Appendix:
Project 25.
Project 25 (P25).
Project 25 is set of standards produced through the joint efforts of the Association of Public Safety Communications Officials International (APCO), the National Association of State Telecommunications Directors (NASTD), selected Federal Agencies and the National Communications System (NCS), and standardized under the Telecommunications Industry Association (TIA).P25 is an open architecture, user driven suite of system standards that define digital radio communications system architectures capable of serving the needs of Public Safety and Government organizations. The P25 suite of standards involves digital Land Mobile Radio (LMR) services for local, state/provincial and national (federal) public safety organizations and agencies. P25 open system standards define the interfaces, operation and capabilities of any P25 compliant radio system. A P25 radio is any radio that conforms to the P25 standard in the way it functions or operates. P25 compliant radios can communicate in analog mode with legacy radios and in either digital or analog mode with other P25 radios. The P25 standard exists in the public domain, allowing any manufacturer to produce a P25 compatible radio product.
- Phase 1
- Radio systems operate in 12.5 KHz analog, digital or mixed mode.
- Uses Continuous 4 level FM (C4FM) non-linear modulation for digital transmissions.
- Are backward compatible and interoperable with legacy systems, across system boundaries, and regardless of system infrastructure.
- Provides an open interface to the RF Sub-System to facilitate interlinking of different vendors’ systems.
- Phase 2
- Wll achieve one voice channel or a minimum 4800 bps data channel per 6.25 kHz bandwidth effi ciency.
- FDMA (Frequency Division Multiple Access) solution is finalized (CQPSK), and an alternate TDMA solution is currently under development.
- 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.
- Phase 3
- Will address the need for high-speed data for public-safety use.
- Activities will encompass the operation and functionality of a new aeronautical and terrestrial wireless digitalwideband/broadband public safety radio standard that can be used to transmit and receive voice, video and high-speed data in widearea, multiple-agency networks.
- The European Telecommunications Standards Institute (ETSI) and TIA are working collaboratively on Phase 3, known as Project MESA (Mobility for Emergency and Safety Applications). Current P25 systems and future Project MESA technology will share many compatibility requirements and functionalities.
See also: Digital Modes page.