GENERAL ARTICLES

FM IS ALMOST HERE

Vacuums, electric razors and X-rays can be going all at once, but FM still comes in clear as a bell. It’s a radio revolution!

HAROLD DINGMAN February 1 1946
GENERAL ARTICLES

FM IS ALMOST HERE

Vacuums, electric razors and X-rays can be going all at once, but FM still comes in clear as a bell. It’s a radio revolution!

HAROLD DINGMAN February 1 1946

FM IS ALMOST HERE

Vacuums, electric razors and X-rays can be going all at once, but FM still comes in clear as a bell. It’s a radio revolution!

HAROLD DINGMAN

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BUCKS

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AN ELECTRIC razor was running in the bathroom, a vacuum cleaner in the living room and an electric mixer in the kitchen. The worst electrical storm of the season was crashing outside. But on my radio there wasn’t a bit of static . . .”

That could be you speaking, if you had FM radio.

FM stands for frequency modulation. In simple language, FM is staticless radio of a tone quality so -improved over your present receiving set that it is startling. It’s the radio of tomorrow, and tomorrow is almost here.

Experts in Montreal and New York say that within a very few years—they think no more than five— almost the whole great radio broadcasting empire on this continent will be switched over from what we now call standard broadcasting to frequency modulation. They say this will involve the scrapping of most of the receiving sets now in use in the larger urban centres and the reconstruction of a high proportion of existing broadcasting stations at a cost of untold millions.

Five FM stations are operating experimentally in Canada now, including two Canadian Broadcasting Corporation transmitters in Toronto and Montreal. Three big radio manufacturing companies are operating private stations—in Montreal, Toronto and Hamilton. Also, there are dozens of applications for FM licenses pending in Ottawa.

The CBC experimental stations are operated by and for the Corporation’s engineers, and broadcast only at hours most convenient to them in their job of ironing out FM transmitting problems. They do not attempt to broadcast regular programs.

There is no record of the number of FM receiving sets in Canada. What few there are have been purchased in the United States or made at home by amateurs, but it is likely that within 12 months FM sets will be on the market at reasonably low prices. For the first year or few years you will buy a radio set that will give you both frequency modulation and the present broadcasting system—amplitude modulation, or AM. Ultimately most sets will be FM.

Clear, Faithful

I HEARD my first FM broadcast in a 42nd-floor penthouse on Madison Avenue in New York City. It was in station WBAM, which is the FM outlet for famed WOR of the Mutual Broadcasting System. With me was a young engineer who knows the business thoroughly and is an FM enthusiast. It was a musical program. The engineer brought it in first on AM. The reception was really excellent. Then he brought it in on FM. The difference was startling, almost shocking. The clear, full, faithful reproduction of the orchestra made me feel as if I were in the same room as the musicians, standing close to them. That is high fidelity, faithful reproduction of all the sounds your ear can hear. It is something that takes getting used to.

That is une peculiar thing about FM broadcasting. I am told that although it is the best broadcasting yet conceived a big section of the public does not like it. The truth is that the public ear for decades has been educated to relatively poor reception. The so-called “mellow” reproduction now characteristic of AM sets is far from higo fidelity. Now the public ear has to be uneducated, reContinued on page 23

FM Is Almost Here

Continued from page 17

tuned and educated to true delivery.

Radio experts in New . York predict that within a few years there will be between 4,000 and 5,000 radio stations broadcasting on FM in the United States compared with the present 900 AM stations. Instead of four big chains as now (NBC, ABC, CBS, Mutual) there will be 10. Crowded air? Yes, but a peculiarity of FM is that although there may be great numbers of stations, they will not crowd each other. FM eliminates to a very large degree what the listener describes as “fading”— where one station’s power dims and another rides in on your set. If you are tuned to an FM station there may be 10 others in your city or nearby but they will not ride into your set on the wave band you have chosen.

