Project 25's History
Friday, June 13, 2008 | Comments


By Vladimir Kaminsky

Trying to cope with multiple problems in public-safety radio development, U.S. governmental and standards organizations started the standardization process for public-safety radio technology in 1989. A mandate for all federal agencies to use the standardized equipment followed. Known as Project 25 (P25), this initiative resulted in a set of standards for interoperable digital radio voice and data communications. Though these standards have been in development for a number of years, only recent events forced competition for commercial equipment based on P25. Even with the slow start, proliferation of this equipment has already created a multibillion-dollar industry.

Unlike many other communications standards and technologies in the commercial wireless industry, public-safety users’ mission-critical requirements drove the development of the standards. More than 15 years old, the P25 effort was spurred by the worldwide community of public-safety officials, U.S. federal officials and a group of key suppliers of RF equipment. P25 is no longer a drawing-board event but a robust marketplace of affordable, backward-compatible radio systems, as evidenced by the numerous companies that offer a full suite of P25 interface-compliant integrated mobile and portable voice and data systems.

The primary objectives of the P25 standards process are to provide high-quality digital, narrowband radios that meet public-safety user needs and to maximize interoperability. Additional objectives include obtaining maximum radio spectrum efficiency, ensuring competition throughout the life of systems and ensuring that equipment meets user needs. Although developed in the United States, P25 standards were designed for the global marketplace. P25 radios are produced for any VHF or UHF public-safety band. The standards developed through P25 have been adopted and published by the Telecommunications Industry Association (TIA) and are also referred to as TIA-102 standards. P25 was designed with the specific goal to satisfy the needs of U.S. public-safety agencies, with their dispersed nature and with requirements to economically satisfy agencies with small numbers of users.

P25 defines both digital trunked and conventional operating modes. The standard offers a richer set of features than traditional FM radio and gives the immediate advantage that voice can easily be encrypted and mixed with other data transmissions. P25’s mission includes these key digital standard attributes:

• Backward compatibility and graceful migration. P25 enables system migration, which is backward compatible with existing public-safety communications systems and allows forward compatibility with next-generation radios.

• Scalable trunked and conventional capabilities. P25 enables systems to be scalable from a single-channel conventional system to a regional trunked network. The protocol can be configured in voting, multicast and/or simulcast communications, and still include the talk-around capability required by public-safety agencies.

• Interoperability. P25 enables communications among neighboring systems. This is important for mutual aid where resources are gathered from many different locations. Such interoperability is stressed in the following major areas network architecture; integrated voice and data; spectral efficiency — P25 enables 12.5-kilohertz system migration to 6.25 kilohertz or equivalent spectral efficiency performance; high-level security; and reliability.

Dr. Vladimir Kaminsky has been working in telecommunications for more than 26 years. He started his career in Europe, where he worked on effective coding of digital information for various types of communications channels. He is currently president of Practel, a consulting company with expertise in digital communications, including trunked radio and fiber-optics transmission. E-mail comments to

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