Broadcasting (Oct 1931-Dec 1932)

Measurement of Station Coverage (Continued from page 11) torily or not at all on the remaining days. 3. The listener cannot receive a usable signal from the station on any day. Now the first condition where the listener can receive the station any day is defined as primary service, while the second condition is defined as secondary service and the third condition is of course no service. Similarly, the nighttime service at that particular receiving set location may be defined as primary nighttime service or secondary nighttime service. To summarize, for a particular receiving location reception from a particular broadcasting station may be defined as (1) primary service, (2) secondary service or (3) no service; and since there are, in general, great differences between nighttime and daytime conditions, the complete description of reception conditions at the receiving location is given by describing first the daytime conditions and second the nighttime conditions. Now, what are the coverage areas of a station? Simply this — the area throughout which in the daytime all receiving sets would receive primary service, if they were in use and tuned to the station, is the primary daytime coverage area of the station, while the area where these reception conditions exist at night is the primary nighttime coverage area of the station. Space is not available for adequate discussion of the complicated technique involved in the scientific determination of coverage by field measurement. Back of the standards and methods used by the author's organization lies a program of research and study extending back to the beginning of broadcasting itself. To give an adequate description would require space enough to fill a book. However, it is essential at this point to direct attention to certain very fundamental facts with respect to the determination of coverage which facts must sooner or later be recognized by all those concerned with the proper development of the broadcasting medium: How Survey is Made 1. Coverage cannot be defined by arbitrary methods. 2. Coverage cannot be predicted from the power assignment to a station. 3. Coverage cannot be determined by the analysis of station mail or by special broadcasts designed to secure mail response. 4. Coverage cannot be determined by studies of listener habits, by house-to-house canvass or other similar methods. 5. Since the factors which determine coverage are engineering in nature, coverage can be determined only by the proper application of scientific methods and standards to the study of conditions throughout the area served. In other words, the determination of coverage is a job for properly qualified radio engineers equipped with adequate apparatus. Any program of stuc'y which does not recognize the truth of these conclusions is bound to produce results the accuracy of which must ultimately be discounted to the extent to which the scientific nature of the radio communication system has been neglected. From the coverage surveys which have been made by the firm of which the author is a member, there has been selected for comparative purposes the daytime coverage areas for WMT, Waterloo, Iowa, (500 watts, 600 kc.) and WJAR, Providence, Rhode Island, (500 watts, 890 kc.) In Figure II the primary daytime area for WJAR has been superimposed upon the primary daytime area for WMT by assuming the transmitter locations to be at the same point. (The nighttime primary coverage area for each station is somewhat smaller than the daytime area due to interference from other stations.) In making a field survey of this sort, the radio engineer with a field car equipped with adequate apparatus travels throughout the area served determining the field intensities produced and the conditions for service. During the investigation which may last from ten days to three weeks, depending upon local conditions, the car will travel from one to two thousand miles or FIGURE 2 Comparison of Primary Daytime Coverage Areas of WMT, Waterloo, la., 500 watts (large area) and WJAR, Providence, 500 watts (small area). See table in text. ticular broadcast station which is important but rather the location and extent of the night and day coverage areas. Consequently the standard market data folders and booklets for these stations are designed to direct attention to the coverage areas and all market data COMPARISON OF PRIMARY DAYTIME COVERAGE OF WMT AND WJAR Ratio WJAR to WMT WJAR WMT (per cent) Primary coverage area 14,689 1,116 8 (Sq. Miles) J 32 ( maximum ) Radius of coverage area in 70 (average) 14 (minimum) | 28 miles t 20 ( average ) Population 599,884 808,515 135 Number of families 155,405 194,128 125 Number of families having radio sets 72,115 105,533 146 Potential audience 283,033 439,208 155 even the most skeptical the importance of coverage. The gradual accumulation of accurate coverage information for a large number of stations secured by the application of uniform standards and methods to all will, as time progresses, prove to be of great benefit to the entire broadcasting industry as it will furnish a sound basis for the evaluation of its effectiveness. The results of the survey are shown in tables and on maps contained in a coverage report which has attached to it an affidavit certifying to the fact that the same standards and methods have been used as are used in making all other commercial coverage surveys. Since the same standards and methods were used in studying WJAR as were used in studying WMT, comparison of the primary daytime coverage areas is particularly interesting because the power assignments are the same. Comparative area, population and receiving set figures are given in the table above. Location Plus FIGURE II does not show clearly that, while Mason City, Newton and Iowa City lie within the outer limits of the primary day coverage area of WMT, these cities are not included in the figures for primary coverage. This is because the requirements for primary service in these localities are more severe than in the more rural localities and these requirements are not met. Similarly for WJAR, the cities of Woonsocket and Taunton were excluded although they lie inside the outer limits of the primary coverage area. Attention is directed to the fact that it is not the location of a par analyses have been made accordingly. The importance of directing attention to the coverage areas in making market data analyses will be obvious to those familiar with marketing problems. Study of Figure II and the table accompanying it will show how widely coverage areas of stations may vary from one another even when the power assignments are the same. Consideration of the essential parts of the entire commercial broadcast system, as shown by Figure I, should make evident to Philco Granted Vision On Time -Sharing Basis SUSTAINING Examiner Elmer W. Pratt ,the Radio Commission on Feb. 9 granted the application of the Philadelphia Storage Battery Co., Philadelphia, for an experimental visual broadcasting station. The grant was made despite objections raised by RCAVictor Co., Camden, now assigned to the same frequencies requested by the Philco set manufacturing concern. (Examiner's Report 303.) The station was authorized to use the medium band of 2750 to 2850 kc. as well as the very high frequency bands reserved for television, ranging from 43000 to 80000 kc, with maximum power of 1500 watts. The station will use the call W3XE. WPTF SERVES THE RICH TOBACCO BELT OF NORTH CAROLINA CENTRAL CAROLINA'S ONLY NBC OUTLET NO OTHER STATION WITHIN 80 MILES Broadcast your 1932 message to the people of the rich tobacco belt of North Carolina — where business is always good. WPTF is the favorite station of the people in this territory. Power 1,000 Watts Western Electric Double Western Electric Frequency 680 Kc. Equipment 78's and 33 l/3's. WPTF RALEIGH, N. C. 1 H. K. CARPENTER, Manager R. L. BRIDGER, Commercial Manager New York Office: Lincoln Bldg., 60 E. 42nd Street Page 24 BROADCASTING • February 15, 1932