Will the RCA-dtc100 unit give me HDTV from an antenna, or must the unit be used with a Digital Dish? The Best Buy clerk could not answer the question. Also, if it does decode from off air local sources, is output blank when the source material is analog only. I hope this question made some sense. I can get one of these for about $250.00 Thanks in advance for your answers. Bill PS, I would be using the unit with a Barco 801 FP.