HD PQ Question

IMHO I think we already hit the HD PQ low last year when they went from 3 mpeg2 channels per qspk transponder to 4 (~18 months or so ago). Since then all HD transponders have been upgraded to to mpeg4 8pspk turbo. I have not seen DISH HD look as good as it is now since DISH had 3 mpeg2 8psk channels per transponder a few years back.

It's true, adding more MPEG-2 HD channels became unreasonable without adding more capacity, and the switch to 8PSK back in 2004 and well as all HD channels being H.264/MPEG-4 now has helped a great deal. However, just as there was a limit to how much they could get out of MPEG-2 before HD equipment upgrades were needed, there is a limit with the MPEG-4, and they have already been sitting on the edge of that limit for a while now with some channels.

highdefjeff said:
FEC schemes all require a minimum amount of signal to work. And if your signal is too low, or if there is too much noise vs. signal, it can cause slow data (low bitrate) which limits the ability of forward error correction (FEC) to be able to even do what it is supposed to.

Ahh yes. FEC schemes is one of the items I couldn't think of. :)

On 110W, 7/8 seems to be used for all of the national QPSK transponders (32Mbps) which is the best QPSK mode available as long as you have a strong signal, and the sat at 110W is new and healthy so all signals are strong. For the 8PSK transponders (for HD) on 110W, the 2/3 (40Mbps) mode is used, which provides the lowest bitrate but is necessary because 8PSK signals are more sensitive to signal disruptions than QPSK. The satellite at 119W is somewhat old and weak, so the code rates for QPSK are mostly 3/4 (28Mbps) for lower transponder numbers and 5/6 (30Mbps) for higher numbers.

As for low signal affecting picture quality, it certainly can be true if you just barely have a watchable signal so that you have blockiness and audio breaking up. Very easy to do if you plant your dish in front of some leafy trees that the wind breezes through. If you're talking about the signal being lower due to a code rate increase, then you would expect better picture quality since the transponder would have more capacity (as long as your signal remains good enough to have a picture of course). Other than that, the signal being higher or lower cannot have an impact on picture quality because the FEC only provides the equivalent of redundant data, not additional data.
 
FEC schemes all require a minimum amount of signal to work. And if your signal is too low, or if there is too much noise vs. signal, it can cause slow data (low bitrate) which limits the ability of forward error correction (FEC) to be able to even do what it is supposed to.

This first sentence alone contains several errors and misconceptions that clearly demonstrate you 1) have never even had a single course in electrical engineering at the college level, and 2) don't have a clue what you're talking about. I have a BSEE and I only had to read the first sentence to realize that you were just cutting and pasting text without having the background to actually understand what it was that you were reading.

This would be even more entertaining were it not for that fact that someone might think that you actually knew what you were talking about.
 
Welcome to the world of HighDeffJeff. He is totally incorrect, but he sure believes he is right:p Honestly, I think he is a good enough guy, just wrong (as do most others)
 
It's not great OTA either. Very shimmery and noisy unless it's a stationary shot like a free throw. Lots of compression artifacts. Still better than SD though, but nowhere near what a good HD broadcast looks like.

I'm afraid the NCAA tourney is not going to be pretty this year on CBS.

Well if you're seeing the same thing OTA then it must be CBS. Hopefully they step it up for the tournament because it looked great last year.
 
ESPN has its own problems too. As far as Dish PQ, IMHO, its better now than it was this time last year. When I moved, I suspended Directv to give the Dish All HD pack a run, was very unhappy with the softness.

I recently dropped Directv to go all OTA, but due to WAF, I needed Food, HGTV and a couple of others. Due to price, I chose TurboHD Bronze, and I must say, The PQ is not bad. I still dont think it equals Directv, but I think its improved and the 722 is a very good dvr.

If I had to rank, Id say D* beats Dish in PQ, for hardware, Tivo and Dish are equal, and Directv is next.
 
