Police scanners allow the public to hear police, firefighter, ambulance and other radio transmissions. During operation, police scanners scan through preprogrammed channels. The type of police scanner depends on the type of radio transmission it is expected to monitor.
Analogue Police Scanners
Analogue or conventional police scanners pick up analogue (non-digital) radio transmissions. A keypad allows frequencies to be entered and stored in the scanner's memory. Many smaller cities and rural areas use analogue radio transmissions.
Analogue Trunking-capable Scanners
In large cities, trunked radio systems allow more users to share the same frequencies. There may be many users sharing a pool of frequencies, and conventional police scanners are unable to monitor all of these users. Analogue trunking-capable scanners successfully monitor trunked radio systems.
Digital Police Scanners
Larger cities are switching to digital systems because of clearer sound and a greater range of reception. With digital systems, channels may be encrypted, and only authorised users hear the transmission. Digital police scanners pick up analogue, trunked and digital radio transmissions and are more expensive than analogue scanners.
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