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cwm1276

join:2004-01-16
Stillman Valley, IL

[DTA] DTA pixelation?

I have 1 DTA which has pixelation and says call comcast on others. History 36 and H2 485 seem to be regularly affected. It does not occur at all times, seems worse during the day.

I replaced the rg59 line to the DTA (short run 20 feet) that seems to help for a few weeks and now it back. The other DTA's and full STB's don't seem to be affected.

The cabling is a 3 way split coming in the house.
1. going to EMTA
2. going to 2 way splitter for STB's
3. going to 8 way splitter for DTA's (5 of them)

This was working fine with until a month ago. Most cabling had been upgraded to rg6 with the DTA's. I had just not done this one until now as it was a short run and the DTA seemed fine.

Any suggestions before I call comcast?



gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4

unless you feel like spending money on splitters, i would just call comcast....let the tech come out and check levels....could be your line outside has gone bad....
--
I'm better than you!



THZNDUP
Deorum Offensa Diis Curae
Premium
join:2003-09-18
Lard
kudos:2
reply to cwm1276

Swap the 'bad' one with one that is working fine. That will see if the problem follows the DTA or the outlet.

You could also swap it with one of the STBs to see if another 7db(+/-) higher signal will help.
--
one should not increase, beyond what is necessary, the number of entities required to explain anything



trythisfirst

@comcast.net
reply to cwm1276

probably low signal, a three way to a an 8 way is a min of 16db of loss, unless your drop is like 40 ft it's probably a little low and gonna need an amp.


cwm1276

join:2004-01-16
Stillman Valley, IL
reply to cwm1276

Last night again it was working Fine. I switched DTA's and the problem remains. The 8 way splitter has been there for a couple of years with the DTA's without any problem.

It almost seems heat dependent. At 90+ outside the 1 DTA does not like to work. It cools off in the evening and then the DTA is fine. It does use the 8 way splitter, but has one of the shortest runs in the house. Longer runs from the 8 way are fine.



trythisfirst

@comcast.net

my post was to reinforce the idea that a tech was needed to actually check, sorry for dragging this on longer than it needs to. You need a service call.


cwm1276

join:2004-01-16
Stillman Valley, IL

What happens when it does not happen when the tech is out? I want to have my bases covered before I go in circles with a tech. I will be at work while my wife let's them work, so I need to be able to give them easy instructions and be able to expect it to be fixed.



gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4

low signal is low signal....it will cross the threshold when it gets hot...just call for a tech.
--
I'm better than you!


cwm1276

join:2004-01-16
Stillman Valley, IL
reply to cwm1276

So why would this just start in the last month, heat is the only thing that has changed.

What everyone said before that is the same old stuff that is always said and it worked for years prior. So I can't believe the root of the problem is a splitter. Plus if it is the outside line, why would the DTA with the shortest run in the house have the problem and not ones further away?

A low signal I can believe and I did not know signal could be affected by heat.

So what happens if the tech comes out when it is cooler, and the threshold has not been crossed?

I am trying understand why this could occur as I won't be able to be home when the tech is out.



trythisfirst

@comcast.net
reply to cwm1276

dta's will work with very poor signal, if it's going out there should be a noticeable problem when the tech checks whether it is visible or not. Could be all kinds of stuff, bad piece of cable, bad fitting, physical damage, or a bad dta. The list of probables is long, beyond the scope of the end user really.



gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4
reply to cwm1276

splitters, chewed cable, long stinger shorting out, braid on center conductor, voltage on the coax, water in the cable, corrosion, mandrel of a barrel spread too wide, dta is bad, etc....list goes on and on....and those are just isolated outlet issues...

signal is affect by heat due to metal being affect by heat.....optimum cable temperature is 68*F, once you get over that you start introducing thermal noise onto the line.
--
I'm better than you!



THZNDUP
Deorum Offensa Diis Curae
Premium
join:2003-09-18
Lard
kudos:2
reply to cwm1276

Here is a simple(? ) explanation of temp effect on coaxial cable attenuation.

Coax cable attenuation/loss will change 0.1% per degree F. change.

The attenuation is usually spec'd by the vendors at 68deg F. So a cable having a 1.43db loss/100ft @500mhz at 68deg F will have a loss of 1.47db/100ft @500mhz at 99deg F.

This is just at air temp. A more realistic upper temp would be 120-150 deg F since the OH cable is in the direct sunlight. Using 128deg F, that same 100ft piece of cable now has 1.51db loss @500mhz.

Still not so much of a change right? Remember there are probably many miles of cable between you and the source. Using 2 miles, the total cable loss from the source to you goes from 151db @500mhz up to 159db @500mhz. That is an 8db decrease in available signal. Could definitely be enough to affect marginal levels.

The above is real simplistic just to show what the temp can do. Actual plant will have many more variables.

As far as only the shortest outlet having a problem when fed from a particular port on the splitter? [shrug] Cables and splitters/ports do go 'bad'. Let an onsite tech with a meter figure out what to do.

BTW, would someone double check the math......
--
one should not increase, beyond what is necessary, the number of entities required to explain anything


cwm1276

join:2004-01-16
Stillman Valley, IL

Thanks THZNDUP. That is what I wanted to know. You were able to explain it clearly. It is the hottest summer in a few years.

I never said I was not going to call for a tech, but I don't want to call and have them tell me nothing is wrong, just because it is working while they are here.



THZNDUP
Deorum Offensa Diis Curae
Premium
join:2003-09-18
Lard
kudos:2

Request a later appointment window when it should be happening. Check the weather forecast for that day/time as well.........
--
one should not increase, beyond what is necessary, the number of entities required to explain anything