What Is Spectrum?

The part of the electromagnetic spectrum we are probably most familiar with is the visible-light spectrum, which runs from the brightest red and its long wavelength and low frequency to the deepest violet and its short wavelength and high frequency.

Physicists measure what we hear or see in two ways: wavelength, or the distance between peaks in the wave, and frequency, or the number of wave crests during a specified amount of time.

If we look at the electromagnetic spectrum, broadcasting makes up just a small piece. We start at the lowest frequency, with audible sound. Next is a swath used for satellites, maritime radios, and AM radio, then TV channels 7 to 13, wireless microphones, FM radio, aircraft communication devices, meteorology satellites, public-safety radios, CB radios, TV channels 14 to 69, aircraft tracking and navigation devices, and missile systems.

These are followed by satellite radio, in-car navigation systems like OnStar, cell phones, local TV stations' live van units, maritime and weather radar, all the way up to fluorescent lighting.

Throughout the upper half of the spectrum, allotments for cell phones and pagers have been made where space was available. From top to bottom there are allocations for various government functions, most of which are classified.

Even the Internet is preparing to make its way to the unwired world, as consumers will use cell phone technology to surf from cars or handheld devices. Soon even the Web will look like today's radio and TV. That's a lot of video, audio, pictures, and data to go wireless.

As new technologies develop and old ones, like radio, convert to digital, the battle for the scarce resource of spectrum is expected to intensify, creating a spectrum traffic jam. "Generally speaking, as technology has advanced, we've been working our way up the spectrum," says media analyst Robert Unmacht.

Consider the most recent figures available from the U.S. Office of Spectrum Management. In 1990 there were 61% more spectrum assignments than in 1980, while at the FCC there were 57% more licenses active in 1989 than in 1980. Until the last decade, advancing technology has always kept ahead of the demand for spectrum, yet today new advances are putting additional pressure on the available spectrum space.