Tuesday, June 9, 2009
[QUOTE=DefDude;1847431]I get a local channel 55 out of mobile/pensacola. last night I noticed that the size of the pic has shrunk down and will no longer fill the screen on any tv, HD or SD.... with any of my receivers 722,522,322. Even when I stretch or any of the zoom's, It looks like a box in a box in any format. this is one the channels I don't get OTA so my question is, does this have to do with the switch to digital, or Dish. the pic quality does look somewhat darker and clearer but I'm sure if it is because of the smaller pic or because it is now a digital signal.[/QUOTE]
It has to do with low signal strength or poor signal quality.
The shrunken picture is a type of scalability that is built into the MPEG forward error correction. Your television receivers AND your Dish receivers (Directv, digital cable) everything using MPEG has scalability, built right in.
When you have less than the minimum of 70 on a standard digital signal quality meter (everyone's meter except the new improved dish signal meter), there is built-in or rather "written" in, coding that allows for the decoding of a weaker, or compromised signal. It is called Scalable Video Coding extension, and has been a part of HDTV since at least 2005.
One of the types of scalability that is available to use, is spatial scalability. This scalability says, "Since the signal is poor and there is not enough data to produce the full size picture at the proper resolution, then I'll display the proper quality, or resolution, at a reduced size."
These are three types of scalability. They are temporal, spatial, and fidelity scaling options. Broadcasters and TV manufacturers use all three of these handy, low-signal digital tricks.
Spatial scalability is what you are witnessing on your TV. Here the quality remains but the size of the picture decreases. Dish does NOT use this type of scaling because it too easily leads to the truth of the picture/signal relationship.
Fidelity scalability is scaling that reduces the quality of the picture (grainy, blurry) but maintains size. Since most people don't see this difference, and the perpetuation of the "all-or-nothing LIE" says that signal is NEVER the problem, this type of scaling is acceptable to Dish.
Temporal scalability refers to time scalability and accounts for a good portion of the audio sync problems that are being reported. Since these also have a reputation of being blamed on software issues and such, this scaling is also acceptable.
Dish receivers use the fidelity scalability and temporal scalability, but they ditched the spatial scalability as rapidly as they could, after the release of the 811's. When the 811's came into widespread distribution, Dish decided quickly to develop the new receivers that would NOT use spatial scalability. And, they haven't used spatial scalability since.
Did you ever wonder why the 811's were so rapidly converted to 381's? With spacial scaling it is far too obvious that digital picture isn't all-or-nothing. All receivers after the 811's use coding that takes advantage of the quality (fidelity) scalability, and temporal scaling, but NOT to use the spatial scalability. Since compression and bandwidth have been getting the heat from all the "experts" concerning picture quality, Dish thought it good that people continue to blame the "technology" instead of the provider.
If this news got out, they would have to spend more money on training to increase the dish alignment skills of their technicians. Dish would also incur a greater amount of responsibility for the quality of their product because - as I've said over and over the last three years - only a dish that is at absolute peak provides acceptable quality HDTV. It appears that over many years Dish (Directv and Cable) have all been charging for avoidable service calls generated at install by their technicians.
Desiring to avoid a fire-storm of public outrage at Dish (because the picture CAN get better if only their techs were trained properly to maximize signal) they killed spacial scaling and dismantled the 811's. And that brings us back to the burning question, "Why did Dish Network change the signal meter?"
Did I answer that one yet?
Saturday, May 30, 2009
"Temperature - Use the "Low" or "Cool" or 6500K setting - or whichever setting is opposite of warm." Yes, opposite.
I will attempt to explain the relationship between 65K/6500 Kelvin and the "Cool" temperature setting on the television. Perhaps I could bring some "light" to the subject in what I will call:
Why is the temperature of a WARM white light 2000 degrees COOLER than a COOL white light?
I am attaching a couple of light temperature charts that should shed some lig...that should be very helpful in this exploration.
Here is a part of the problem. We have two conflicting arenas for description, and even two seemingly "contradictory" sets of terms to describe light. We describe light by its color, by it's temperature, and by its "feel".
To illustrate this, let's consider fluorescent light bulbs. We have fluorescents that are termed "Warm White" and "Cool white" and also, "Daylight".
"Warm white" fluorescents are found in rooms and places where you desire a "warm emotional atmosphere". They are generally dimmer than the others and they emit a more red spectrum of light. This light is considered to "feel" warm. Red as a color is described intuitively, as warm. The red coals of your fire are around 2100K. They glow with a red light, and the coals are cozy and warm. We attribute the "feeling" of warmth, to the color red. When the quality of this light is quantified on the Kelvin scale, it has a Kelvin temperature of around 2100k. (Kelvin temperature scale refers to the light emission of a black body heated to a specific degree, like a charcoal briquette that glows red.)
The cool white lamps are what is most commonly found in fluorescent fixtures today. Without a trained eye or a side-by-side comparison, these lamps are perceived as white, thus the white of "Cool white". Cool white's color emissions, however, are in the yellow visible spectrum and the lights are indeed yellow. COOL white registers on the Kelvin scale around 4100k; that's 2000 degrees HOTTER, than WARM white. Cool white emotionally "feels" cooler than the red light. Want a hot room? Paint it red. Cool room? Paint it blue.
