Signal issue only on certain channels

[jtrain73]

Hello, I am a Brighthouse Central Florida customer (Oviedo area) and just had digital cable (HD DVR, SA 8300HD box) installed.

Everything seems to be fine, except a handful of channels in the digital tier (mostly HBO) have pixelization and breakup.

I found the shortcut to see the signal levels on the box, and the QAM SNR level on these HBO channels (which are 627.0 Mhz) is too low at 27 or 26, whereas most of my other channels are 31-35.

Why would I have a signal issue on just this frequency? I have removed splitters, cable modem, etc. from the loop with no difference - this issue exists if I have a direct shot into the box.

Any suggestions? I am hesitant to call BHN without knowing I really need to first.

 

[HDTVFanAtic]

27 is not going to work for a 256 Digital QAM. If the other channels are ok, they need to rebalance your line. Amps and other devices along the route don't keep all frequencies at the same level - thus they need a work order for someone to start working backwards to find out where the problem lies - and then rebalance it so its as flat as they can get it across the entire spectrum.

 

[jtrain73]

Thanks for the reply. I will call them and request a service call. How do they balance the line? What do they do? Is that something they can set in the little green box on my front lawn or do they have to do it elsewhere?

What should I tell the tech to look at when he comes? Just look at the picture on the bad channels? Can he measure the signal on certain frequencies?

 

[iceturkee]

anybody else having problems with tnthd during the nba games? i'm losing video and audio in large chunks at a time. last week's early game seemed okay but i honestly dozed through part of it! bhn says it isn't the network and it must be something on my line.

 

[Khandurian]

Thanks for the reply. I will call them and request a service call. How do they balance the line? What do they do? Is that something they can set in the little green box on my front lawn or do they have to do it elsewhere?

What should I tell the tech to look at when he comes? Just look at the picture on the bad channels? Can he measure the signal on certain frequencies?

Ok, they will send out a tech and check your house lines first. Re-balancing a line is NOT done by the guy they will send out the first time. They have special people to do that.

Here's some information on what that first tech that comes out will do. First he will inspect ALL of your line. He will check to make sure they are RG6 cable. If not, you wasted his time, you will need to call back and have a(n) contractor come out to replace your lines.

If your lines are all RG6, the next thing he will do is check the signal level outside at the house. He will then check the level at the underground tap or the pole tap. This will determine if the drop is good or not.

Most likely if the drop is good, and the lines check out that their good, he may put in an amp to help boost up the signal. At this point, he will call up his main office and report his findings. If he finds that the signals at the pole or ped are low, they will then send another tech that will not even show up at your house.

This tech will go to the closest amp on the main line and boost and re-balance the line.

Although 99% of the times, it's a problem with your house wiring.

 

[iceturkee]

the rg6 is the thick cable right? they replaced my home run earlier this year and ran heavier cable, since my box is a good distance from the pole!

 

[HDTVFanAtic]

Most likely if the drop is good, and the lines check out that their good, he may put in an amp to help boost up the signal.

Everything besides that statement is correct.

If you put in an amp, you will not change your signal to noise balance - as you will boost both signal and noise with the amp.

If someone trys to put in an amp to boost the signal if its low overall, they are not doing it properly anyway. There should be a certain level coming off the tap (which can be changed out with various levels at the box/pole). If its not there, then everyone around you will probably be experiencing the issue as well.

If you have a long run to your house, as you say, then they might need to boost the signal at your house, especially if you have a number of drops. If the signal is at the lower side at the tap - combined with a long run - and a number of drops in your house, an amp is very possible.

However, that will NOT correct the prbblem you reported of a bad S/N Ratio in a certain QAM frequency - and if not a bad piece of coax (unlikely to be so specific in nature as it would roll off at a certain frequency from there on out) it means that the run needs rebalancing.

 

[jtrain73]

First of all my house is a new construction (3 years old now) and my cable is all quad shielded RG6, so very unlikely to be a cable issue.

