This extra-speshul piece of mal-designed mal-de-mer has been just one thrill after another. Apparently it's not actually fast enough or smart enough to handle real HD.
Add to that the wildly over-optimistic concept they have of the bandwidth/capacity of their system.
I am not the only person in this complex who has internet AND cable AND HD, and some poor fools actually pay for Comcast's massively overpriced voice-over-IP service. So.
My apartment complex has about 20 buildings, each with 10-12 apartments.
I am surrounded by other apartment complexes. We share the same cable trunk. Amazingly, through the wonder of broadcast packets, there is sufficient bandwidth for the full set of HD channels and regular channels and standard television all on the same cable.
Except. I originally had a basic digital plan that they have grandfathered several times into the next-level, and somehow this MAY have been keeping my digital box from authorizing the full set of channels that I am currently paying for. It certainly makes more sense to me than the idea that there is a SIGNAL QUALITY issue whereby a set of DIGITAL channels is not delivered properly. Unless they're using multiple frequency domains to carry different data over the copper, and it JUST happens that the channels which would be part of a particular package are all on that one special frequency domain, this makes no sense.
Edit to add resolution:
The cable guy was the one who was the trainee last time they "fixed" this problem.
Very friendly, very smart Latino guy. Unlike last time when his trainer did NOT check the breakout box in the apartment, he did, and found that the signal spreader there was leaky (loose connection allowing radio to infiltrate the cable) and the HD Digital box from hell was showing 5+ packet errors per second, which is easily enough to disrupt the signal.
They DO multiplex the digital channels by using frequency domains - this particular domain centered on 26MHz - and contained all the channels I wasn't getting that I was supposed to. And the noise getting in was radio broadcasts at that frequency.
I wonder what uses 26MHz.