Application Note: Introduction To Project 25

Project 25 is a digital radio system designed specifically for public safety applications by police, fire and medical services. It will also find applications with utility operators and other government agencies.

With interoperability and maximizing radio spectrum efficiency as fundamental requirements, Project 25 Phase I uses digital voice encoding to reduce the required bandwidth for speech transmission to 12.5 kHz, while simultaneously maintaining backward compatibility and interoperation with the existing 25 kHz analog FM systems. A further development of the specification will reduce the required transmission bandwidth for voice down to 6.25 kHz, thus freeing up more spectrum for future use.

The Project 25 specifications are available in the public domain, enabling multiple equipment vendors to compete for this market with the objective of reducing end user costs and providing interoperability both within and between user communities.

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