A DTV signal is almost impossible to keep if the set is moving around. I gave up on DTV in the car because even sitting still parked (of course), I could get like ONE station....where I used to be able to choose from about six analogue channels.
I only keep the tuner in the car (as part of the "carputer")...for the possibility of something "happening" and I end up having to TRY and get information while not at home. I have an "Auvio" (or somesuch name) little 7" LCD that has an ATSC tuner, but same problem. If you CAN get a digital station, you certainly can't walk around watching it. The "go or no" quality of the signal means you either get a GREAT pic and sound....or absolutely nothing, so there is no settling for just okay reception.
I don't know a single person that is watching local channels via any antennae in my area. Even the old man downstairs that had the big rabbit ears has had to go to at least "basic" cable....just to watch the local news
That old man downstairs likes my having the "in-house" transmitter in my flat. He can tune to "just over channel 13" and watch whatever I happen to be watching on my cable box...unless I am playing old Lucy reruns from the Archos player...which he also doesn't mind :-)