[David MacLeod]

first, before I installed monopoles gusting over 25 wind would slightly vibrate dish reflector. signals were still high.
since I installed poles the winds are actually higher (for the most part 30-40) but my HD picture quality is noticeably clearer on both dvr's. and I mean it is really noticeable.

is it possible for those small vibrations to have been causing a slight loss of HD clarity without causing a noticeable signal strength loss when I'm checking it?

I noticed the difference yesterday within 10 minutes of installing the monopoles but wanted to watch it a bit in case it was a placebo effect.

 

[harsh]

The signal strength/quality numbers don't react instantaneously. If you're getting an intermittent signal, you're going to get a crummy picture.

There is not much middle ground in this and you can't really extrapolate or reconstruct the image from a signal that is being periodically (or aperiodically) interrupted.

 

[David MacLeod]

my pictures always been good, I was wondering if maybe the picture was reacting quicker than the signal meter could.
probably should have mentioned that, I think thats a better way of phrasing it.

 

[RobertE]

There is absolutely no difference in the picture with a signal level of 40 than there is of that of a 95. By the nature of the way things work, you get a picture, severe pixalization, or no picture.

What a signal of 95 WILL get you over a signal of 40 however is a considerably more margin against weather fade.

 

[David MacLeod]

well it is the oddest thing then. unless there was something being done on the D* end while I was mounting the poles I am out of ideas.
both dvr's, both tv's are noticeably better on HD channels.
been no reboots either.

 

[Kansas Zephyr]

There is absolutely no difference in the picture with a signal level of 40 than there is of that of a 95. By the nature of the way things work, you get a picture, severe pixalization, or no picture.

What a signal of 95 WILL get you over a signal of 40 however is a considerably more margin against weather fade.

+1

Digital TV has a cliff.

If you are on the cliff you have THE image. The PQ is the same if you are 1 mile or 1 foot from the edge.

If you are teetering, you have pixelization, blocky, intermittent reception.

If you are off the cliff you have no image.

Beware of the placebo effect.

 

[David MacLeod]

well, maybe it is a placebo effect, but wife also noticed it last night when she got home.
lol, shared psychosis maybe
knew I should have left those mushrooms on the compost pile...

 

[1948GG]

+1

Digital TV has a cliff.

If you are on the cliff you have THE image. The PQ is the same if you are 1 mile or 1 foot from the edge.

If you are teetering, you have pixelization, blocky, intermittent reception.

If you are off the cliff you have no image.

Beware of the placebo effect.

You know, I'm a bit tired of trying to explain why this idea is so incorrect, at first I was going to let it go; but it being Friday, and the Rays/RedSox game is 'droning' on in the background (GO RAYS), that a bit of brainpower can be dedicated toward a response that is quite a bit more accurate.

Yes, on the 'bulk' side of things, there is a 'digital cliff' so to speak.

BUT...

As the signal drops toward that 'cliff', the FEC (forward error correction) AND the transmission error scheme ((DVB-S2 in the case of DirecTV's HD or Ka/Mpeg4/SD transmissions), has to work harder in recovering the bits.

All kinds of 'effects' can be seen (or not, as the case may be) as the signal drops towards that 'cliff'. When (and IF) you see it may depend on several factors; first and foremost, if you have been trained or are natively sensitive to the effects. Second, if your display is sensitive in and by itself, allowing you (whether sensitive or not) to readily 'see' the effects easily.

The display factor is increasingly something to think about, as typical consumers continue to purchase what I (and most others who have worked in the field) consider to be abysmal display technologies, such as LCD, Plasma, and DLP types.

Those continue to get better over the years, but don't hold a candle to CRT's. There are at least 2-3 different technologies that MAY be able to give them a run for their money. Give it another 5 years.

Getting back to the basics, though, the computational power of the receivers (really, the Mpeg2/Mpeg4 decoder chip), is the limiting piece. As the decoder has to work harder, such things as 'mosquito noise' and 'mini-macro-blocking', effects that poor displays can either mask (or exasperate) come to the fore.

Now, to get to your (potential) problem; Yes, as the dish 'wobbles' (and yes, I also am in a 'high wind' area, the other day the sway of the 130' Evergreens across the street from my house were, well, jaw-dropping (!). But 1s I don't believe that putting the dish on a roof or other 'high' areas is a very good idea, mine is as close to the ground (just enough to clear the 15' tall holly trees), I haven't had to 'tweak' the thing (an AT9/Sidecar) since some 2-3 months after original installation some 3 years ago.

But I have put both AT9/AU9Slimlines on the top of multi-story apartment buildings. I think the 'vibration' you may be seeing mechanically on the dish, in severe wind loads, may cause problems as I pointed out above (make the error-correction work harder, and cause visible picture artifacts, even with monopoles correctly installed and make the dish as rigid as you can get it.

If you are really in a VERY high wind area, and can't get the dish lower (do to any number of factors), you may take a look at putting it inside a microwave transparent dome (fiberglass). I have several dishes inside such an arrangement here, both for wind but also for rain/snow protection.