So I called BHN and they were out yesterday (kudos to them for customer service, I called at 9AM and had a tech out by Noon).

The first tech was a good one, he knew what he was doing and I was able to show him the SNR on the various channels we witnessed the night before. The numbers were higher than the night before, but still on the low side (29-30). Not sure why the time of day would matter (more people using cable modems in my neighborhood at night???).

Turns out we had low signal at our cable box outside (he said -3) and then it is a long home-run of about 50 feet and then another 100 feet to my panel. He installed a +4 amplifier at this point, which he said would help, but he called in the line for a line tech to look at.

>>> Side question: he split the incoming cable line before the amp, 1 line to my cable modem, 1 to the amp (and then on to my cable box and other lines). Why is this done? Can a cable modem not handle an amplified signal??? <<<

To my surprise the line tech was out later that afternoon and he checked the line quality at the box on my front lawn, the main box for our street (down the street a bit) and another box somewhere else. He said he adjusted levels at each of the two other locations and that I should be good now. Long story short, my SNR on the problem frequencies (627.0 for example) is now 31 to 32 instead of 27 and everything seems to be working well now.

If anyone could answer my question about the cable modem, I would appreciate it. Thanks everyone.

 

[HDTVFanAtic]

First of all my house is a new construction (3 years old now) and my cable is all quad shielded RG6, so very unlikely to be a cable issue.

So I called BHN and they were out yesterday (kudos to them for customer service, I called at 9AM and had a tech out by Noon).

The first tech was a good one, he knew what he was doing and I was able to show him the SNR on the various channels we witnessed the night before. The numbers were higher than the night before, but still on the low side (29-30). Not sure why the time of day would matter (more people using cable modems in my neighborhood at night???).

Turns out we had low signal at our cable box outside (he said -3) and then it is a long home-run of about 50 feet and then another 100 feet to my panel. He installed a +4 amplifier at this point, which he said would help, but he called in the line for a line tech to look at.

>>> Side question: he split the incoming cable line before the amp, 1 line to my cable modem, 1 to the amp (and then on to my cable box and other lines). Why is this done? Can a cable modem not handle an amplified signal??? <<<

To my surprise the line tech was out later that afternoon and he checked the line quality at the box on my front lawn, the main box for our street (down the street a bit) and another box somewhere else. He said he adjusted levels at each of the two other locations and that I should be good now. Long story short, my SNR on the problem frequencies (627.0 for example) is now 31 to 32 instead of 27 and everything seems to be working well now.

If anyone could answer my question about the cable modem, I would appreciate it. Thanks everyone.

That's what is needed to be done as the problem was the signal wasn't flat across the entire frequency somewhere upstream and thats why it needed rebalancing.

Many times the problems show up with the change in temps as we have seen over the last 2 weeks - which is probably what happened to you.

A resistor or capicator didn't keep its value with the temp change out in the elements and so it screws up.

As to why the different levels, it can also be temp related. You noted it was worse at night (cold last several nights) and warms up during the day - same reasons - when they go bad.

 

[jtrain73]

Thanks. Any idea on the cable modem split before the amp question (copied in below)?

>>> Side question: he split the incoming cable line before the amp, 1 line to my cable modem, 1 to the amp (and then on to my cable box and other lines). Why is this done? Can a cable modem not handle an amplified signal??? <<<

Basically want to know if it is safe to remove that split and connect the cable modem to an output of the amplifier.

 

[Khandurian]

Everything besides that statement is correct.

If you put in an amp, you will not change your signal to noise balance - as you will boost both signal and noise with the amp.

If someone trys to put in an amp to boost the signal if its low overall, they are not doing it properly anyway. There should be a certain level coming off the tap (which can be changed out with various levels at the box/pole). If its not there, then everyone around you will probably be experiencing the issue as well.

If you have a long run to your house, as you say, then they might need to boost the signal at your house, especially if you have a number of drops. If the signal is at the lower side at the tap - combined with a long run - and a number of drops in your house, an amp is very possible.

