Riding the radio waves
Demystifying the magic of local radio transmission

Bruce Anderson holds an antenna while standing amongst a dozen low-powered, two-way radio antennas. Anderson is the local expert on broadcast transmission and also the chief engineer for Four-Corners Broadcasting. /Photo by JaredBoyd

by Jeff Mannix

One look into the Colorado sky inspires reasons for living apart from the centers of culture and the bustling markets of commerce. White clouds suspended in fathomless blue, the brilliance of the sun, galaxies of stars spread throughout vivid black nights, fresh air that can be seen through for miles. If, however, you saw the electronic data being transmitted above, below and around your head, you might think again about how you define pristine.

Think about what's out there, what can't be seen, for a moment. There are cell phone frequencies, AM and FM radio channels, television channels, two-way radio bands, ham radios, police radios, radar, radionavigation and radiolocation frequencies, wireless internet, cordless phones, garage door openers, wireless clocks and more. When you count all the frequencies blasting electronic impulses through the air, there are thousands of waves of amplified energy swirling in our cerulean sky. Add to that the thousands of satellite transmissions from a couple of hundred globes orbiting 22,500 miles from Earth, we may just be slowly cooking as if we were in a microwave oven.

Bruce Anderson is the chief engineer of Four Corners Broadcasting and an undisputed expert on broadcast transmission. Asked if we had anything to fear from all this electromagnetic radiation, Anderson says, "Compared to the sun, all this stuff is nothing. The sun zaps you with more electrical energy in one moment than all the manmade radiation could ever effect."

Anderson goes on to explain just how radio waves - the name given all broadcast transmission - originates, travels and comes so effortlessly out of our everyday gadgets. "If you could see it, see all the radio waves, it would appear as a constant haze, with plenty of light coming through," describes Anderson, reassuringly.

Electromagnetic radiation increases in frequency from AM radio to FM radio, TV, microwaves, infrared, visible light, ultraviolet light, ultra-violet radiation, X-rays and, lastly, gamma-rays. All this transmission is measured in hertz, named after Heinrich Hertz, who in 1888 discovered the first very low frequency radio waves. It all travels at the speed of light, which is 180,000 miles per second, or seven times around the Earth in one second. There is an element of magic to all this, but the ability to transmit sound and image through the atmosphere, even the stratosphere, is a most remarkable and interesting phenomenon of such consequence that the radiating haze surrounding us may just be forgivable.

Without going behind the curtain to see the wizard at work, the basic principles of broadcasting electromagnetic waves is easy to understand, albeit with a healthy dose of blind acceptance. An electromagnetic impulse - let's call it noise - is inaudible at 40 cycles per second (40 hertz), possibly audible at 60 hertz, clearly audible at 120 hertz, then inaudible again to the human ear at 18,000 hertz (18 kilohertz). This noise, as all noise, travels in a wave that oscillates in cycles between troughs and crests corresponding to the low and high sounds. Frequency is the number of times per second that the crests, or waves, occur, and in the case of our local AM radio station, KIUP, the Federal Communications Commission has assigned the frequency of 930 kilohertz, or 930,000 cycles per second. Durango FM station, KIQX, has been assigned a frequency by the FCC of 101.3 Megahertz, or 101,300,000 cycles per second (hertz). And as you twist the dial of your AM or FM receivers, you will see just how many broadcast frequencies there are, all separated from each other by an assigned speed of transmission, which is compressed or processed at origination to not leak into neighboring frequencies, then stopped down in your receiver so it is in the audible range of the human ear.

"Now we go to the easy part. Let's just take as example speaking into a microphone," chuckles Anderson, like this was a simple recipe for cooking meatloaf. "The speaking voice is about 200 cycles per second, or 200 hertz. The microphone is a simple device with baffles that convert noise into electrical energy carried through a wire to an amplifier," explains Anderson. "The amplifier processes that electrical input, boosting the low notes and compressing the wavelength and sending it to the transmitter by microwave."

Four Corners Broadcasting radio signals are transmitted to an antenna on Smelter Mountain. Line of sight from transmitter to transmitter is vital in this initial process. Now the receiver on the Smelter antenna forwards the sound to an adjacent transmitter that relays a radio wave to a receiver on the antenna at Missionary Ridge, at a power of four watts, hardly more that a whisper but enough to get it there.

"Missionary Ridge has the big stuff," Anderson explains with a noticeable sense of pride. "Here the radio wave goes through a series of amplifiers, from four to 12 watts to 250 watts to 1,500 watts to 25,000 watts of effective radiated power, which is the measurement rating by the FCC for the stations."

AM radio stations, with their low frequencies, can follow the terrain of the earth and reach great distances. FM radio, broadcasting in thousands of cycles per second instead of hundreds, must go from antenna to antenna in clear sight of each other, which is why you can drive out from under an FM frequency and sometimes hear an AM station halfway across the country. Television frequencies also require line of sight antennas, which is why roof antennas are being displaced by cable and satellite transmission.

The old tale of the hillbilly who hears a radio station coming in through his tooth filling is quite improbable but indeed possible, according to Anderson. "If atmospheric conditions are just so, and that silver filling is just the right shape and density, theoretically it can happen," he says. And the kooks wearing the tinfoil hats to protect against mind control and brain damage from the electromagnetic radiation, well, the mind control part is treatable paranoia, but if brain damage is indeed possible from this haze of radiation, the tin hats could save the old squash. •

 

 

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