In the last few years it has come to lig...it has been found that the yellow "Cool white" fluorescents cause eyestrain, computer screen glare, and mood swings, ushering in the days of the Daylight fluorescents.
What is so special about the Daylight bulbs? "Special" is called "Full Spectrum" in lighting or light. These lights emit THE spectrum where WHITE light resides. These lamps give you vibrant colors in a store, and make everything look cleaner. They are also good for your health (complete like sunlight), used to treat bilirubin deficiencies and depression. These are one type of lamp used in color matching and they are also great for use as grow lamps! (Settle down out there!) And guess what? They come in at 6500 on the Kelvin scale. These are truly the white lights because for something to emit the "color" white in light, all of the colors of the spectrum have to be there, because white light is comprised of all of the colors. (Don't confuse this color mixing in light with painting or pigment! In pigments, the opposite is true. Gee that helps, too.)
The reason why Daylight bulbs produce the most vivid color, is that all of the colors of the palette are available in white light. The reason why 6500k is desirable in a television is exactly the same.
Now reference the color charts and take a look at how the mix of terms and temperatures clash.
Now add the television manufacturer's who can't or won't standardize a remote control, user menu, or even the same term for the
"aspect ratio/format/ZOOM/Picture" button. Did I miss any?
Anyway, some manufacturers use LOW/MEDIUM/WARM, some use COOL/NORMAL/WARM, and there are still others. (We'll find out soon enough.)
To refer once again to the lighting situation, why does the warm white fluorescent lamp produce a redder room, and why does a cool white lamp produce a yellower room? Because they lack the parts of the spectrum to produce white, in other words, they don't have all of the colors available to produce white.
What if you use the "warm" temperature setting like everyone else recommends?
I believe that within the calibration world there is a bit of unintentional confusion on this one. That would explain why EVERY television is "hot" on the red.
One thing I am certain of is this: It doesn't take a week to see a great picture, or WOWVision! would have been named, "Call-you-in-a-week-Vision!"
Saturday, May 23, 2009
Why Did Dish Network Change Their Signal Meter?
Recently, Dish Network sent out an announcement that there has been improvements made to their signal meter. The "improvement" did several things - none of which are an improvement from a troubleshooting or an installation standpoint. Let us examine these changes.
One change was to even all the signals across all receivers.
Prior to the signal meter "improvement", each of the receivers (by model number) had different readings. Receivers with the same model number all showed similar signal. The signal meter showed the highest signal readings on the simplest receivers like the 301. Each successive receiver showed a lower reading with the HD/Dual/DVR receivers showing the lowest of all.
The signal meter readings were different for good reason. Two good reasons, actually. The readings reflected the added intrinsic noise of the receivers and they showed the greater signal demands of HDTV.
Dish meters measure signal quality/fidelity/integrity, not signal strength. The meter reflected the difference in the signal integrity between the receivers.
Given: The same signal STRENGTH produces less signal integrity as you add noise.
Each of the higher numbered receivers showed this decrease in integrity as additional components added noise and reduced the integrity of the signal (dual receiver-added tuner etc, DVR capability).
Given: The same signal STRENGTH produces less signal integrity for an HD signal than it does for SD.
The astounding jump to the lowest signals ever, those of the HD models, reflect the need for additional signal. (Warning: Cliff!)
The effects of the leveling signals across models:
Removes the ability to compare other readings in the home.
Removes the ability to switch places with an existing receiver to check the signal integrity of the line.
Removes the question of “Why there is plenty of signal on my SD receivers but not for my HD?”
A second change was to change (reduce) the scale of the signal meter.
Reduction in the scale of a measurement device causes a reduction in precision. (Sad.)
Changing the scale also did away with the one benchmark that there was in digital scale meters. That benchmark is/was 70. Here again, while few remember that there WAS a standard, those who would apply it to the average HD signal readings found across the country would see that HD signal is pretty much ready to fall off the digital cliff!
Effects of reduction of scale:
Reduces the precision of measurement.
Negatively impacts troubleshooting and installation.
Confuses installers and customers.
Effects of changing the scale:
Confuses installers and customers.
Now, of course, there is much guesswork about what is good signal strength. (And the benchmark of 70 that is still used in digital technology, is just not used by Dish.)
Lastly, in the signal meter "improvement", Dish also saw fit to increase the latency time for channel changes.
At present, all receivers read the same meter readings (HD’s lower readings) and all of them change channels far slower than ever. (They increased buffer size to try to accommodate their cliff-dwelling signal, but I’ll address that later.)
Why would changing the amount of time it takes to change channels matter?
As a troubleshooter, the first evidence of low signal readings was slow channel changes. Now they all change at the same slow rate.
Effects of latency time:
There goes another troubleshooting method.
So why did Dish Network change the signal meter?
If you are still wondering why, perhaps you should tune in for part 2.
Something smells fishy, very fishy.