However, that will NOT correct the prbblem you reported of a bad S/N Ratio in a certain QAM frequency - and if not a bad piece of coax (unlikely to be so specific in nature as it would roll off at a certain frequency from there on out) it means that the run needs rebalancing.

If everything DOES check out good, good drop, good internal lines, signal at the ped/pole is within parameters, an amp WILL solve the problem. I have seen it more times than I can count.

In alot of areas where I live, the signal at the pole is +30. However, because the house is located on 4 acres of land, the signal loss from the pole to the house is high. Therefore, by adding an amp at the house will resolve the situation. Please dont say that statement is incorrect because it is correct.

As usual, the post is picked apart and the rest of the relevant information is left out because of a disagreement over one sentence.

The following sentences after that tells what the next step is.

If he finds that the signals at the pole or ped are low, they will then send another tech that will not even show up at your house.

Reading a post and only reading one sentence at a time, instead of the whole paragraph is not a good thing to do. It then goes on to say

If he finds that the signals at the pole or ped are low, they will then send another tech that will not even show up at your house.

Ok, so the tech came out and still amplified the line even though the tech KNEW that the signal at the pole was low. Why? Standard Procedure. It "helps" to temporarily relieve the situation. It's not the cure all, but helps. Low tap signals does not mean theres noise in the main line.

Now I can see you asking or going why is that standard procedure? Thats stupid/insane cause all your doing is amplifying noise.

If the drop was bad, or questionable, then yes, that would be the case. If the main line had noise registering, then yes, he would just be amplifying the noise.

In case of a bad drop (main line to the house), He would then replace the drop (or lay a temp if underground as most of those techs wont bury a line) and then he would STILL amplify the signal due to that it will help to relieve the situation if he founds signals at the tap are low.

Just because signals are low at the tap, does not mean that these signals are bad. In this situation it was a re-balance. This does not make bad signals and an amplifier will solve the situation until the line techs can come and re-balance the main lines.

My original post shows the standard procedure of what happens when you call up for a service call and a technician comes out to look at your problem. Which was confirmed by jtrain73.

jtrain73 --
>>> Side question: he split the incoming cable line before the amp, 1 line to my cable modem, 1 to the amp (and then on to my cable box and other lines). Why is this done? Can a cable modem not handle an amplified signal??? <<<

It is rumored, I have not seen it personally, that amplifying the broadband line can/will/maybe/might fry the modem internally. Too much signal coming into the modem will burn out the receiver part of the modem.

The common reason that is told to the customers, is that an amplifier only amplifies the Upstream, (signal to modem) which in turn decreases the downstream (modem to head-end).

Basically it makes it so the modem has to increase its internal power to be able to broadcast its responses. Which in turn can burn out the transmit from being overworked.

 

[stevenl]

Well technicly adding an amp does push the signal away from the noise thats what an amp is designed to do. However it does also cause the distortions to go up. For every 1 DB of of signal gain you increase your distorations by 50%. (give or take)

If it is only one QAM of channels having a problem id be apt to say it may be a problem on the system rather then in your home. However it could be as simple as a connector not installed properly causing trouble for that qam.

as far as levels changing during the winter months this is ALWAYS a busy time for cable guys specially after the first couple big "cold nights" because of the cable expanding and contracting. (when its cold or hot) they install whats known as an AGC (automatic gain control) This device will adjust the signal to the proper levels to keep it high enough to stay away from the noise floor but low enough to not affect the distorations. if this device is working properly you will have seemless change of levels however they are not perfect and are known to go bad. This is usally noticed by signal levels that are inmproper and pixeling on your tv.

hope that helps.


and on Khands point if there is 30db on ANY freq coming out of a tap id say it was a system problem as those levels are to high. Our line ampliifers (750mhz) brands are designed to only push out 39 on ch 61 and 32 on ch 2 (our "test" channels) and around 40 on our digital band. and usally the first tap after the amp is a 23value tap (- 23db flat) so that would give you 16/9 out of the first tap.... to high of signal is a problem as is to low of a signal..

