I currently use an external tuner to receive ATSC broadcasts (Hughes HTL-HD DirecTv receiver - this DirecTv receiver allows you to get ATSC/OTA reception without a Directv subscription! ). The tuner is then plugged into my PVR150 for capturing through GBPVR. If I set the tuner format to 480i, then all HD programs are downconverted to SD (which is what I need since I do all of my viewing with the MVP - and that's probably the only format that the pvr150 would record). I use a serial cable connection to change channels with a custom executable that I wrote.
The whole system works great, but I'm wondering if there is a more efficient way to do this? I assume that what's happening is that the tuner is converting from digital to analog, and then the pvr is converting from analog back to digital. It seems like there should be a better way to do this. Are there any ATSC capture cards that will downconvert to SD? Or would you just have to use transcoding afterwords. Transcoding seems like more of a hassle than my present setup, though it would be nice to get rid of the rather large external tuner.