EDACS

EDACS, or Enhanced Digital Access Communications System, is a family of trunked radio systems originally developed by General Electric and later acquired by Motorola Solutions. It is used for public-safety and commercial two-way radio networks to provide shared, scalable communications across multiple agencies or departments. In EDACS networks, each site consists of base stations and a site controller. A dedicated control channel continuously broadcasts system information; when a subscriber unit initiates a call, the network assigns a voice channel from the pool of available channels and routes the traffic to the intended talkgroup. Talkgroups group users by agency, function, or incident, enabling coordinated communications without tying up a single frequency.

EDACS supports digital voice and data, selective signaling, encryption options, and scalable architectures ranging from small municipal systems to nationwide networks. Variants include the original EDACS and EDACS II, and deployments spanned VHF, UHF, and 700/800 MHz bands. The technology was widely adopted in the United States during the 1990s and 2000s, competing with other trunked systems such as Motorola’s Smartnet/Astro and Ericsson’s EDACS-based implementations.

Over time, many agencies migrated to interoperable standards such as P25, due to open standards and interoperability benefits, leading to a decline in new EDACS deployments. Some EDACS networks remain in service, often with ongoing maintenance or migration plans. The system architecture emphasizes centralized or distributed control with dynamic channel allocation, prioritizing rapid, reliable communications in emergency and routine operations.