Radio today (Jan-Mar 1939)

FREQUENCY MODULATION STILL EXPERIMENTAL Lack of transmitting facilities and technical difficulties make immediate change-over impossible Staticless radio reception recently featured in the daily newspapers is not going to revolutionize our present radio broadcasting set-up overnight. Unfortunate publicity in the press has led consumers in some areas to expect that the new frequency-modulated radio transmissions will be common and outmode present amplitudemodulated broadcasts at once. Radio dealers everywhere should explain to their customers and prospects, that the new type of radio transmission is a long way in the future, and that for the present it will only supplement the standard broadcasts. That frequency-modulated broadcasts are an improvement cannot be denied; that they eventually may be the primary source of reception is possible. However, with 40,000,000 radio sets in use and 765 broadcasting stations on the air, nothing will cause an immediate abandonment of our present system that has served so well for almost 20 years. First of all the frequency modulation takes place on wavelengths shorter than ten meters (more than 30,000 KG). Use of these frequencies restricts operation to the limit of the horizon as with television. Antenna installations are absolute necessities and involve many of the problems found in television. No programs available From the viewpoint of programs, there is very little yet available on the ultra-high frequencies. All transmissions to date are experimental — commercially sponsored programs are out. Even if all existing stations licensed for these wavelengths were to go on the air immediately with sponsored programs, most locations would have no reception because of the horizon limit. Persons living within range of a transmitter would have to be satisfied with but a single program, for there are few cities having more than one ultra-high-frequency transmitter. Dipping into the future, we find that a chains of U-H-F transmitters could easily be built. Persons within the range of these stations will receive high-fidelity, static-free programs with a much wider volume range than is now possible. Since the transmission range is definitely limited to the horizon, there will not be interference between various stations as now exists in some locations under the present broadcast set-up. Engineers of the General Electric Company recently completed a long series of tests to determine the relative merits of frequency modulation and present methods on the ultrashort waves. Increased coverage They find Armstrong's system of frequency modulation to be superior in every respect. They state that comparable service to a given area can be attained by Armstrong's system at one-sixteenth the cost of present methods, and conclude with the statement that "Frequency modulation is the only system worthy of consideration for use in an ultra-high frequency network." Mountain tops offer a new possibility in broadcast coverage. In New England, for instance, the Yankee Network is constructing a 50 KW sta tion on a mountain near Worcester, Mass. Such a station can push clear, high-fidelity programs into Boston at all hours of the day and night without fading. Likewise the transmissions will extend westward beyond the Connecticut River, southward into R. I.'s densely-populated districts and northward to the southern N. H. manufacturing centers. Today there is no station on the broadcast band capable of such coverage. Another similar station is being built atop of New Hampshire's famous Mt. Washington, and it should bring fine reception to the northern New England states. It has been stated that these two stations will bring 24-hour a day reception to many outlying districts for the first time. It is possible that frequency modulation may be applied to the audio transmitters of television stations. Since few receivers are in the field, there is no reason why such a change would cause much difficulty at the present state of the art. (Continued on page 56) NEWSPAPERS BY RADIO FACSIMILE NOW AVAILABLE FOR HOMES This boy is making up his own newspaper from a facsimile broadcast, received and printed by an RCA set. February, 1939 17