I have a Roamio 4-tuner, currently setup with cablecard. If I recall correctly, this model can also handle the digital signal broadcast OTA by local television stations. I would like to evaluate OTA reception and video quality pursuant to potentially dropping Comcast's TV service. What would you recommend for an indoor antenna? The house is cinder block construction, which I imagine may present some problems, but the TiVo and antenna would be located near an open end of the structure (no cinder block outside wall there).