Putting an amp on a line simply because levels are low is a bandaid and often times can create more problems then it fixes. Fix the problem and you will not need an amp. VERY rare case's amps are required like an example Khand gave if the customer has aHUGE 400 drop and 5+ lines an 8 port amp would be needed to compensate all that loss... But if you just throw an amp on a line with bad signal all you get is more bad signal...

and the reason your cable modem just like Khand said is split off is to isolate your line, although the amp will increase the fwd signals it doesnt do the same for the rev. so a 8port amp has 10 DB of loss on the return a 2 way splitter only has 3.5 so putting it on the splitter saves your return path. (upstream)

oh ya and on HDTVFanatics statement you dont want flatt levels out of the tap or on the system as you know the higher the freq the great it attenuates over the cable system, so you want your high freq. (high band) to be very High in signal and your lower freq (low band) can be lower, so by the time it gets to your house or tv then it should be close to flat, but most the time it will be titled with your low band higher then your highband.

 

[HDTVFanAtic]

If everything DOES check out good, good drop, good internal lines, signal at the ped/pole is within parameters, an amp WILL solve the problem. I have seen it more times than I can count.

In alot of areas where I live, the signal at the pole is +30. However, because the house is located on 4 acres of land, the signal loss from the pole to the house is high. Therefore, by adding an amp at the house will resolve the situation. Please dont say that statement is incorrect because it is correct.

As usual, the post is picked apart and the rest of the relevant information is left out because of a disagreement over one sentence.

The following sentences after that tells what the next step is.



Reading a post and only reading one sentence at a time, instead of the whole paragraph is not a good thing to do. It then goes on to say



Ok, so the tech came out and still amplified the line even though the tech KNEW that the signal at the pole was low. Why? Standard Procedure. It "helps" to temporarily relieve the situation. It's not the cure all, but helps. Low tap signals does not mean theres noise in the main line.

Now I can see you asking or going why is that standard procedure? Thats stupid/insane cause all your doing is amplifying noise.

If the drop was bad, or questionable, then yes, that would be the case. If the main line had noise registering, then yes, he would just be amplifying the noise.

In case of a bad drop (main line to the house), He would then replace the drop (or lay a temp if underground as most of those techs wont bury a line) and then he would STILL amplify the signal due to that it will help to relieve the situation if he founds signals at the tap are low.

Just because signals are low at the tap, does not mean that these signals are bad. In this situation it was a re-balance. This does not make bad signals and an amplifier will solve the situation until the line techs can come and re-balance the main lines.

My original post shows the standard procedure of what happens when you call up for a service call and a technician comes out to look at your problem. Which was confirmed by jtrain73.



It is rumored, I have not seen it personally, that amplifying the broadband line can/will/maybe/might fry the modem internally. Too much signal coming into the modem will burn out the receiver part of the modem.

The common reason that is told to the customers, is that an amplifier only amplifies the Upstream, (signal to modem) which in turn decreases the downstream (modem to head-end).

Basically it makes it so the modem has to increase its internal power to be able to broadcast its responses. Which in turn can burn out the transmit from being overworked.

blah blah blah

sorry, you are incorrect

The signal to noise ratio is A RATIO of signal to noise. If you amplify the signal, you amplify the noise and ratio remains the same.

An amp does not help a signal to noise ratio and that part of your post is incorrect - as is your reply.

My original post shows the standard procedure of what happens when you call up for a service call and a technician comes out to look at your problem. Which was confirmed by jtrain73.

Yes, jtrain73 confirmed what i said was the problem - without all the additional stuff you put in that would be checked for first. You went through you standard procedures - I just jumped to the part where I told him what was wrong and confirmed by the solution.

Bottom line - I told him what was wrong both times in the first sentence.

You told him 99% of the time it was his wiring.

I was right - your 5th option was correct.

