Interoperability is one of the major objectives of P25. Interoperability is the ability of public safety personnel to communicate by radio with users from other agencies or departments. Interoperability with analog radio equipment also provides a migration path to digital. Radio systems offer different levels of interoperability. Task forces need a high level, while a lower level suffices for routine public safety operations. SAFECOM, a US Federal organization concerned with interoperability issues for radio communications systems, has endorsed an analysis which defines six levels of interoperability. The table below summarizes these levels, from the highest (shared systems) to the lowest (swap radios). Levels of interoperability for radio communication systems (as endorsed by SAFECOM)
|Level 6 Standards-based Shared Systems||One large shared system with common or coordinated administration||Supports a full range of features. Wide area.|
|Level 5 System-specific Roaming||Use compatible radios and prearranged roaming agreements and authorizations.||Supports a full range of features. Wide area.|
|Level 4 Gateway (Console Patch)||Dedicated hardware temporarily connects two incompatible systems together via 4-wire audio or RF links.||Requires time and effort to set up on the fly. Radio can’t leave home system.|
|Level 3 Mutual Aid Channels||A Mutual Aid repeater system has been set up. Users manually switch to a mutual aid channel when they want to communicate with users from another agency.||Requires planning and radio programming. Disconnects radio from home system.|
|Level 2 Talkaround/Direct Mode||Users from different agencies select a channel that bypasses their repeater systems. The users communicate directly with each other.||Simple short-term solution. Limited range.|
|Level 1 Swap Radios||One agency supplies some of its own radios to another agency.||Simplest short-term solution. Requires cross-training on radios.|
Interoperability in the following ways may be required:
- Gradual migration to digital
It is not always possible (financially or logistically) to upgrade an entire radio fleet at one time. It is often necessary for the new radios being installed to operate with the existing radios until all can be replaced over a period of time. Only when all the radios have been installed and/or issued can the transition to P25 be completed.
- Day-to-day interoperability
Involves coordination during routine public safety operations, for example: Neighboring law enforcement agencies must work together during a vehicular pursuit.
- Mutual-aid interoperability
Involves a joint and immediate response to a catastrophic accident or natural disaster and requires tactical communications among numerous groups of public safety personnel. For example:
- Aircraft crashes
- Terrorist incidents
- Wide area wild fires
- Task force interoperability
Involves local, state, and federal agencies coming together for an extended period of time to address an ongoing public safety concern. Task forces lead the extended recovery operations for major disasters, provide security for major events, and conduct operations in prolonged criminal investigations.
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