By Hannah Holmes
An equally puzzling question might be, "Why are there 13 channels on a TV?"
'Scuse the arcane concept, kids. Not so long ago, people changed the television channel using a dial on the television, not a remote on the sofa. And the main dial, to the mystification of many, offered channels 2 through 13 -- there are actually only 12 channels on these televisions.
(Shocking though it may be to members of the cable generation, some people still have televisions that get only two or three channels. As for folks with dial TVs, those who don't already change channels with pliers certainly will once some hip New York decorator recognizes the dials as "Americana" and starts paying rural grandmothers 40 bucks for them.)
So, anyway, how come?
The story starts at the end of the nineteenth century, with the taming of radio waves.
The new "wireless telegraph" was a wondrous alternative to the telephone and telegraph, although it took people some time to identify the usefulness of sending a telegraph to everyone. One historian notes that "the fact that radio waves spread outwards in all directions from their point of origin ... was seen as a nuisance from the military point of view."
But eventually, people recognized the charms of casting radio waves broadly -- or broadcasting. A broadcaster would choose a wavelength from the wide spectrum of radio waves and generate a signal. Anyone with a receiver tuned to that wavelength could pick up the signal and amplify it to recreate sound. The first broadcasters, in the 1920s, produced a variety of sounds by altering the amplitude (height) of the radio waves: Amplitude Modulation, or AM radio, was born. One of the early companies to produce radio programs was the Radio Corporation of America, or RCA.
AM radio stations were soon making money selling commercials. But AM took up just part of the radio spectrum -- there was a lot of beautiful "bandwidth" going unused. Some companies wanted to fill it with a new kind of radio signal alleged to carry music better, Frequency Modulation.
But David Sarnoff, RCA's beefy chief, decided the future was in broadcasting pictures.
In 1939 RCA asked the Federal Communications Commission to designate 13 television channels, enough to deliver three networks to every part of the country without interference. Even though each TV station would eat 30 times as much spectrum as one FM channel, Sarnoff tried to force the FCC's speedy approval -- mainly by demonstrating television at the 1939 World's Fair.
Peeved at Sarnoff's bullying, FCC chair James Fly responded with populist fury: He believed bandwidth should deliver information and entertainment to every woodland shack before it delivered flashy TV to people who could, in 1939, afford a $600 set. Television, he announced, could ask for its bandwidth after FM radio got what it needed. And he promptly gave part of RCA's proposed Channel 1 to FM.
A word about the spectrum:
The radio spectrum is divided into frequencies, or Hertz. Very High Frequency (VHF) waves, which run from 30 megahertz (MHz) to 300 MHz, are easy to control, and go a long distance on a little power. Everybody wants a piece of VHF.
The FCC originally gave FM the VHF between 42 MHz and 50 MHz, divided into 40 channels. Individual stations were assigned particular frequencies. They also got power ratings, so that two stations in neighboring areas could broadcast on the same frequency without overlapping. Then, figuring that judicious allocation of spectrum would allow TV and FM to share spectrum, FCC gave television 13 channels, 6 MHz each, right on top of FM.
They figured wrong. Too many broadcasters wanted spectrum, and television and FM were tangling.
In 1948 the FCC shifted FM up the spectrum to 88 through 108, which is how your radio is numbered today. It gave the remnants of television's Channel 1 to "land mobile," a class of radio users that included dispatchers and police.
Television was given pieces of what remained in VHF: Channels 2, 3 and 4 reside between 54 and 72 MHz. Channels 5 and 6 live just below FM radio, at 76 to 88 MHz. (My radio tunes in Channel 6.) Channels 7 through 13 occupy 174 to 216 MHz, far above FM territory.
The FCC also gave television lots of spectrum in the UHF, or Ultrahigh Frequency range, which is above 300 MHz. (Kable Kids: The UHF dial, separate from the main dial, tuned in channels 14 through 83, but it was usually empty. Broadcasters preferred VHF, and clustered there whenever it was available.)
And, speaking of cable, you can file this whole column under "Ancient History." Broadcasting had its day, but the distribution of television programs through cable is now threatening to reduce the TV antenna to a quaint artifact. Look for them on the walls of well-decorated New York apartments.