Project 25, also known as P25 or APCO-25 is a digital radio system used for land mobile applications, especially by the federal, state or province and local public safety agencies. P25 radio is most widely used in North America.

P25 radio is a set of standards that defines the radio system.

P25 radio, APCO & TIA

P25 radio has been defined under the auspices of APCO - Association of Public-Safety Communications Officials. APCO International is an organization of public safety communications professionals.

It aims to serve the needs of public safety communicationsusers and hence provide for the welfare of the general public as a whole. APCO provides expertise, professional development, technical assistance, advocacy and outreach.

APCO promotes many projects. These are given project numbers, and hence the project to develop a standard for digital radio communications for the emergency services was given a project number - Project 25. The name Project 25 or P25 radio has remained with the technology.

The standards themselves are held under the auspices of the TIA, Telecommunications Industry Association.

The P25 standard was established in October 1989 when APCO2, NASTD3, NCS4, NTIA5 , andNSA6 collaborated in the creation of the APCO-NASTD-Fed Project 25 which is now known as Project 25. The system is now widely used in North America and has grown its presence in Australia (APCO Australasia).

What is P25 radio

P25 radio is a standard that defines a form of interoperable digital two-way wireless communications products. The P25 radio system was developed in North America with state, local and federal representatives and Telecommunications Industry Association (TIA) governance.

The P25 radio standards are administered by the TIA (Mobile and Personal Private Radio Standards Committee TR-8). P25 radio technology uses digital techniques for the transmission of voice and data.

The P25 radio technology is being developed in two phases:

  • P25 Phase 1

    The phase 1 Project 25 radios can operate in 12.5 kHz analogue, digital, or a mixed mode format. The Phase 1 radios use a form of modulation known as Continuous 4 level FM, C4FM. Phase 1 P25 compliant systems are backward compatible and interoperable with legacy FM systems. In addition to this, the P25 standards provide an open interface to the RF Sub-System to facilitate interlinking of different vendors' systems.

    P25 Phase 2

  • Phase 2 P25 radio systems are based around a 6.25 kHz channel bandwidth> within this they achieve one voice channel or a minimum 4800 bps data channel. P25 Phase 2 uses FDMA - frequency division multiple access and the modulation format is CQPSK. An alternative 2 slot TDMA solution is currently under development. Phase 2 implementation achieves the goal of improved spectrum utilization. Also being stressed are such features as interoperability with legacy equipment, interfacing between repeaters and other sub-systems, roaming capacity and spectral efficiency/channel reuse.
  • P25 Phase 3

  • With the growing need for high speed data in many areas, Phase 3 of the P25 radio standards will address this requirement. Additional features are aimed at providing functionality for a new aeronautical and terrestrial wireless digital wideband/broadband public safety radio standard that can be used to transmit and receive voice, video and high-speed data in wide-area, multiple-agency networks.

For more information about P25 Contact AA Radio