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Allegheny County Radio System Upgrade Project In 2023, ACES contracted with a vendor to design and implement a new digital trunked land mobile radio (LMR) system to replace its legacy analog conventional system that has reached its end of life. The new system will operate in the ultra- high frequency (UHF) band, as did the legacy system, and will provide improved coverage, capacity, reliability, resiliency, and security. The new system will comply with the Project 25 (P25) standards that govern public-safety digital LMR systems. Considered the gold standard for public- safety communications, there are currently more than 1,200 P25 systems worldwide. Nearly 400 public-safety agencies in Allegheny County will use the new system, including the 9-1-1 center, police departments and sheriff’s offices, fire/ rescue departments, and emergency medical services (EMS) agencies. The system eventually might be used by other critical entities within the county and its municipalities — such as port and transit authorities, utilities, parks, public works, and transportation departments.
(TDMA) technology, which provides two talkpaths for every channel; in contrast, analog systems provide one talkpath. In addition, the new system will be trunked. Analog systems assign a channel that is dedicated to a specific group of users; in contrast, trunked systems employ a control channel that dynamically assigns any available channel from a pool to any user at any given moment. The combination of TDMA and trunking will dramatically enhance capacity, meaning that users should be able to access the new system at virtually any time. • Improved coverage — The new system was designed and engineered from the outset to meet the county’s coverage requirements. In contrast, the legacy system was cobbled together in a patchwork-quilt manner, with coverage gaps resulting. The new system design features 32 tower sites, plus two more at Greater Pittsburgh International Airport and Allegheny County Airport, while the legacy system utilized 42 sites. Some of the new system sites will be newly constructed, some of the legacy system sites will be repurposed, and certain legacy towers will be decommissioned. Though the new system has fewer tower sites, they will be more strategically placed due to the system engineering that occurred, resulting in enhanced coverage and the closing of gaps. Further, the new system will be capable of simulcasting, which also will extend coverage over a wider area. • Improved reliability — The legacy system
Benefits of the new system include:
• Improved audio quality — Digital LMR systems provide stronger and clearer voice communications all the way to the edge of the coverage footprint. In contrast, the voice quality provided by analog systems gradually degrades as the user moves closer to the edge. • Improved capacity — The new system will leverage Time-Division Multiple Access
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