I’ve been logging something on 87.9, too, lately (at first confusing it with our friend on 97.7), up here in the Danvers-Beverly-Peabody area.
Then, last Saturday, over at Market Basket on 114 in Middleton, a weird mix was on—including one of Madonna’s oldies—that I also thought was coming from a local bluetooth/FM converter type microtransmitter.
Then I caught an ID, “Custom Radio” (or something like that), that also seemed to me to sound like a nursing home/hotel/store type audio service.
On a related note, I’ve also noted a weak Spanish/Creole/(Italian?) pirate on 107.1 at times—isn’t there one in the Mattapan-Dorchester area? It sounds more like an old fashioned, one lung, night/weekend bedroom operation, rather than one of the big time, “commercial”, flamethrowing pirates!