Communication: How Radio Scanners Work

Radio scanners pick up various frequency waves through antennae and tuners, amplify them and feed them to speakers after decoding for an operator to hear.

The air is full of waves that we cannot see. Switch on a radio set and the plethora of stations will be difficult to keep apart! Television stations and cell phones add to the enormous traffic of radio signals. Radio signals emanate in the form of a wave pattern. Each signal has a distinct pattern that is called a frequency. A radio scanner enables a person to receive signals within a set range of frequencies.

A radio scanner works by tuning in to various set frequencies and tries to locate a particular broadcast or transmission. This could be a music station or news channel or a wireless conversation between 2 or more people. A radio scanner must have an antenna to receive signals. An external antenna will be more sensitive and will have a wider range whereas an internal or an attached antenna makes a scanner easier to carry. The radio scanner has a tuner that is able to distinguish between waves of various frequencies that are received by the antenna. The tuner amplifies a chosen wave by resonating with it. A demodulator decodes the information carried by the wave. The radio scanner displays the frequencies being scanned. The user can control the frequencies to which the scanner is tuned. The scanner can also search for signals within a given range of frequencies on its own. The user, in such a case, can record a particular frequency in the radio scanner's memory. This feature can be used to reach a desired frequency immediately on switching on the radio scanner. Older models of radio scanners come with crystals, each of which works within a certain range of frequencies. Newer models have frequency synthesizers that can receive a wide range of frequencies without the owner having to buy separate crystals.

The resonated and demodulated wave is fed to an amplifier that conveys the sound to speakers. The volume can be controlled as can the background noise. The latter is an important feature for reception and sound quality as there is much static in the air. The static emanates from transmitters that are not in operation at a particular point in time. Some models of radio scanners are small and run on batteries while others are larger and use power from a mains supply. A sound card in a computer can make it work as a radio scanner.



There is a conflict between the ability of a radio scanner to receive signals and privacy as well as security. Law enforcing agencies and the military use very high frequencies beyond the range of ordinary radio scanners but sophisticated models can receive such very high frequencies as well. It is now possible to encode signals in a manner that the lay public cannot listen in on them. Laws govern radio scanning and it is prudent to be familiar with such laws before operating a set. You could also restrict scanning to frequencies that are advertised and widely known to be available for everyone's reception.

Radio scanners have important community roles especially in emergencies. They can be used to receive warnings of adverse weather such as a storm. This can help save damage to property and lives as well.

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