I have the exact same issue cited above - "mosquito noise" and macroblocking (I think). Perhaps I can add some data.
Details
I used to have cable service to my approx 13 yr old 32" Sony TV (obviously standard def). All was well with cable except for pricing and customer service. The picture quality was fine. I switched to Dish a few weeks ago and my picture quality has been poor on most channels. Some details:
(1) I have the standard, "bronze" non HD package
(2) The channels that are labeled "HD" look much better than the others - no image problems. I think my local nonHD channels look better as well - maybe it is the 61.5 satellite.
(3) The standard signals have the PQ issue. It looks like I am watching a low res mpeg file.
(4) The image from my DVD player looks fine.
(5) My satellite receiver is HD compatible and the dish is pointing to the satellites that carry HD signals.
Set-up and Equipment
TV: sony trinitron KV-32S25
receiver: VIP22k
new coax from dish to receiver
RCA (yellow, white, red) to the TV
all connections look / feel ok
The interesting thing is that a few channels are available in HD and SD, and the HD channels seem to be much clearer than their SD counterparts. For instance CBS-C HD is perfect (as much as possible on SD), while CBS-C SD looks like crap. My local channels are all HD and they look great. Picture quality is not bad across the board. That seems to rule out a connection or cabling.
The phone rep went through the typical troubleshooting - switch check, dish alignment, signal strength etc - no change.
During the first visit to my house, the tech acknowledged that my PQ is bad. He gave me a new receiver - no better.
In a subsequent phone call, the rep mentioned that they should have used a SD receiver on my install since I have a SD TV.
The next tech at my house did not think that was the issue, but he went ahead and installed a new dish and pointed it at the non-HD satellites but did not change receivers - no change in PQ. It wasn't until after he left that I remembered the phone comment about an SD receiver.
Given that my cable PQ looked good and my DVD looks great, I know my TV is capable. I think it is the signal.
I'm appealing to the collective wisdom of this forum:
Does anyone know of a difference in the SD signal from the HD compatible receiver vs. the SD-only receiver.
Could that be the issue, as stated by the phone rep?
Any other ideas?