Fred LaPiana is just one of an unknown number of people who cannot get service from Martha’s Vineyard’s monopoly cable television provider, Comcast.

But as Tisbury’s director of public works and a prime mover in the renegotiation of Comcast’s franchise agreement with Island towns, he is in a better position than anybody to do something about it. Or so you would think.

Back at the start of March, he wrote, in his official capacity, to Comcast, seeking what are known as strand maps, showing how Comcast brings its television signal to the Island, and how that signal is distributed.

And by way of response he got nothing. Comcast claimed the strand maps were proprietary information, and would not forward them.

On Tuesday this week, Mr. LaPiana had another go at it. He prevailed upon the Tisbury selectmen to send another letter, again requesting the map. This time the letter invoked the name of counsel advising the Island towns during the franchise negotiations. It also politely noted that Tisbury had an ongoing project to put utilities underground, in the downtown area, and the information would be helpful.

They await a reply. But assuming they get access to the maps, it will shed light on a couple of mysteries about Comcast’s operation here.

For one, it will give Island authorities a much better idea of how many others are in the position that Mr. LaPiana is at the DPW office, unable to get Comcast service.

For another it might show exactly how Comcast gets its service to the Vineyard in the first place.

“This has been a mystery for years,” said Mr. LaPiana on Wednesday.

“Where does the signal come from, off-Island? We have an idea the signal is transmitted not from the town of Tisbury, but from somewhere in Oak Bluffs. We would like to know what the infrastructure is for getting that signal to us, so we can see if we’re getting the best possible service from the company. That is, state-of-the-art broadband service, which is what we’re trying achieve, and have been for the past two years.

“We want to know what fiber, if any, they are using to bring their signal across,” he said.

Mr. LaPiana has a theory — which is all he can have, given the cable provider’s reticence — that they are piggybacking their service on an NStar fiber cable.

“And that cable was damaged years ago by anchor. There may be six or seven or eight strands of fiber that survived. Is NStar leasing that to them or not?” he asked.

If that is the case, he suggested, it could explain deficiencies in the service Islanders receive.

“To put it simply, they could have a very small pipe and be trying to push a very large signal through it.”

That’s just his theory, of course — although a Comcast spokesman in later conversation with the Gazette gave some credence to it, which we’ll get to later.

Whatever the reason, said Mr. LaPiana: “The effect is huge, although people here probably don’t know because they haven’t experienced the difference from what they can get on the mainland.

“You can’t get HDTV on the Comcast system, for a start,” he said.

Then there was the issue of access. Apart from the Department of Public Works, Mr. LaPiana had little idea of who else lacked service in Tisbury, although he thought some of the areas around Lake Tashmoo were among them. Tisbury, he conceded was relatively well-off. Residents of Chappaquiddick, large parts of Aquinnah and all the Elizabeth Islands were not served, he said.

The quality and quantity of television available through the Comcast network is central to negotiations over the renewal of its 10-year franchise agreement with the Island towns. But the cable issue relates to more than that, although here the picture becomes a bit complicated.

“This franchise agreement only covers TV,” said Mr. LaPiana. “We cannot formally discuss Internet or telephone, even though they are commonly bundled that way.

“The laws have really not caught up to the technology. [They] were written around cable TV alone [but] no one envisaged at the time that you could share a cable and provide Internet or any of that stuff on the same cable essentially,” he said.

Also, the law does not allow for negotiation over the price of service, just the franchise fee Comcast pays to the towns for access to their public ways — in essence the towns’ cut, which is used to fund MVTV and other community services

“But it does give us a forum to discuss informally our pricing concerns,” said Mr. LaPiana.

“By and large we’re concerned about our fixed-income folks and making sure basic services have a modest fee structure. But also of great concern to the whole Island is that we have good broadband capacity.”

Mr. LaPiana is of the view that the only thing which will help on the pricing front is competition.

And for the past couple of years he and the town have been trying to facilitate that, via a company called GPCS, which is in the latter stages of permitting to run a fiber cable from Fairhaven to come ashore at Tashmoo beach.

The plan currently is to have it here by next fall, but already, the group has laid about five miles of conduit, and continues to lay new cable under Tisbury sidewalks as the town pours them.

In response to Tisbury’s letter and Mr. LaPiana’s claims, Marc Goodman, a Comcast spokesman, did reveal something.

The company’s service comes to the Island via an NStar cable, he said.

From there it travels via a combination of fiber and coaxial cable across the Island.

Mr. Goodman said Islanders did have current access to high-definition signal, that Comcast provided 3,000 high-definition program choices per day.

Furthermore, he said, the Island soon would benefit from something called a digital net enhancement project, which would move some channels from analog to digital and increase net speeds.

He said he could not provide precise figures on the number of Island residents who were not served by Comcast, but said the company covered the vast majority of Islanders.