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frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

Line Attenuators

I was having a problem with two HD channels not coming in. I removed some of the line attenuators that the original install tech put on the line and all is fine now.

Are the attenuators still really needed? Maybe Verizon has lowered the Db level from about 1 1/2 years ago? i now have only 1 attenuator left on the line coming out of the ONT to the splitter.

danclan
join:2005-11-01
Midlothian, VA

danclan

Member

maybe your cable plant is the issue. Either connections or aging wire.

I know I had specific issue with 2 hd channels and merely refitting all the cables together resolved it.

I wouldn't remove the attenuators unless recommended by verizon as you could damage the stb's.
pdressler
join:2001-03-04
Wyckoff, NJ

pdressler to frankpf3

Member

to frankpf3
I was having some issues with the picture stuttering on HD channels during HD football games. Anyway the tech (who seemed knowledgeable) came to look and saw that my original installer used a few attenuators. He told me that they do cause some problems and that a proper install should not use them at all. The preferred method is to come out of the ONT and split as many ways as needed to have the correct DB level on each line. For me it was 8, so I have an 8 way splitter right after my ONT and no other splitters or attenuators in the system. Note you do not have to use all the lines just because you split it that many times for the correct levels. I have not had any problems since that.

I don't know if this is really legit or not but it seemed to work for me so take it for what it is worth.

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

I had a problem on my DVR which is farthest away from the ONT. Channel 803 and 804 was coming in as "channel unavailable". I removed the attenautor and all is fine. Now I just have one attenuator on the coax coming out of the ONT (the attenuator seems built into the connector, I can't remove it) and this goes into a 3 way splitter, with some in line extenders along the way.

Can the in line extenders reduce the signal also? And why would this be needed at intall alsomost 2 years ago, but now cause me problems? I bet the signal strength dropped for some reason?

matcarl
Premium Member
join:2007-03-09
Franklin Square, NY

matcarl

Premium Member

Line extenders do drop it down a little, but it is a mystery why it would change if nothing was touched. I have noticed slight variations on my lines too which haven't been touched. I wonder if my levels have dropped too.

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

I was one of the first in my area to get Fios TV when it rolled out around November of 2006. I wonder if because most likely their is a larger user base, the Db level has dropped to each home, where 2 years ago, the signal was hotter with less users on board.

if this is true, Verizon is going to have problems with all those initial installs and all those attenuators sitting on everyone's lines.
DMS1
join:2005-04-06
Plano, TX

DMS1

Member

said by frankpf3:

I was one of the first in my area to get Fios TV when it rolled out around November of 2006. I wonder if because most likely their is a larger user base, the Db level has dropped to each home, where 2 years ago, the signal was hotter with less users on board.

if this is true, Verizon is going to have problems with all those initial installs and all those attenuators sitting on everyone's lines.
It doesn't work like that. The signal level on the coax is governed by the ONT. Although the optical power level of the video signal could change, the ONT has an automatic gain control to peg the output level at +18 dBmV.

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

Then why all the attenuators and why such a high gain? Shouldn't the tech then adjust the gain through the ONT?
DMS1
join:2005-04-06
Plano, TX

DMS1

Member

said by frankpf3:

Then why all the attenuators and why such a high gain? Shouldn't the tech then adjust the gain through the ONT?
It's not adjustable. The purpose of the AGC is to maintain a constant output level regardless of the input level. I'm not sure why the ONT designers chose the level they did. It does correspond to the ideal level at the tap for cable TV, but then there is normally a lengthy cable run from the tap to the first splitter with cable. A level of +15 dBmV would have probably been more suitable for most cases. May be they went on the high side because attenuators are cheaper and easier to install than amplifiers.

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

My first and only 3 way splitter is as soon as the coax comes out of the ONT. Then the cable run comes into the house with a few line extenders along the way. i did remove one attenuator they had directly behind the DVR box itself. It did correct my channel unavailable problem. Should I be concerned about frying the box?
knarf829
join:2007-06-02

knarf829

Member

said by frankpf3:

My first and only 3 way splitter is as soon as the coax comes out of the ONT. Then the cable run comes into the house with a few line extenders along the way. i did remove one attenuator they had directly behind the DVR box itself. It did correct my channel unavailable problem. Should I be concerned about frying the box?
1. If you weren't getting some channels, obviously the signal was too low. Taking the signal level up to acceptable levels will not fry the box.
2. It's a rental - who cares?
3. What do the signal levels look like in the diagnostic menu?

