� P25 comes from the Association of Public Safety Communications (APCO) Project 25 set of standards. This is a broad set of standards that defines a number of methods and requirements for Government and Public Safety agencies to transition to “Narrowband” and digital two way radio communications.There are multiple phases to this transition. Phase 1 addresses the digital radio technology that we will discuss today.

� Within the Project 25 Phase 1 specifications, is the requirement that 12.5 Khz Channel Spaced/ 2.5 Khz bandwidth analog FM voice be supported, as well as 12.5 Khz Channel Spaced Digital Voice. This means that P25 repeaters and radios must support both analog and digital communications. The repeaters CAN operate in a “Mixed Mode” configuration, with the capability to automatically switch between analog and digital modes.

� Includes support for Conventional and Trunked system configurations.

� Equipment is interoperable in both conventional (non-trunked) modes, and in trunked configurations. End user radios still require specific programming to be used on specific trunked systems. TCP/IP networking is included, and there are interoperability standards for it. This assists with providing connectivity between different vendors systems.

� Additional Digital capabilities include Selective Call and paging, Encryption (optional), Over the Air Programming (OTAP), and text messaging.

� Network Access Codes (NAC)–Similar in concept to CTCSS or DCS / DPL. The NAC is a three digit hexadecimal code, that is required for the data packets (Digital Voice) to be accepted for processing in P25 Digital equipment.

� There are two P25 Phase 1 digital mode emission types.Continuous 4 Level FSK (C4FM, 8K10F1E) and Compatible quadrature PSK (CQPSK, 5K76G1E). Each used in a Frequency-Division Multiple-Access (FDMA) mode, with Forward Error Correction (FEC).

� C4FM is usually used in single site and hybrid trunk systems that do not use simulcasting. CQPSK is usually used with larger trunked systems that have simulcasting across repeater sites.

� Amateur Radio usage is typically in C4FM modulation mode.

� P25 Phase 1 Digital uses the DVSI IMBE Vocoder for Digital Voice. 4400 bps speech + 2800 bps FEC + 2400bps signaling info = data rate of 9.6Kbps

� Many two way communications vendors market Project 25 compliant equipment, including Motorola, Icom, Kenwood, EF Johnson, Datron, Harris, Daniels, Midland, Relm, Tait, Thales, Zetron, Vertex, Catalyst Communications, and many others.

� Currently there is not any Commercially manufactured Amateur Radio equipment that will work with the P25 Phase1 digital modes.

� Most Amateur Radio P25 digital activity is accomplished by HAMs using retired or surplus equipment from government agencies, or by individuals who work for government agencies and have radios issued to them that work in the Amateur Radio bands, or by individuals who work for communications companies that support and market P25 equipment.

� Purchasing used P25 digital equipment can be tricky. It is best to rely on someone to assist, who has experience and knowledge of the complexities of various vendors’ equipment.

� Even retired or surplused P25 equipment can be of high quality and very durable. These products were generally designed for Public Safety use in harsh environments. Often they become available due to upgrade cycles, instead of simply being “worn out” or obsolete.

� Used P25 portable and mobile radios can sometimes be purchased for less than $200.00, or as much as $4000.00 +. Pricing depends on the included features and the age of the radio. Most equipment is single band, and then often it is just a certain “split” within a band. There are only a few models of multi-band P25 radios, and they are pricey.

� Programming is often an issue with most Commercial and Public Safety radio equipment. There are a few models, usually quite old, that have software that is freely available. Software for P25 compliant radio equipment can cost hundreds of dollars. Special programming hardware is often also required.

� Sometimes you can find someone who has the software already and they can assist with programming. Programming can be complex, and it is helpful to have assistance from someone with experience on this type of equipment.

� There are a few models, or special versions of models, of P25 radios that have what is known as Front Panel Programming (FPP) capability. The level of FPP editing will vary by radio model. These radios often command a higher price on the used market.

� As mentioned in the beginning of this presentation, the Project 25 Phase 1 specifications call for analog support in both repeaters and user radios. So there is a level of Interoperability right there. Also mentioned previously, are the TCP/IP networking standards to help ensure Interoperability.

� In our Emergency Communications roles, sometimes we need to communicate with government agency employees, and sometimes those employees are also HAMs. Having the ability to communicate with those individuals, whether in analog or digital mode, can be beneficial.

� There are P25 Amateur Radio systems that also have VoIP connectivity, using VoIP systems such as EchoLink.

� P25 Digital can be monitored on-air with a number of COTS radio scanners. It can also be monitored with various computer programs, with certain models of radios / receivers.

� There six P25 mixed mode repeaters in Central Florida at last count.

� The 442.075 mixed mode repeater in East Orange County is a wide area coverage repeater.

� Lake County Government hosts three 2 meter P25 mixed mode repeaters that are networked together on the county network.

� P25 repeaters are in every region of the state, with Central and South Florida having the greater concentrations.