P25 Digital Radios


The US Congress, through the National Telecommunications and Information Agency (NTIA), has mandated that all federal government radio operations in the Very High Frequency (VHF) and Ultra High Frequency (UHF) government radio bands be "narrowbanded." The transition to narrowband channel spacing should have been accomplished by January 1, 2005 for the VHF band. The date for "narrowbanding" the UHF band was January 1, 2008. Narrowbanding means the changing from 25 kHz channel spacing to 12.5 kHz channel spacing. This effectively doubles the number of channels/frequencies available for government use in the same amount of electromagnetic spectrum. 

Concurrently, new digital technologies for Land Mobile Radio (LMR) are being developed. This is being accomplished jointly among the federal government, the telecommunications industry, and the Association of Public Safety Communications Officials - International (APCO). The standard for digital LMR radio is known as "P25", "APCO Project 25" and as the Electronics Industry Association/Telecommunications Industry Association "EIA/TIA-102" standard. 

At the recommendation of the Department of the Interior (DOI) Radio Liaisons, DOI decided to adopt the P25 digital radio standard as the standard for all radio purchases within DOI. DOI has also mandated that all radios/radio systems that carry law enforcement traffic comply with the EIA/TIA-102 standard which include encryption capabilities/technologies. These mandates are outlined in DOI IRM Bulletins 1998-001, 1998-002, and 1998-003. 

As of October 1, 2005, the US Department of Agriculture Forest Service (USFS) has also mandated the purchase of P25 compliant radio equipment. The USFS is requiring the purchase of digital P25 radio equipment from the DOI Digital Radio contract. 


DOI Narrowband Digital Radio Contract 

Due to the substantial investment in digital radios, and the potential to realize significant cost savings, DOI established a multi-year, multi-vendor contract for the purchase of P25 compliant digital narrowband radio equipment. The first five-year contract was awarded on August 21, 1998. The current DOI P25 digital radio contract is currently having submitted equipment tested. 

EIA/TIA-102 (P25) Functionality and Capabilities 

There are numerous questions concerning the functionality and compatibility of analog radios vs. digital radios. The biggest question seems to be: "Will the new digital radio work with the current (analog) wideband and narrowband radio systems?" The answer is "yes". All P25 compliant radios are "backward" compatible with both wideband and narrowband analog radio systems. Backward compatibility refers to a P25 radio's ability to communicate with older wideband and narrowband analog technology radio systems. 

P25 radios have a "multi-mode" receive function which allows the radio to be programmed to receive both analog and digital transmissions. However, if a digital channel is currently selected, most radios must be switched to an analog channel to reply in the analog mode. 


Testing for the Fire and Aviation Community 

As directed and chartered by the National Fire and Aviation Executive Board (formerly the National Interagency Fire Directors), the NIICD Engineering and Development Section performs the "Fire Radio Certification" testing for all of the federal wildland fire agencies. Each radio submitted under the DOI Digital Radio contract as a "fire radio" undergoes additional functionality and performance testing. This testing includes "field tests" to insure it will meet the extreme operational requirements of the wildland fire and aviation community. Once a radio has passed these additional tests, a recommendation for inclusion on the "fire certified" list is sent to each of the National Fire Directors at the National Interagency Fire Center. Once approved, the updated list is distributed throughout each director's agency. 


Questions concerning the fire certification process can be directed to NIICD's Engineer