The Reasons

There are two reasons for this. One is that the channel allotted to each FM station is 20 times as wide as those now occupied by AM broadcasting stations. This means there is less likelihood of a station slopping over the edge of its wave length and interfering with its neighbors on your dial.

But there is an even more important reason. Very high frequency waves, such as are used for FM and television, reach only to the horizon. They do not bend around the surface of the earth, as do the longer waves used in AM, which can be picked up thousands of miles away. This means that faraway FM stations never reach your radio to clutter up your dial.

Inventor and prophet of the FM system is Major Edwin Howard Armstrong, one of the greatest names in radio. Like all inventors he has been harassed, set upon and tormented for his ideas, also, in the inventor tradition, his scorners later honored him.

Major Armstrong was born in New York. Before World War I he was an assistant professor at -Columbia University. Then he was in the signals corps of the U. S. Army. Today he is professor of electrical engineering at Columbia at $1 a year.

Before FM he invented (1) the regenerative circuit, (2) the superheterodyne method of reception and (3) the superregenerative circuit. The regenerative circuit invention, which came in 1912, revolutionized the then existing means of radio communication and made possible overseas reception and radio broadcasting. The superheterodyne principle is used in practically all receivers manufactured today. Both the Armstrong superregenerative circuit and the Armstrong FM system have been used by the Allies since the beginning of the war in communication between planes, tanks, and so on, and in walkie-talkies. For this war use Major Armstrong waived all royalty payments.

While I was in New York I went to see Major Armstrong and asked him to explain his miracle. He lives in a huge roomy apartment in a newish building development on what has been described as the swank edge of Manhattan —on East 53rd Street right down on the Hudson’s bank. He is an easily accessible man, tall and friendly, his big frame clothed in loose tweeds, his head bald and shiny, his smile quick; hardly the traditional inventor type. He is nearing 60, and has spent 40 years in radio experiments. From his inventions he is now a man of wealth. Any need for his easy accessibility—to propagandize FM—is, of course, past. But he talked more than an hour.

“The time is surely coming,” he

said, “when the noise of thunder coming in your window will be more annoying than the effect of the lightning in your radio set. In fact that is already true—I don’t know why I say it is coming, because it is Here. But most people don’t know about it.

“If lightning strikes within a few miles you get a single clunk in an FM set.” He snapped his fingers to indicate the volume of the noise. “Nothing more. Beyond 10 miles you don’t even hear it.”

“What is FM?” I asked.

This is his answer:

“Every radio wave has two characteristics—amplitude, or, in other words, strength; and frequency, or, in other words, the number of vibrations per second. In standard broadcasting you transmit the message by varying the strength of the current, and in FM you transmit the signal by varying the number of vibrations per second.

“In order to make the principle clear I will have to go back quite a way in the history of radio. Along about 1914, after the invention of the regenerating circuit, which revolutionized the radio art at that time, the problem of static interference became the great problem. Many attempts were made to solve it. The results were unsuccessful, and at first the reason for the failure wasunknown. Eventually it was understood that static could not be filtered out of a radio wave because static was practically identical in nature with the waves we were using in radio broadcasting.

“About 1924 the problem was practically given up as insoluble. Then I got an idea which led me into a line of research which resulted in the discovery of a new goal to aim at—to produce a wave different in character from that of static disturbance.

“It was done by using an old method of modulation in a new system and in a new way. Once we got that staticrepelling wave, it was also possible to make a receiver which refused to respond to waves of the ordinary kind or to those waves produced by static— a set responsive only to the new type of wave. Now that system has become known as frequency modulation.”

To understand why FM gives so much more faithful reproduction than AM, it is necessary to remember what sound is. A basic musical note, for instance, is a sound made by a string or a reed or a vocal chord vibrating a certain number of times per second. A piano has a range from 26 vibrations a second for its lowest note to 4,138 for the highest note—and that range embraces most instruments. This is the range of basic musical tones.

