Emergency Communications 101: Basic Radio Info

Often public safety telecommunication personnel are left out of the loop as technology becomes more and more complicated. We are given systems to figure out and use. With all the radio changes coming at us, we’ve missed out on the basics. Here’s an...


As I browsed the Exhibit Hall and lingered outside professional development sessions at APCO 2013, I found a consistent theme in the conversations I overheard and those I entered myself. Most communication center managers had come to APCO to discover the latest products and the exhibitors did not disappoint. Although there was a lot of glitz and glamour, hardware and software of the future and tons of talk about high-end technological progress, many of the managers had no idea what they were looking at or what all the tech-babble even meant.

Covia Labs, CEO David Kahn summed it up perfectly during our interview when he explained there were a lot of companies producing products designed to make the telecommunicators adjust to the system and not the other way around. He expressed concern that the needs of the telecommunicators were being lost in the process of the next great thing. I would agree based on the lost look in the eyes of so many attendees as they stood in booths being told what that manufacturer’s product could do.

After a conversation with a former co-worker of mine who has been tasked with assisting her major metropolitan communications center into the next generation, I realized somehow we’ve missed a step in this curriculum of new technology: the basics. After speaking with numerous people, research and attending sessions, I present a two-part column on Radio 101.

Equipment

All wireless technologies use radio waves to communicate. Radio waves transmit sound and data invisibly through the air. To use radio waves, there needs to be a transmitter and a receiver. I won’t get into all the technological terms regarding the various parts of equipment but if you’re interested ask your IT personnel. I’m sure they’d be thrilled that you care. Basically, the transmitter takes the message (voice, picture, text, etc) and encodes it into a wave. Modulation is used to encode the message and our systems use frequency modulation to accomplish this. Then, this wave is sent out to a receiver that decodes it by demodulating and then amplifying the message. Both sites use antennae (a metal stick that launches and catches waves) to facilitate this process. A wireless device (such as a cell phone) has the transmitter and receiver inside and can use both simultaneously. Radio towers (antennae) are generally throughout the user area and many times on top of the communications building.

Frequency

One characteristic of the wave is its frequency. The frequency is the number of times the wave oscillates up and down per second. A cycle per second is called a hertz (Hz). Kilohertz (KHz) is thousands of hertz and megahertz (MHz) is millions of hertz. An 800 MHz radio is broadcasting at 800,000,000 cycles per second. As the frequency goes up, the wavelength gets shorter. The radio spectrum is the radio frequency (RF) portion of the electromagnetic spectrum. This is a chart that shows what bands (portions of the spectrum) each wireless technology gets to transmit on. Everything from AM/FM radio, to television stations to individual cell phone carriers to police radios is assigned to a band. A bandwidth is how much space your frequency takes up.        

Analog vs. Digital

Television and cell phones have already switched completely from analog to digital radio waves. Police communication centers throughout the country are a mix of analog and digital. Analog is a continuing stream of electrical signals that vary in intensity over time. Analog signals use modulation and are easily disturbed by environmental interference such as storms. A benefit of analog is that only a portion of the signal is disturbed so partial transmissions can be heard. Digital, on the other hand, changes information into a mathematical code which is sent in non-continuous block segments. These pulses of information are less disturbed by environmental factors but if a segment is disturbed, it is lost in its entirety. Because digital can be confused by background noise, many public safety communications professionals still believe that the “old way” of analog is more appropriate. The good thing about digital is that companies are still researching and developing ways to improve it. Hopefully, one day we will have the best of both worlds and the days of garbled and lost transmissions will be over. 

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