I do not think we will be seeing good options for portable digital TVs until the ATSC (the entity) gets their standards fixed up. It seems when the initial standards for ATSC (the format) were adopted, consideration for portable, mobile devices was very lacking. It turns out that portable, mobile TVs cannot get very reception at all using the regular ATSC format due to the fact that they move around. The future
ATSC-M/H (Mobile/Handheld) standard is designed to accommodate these devices.