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Digital Radio
Some new radio systems use digital voice transmission in order to
improve sound quality and to provide immunity from interference. These
radios digitize the voice signal by converting it into binary data before
transmitting it. The receiving radio then turns this digital data back
into a voice signal. A person listening to such digital signals without
the correct decoder will simply hear loud noise. Some police, fire, local
government, and even business radio systems are starting to use these
digital protocols. The most common digital protocol, or format, is called
APCO Project 25 Digital Voice Modulation, often referred to simply as
APCO-25. Digital protocols like APCO-25 may be used with either
conventional or trunked radio systems. Fortunately, there are now scanner
radios available that can receive APCO-25 digital voice modulation, listed
in Category 5: Digital Trunking Scanners. Other digital formats and
digitally encrypted signals currently cannot be monitored on any radio
scanners. Fortunately, few departments use these other digital
formats.
If any of the police, fire, or other services you would like to hear in
your area use the digital APCO-25 format, regardless of whether the system
is in conventional or trunked mode, you will need a police scanner in
Category 5. For more information on digital scanners, please see the page on picking a digital scanner. For a side-by-side table comparing models, please see Category 5: Digital Trunking Scanners. Please note that all Category 5 scanners can also
monitor analog conventional and analog trunked systems. If some
departments in your area use analog systems and others use digital, a
Category 5 scanner will be able to monitor both.
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