AM vs. FM

Rich quality in music or voice, however, comes from overtones, which are superimposed on the basic tone. For instance, when a violin string vibrates 260 times per second to produce middle C, it and the other strings also vibrate at other higher rates. These may go as high as 13,500 vibrations per second. Even a tuba rumbles away in overtones of about 6,000 vibrations per second.

In transmitting sound by radio these vibrations are changed into electrical impulses (cycles) which in turn revert to sound when they hit your receiver. That, simply stated, is frequency—the number of electrical impulses per second; 260 for middle C on a piano, or 13,500 for high violin overtones.

The reason why your AM radio can’t handle the latter properly lies in the nature of its carrier wave. This carrier wave is just like an electrical highway. By itself it makes no sound in your speaker, but on it travel the vibrations which eventually will come out of your

radio as sound. The trouble with AM radio is that the size of this highway is restricted. Let us say a station has an assigned frequency of 740 kilocycles (740,000 cycles a second.) That means its carrier wave comes into your radio when you turn the dial to 740. This assigned frequency allows a variation of five kilocycles each way, which means that the carrier wave on your AM radio has a range of 10 kilocycles; five each way from the basic frequency.

That carrier-wave width is decided by international agreement. But although it is 10,000 cycles (10 kilocycles) wide, transmission is restricted to tone variations of 5,000 cycles, because a guard band must be left at each side to prevent the station overlapping the next assigned frequency and cluttering up some other station’s programs.

Now let’s use that carrier wave. An orchestra is playing in a studio. Its high notes may range up to 13,500 vibrations. Naturally the 5,000-cyclewide AM wave can’t handle that. A control engineer works constantly to modify the extremes, so you won’t cringe too much at the groans and screams at the other end as your radio tries to compress 20 to 13,000 vibrations per second into a loudspeaker built to produce 40 to 5,000. Distortion is the result, because the low notes boom, the high notes screech and the middle ones come out not too badly.

FM Changes All That

With FM it’s different. The FM carrier wave is 200 kilocycles wide— lots of room for vibrations to roam. Every tone and overtone can be reproduced faithfully, so there is no need to alter the strength of the wave to save your eardrums. You get the orchestra strong when it plays forte, and softly when it plays pianissimo. And the carrier wave is of such a nature that ordinary static waves can’t muscle in and distort the broadcast. The reason is that static waves distort the strength of the regular radio waves they encounter—and your FM receiver is built to ignore difference in strength and concentrate only on frequency.

Although you have been and still are listening to standard broadcasts on standard receiving sets, and hence getting your full share of static, the simple truth is that radio reception without static is more than 10 years old.

Major Armstrong first took his invention to Radio Corporation of America. For two years, starting in 1933, experiments were carried out. At the end of the two years, when the company did not go ahead with commercial production, Armstrong took it away from them and built his own station (W2XMN) at Alpine, N.J. It is still operated by him. The station cost him $300,000 of his own money, but he proved to the world that he was right—that his staticless system would work. In 1935-36 he spent day after day demonstrating W2XMN, first taking people to see the transmitter, then driving them 100 miles or so distant and turning on the FM set in his car. In his earliest tests he was getting perfect reception at a distance of 70 miles through lightning and storms and all sorts of man-made static—all the things that make your radio sizzle like a frying pan.

As FM goes only to the horizon, and the horizon extends as you climb to greater heights, it is better, obviously, to broadcast from the heights. In the western United States and Canada mountain ranges will help reach scattered populations. In the eastern United States and Canada there are great concentrations of populations, and AM stations less than 100 miles

apart. By switching to FM they could reach the same masses of people with staticless programs. That leaves the great open spaces of the Middle West in Canada, Northern Ontario, northern Quebec and the far-distant Arctic reaches. But already high-powered AM stations are servicing those areas.

The great switch-over will include almost all the 99 stations now in business in Canada—-and many more new ones. Probable exceptions will be such high-power AM stations as CBL, Toronto, and the big one at Watrous, Sask., which were designed to cover great areas and scattered populations.