FEC schemes all require a minimum amount of signal to work. And if your signal is too low, or if there is too much noise vs. signal, it can cause slow data (low bitrate) which limits the ability of forward error correction (FEC) to be able to even do what it is supposed to.

Here is some information that many of you will find shocking and some of you will still deny.

This is from: "On Shannon and “Shannon’s formula” written by Lars Lundheim of the Department of Telecommunication, Norwegian University of Science and Technology (NTNU)

“Shannon’s formula” (1) gives an expression for how many bits of information can be transmitted without error per second over a channel with a bandwidth of W Hz,
when the average signal power is limited to P watt,
and the signal is exposed to an additive, white (uncorrelated) noise of power N with Gaussian probability distribution."

AND,

"The essential elements of “Shannon’s formula” are:
1. Proportionality to bandwidth W
2. Signal power S
3. Noise power P
4. A logarithmic function (FEC)
The channel bandwidth sets a limit to how fast symbols can be transmitted over the channel.
The signal to noise ratio (P/N) determines how much information each symbol can represent.
The signal and noise power levels are, of course, expected to be measured at the receiver end of the channel. Thus, the power level is a function both of transmitted power and the attenuation of the signal over the
transmission medium (channel)."

AND,

"Why did it take twenty years to fill the gap between Hartley’s law and Shannon’s formula? The only necessary step was to substitute 1+C/N for m in (4). Why, all of a sudden, did three or more people independently “see the light” almost at the same time? Why did neither Nyquist, nor Hartley or Küpfmüller realize that noise, or more precisely the signal-to-noise ratio play as significant a role for the information transfer capacity of a system as does the bandwidth?"

"Shannon, furthermore, uses this concept in his general definition of channel
capacity:
C = max[ H(x) – Hy(x)].
This expression can be interpreted as the maximum of the difference of the uncertainty about the message before and after reception. The result is given in bit/second and gives an upper bound of how much information can be transmitted without error on a channel."

Yes, Virginia, low signal can affect picture quality.
Are you kidding? Where did you get your degree? :rolleyes:
Let me know so I don't send my kids there!
 
When DISH first put up HD there was a great deal of discussion of HD lite- I'm not as expert as some
posting then or others posting now- but I thought 1920 x 1080 was doable (before Japan was talking
about 4x the resolution in a new standard - don't know the exact numbers). I noticed HD channels I got back then - 3 years ago? my aging memory starts to fade - were adjusted and then not as clear, even on lesser HD TV's. There were in depth analyses down and measured and reported as things changed....
 
I think Dish has had 1280x720 and 1440x1080i for awhile. Direct's new HD is supposedly 1920x1080i for 1080i(I think they were doing 1280x1080i which brought out the HD Lite stuff), but its not certain. Directv does, however, have more bitrate per channel than Dish. So even if these providers start passing thru native resolution, it wont stop them from cramming more channels per tp which effectivley hurts PQ too.
 
Dish Network HD quality has been suffering since October 2005 - it's all over the place but mainly on the HD-lite side. Don't get me wrong...quality source progrmaming still displays a pretty nice picture on E*, but there is a discernable difference on FiOS TV, and DirecTV for that matter. Of course, there appears to be an almost endless supply of poor quality HD and stretch-o-vision being pawned off as HD by the programmers these days. I see it daily on FiOS TV. Additionally, the quality of OTA has also degraded with the local broadcasters multicasting 2 subchannels of news and weather. The CSIs and NFL Football lack the snap 'n pop of years gone by.

To be honest, sports on HDNet, TNTHD, and ESPNHD offer a much better picture (greater detail and depth of image). Anyway, here are some bitrates (MPEG2) I pulled from some of my other posts. Although I love Big Ten Sports, and the HD looks pretty good, their sports looks as soft as the Stay Puft Marshmallow Man when compared to HDNet and ESPNHD. In my humble opinion, Big Ten Network HD looks very similar on E*, D* and FiOS TV but high bitrate HDNet and ESPNHD looks better on D* and FiOS TV.

