The Duke County sheriff has secured $1.7 million in state funding for the next phase of upgrading radio communications for Martha’s Vineyard emergency departments.

The grant comes from the Massachusetts 911 Department, which oversees the 911 emergency call system in the commonwealth.

It is the second part of a four-phase project, Sheriff Bob Ogden said.

“This is the construction piece of it,” Sheriff Ogden said, speaking about the project. “This is when we start building the infrastructure, while the first year was all about planning.”

The planning phase began last year when the proposal to upgrade the Island’s emergency services communication networks was reviewed by the Martha’s Vineyard Commission as a development of regional impact (DRI).

The commission approved the plan to build a new 140-foot emergency services tower at the Oak Bluffs transfer station as well as refurbishing five towers already in place in different locations.

Currently, Island emergency services personnel rely on a radio system that uses outdated technology. The system includes copper lines that have degraded to a point where there is little to no service in many key points on the Island.

The current network also relies on a so-called spoke and hub system, with a centralized tower at the sheriff’s office near the airport. If the centralized tower, or hub, goes down, Island emergency services departments would lose their ability to communicate with each other. And if one of the spokes goes down, an entire town could lose the ability to communicate with dispatch and other departments.

“There are hundreds of examples where police, fire and EMS haven’t been able to communicate with each other,” the sheriff said. “It poses a real threat to public safety.”

The new network will operate on a redundant system, creating a backup loop for communications to hop one of the other five towers in the event of a storm or a situation where communication through the closest tower goes down. Essentially, the sheriff said the new system will create backup capability which does not exist currently.

He also said the new network will be a closed public safety communications system so nonemergency personnel can’t tap into the chatter with police radios and possibly clog the system.

“The state is confident that we are doing the right thing and moving in the right direction for supporting MV communication,” the sheriff said.

He said the plan calls for the infrastructure to be built by the end of 2020; from there the department can go on to the next phases of development.