Originally Posted by captain_video
I was always under the impression that digital TV was more or less immune from multi-path interference, or at least less susceptible to it.
If the multi-path signals are much lower in amplitude than the strongest amplitude path, they may not be strong enough to affect the final result at all. That's the good part.
Whereas you used to see "ghosting" and other artifacts on "analog" TV, even at low interference signal strengths.
But when multi-path or anything else does interfere, it tends to mess more up, partly because ATSC digital TV is compressed, which means that a very small number of bad bits can mess up everything completely for a while - even though, last I knew, if I have this right, everything was transmitted twice. The result is that "analog" TV was effectively more robust, in that you could often still figure out what was happening.
Resistance to such problems isn't why the FCC chose digital - quite the contrary. They went digital to make it easier to perform high levels of compression, so that TV signals could be transmitted in less bandwidth, so that the FCC could auction off that bandwidth for other uses, providing more money to the FCC, which is not taxpayer supported. Compression also had the side effects of improving achievable resolution (# of pixels) within a given bandwidth, simplifying encryption (which various content providers and cable operators liked), and digitization and compression made it more practical to transmit the signal over digital networks, such as the Internet and some communications satellites. And it gave AV equipment and chip manufacturers a way to make extra money, because digital outdated a lot of old equipment. Perhaps most importantly, for a while at least, it mostly killed the VCR and DVR markets on OTA signals, making it harder to skip commercials, which the content providers and advertisers, who provide the user fees that largely support the FCC (along with income from auctioned bandwidth), loved.
Anyway, digital is not immune to interference in general. Just look at how sensitive HDTV is to minor HDMI cable connection problems.
Add to that: ATSC "digital" is actually analog-encoded-digital, and old NTSC "analog" contained some digital components, and included some forms of analog compression. Nothing is simple.