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

1.) Ok good point.
2.) Yes, it is a rental, but we all know how Verizon billing works. I don't feel like fighting with them because I received a new box and they are charging me for a damaged one.
3.) I am familiar with the diagnostics menu, but where does it show the signal level?
knarf829
join:2007-06-02

knarf829

Member

»cjhengineering.com/hdtv/ ··· diag.htm

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

Can we get to this menu on the moto boxes? I am used to the diagnostic menu that we normally see by hitting "select than menu". Doesn't look like this though...
knarf829
join:2007-06-02

knarf829

Member

It is a menu for the moto boxes, so of course you can.

The directions are right on the link. Of course, your IMG added an extra select, so it's Off - Select - Select
DMS1
join:2005-04-06
Plano, TX

DMS1 to frankpf3

Member

to frankpf3
said by frankpf3:

3.) I am familiar with the diagnostics menu, but where does it show the signal level?
It doesn't. What it does show is the signal to noise ratio and the AGC level, along with a rating for each (poor, fair or good). You want both to be "good".
JMikeF
join:2005-05-05
Alexandria, VA

JMikeF to frankpf3

Member

to frankpf3
The POS Motorola HD-PVR receiver has a very low tolerance for signal strength that does not fall within a very narrow range. Most FIOS setups run hot with strong signals that can overload these boxes.

I'm hoping that Verizon will do the math and realize that the crap Moto boxes are costing them an arm and leg to support. One tech told me that Scientific Atlanta is working on a replacement.

It can't come soon enough.
DMS1
join:2005-04-06
Plano, TX

DMS1

Member

said by JMikeF:

The POS Motorola HD-PVR receiver has a very low tolerance for signal strength that does not fall within a very narrow range. Most FIOS setups run hot with strong signals that can overload these boxes.

I'm hoping that Verizon will do the math and realize that the crap Moto boxes are costing them an arm and leg to support. One tech told me that Scientific Atlanta is working on a replacement.

It can't come soon enough.
I'm not sure where you get your information from, but the QIP64xx series works with input levels of -12 to +15 dBmV for QAM256. I would not expect any vendor's hardware to support higher levels.

CATV aims to have a signal strength of close to +15 dBmV at the ground block. They do this by having the tap output level 3dB higher, knowing that a few hundred feet of drop cable will attenuate it down. The problem is that the ONT has the same output level, but is only a few feet away from the ground block.

GeekGirl1
Premium Member
join:2007-01-28
Morrisville, PA

2 edits

GeekGirl1 to knarf829

Premium Member

to knarf829
said by knarf829:

The directions are right on the link. Of course, your IMG added an extra select, so it's Off - Select - Select
Thanks! Was wondering how to access it. Works fine.

SNR (Signal to Noise Ratio) is under "D04 Inband Status".

I've got 37.4 dB SNR for my Comcast Sportsnet-HD channel (256-QAM). No errors. That's about 7 dB better than when I had Comcast cable.

fiosanon101
@verizon.net

fiosanon101 to frankpf3

Anon

to frankpf3
Attenuators suck, if they are used they should be placed at the output of splitter. They seems to act up if they placed at the STB.

keyboards
join:2001-02-14
Doylestown, PA

keyboards

Member

said by fiosanon101 :

Attenuators suck, if they are used they should be placed at the output of splitter. They seems to act up if they placed at the STB.
From an RF standpoint, the correct place to attenuate is at the STB (end of the run). This is because if you attenuate at the splitter (assuming home runs to the STBs from the ONT) then the SNR (signal to noise ratio) will get worse since the cable itself attenuates the signal to some extent (depends on the length of the run - the longer the higher the attenuation). In other words, keep the signal big for as long as possible

If your splitter is at or near the STB then it really doesn't matter for the few feet of cable from the splitter to the STB.

