Broadcasting (July - Dec 1940)

An FM Auto Listener Gets Around 'New York Motor Tour Shows Remarkable Reception By ALVIN VON AUW Western Electric Co. ONE DAY, a few weeks ago, a day when the outside of the office looks bettei' than the inside, the writer signed on with an expedition to tour the Long Island and Westchester countryside with an ear to the quality of FM reception in that area. At the controls of the test car sat Charles Singer, superintendent of WOR's transmitters, while Rinehart Rast, recent U of Connecticut graduate now a member of the engineering staff of FM station W2X0R, fiddled with the controls of an FM receiver [General Electric], mounted on a wooden framework between the front and rear seats of the car. Along for the ride were Will Whitmore, advertising supervisor, Western Electric Co., and the writer. A Dearth of Gadgets The intricate array of gadgetry usually associated with field strength surveys was left strictly to home. This was to be a layman's listening test. The writer, for instance, though only vaguely aware of the meaning of a decibel, is, however, all too familiar with the phenomenon of static interference and has been conscious of a decided difference between the range and quality of the music heard in the concert hall and that which issues from the "mighty midget" next to the easy chair at home. During our test we kept the receiver tuned for the most part to FM station W2X0R, inasmuch as that station is furnishing an uninterrupted 15-hour service every day, the only FM station in the metropolitan area to do so. The W2X0R programs were picked up from the air by what Mr. Singer described as a "vertical dipole antenna with a coaxial transmission line between antenna and receiver". This antenna was mounted at the left rear side of the car so that its lower section cleared the fender by about five inches. Our trip started from the WOR transmitter building at Carteret, N. J. The Mutual programs transmitted from W2X0R atop 444 Madison Ave. in Manhattan poured from the FM receiver true and clear. No background noise, no fading was observed as we drove from Carteret to Manhattan via Route 25 through Elizabeth, past Newark Airport and along the Pulaski Skyway. As we left the Skyway and entered the heavily industrialized countryside, we passed through a broad underpass and cocked our ears for a possible fading of the received signal. The signal did not falter. After crossing to Manhattan through the Lincoln Tunnel, we drove down the West Side Highway to Manhattan's toe, thence up DEEP in a sand and gravel pit, at Port Washington, Long Island, an FM test car finds that the high ridge, directly in the path of an FM transmitter, didn't cause the slightest diminution in signal strength or equality. Even steel bridges failed to affect the signal. through the concrete and steel canyons of lower Broadway. We might just as well have been in the middle of a cow pasture on a direct line-of-sight from the transmitter for all the difference it made in the consistently-steady FM reception. Defies a Bridge From Broadway we cut over to Fourth Ave., then to Madison, passing the site of W2X0R's transmitter on our way to 58th St. where we headed east through heavy traffic to Queensborough Bridge over the East River. There the AM re ceiver in the car was switched on and tuned to WOR for comparison of its signal with the FM signal from W2X0R. As we progressed through the latticed girder consti-uction of the bridge, the AM signal from Carteret was swamped in the rising noise level, while the FM signal continued to ignore the fact that it was passing through an area of maximum shielding. Beyond the bridge WOR's powerful 50 kw. signal returned to its normal high level. Proceeding in an easterly direction along Queens Boulevard, we arrived at our first Long Island listening point at the corner of 72d Ave. and Queens Blvd. in Forest Hills, 7% miles from the transmitter. We parked the car between two groups of apartment buildings. However, no shadow effect, if any was present, could be detected in the FM reception. Without Static Our trek continued along Queens Boulevard for a mile or so, then crossed over to Grand Central Parkway. As we passed under the Parkway's numerous bridges, the FM signal came in strong and clear in contrast with conventional reception. We parked the car under a large concrete bridge to observe this phenomenon and wondered why FM has been considered unsuitable for auto radios. The only interference with the FM signal we observed on our tour — and this was negligible in comparison to the static that AM auto-listeners accept as a matter of course — oc Conference Is Summoned by the FCC To Discuss Proposed Ratings for FM ACTING upon the request of several equipment manufacturers, the FCC Engineering Department has called an informal engineering conference for Dec. 9 to consider transmitting equipment ratings for FM with respect to power. Ratings offered as a basis for discussion range from 250 to 100,000 watts. To be presided over by Assistant Chief Engineer A. D. Ring, the conference will discuss (1) maximum power rating and operating range of standard FM transmitters