Originally Posted by Word Maestro
Since you are comparing different networks, you may be correct.
However, what explanation accounts for the following?
Lets assume you restricted your viewing to only one network. Lets say it was NBC. If one further assumes that the signal emanating from NBC is picked up by Cox/D*/and Dish, and sent out to the public via their individual facilities, .....why, if the quality of the signal is only determined by NBC, is there a discernible difference between the video and audio provided by Cox, D* or Dish?
Now a viewer may feel that any one of those three entities provides the best HDTV experience. Which of the three they think is best, is of little consequence. Nevertheless, if the source (NBC) of the signal is the same in every case, those discernible differences MUST be the result of signal processing (or lack thereof) by the company which delivers the signal to the viewers home.
You answered your own question at the end of your message.
First, lets rephrase that local stations are not "picked up" by the providers, but are "Delivered" to the providers by the stations based on retransmit contracts - There is a big difference.
Local stations deliver their signal to all the other providers and OTA users. The OTA signal AND cable signal is directly controlled by the local station (ABCHD went down on Cox because ABC had a failure of thier delivery equipment during their studio move and had to get equipment flown in over the holiday) That same signal sent to DirecTV can be RE-ENCODED, RE-SIZED and RE-COMPRESSED from that original signal to fit on their sats in a different mpeg format that is not the original signal anymore. This is why as long as it has been available, there have been no discernable differences between OTA and Cox delivered signals.
The last factor is the tuning and local delivery and display method in the home. Where is the signal tuned depends on a STB, or internal tuner for OTA. Those with internal QAM (Cable tuners) and 8VSB (OTA tuners) see the exact same signal quality between the two outlets. Using a STB to tune an OTA signal or from Cox has the added difference of the STB outputs, the connection method used and the TV's input processing or lack therof on varying inputs. Most STB's outputs are very similar between HDMI and Component connections, but most TV's will do some processing on the component connection, but not on the HDMI connection. Getting all your inputs calibrated helps this dramatically.
As for STB's, each one will have a unique look, similar to how different DVD players look different with the same DVD. SA STB's have been reported as being softer than other STB's as they usually do processing in the analog demain (softer image, but with more detail), while Dish's STB's have been reported as having much harder contrast, eliminating many fine details or thin lines, while emphasizing thick lines with hard edges (harder image with less detail). DirecTV's STB's have been more middle of the road providing decent quality and output that is pleasing to the eye for most users. Until recently, DirecTV used OTA tuners for local HD channels, but their newest STB's will only get the signal from the sat after it's been re-encoded and converted to Mpeg4 format.