said by 88615298:The OP did not say what his budget was and QAM/ATSC modulators are not cheap.
too bad DirecTV uses neither QAM nor ATSC
A QAM/ATSC modulator would take the output from a DirecTV receiver and feed it over the house coax to the other TVs, which would then "tune" the channel just as if it was OTA. It's the HD version of those old coax modulators that fed a 480 line RCA input over coax on channel 3 or 4.