and (2) performance characteristics of audio amplifying equipment when obtained separately and as a complete unit. Maximum Ratings The FCC's public notice, calling the conference for 10:30 a. m., at Room 7416, New Postoffice Bldg., Washington, states: The Commission has been informed that it would facilitate the manufacture of standard high-frequency (FM) broadcast transmitting equipment if maximum power ratings could be standardized. Also, the operating power range of the transmitters of different maximum power ratings should be standardized for the equipment made by different manufacturers. As the Commission regulates only the external performance characteristics, it ordinarily would not be particularly concerned with power rating except insofar as it must be considered in obtaining the necessary perform ance. It has been agreed, however, to discuss these matters with the several manufacturers so as to standardize the power ratings in order to expedite manufacture at this time when most of the engineering facilities of the manufacturers are devoted to defense engineering. The following power ratings are offered as a basis of discussion : Maximum Power Rating 250 watts 1250 5000 25,000 100.000 Operating Power 50 to 250 1,250 5,000 25,000 Range 250 1,250 5,000 25,000 100,000 watts High-frequency broadcast stations are not rated on the basis of power output. They are rated on the basis of service area. The service area is established from economic data and certain technical considerations. Since all stations serving the same city must have substantially the same service area and as the antenna height and antenna gain vary in all eases, the operating power will, in most cases, be odd values (such as 1190 watts, 19.2 kw, etc.) While stations are not to be rated on the basis of operating power, consideration should also be given the determination of the operating power for the authorized coverage. Even though standard maximum ratings as given above are adopted, it may be desirable to make provision for immediate steps by reducing the number of tubes or using tubes of different power ratings in the last radio stage when the operating power is considerably below the maximum pow curred when we pulled up for red lights next to cars with unshielded ignitions. Beside a Ridge Turning right off Grand Central Parkway, we bounced along on rural routes, then cut across country down a rutted farm road where projecting brush snapped off the lower half of our antenna. With two cows as interested witnesses. Singer dragged a supplementary antenna from the rear compartment and installed it in little more than ten minutes. The FM signal continued to pour in throughout the operation. The farm road dumped us down on the west shore of Hempstead Harbor, where the road is bounded on one side by water and on the other by a long ridge varying in height from 50 to 125 feet. In order to make some stationary tests, we drove into the largest of the many sand and gravel pits in that area and parked the car close to the wall with the ridge squarely in the transmitter-receiver path. At no time did the response fade to a point beyond normal program enjoyment. On Beacon Hill above Port Washington, some 17 miles airline from the transmitter, you can see the | towers of Manhattan on a clear day. In this line-of-sight position we attempted listening tests of the signal strengths of W2X0R, W2XMN, W2XWP and W2XQR. The signals of all these stations poured in with such strength that an aural comparison of their respective powers was impossible. Only a Few Dips From Port Washington we drove to the Bronx Whitestone Bridge and thence to the Hutchinson River Parkway as far as Purchase St., in Rye, N. Y., an airline distance of 22 miles from the transmitter. The signal came in solidly with no noise throughout this area and stayed with us consistently all the way back to New York, although we noticed a few narrow dips in signal strength in the area of Saxon Woods. Coming down the Henry Hudson Parkway, we passed through a toll station and over the wire which projects from the road and drains off the car's static elec (Continued on page 57) er rating. This is suggested for economy only. It has come to the attention of the Commission that the performance characteristics of the speech input equipment is dependent upon the input and output circuits employed. Unless each unit is designed for the impendance characteristics of the load, the performance (frequency and amplitude) may be different from the published data. The claims for overall performance of high-frequency broadcast equipment are, in many cases, based upon the performance of individual units which may not, in some cases when not matched, give performance meeting the requirements, unless all units are equalized as a whole. It is desired to discuss these problems with the view of standardizing a method of specifying characteristics and load conditions. High-frequency broadcast stations are required to submit proof of audio performance during tests as a complete station before a license will be issued by the Commission. Page 18 • December I, 1940 BROADCASTING • Broadcast Advertising