NBC Transmitter (Mar-Oct 1941)

16 NBC TRANSMITTER FREQUENCY The hullabaloo that launched Frequency Modulation (FM) sound broadcasting has subsided a little, leaving the new method to progress strictly on its public appeal. Practically everybody has heard of FM. Thousands have heard FM broadcasts. And some have bought FM receivers in those areas where there are FM stations. NBC, applying its policy of furthering any development that promises to better radio service, established an FM transmitter at New York in 1939. The station, W2XWC, now broadcasts eight hours a day, five days a week. The station’s power is shortly to be boosted. There’s a lot of curiosity about FM. The initials themselves carry a suggestion of mystery and the claims for it intrigue some persons whose morning listening is rudely shattered at times by the neighbor’s electric razor. Frequency Modulation, as a broadcasting service, is new. As a method of radio, it goes back to a patent applied for in 1902. It extends through patents in practically every year between that year and this. A lot of engineers have had a hand in its development. But developments in the last few years, both in the use of ultra high frequencies and in FM itself, have made the system practicable for broadcasting. Practically all of radio the world over uses amplitude modulation (AM). With this system, the transmitter’s carrier wave remains unchanged. Only the amount of power radiated by the transmitter on its carrier wave varies from instant to instant. In FM the radiated power remain's constant, but the carrier frequency changes in accordance with the sound being broadcast. That’s the way O. B. Hanson, Vice President and Chief Engineer, would put it, except that he would draw a few illuminating diagrams that would pretty much clear up any further confusion. Mr. Hanson agrees that FM is an improved method of modulating a carrier wave and that FM results in noise-free reception at lower signal strengths than is possible with AM. Frequency Modulation, he says, gives greater fidelity, partly because it is less noisy and partly because the Federal Communications Commission has set aside channels 200 kilocycles wide for FM stations. This enables broadcasting to escape the constraints of the 10-kilocycle band. It’s simply a matter of getting more of the overtones into the transmission to give the program greater richness. A good deal of FM’s static-free quality is due, according to Chief Engineer Hanson, to the fact that FM stations use ultra short waves. These are practically free of natural static. NBC’s experimental UHF stations, using frequency modulation, cut blithely through terrific thunder storms with no more than a faint click in the receiver. Frequency Modulation has one . . . that the rugs in NBC are shampooed? Soap suds and all. . . . that the Wilson sign on Broadway, featuring those very amusing silhouettes, is actually television in its early form? . . . that the second floor of NBC is regarded by theatrical folk as the successor to the front of the old Palace Theatre? . . . that not every NBCite knows that the NBC Studio-Television Tour is the number one tour attraction in the country? . . . that the worst air conditioning problem is encountered in the control rooms? Seems every agency man has six assistants. . . . that Lorin Maazel, French youngster who conducted the NBC Symphony Orchestra at the age of 1 1 , first conducted at 8 years, has absolute pitch, rehearses and conducts without a score? MODULATION distinct advantage over Amplitude Modulation, Mr. Hanson says. That is the effect of the “limiter.” action in the receiver. This is a gadget that keeps out all the pesky man-made noises that occasionally disturb AM reproduction. Vacuum cleaners, the aforementioned electric razors, diathermy machines, electric coils, transformers — the last are those black boxes you see situated at regular intervals on telephone poles — all disturb AM reproduction often enough to be very annoying. Under FM, they amount to nothing. Tube hiss also is held to a minimum. How fast ultra-high frequency broadcast services, making use of this new method of modulation will spread is still an unanswered question. To take advantage of the greater fidelity that is possible with FM, the receiver has to have a speaker unit capable of reproducing, without distortion, the wide range of sound frequencies. Consequently, the prices of quality FM receivers will be relatively high. That’s just about the problem, greatly simplified, that FM faces. It may grow along with television. Both use UHF and television sound is FM. Meanwhile, NBC will continue to operate VV2XWC; it will be W51NY when it goes commercial. A Chicago station will be built in that future. When demand for FM spreads, NBC will apply for permission to establish still other FM stations in still other parts of the country. DID YOU KNOW? . . . that Personnel interviews approximately 18,000 people a year seeking positions with NBC? . . . that NBC people have seen more of the Rockettes across the way than any one else? . . . that WEAF broadcast its first commercial on September 7, 1922? . . . that 500,000 pounds or 1 1 carloads of rock-wool insulates this building?