Federal Radio Commission, except that pertaining to the degree of accuracy and the extra tuning device at the one station. Thus it can be seen that the cost of this extra degree of accuracy is so small in comparison with the returns resulting from service rendered by the stations that it represents an outstanding advance in the practical art of broadcasting. The coming of winter, with its normal increase of adverse interference conditions, will be a test for these four pioneer stations. It will demonstrate whether or not further steps are necessary. It is predicted that such steps will not be required, but if by chance such a need is proved there remains a probability of solution. This solution will have to be in the nature of reducing the effect of the "sky wave." This is the wave that carries the interference to a distance. The actual solution of this phase of the problem will have to lay in antenna design. Fortunately for the stations any steps along these lines will also result in a further increase of coverage. The experiment to date indicates that, while the results cannot be called a general panacea for the improvement of broadcasting as a whole, there has been demonstrated the possibility of many applications which will be to the advantage of both the public and the individual broadcasting station. In any event, based upon the observations made in the summer months, there is assured a complete absence of the phenomenon called audible heterodyne, which is the "squeal" of broadcasting, and a substantial increase in the quality and coverage of the service of these broadcasting stations. Community Station Plan to Be Refiled THE APPLICATION of Community Radio, a corporation to be formed, for 25 channels for the exclusive use of community broadcasting stations in 267 cities will be refiled within a few months, according to C. R. Cummins, Williamsport, Pa., sponsor of the project. In Washington on Oct. 20 to attend a hearing involving his station, WRAK, Williamsport, Mr. Cummins said the application would be resubmitted just as soon as certain tests are conducted involving operation of local stations on channels only two kilocycles wide. The whole plan hinges on the blocking off of 25 channels to be used by stations on the two kilocycles separation basis. Power would be allotted to the cities and towns in which stations would be allocated on the basis of one watt per 1,000 population. The original application was filed by Mr. Cummins as trustee for Community Radio last March, and a hearing was scheduled for Oct. 16. The hearing, however, was ordered in default by the Commission because Mr. Cummins had failed to file the necessary appearance papers. The application enumerated the cities and towns in which the 267 stations would be located. By states, the stations were to be allotted as follows: Pennsylvania, 41; Massachusetts, 38; Ohio, 32; Illinois, 28; New York, 22 ; Michigan, 21 ; Connecticut, 17; Indiana, 17; New Jersey, 11 ; New Hampshire, 9 ; Maine, 8; Rhode Island, 7; Kentucky, 6; West Virginia, 5; Wisconsin, 3; and Iowa, 2. Bay City Station Files Appeal on Wave Shift AN APPEAL from the Federal Radio Commission's decision denying WBCM, Bay City, Mich., a change in frequency from 1410 to 940 kc, with its present power of 500 watts and unlimited time, was filed in the Court of Appeals of the District of Columbia Oct. 21. (Court of Appeals No. 5528). Claiming that the purpose of the application was to obtain from the Commission maximum restoration of its former service area with minimum disturbance to the present allocation, the petition said the Commission assigned seven stations to the 1410 kc. channel without notice of hearing to WCBM. As a result, it charged, the service area of the station was reduced. November 1, 1931 • BROADCASTING Page 15