New ones are bloody expensive, but as I'm obviously near the ocean, used radomes are easily found in junkyards. If your wind/snow problems are really something to 'write home about', you might take a look at what you can come up with.

FYI, I have some relatives that live in Bar Harbor, been a few years since I visited. I can easily envision their poor dish holding on to the mount for 'dear life' during several goodly storms a year!

 

[rudeney]

As the signal drops toward that 'cliff', the FEC (forward error correction) AND the transmission error scheme ((DVB-S2 in the case of DirecTV's HD or Ka/Mpeg4/SD transmissions), has to work harder in recovering the bits.

All kinds of 'effects' can be seen (or not, as the case may be) as the signal drops towards that 'cliff'. When (and IF) you see it may depend on several factors; first and foremost, if you have been trained or are natively sensitive to the effects. Second, if your display is sensitive in and by itself, allowing you (whether sensitive or not) to readily 'see' the effects easily.

Getting back to the basics, though, the computational power of the receivers (really, the Mpeg2/Mpeg4 decoder chip), is the limiting piece. As the decoder has to work harder, such things as 'mosquito noise' and 'mini-macro-blocking', effects that poor displays can either mask (or exasperate) come to the fore.

This is correct. The error correction done on these compressed digital signals can certainly result in degraded picture quality when signal strengths are low.

The display factor is increasingly something to think about, as typical consumers continue to purchase what I (and most others who have worked in the field) consider to be abysmal display technologies, such as LCD, Plasma, and DLP types.

Those continue to get better over the years, but don't hold a candle to CRT's. There are at least 2-3 different technologies that MAY be able to give them a run for their money. Give it another 5 years.

This I have to disagree with, especially in regards to plasma. Plasma and CRT technology are almost identical except for the mechanism used to spray electrons onto the phosphors.

 

[Kansas Zephyr]

You know, I'm a bit tired of trying to explain why this idea is so incorrect, at first I was going to let it go; but it being Friday, and the Rays/RedSox game is 'droning' on in the background (GO RAYS), that a bit of brainpower can be dedicated toward a response that is quite a bit more accurate.

Yes, on the 'bulk' side of things, there is a 'digital cliff' so to speak.

BUT...

As the signal drops toward that 'cliff', the FEC (forward error correction) AND the transmission error scheme ((DVB-S2 in the case of DirecTV's HD or Ka/Mpeg4/SD transmissions), has to work harder in recovering the bits.

Sorry you're tired.

But, what you have described is what I called teetering. That's all.

If you have just enough signal for 100% PQ...it will look the exactly same as if you double or tripled the signal (assuming you are not overloading).

Sorry I didn't get into macroblocking, etc. But, I've seen people post on here how much better their PQ was after switching from crimp-on to compression connectors, removing a surge protector, using monster HDMI cables over non-monster brand HDMI cables, and other nonsense.

 

[David MacLeod]

I've never seen a difference swapping cables, unless it was a broken cable

But I have put both AT9/AU9Slimlines on the top of multi-story apartment buildings. I think the 'vibration' you may be seeing mechanically on the dish, in severe wind loads, may cause problems as I pointed out above (make the error-correction work harder, and cause visible picture artifacts, even with monopoles correctly installed and make the dish as rigid as you can get it.

with monopoles there is no vibration, bottom of dish pole is ~6 feet, lnb is just out of arms reach when stretching. its also mounted in a manner that the house itself helps reduce vibration from reflection.
while I wasn't seeing any noticeable artifacting, if I understand you right I may have been seeing a degradation due to the processor having to work harder for error correction.
today (whole week actually) was one of the windier days we've had in a long time and my picture on both units has never been clearer.
dish is extremely rigid now, I can hang off it without it moving.

edit: the vibration I was seeing was movement of approx 1/32 inch across reflector. just enough so that I could see it was vibrating in wind. placing finger on dish edge verified a vibration without a lot of movement.

 

[Kansas Zephyr]

With that minimal amount of movement, I doubt that there was enough signal degradation to make a difference.

But hey, you'll see what you think, or want, or what there was, to see.

Enjoy the better picture.

 

[Grentz]

The only thing CRTs have the edge in are black levels...just as a nature of how they work.

For many years I had access to one of the studios that had full broadcast and over consumer HD quality CRT displays, the studio plasmas still looked better as far as colors except for the black levels, but they came darn close in that department too.

Different types of displays each have their own characteristics and style. CRTs have their own style as well, not necessarily all good or all bad, just different. Personally I am not much for the CRT style as it gives me a headache a lot of the time and is not as clear to my eye. I also prefer LCD over plasma while some like the plasma or DLP look much more. It comes down to your personal preference.

 

[David MacLeod]

I would have chalked it all up to coincidence if the wife, who never catches this stuff, hadn't also noticed it. possible that while attaching poles I may have altered aim a small amount too, I checked and signals were the same as before attaching poles but I may have misread some before.
don't know, picture is better so I'm going to enjoy it