Manhunter 1/22, 13.18GB, 14.06 Mbits, SHWX 874
Michigan vs Northwestern, 17.50GB, 12.96 Mbits, Big Ten 585
Jan Leno 1/23, 6.69GB, 14.39 Mbits, NBC 505
HDNet Fights 1/23, 23.56GB, 17.45 Mbits, HDNet 569
Numbers 1/23, 6.53GB, 14.51 Mbits, CBS 511
NBA DET-HOU 1/25, 27.67GB, 17.57 Mbits, ESPNHD 570
The Last Templar 1/26, 12.31GB, 13.68 Mbits, NBC 505
The Last Templar 1/26, 12.46GB, 13.84 Mbits, NBC 5-1
The Closer 2/16, 7.65GB, 60 minutes, 17.00 Mbits, TNT 551
The Mentalist 2/17, 6.59GB, 61 minutes, 14.40 Mbits, CBS 511
Criminal Minds 2/18, 6.21GB, 60 minutes, 13.80 Mbits, CBS 511
CSI: NY, 2/18, 2/18, 6.33GB, 60 minutes, 14.07 Mbits, CBS 511
CSI, 2/19, 6.40GB, 61 minutes, 14.22 Mbits, CBS 11-1
UM vs. OSU Hockey, 16.33GB, 165 minutes, 13.20 Mbits, BTN 585
HDNet Fights 2/20, 23.80GB, 180 minutes, 17.63 Mbits, HDNet 569
 
I think Dish has had 1280x720 and 1440x1080i for awhile. Direct's new HD is supposedly 1920x1080i for 1080i(I think they were doing 1280x1080i which brought out the HD Lite stuff), but its not certain. Directv does, however, have more bitrate per channel than Dish. So even if these providers start passing thru native resolution, it wont stop them from cramming more channels per tp which effectivley hurts PQ too.

Has anyone ever actually measured the bitrate of DirecTV's HD? I haven't read of any actual measurements... just lots of guessing.
 
Someone at DBS has a screenshot of 1920x1080i that they grabbed after the big D* HD launch in 2008. It has been seen, whether its still there, I dont think anyone says. Current speculation is that its 1080i resolution is 1920x1080i, and they are running 5 channels per 38 mbps tp, which comes to 7.6mbps. These are not variable, so I would reckon that each channel shares an equal amount.

The Dish ones are 43mbps (i think) at 7 channels(??) which is 6.15. Dish is variable so you cant compare them directly. IMHO, its not a guess that D* is giving their channels more bitrate at 7.6.


Digi and P Smith can prob add better numbers.
 
You can't compair D* Vs E* channels Per Transponder. D* is a KA system Completely different then E* KU system when it comes to channel per transponder.
KA has a frequency Range that can't be exceeded I believe in a single orbital location, Where as E* has KU for HD that limits the amount of Transponders that can be used in an orbital location. So 5 channels per transponder doesn't mean the same .
 
I don't think to many really know about D* KA specs. This has been disputed before. I just don't think we have all the info we needed.
Wasn't it "Rad" and "Goliebob" Trying to figure this out in an older thread?
 
I know both companys can lower and raise bites as needed where its needed per Channel or TP. So it always Varys depending on what your watching.
D*vs E* I give it 70/30 70% D* HD is Better. So if your watching Cinemax in HD It is possible certain movies may look better on E* then D* and Vise versa. But again that only about 30% of the time. Like when D* needs it all for their MLB EI or NFLST HD. They will steal some bites from other not quite as important HD channels from time to time.
E* Too.
 
I doubt it matters much. Dish HD looks perfectly fine on my 67" set, and some channels look amazing (NatGEO, HDNet). I could switch to DirecTV but I'd lose my external hard drive archive and VIP hardware. I could switch to Comcast and lose 2/3 of my HD channels and pay through the nose for the privilege. Or I could switch to UVerse and suffer with horrible PQ.

Dish seems to be the best overall at this point in an area that will probably never see FIOS.
 
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