ORLANDO—Architects of an interoperable communications system deployed in southwestern Texas stressed the importance of cooperation, planning and teamwork during a session held this week at the Association of Public-Safety Communications Officials conference.

Robert M. Adelman, public-safety communications manager for the Bexar County Sheriff’s Office, said his team wanted to develop a system that would cover more than 1200 square miles, and would be compatible with nearly 10,000 land mobile radios deployed by 40 agencies working in the county, which includes the City of San Antonio, 22 smaller cities and towns, four military bases, and federal and state agencies.

His first step was to pitch surrounding communities on a cooperative effort and disaster response strategy that “looked beyond our backyard,” he said. The county forged a cooperative agreement with Bexar Metro 911, an agency responsible for operating 18 public-safety answering points, or PSAPs, in a three-county area. The Alamo Area Council of Governments and the Lower Colorado River Authority Utility, charged with monitoring power generation for a 53-county area, also joined the county’s interoperability initiative.

“Cooperation is very critical to future success,” Adelman said. “Until you can establish working relationships with other agencies, how can expect to have any hope of establishing any sense of interoperability?”

Creating these relationships let his agency secure additional funding opportunities and dollars. For example, a $1 million mobile command-and-control bus was purchased through an Urban Area Security Initiative grant, a “powerful funding tool” that lets qualified cities and counties invest in and share equipment, he said.

Bexar County employs a M/A-COM EDACs 800 MHz radio system. In addition, the county’s command center has a six-site simulcast system surrounded by six additional single-site systems tied together with a multi-site switch. There also are more than 50 VHF conventional channels used by various federal, state and volunteer organizations in the county, as well as miscellaneous 800 MHz and 900 MHz trunked systems, which added another layer of complexity.

Bexar County officials asked Catalyst Communications to provide the back-up dispatch portion of their interoperability strategy. The county’s dispatchers needed access to tens of talk groups simultaneously, and wanted advanced functionality, such as Unit ID. It also was important to maintain connectivity to outer single-site transmitters and maintain communications during a catastrophic failure. In addition, they wanted interoperability for those agencies working within, as well as outside, of Bexar County.

“It was quite a communications challenge for this very large county,” Catalyst President Robin Grier said.

The county chose Catalyst’s radio-control-over-IP system consisting of multiple computer gateways and mobile radios, Grier said. The system offers flexibility in talk group selection, links different agencies and orphaned sites, allows for high-speed wireless laptop data transfer and provides a single architecture for back-up dispatch and interoperability.

The system continues to grow. In 2006, the county completed a VHF expansion with seven VHF gateways in two locations linked by 800 MHz gateways.

Adelman stressed the many lessons learned during the interoperability process. He said relationships are paramount, pre-planning essential and flexible tools key. He also encouraged agencies to avoid “warehousing the technology” and instead use the tools regularly so users can learn from each emergency incident and identify areas of improvement.