P25 Radio Standards

Project 25 (P25 or APCO-25)

Project 25 is a suite of standards for digital mobile radio communications was originally designed for use by public safety organizations in North America. P25 radios are a direct replacement for analog UHF (example FM) radios but add the ability to transfer data as well as voice, allowing for a more natural implementation of encryption or messaging.
Project 25 was initiated by the U.S Association of Public Safety Communications Officials, or APCO. APCO International is the world’s oldest and largest organization of public safety communications professionals. Currently P25 is a popular technology choice for mission-critical communications users with majority of systems in the US, Canada, Australia, New Zealand, South America and the UK.

Project 25 concerns the development of a standard for digital radio equipment embracing the public safety-focused features of interoperability, spectrum efficiency, and cost economies. An important feature of P25 is that the development is user-driven. The needs of public safety professionals are paramount.
Project 25 is not finished. The standards are constantly being enhanced and refined as new requirements are identified. Another key aspect of P25 is the importance of migration strategies and backwards compatibility with existing equipment.

The Telecommunications Industry Association, or TIA, formulates and maintains the TIA-102 series of standards for APCO P25, on behalf of APCO International. The Project 25 standards enable interoperability among multiple manufacturers of P25 products. This results in a greater range of products, both mobile and portable radios used by front line staff and also the network equipment, stored on hilltops and in dispatch centers.

Starting around 2012, products became available with the newer phase 2 modulation protocol, the older protocol known as P25 became P25 phase 1. P25 phase 2 products use the more advanced AMBE2+ vocoder, which allows audio to pass through a more compressed bitstream and provides two TDMA voice channels in the same RF bandwidth (12.5 kHz), .
For more information go to http://www.project25.org/