mattb said:
If anything, if you can get a digital signal you should be able to get the analog, most Digital stations are not broadcasting at full power (mostly due to saving money or not fully built yet) so the analog area should extend a little further than the Digital area.
Well, I respectfully disagree. With digital, it's an all or nothing (black or white). You either get it or you don't. With analog, you have black and white and various shades of gray.
You may very well get a digital channel in and watchable and still not be able to pick up analog.
Where I lived in Suburban DC is a perfect example. I could watch all of the HD channels there just fine, but there was no way I could get even a grade B analog signal.
Also, nothing we have mentioned so far answers the OPs original question.
Eligability is determine on a number of factors, mainly what's called the Grade B Contour. The Grade B Countour is basically an arbitrary alogrithm that takes in to account terrain, distance from transmitter, transmitter power and various other things like frequency of channel and height above average terrain. From this, a model (Longley-Rice) is constructed and based upon your address, your eligability is determined.
In laymans terms, if the channel you are trying to view is Channel 20 and you live in a mountainous area, you countour would be approx 50-60 miles.
Same channel in the flatlands of Arizona would be 60-70 miles as an estimate.
Hope that clears things up
Casey