In Canada we are only entering the transition period. The United States already is in the transition period, with 46 FM stations operating and 557 applications pending. There are approximately 400,000 FM receiving sets in use in the U. S. This number does not include adapters, converts, and built-up equipment used to transform AM sets to receive FM broadcast.

A year or more ago manufacturers were predicting that 5 million FM sets would be sold in the first postwar year of civilian manufacture in the United States. That prediction is now obsolete. Last spring a survey was made by one manufacturing firm, which discovered that there will be a market for 20 million FM sets as quickly as they can be produced. This same survey indicated that the American public eventually wants 90 million FM sets. The present number of AM sets in use is 60 million. Some manufacturers expected to be on the market with sets by the first of the year and others look to production in hugequantities by March.

In Canada there are some 5 million AM sets, but nocompany at this writing seems willing to estimate the first year’s production of FM-AM sets. However, once the change-over in the United States gets into its headlong rush, Canada—because of its proximity to the U. S.—will have to catch up.

As is common with many other articles, we in Canada will pay more than U. S. citizens for FM sets. Major Armstrong told me he thought they would sell for $75 in the first year of production and $50 in the second. In Montreal radio circles it is expected that Canadian costs may be double that.

Now, then, we come to the frequency at which FM is to operate. AM stations now operate between 550,000 cycles

$nd 1,600,000 cycles, which is the familiar 550 to 1600 on your dial. FM now operates on 42 to 50 megacycles, or 42 million cycles to 50 million cycles. But under a new ruling by the United States Federal Communications Commission, FM must now move up to 88-108 megacyles. This is what is meant when you hear the phrase “FM is moving upstairs” or “radio is moving upstairs.” It operates better in the higher areas, v Also, the higher frequency area of radio air is not crowded. That’s why FM can use the wider band necessary for high fidelity.

Much At Stake

Those who are impatient for FM and for television should stop a moment to consider the gigantic stakes involved. The best summary of the issues involved, that I have seen, was made by Paul W. Kesten, executive vicepresident of the Columbia Broadcasting System. He said: “American listeners are accustomed to receiving more than $100 millions worth of program service every year.

“Unknown to most of these listeners, the physical plant which delivers this program service to them is about to undergo a revolutionary change. Moreover, its integral parts are about to be vitally changed in relation to each other, since FM cannot duplicate the individual coverage areas of present AM stations. Somehow the way must be found to permit all this to be accomplished without substantial injury to the listener.

“Putting it in another way, we are about to tear up and replace all the roads over which millions of listeners travel, at the flick of a switch, to reach their favorite radio programs—yet we must not for one hour interrupt the enormous flow of listening traffic which these highways carry.”

One of the war secrets of the CBC concerns FM and, as far as I know, has never before been told. Back in 1940 and 1941, when there was some danger of our east and west coasts being attacked, and our wire communications disrupted, the CBC installed a relay chain of FM stations to maintain communication between central Canada and both coasts. It was a patchwork job, because new equipment couldn’t be purchased, but it was a workable Continued on page 26

Continued from page 24 system. Every 50 miles or so inland from coast to coast, to strongly established regular CBC points, an FM transmitter was set up, so that if wires were blown up contact could be maintained with the coastal areas.

This leads to another highly controversial issue now being debated, to put it mildly, in the United States. Such relay stations as I have mentioned could be established and completely wipe out the necessity of leasing telegraph or telephone wires between radio stations.

In most cases at present these leased wires—used extensively in AM to “pipe” a program from one locality to

another—cannot handle enough cycles to maintain FM’s high fidelity. The telegraph companies aro planning to counter with a new wire that will carry ’ much higher frequencies. For the next few years, however, this question will be in the background until FM is established more solidly. The leased wires will continue.

In Canada, as in the United States, there is a school of thought that talks down FM. You find it in high places in the radio world, but the voices that doubt FM are weakening in the face of already established success in the commercial field. As one high radio official put it, it’s as inevitable as substituting a flashlight for a candle.