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Radio Scanner Guide


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Part 2: Technical Tidbits

The 2-way radio systems heard on scanners are similar in many ways to radio signals heard on commercial FM radio and television. All radio signals are examples of electromagnetic waves, like light waves, infrared, and X-rays. The diagram below shows relationship between radio frequencies and other electromagnetic waves. The 2-way radio systems you will hear on a scanner radio are in the "VHF" and "UHF" part of the spectrum. 

Electromagnetic Spectrum Diagram.

In both 2-way radio systems and commercial FM radio, stations are separated by broadcasting on different frequencies. For example, a popular FM music station may be on 103.7 MHz. Another music station may be on 105.3 MHz. Your radio will tune to one station while filtering out the other station because the two stations are on different frequencies. A busy police dispatch station may be on 154.720 MHz while another may be found on 155.700 MHz. Groups of adjacent frequencies are referred to as radio bands. The FM Broadcast Radio Band is between 88 to 108 MHz while 2-way radio systems are most commonly found in the following radio bands: 30-50 MHz, 150 to 162 MHz, 450 to 470 MHz, and 851 to 869 MHz. The Radio Spectrum Diagram below shows most of the major radio bands that scanners receive. This website will help you select a model that includes the radio bands and features you need.

Radio Specturm Diagram

The range of 2-way radio communications depends primarily on the height of the antenna and the power used. Hand-held radios using only a few watts can only be heard by scanners from a few miles away while base stations and repeaters usually can be heard from 30-40 miles or more. Aircraft in flight can often be heard over 150 miles away, making them an easy catch for your radio scanner!

Table of Contents

Part 3:  Monitoring the Action

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