 

[Khandurian]

whatever, this is the reason why I dont post here. Again you say i'm wrong, im not wrong.

Just cause you skipped standard procedure of what a tech will do when he comes out on a service call. I guess 18 years as a service tech makes me wrong. what ever.

 

[HDTVFanAtic]

whatever, this is the reason why I dont post here. Again you say i'm wrong, im not wrong.

Just cause you skipped standard procedure of what a tech will do when he comes out on a service call. I guess 18 years as a service tech makes me wrong. what ever.

I just spoke to the head of Technical Operations in Pinellas County and if you think an amp solves a signal to noise issue, you need more training.

He also says the balancing at the actives will, as I stated, change from Summer to Winter with the temp changes - especially the cold snaps.

He points out that where you are in the feed determines how bad this is. If you are near the head end and only 1 active down - a 1db change won't be dramatic - but if you are 3+ actives down and all of them shift 1db with the weather change, then all the sudden you are down 3db+ in a certain frequency downstream.

 

[Khandurian]

I never said it would SOLVE a signal to noise ratio. stevenl did. holy crap now your reading things someone else posted as my own. think what ever you want. its now clear you have completely read my post wrong and confusing someone elses post with mine.

Ive tried to drop it but its clear that you dont want to. however, i am no longer gonna indulge your inability to be able to read who's post is who. Goodbye

 

[stevenl]

Which is a true statement, when you amplifie the signal on the line you are doing a "balanceing act" with your noise and distorations. The higher you amp it the more distorations you get but the higher the signal is away from the noise. example on the "express" feeder lines (those that donot feed customers but feed the "feeder lines" that do feed customers) we typically run the signal at a much lower level to keep distorations low (but sacrificing the signal to noise) then when it hits the feeder distribution the signal is cranked up high to push it away from the noise, and because its only going 1-3 amps your not to concerned over distorations as long as you follow the "unity gain" laws, meaning you only gain as much as you lose in a perfect world...

if your noise floor is about -35db to -45db which is acceptable and your fwd signals are say +32 that would be your carrier to noise ratio the differnce between the to.. The higher you amp the fwd signals the further it gets from the noise however the more distortions that are created you get sub-signals created along the regular signals know like CTB (composite triple beat) and CSO (composite second order) in a perfect world if all the amps were liner (input equal to output) these wouldnt show up but unfortunately for us the world is not perfect.

oh and you increase chances of XMOD (Cross Modulation) and HUM Modulation but damnit im not teaching a class here....

 

[HDTVFanAtic]

I never said it would SOLVE a signal to noise ratio. stevenl did.

If everything DOES check out good, good drop, good internal lines, signal at the ped/pole is within parameters, an amp WILL solve the problem. I have seen it more times than I can count.

The mind is a terrible thing to waste.....especially as the only problem that he stated prior to the service call was a a low SN reading of 27 on 627mhz.

its now clear you have completely read my post wrong and confusing someone elses post with mine.

however, i am no longer gonna indulge your inability to be able to read who's post is who.

Last time I checked StevenL doesn't look anything like Khandurian

 

[stevenl]

agreed im much cuter

 

[Khandurian]

Once again, your in-ability to prove me wrong is just mind boggeling. AGAIN you have taken my post out of context.

LOOK CLOSLEY VERY VERY CLOSLEY

Originally Posted by Khandurian
If everything DOES check out good, good drop, good internal lines, signal at the ped/pole is within parameters, an amp WILL solve the problem. I have seen it more times than I can count.

No where in that statement does it say that it has a bad signal to noise ratio.

Im about fed up with your insults. Your second post with a starting reply of

blah blah blah

shows your inability to have a conversation and/or debate in a civilized manner.

He may have called in a service call to the CSR and stated his findings, but guess what, when the technician receives his work order. It doesnt have that information on it. Even if it did, a GOOD technician is going to follow the procedures outlined in his manual. Which is exactly what I posted, and is EXACTLY what the technician did when he was out to the guys house.

Drop it already.