That is interesting as my signal strength for Cinemax (129 tp27) is 55. Wouldn't the impact on quality due to FEC be consistent across channels with a similar signal strength? My SpikeHD (129 tp26) has a signal strength of 55 as well, yet the quality of the image is quite different. I would expect that the digital OTA signals also include some type of forward error correction.
Remember that there are so many factors that we are dealing with including the difference in quality from the original source. Your FEC is doing equally the best it can at 55 for both streams but the final result is still dependent on other factors. A signal quality of 55 doesn't give us a determination of which bits of data are corrupted or how they will manifest in the picture.
Another thing we have to consider is that it takes more signal (approximately 6 times the amount per second) to render an HD picture than an SD. Even comparing SD to SD or HD to HD, the complexity of the scene and the amount of motion (fast vs. slow) both factor into determining the final quality of the two streams at similar signal readings.
I have included a graph to illustrate. I have rotated the graph so that it would represent increase when read from left-to-right. You might imagine your signal meter bar across the bottom.
The curves on the graph each represent bit streams of differing complexity. The M4 curve represents the simplest SD stream while the M256 represents the most complex. The scale on the right labeled Eb/No is equivalent to SNR. What we need to see here is that for Eb/No of 10, the simple bit stream (M4) we are getting a BER of 10-6, which is good quality. But at the same Eb/No, the complex bit stream is only at BER of 10-1, which is just beyond "signal lock". So while your signal quality reading is 55 for two different feeds, the resulting BER and PQ will still differ.
Before Dish Network supposedly "improved" the signal meter (leveling the signals across all receivers), this was easier to see. A simple SD receiver (311 for example) would give readings over 100 on both 110 and 119 when the dish was peaked. But when an HD receiver was installed on the same system, then signal readings were mid 80's (in STL).
At the time I didn't understand why the HD receivers produced such a low reading, but I used this information to double check alignment. I would check the signal meter on a simpler receiver to make sure the dish was properly pointed. If the signal meter on a 311 that was on an HD dish was as good as on the Dish 500, I was confident (despite lower HD receiver readings) that alignment was good.
Since the signal meter "improvement", they have caused all receivers to mimic the readings of the HD receivers and have decreased the precision of the meter. According to Dish, this was changed to reduce confusion over the variation in meter readings. What they actually did was to remove the "known" and "familiar" readings because of the increase in signal strength complaints and the upcoming roll out of the under-performing Eastern Arc dish.
And, yes, OTA follows the same parameters and uses the same technology. The reason that OTA PQ is better than Dish (only slightly all things maximized) is that with the current size of the dishes in use, you can't even reach the point of too much signal (that causes overload and signal drop out) as you can with OTA. And with the "as long as you have lock" mentality and training provided by Dish, most people are viewing a "portion" of the quality that the system can provide versus when the dish is accurately peaked for maximum signal across all satellites.
The hope of Dish Network is that continued improvement in coding efficiency will compensate for the dishes being too small and the installers not being trained correctly. In the mean time, the signal meter change has kept the complaints and the understanding of signal effects to a minimum, leading us to believe that what you see is what you get.
My hope too, is that better coding will bring better results. Certainly, Dish has made no effort to alter training or to increase the size of the dish. And installers can still tell you, with clean conscience, that signal doesn't matter - because that is what they've been taught.
I am including another graph that represents Errors/Time. It has a red to green scale similar to what you see on your signal meter. I have oriented this graph to again represent the same aspect as your signal meter - increasing quality as you read to the right. You will notice that the curve represented is the same as other BER performance curves, with one exception. Where the errors per second "leave" the scale of the graph, they "rocket" skyward. This graph is pretty much identical to the graph of BER vs MER.
Have no idea can't chk, Burning off stuff to DVD to send to my daughter for X-mas. BTW underline didn't seem to work.