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

To contradict your explanation, The Verizon techs installed an attenuator right on the coax coming out of the ONT into a three way splitter. This attenuator is built into the connector and cannot be screwed off.

I have three lines that come into the house, 1 for a HD-DVR, 1 for a HD Box, and one for the Router.

Two of these lines have in line gold splitters for continuation, does that then not qualify them as a "Home Run"???

nteeman
join:2000-11-21
Port Washington, NY

nteeman to frankpf3

Member

to frankpf3
FWIW, the Verizon tech that did my install placed the attenuators at the end of the lines before the STB. He measured the signal at each line end and that level determined if and how much attenuation is needed. After he placed the attenuator on the end of the line he measured it again. He explained to me that this was part of the trainining he received to do the install correctly.
DMS1
join:2005-04-06
Plano, TX

1 edit

DMS1 to frankpf3

Member

to frankpf3
said by frankpf3:

To contradict your explanation, The Verizon techs installed an attenuator right on the coax coming out of the ONT into a three way splitter. This attenuator is built into the connector and cannot be screwed off.

I have three lines that come into the house, 1 for a HD-DVR, 1 for a HD Box, and one for the Router.

Two of these lines have in line gold splitters for continuation, does that then not qualify them as a "Home Run"???
A "home run" would be a direct connection from a single load back to the master splitter.

In the case where one or more runs is split further, it is likely that these runs don't need further attenuation. An ideal solution in this case would be to put attenuators on just the outputs of the master splitter that aren't going to be split further. These should be placed close to the master splitter to maximize the SNR. In practice, however, attenuating everything is unlikely to do any harm since the STBs do accept a wide range of input levels.

Doh! Brain fade. I meant to say that the attenuators should go close to the load, not close to the splitter.

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

My two lines are a direct connection back to the master splitter by the ONT, they just have gold in line connectors because the run was originally too short. The in line conenctors are not necessarily splitters.

Do that then not qualify them as "Home Runs"?
DMS1
join:2005-04-06
Plano, TX

1 edit

DMS1 to nteeman

Member

to nteeman
said by nteeman:

FWIW, the Verizon tech that did my install placed the attenuators at the end of the lines before the STB. He measured the signal at each line end and that level determined if and how much attenuation is needed. After he placed the attenuator on the end of the line he measured it again. He explained to me that this was part of the trainining he received to do the install correctly.
That's a good practical solution since it allows the signal level to be adjusted for each STB without having to know about the splitter configuration and without worrying about the other STB levels changing too.

keyboards
join:2001-02-14
Doylestown, PA

keyboards to frankpf3

Member

to frankpf3
said by frankpf3:

To contradict your explanation, The Verizon techs installed an attenuator right on the coax coming out of the ONT into a three way splitter.
That may be the method your installer used, but it contradicts RF theory and proper practice. I'm sure you installer doesn't have 30+ years as an electronics engineer dealing with signal distribution and SNR issues. That being said, the signal out of the ONT is probably strong enough that it doesn't matter where you attenuate the signal (with the exception of some of the new McMansions that may have extremely long runs).

The install method used by NTEEMAN's installer (posted a few back) is the fully correct way to add attenuators. Bravo to his installer and the training received.

FFJOHNL312
Premium Member
join:2007-12-16
Moorestown, NJ

FFJOHNL312

Premium Member

As a tech outside who has been doing this stuff for a while (voice and data since 11/05 and video since last June), all I can tell you is the training tells us to place the attenuator at the end of the run. No theory, just that it was the best place to attenuate.

Training does you no good unless you decide to pay attention to it and don't carry the attitude of 'I need future work'.

John

frankpf3
Verizon Fios
join:2007-08-09
Huntington Station, NY

frankpf3

Member

Could cold weather add to the "natural" attenuation of a line?
DMS1
join:2005-04-06
Plano, TX

DMS1

Member

said by frankpf3:

Could cold weather add to the "natural" attenuation of a line?
The loss on the coax is likely to be lower in cold temperatures, not higher, but there will typically be very little of the coax exposed to outside temperatures in a FiOS installation.