Tuning In

I love NPR. That’s ‘National Public Radio’, for you nonbelievers. ‘Car Talk’ really makes me laugh. I enjoy the music played on ‘Fresh Air’, and I love the soothing voice of those on ‘All Things Considered’. Besides these classics, NPR broadcasts my all time favorite radio show, ‘A Prairie Home Companion’.

A favorite pastime for me is Sunday driving, discovering PHC on the local public radio station, and extending my short drive into a long one just so I can hear the comedy that Garrison Keillor and the rest of the cast dish out. Since moving to Colorado, I am finding that extending my drive to hear the show is not a solution. This is because of the canyons.

Colorado is chock-full of canyons. Besides being natural rock formations that are pretty to look at, canyons specialize in blocking radio waves. This means that the radio listener is presented with a catch-22: Listen to the radio show, but you can’t go on that drive. Go on that drive, but you can’t listen to the radio show. The middle ground is to go on the drive AND listen to your radio show, just know that it will sound something like this: “chhhhh…ninth inning excitement chhhhh …a tie, unbelievable chhhhh is up to bat chhhhh chhhhh chhhhh amazing miracle chhhhh chhhhh and chhhhh chhhhh wins the World Series!”

In a lot of U.S. states, people will turn the radio to another channel if the station is riddled with static. Not in the Rocky Mountains. Static is just another instrument. It has to be; otherwise most radios would have to remain in the ‘off’ position. Perhaps the intermittent radio is a boon to compact disc sales in the Rocky Mountain region.

The frequency band that the radio is tuned to makes a large difference in the reception. The two types of radio waves that reach your car’s antenna are FM and AM waves. FM, or frequency modulated waves, sound sharper than amplitude modulated waves. If you were to imagine what these radio waves looked like, FM waves are sharp up and down zigzags. AM waves look like gently rolling hills. AM radio travels farther than FM, and even farther at night! Without solar interference, AM waves bounce off the ionosphere and can be heard from hundreds and hundreds of miles away! FM waves pass right through the ionosphere.

All radio waves travel in straight lines, but FM waves tend to crash into objects such as buildings, towers, cars, and canyons. So while the FM signal sounds crisp compared to AM radio, the signal is prone to interference by these earthly objects. FM radio also fades or comes in clearer depending on how close you are to the transmitting source (the radio station). On the other hand, AM waves easily pass over buildings and even mountains and can be heard at a greater distance from the radio station. The buzzing and hollowness associated with the AM sound is caused by atmospheric interference.

Radio waves are measured in Hertz (Hz). If you listen to an FM station at 94.3 on the FM dial, you are listening to a radio station that is propagating radio waves at 94, 300, 300 cycles a second – or 94.3 megahertz (MHz). The frequency is the number of cycles in one second. A cycle would be a zig AND a zag – think of the shape of the FM wave. AM radio stations are found at lower frequencies (535 kilohertz – 1600 kHz). This means that AM waves cycle from “only” 535,000 to 1,600,000 times a second. Now you can imagine the gently rolling hills – at least when compared to the sharper FM wave. AM radio is older than FM radio, which may explain how AM ended up lower on the spectrum. Who assigns frequencies of the radio spectrum? In the United States, the Federal Communications Commission (FCC – the same people who like to sue Howard Stern) has this job.

Radio waves are fascinating. Everything from your garage door opener and baby monitor to your television and cell phone operate using frequencies on the radio spectrum. All these signals are flying around your head, unnoticed. Unnoticed, that is, until you are driving through a canyon and you lose contact with your favorite radio show.

For tips on improving your AM or FM experience, check out Colorado Public Radio: http://www.cpr.org/html/amfm_reception.htm