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Robert
Premium Member
join:2001-08-25
Miami, FL

Robert

Premium Member

[Connectivity] Signal Levels

This morning I was unable to get online. I didn't take a screenshot of my levels then, but my PowerLevel was -9 to -10 dBmV. After I removed the -3.5dBmV splitter for cable modem & TV, I was able to get back online and here is a screenshot of my levels.




I have a tech scheduled for tomorrow. It's been really hot lately, and I think that might be affecting the signal.

I thought -9 to -10 dBmB was still "acceptable" to connect?

Here's what I don't get. Here is what my modem lights look like:




Lights 1, 2 & 3 go solid (2 & 3 are blue). Light #4 just blinks and never goes solid. If it's able to lock into the downstream and upstream, what is light #4 doing?

MDA
Auto Negotiating
Premium Member
join:2013-09-10
Minneapolis, MN
Netgear CM600
Asus RT-AC66U B1

1 edit

MDA

Premium Member

Warmer weather causes the copper conductor in the coax cable to expand and loss some of it's conduction, vice-versa in colder weather. This is probably what you are experiencing.

Lights two and three turn blue if channel bonding is in use so that is good.

EDIT: excuse me, Light FIVE is link activity from your modem to your router so if it blinks, that is a good thing.

Light four probably deals with dhcp registration from the cmts to the modem.
If it doesn't turn to solid green, you might be having T3 timeouts/loss of sync. That may be why your connection is dropping.

Jim721
join:2014-07-31
Belleville, MI

Jim721 to Robert

Member

to Robert
Motorola modems are real sensitive to marginal signal levels your downstream is still in spec but on the low side. Your one upstream channel at 50 is right about as high as the modem can handle and may be going even higher at times this is probably your issue. Is there any splitters you remove or reconfigure ? As far as light 4 that should be solid it looks as if the modem is having a hard time syncing to the network. Light number 5 should be the only light that blinks non stop.

Robert
Premium Member
join:2001-08-25
Miami, FL

Robert to MDA

Premium Member

to MDA
said by MDA:

Warmer weather causes the copper conductor in the coax cable to expand and loss some of it's conduction, vice-versa in colder weather. This is probably what you are experiencing.

Yea, and its been really hot lately. Right now it's 90 and feels like 102.
Robert

Robert to Jim721

Premium Member

to Jim721
said by Jim721:

Motorola modems are real sensitive to marginal signal levels your downstream is still in spec but on the low side. Your one upstream channel at 50 is right about as high as the modem can handle and may be going even higher at times this is probably your issue. Is there any splitters you remove or reconfigure ? As far as light 4 that should be solid it looks as if the modem is having a hard time syncing to the network. Light number 5 should be the only light that blinks non stop.

I removed the splitter in the room where the modem & TV connect in order to get the modem to sync. With the splitter, the modem never syncs.

I haven't touched anything else.

Jim721
join:2014-07-31
Belleville, MI

Jim721 to Robert

Member

to Robert
The hot weather may be your issue but your signals should not get close to out of spec just because it's hot you want to have them were you have wiggle room so problems like this don't happen in the first place.

What are your signal levels now that you removed a splitter ?

Robert
Premium Member
join:2001-08-25
Miami, FL

Robert

Premium Member

said by Jim721:

The hot weather may be your issue but your signals should not get close to out of spec just because it's hot you want to have them were you have wiggle room so problems like this don't happen in the first place.

What are your signal levels now that you removed a splitter ?

The screenshot in my original post are my signals without the splitter. With the splitter, I am at -9 to -10 dBmV.
Robert

Robert

Premium Member

These are my levels WITH the splitter connected.




Interesting.. I added the splitter back, didn't reset my modem, and I'm still online.

Jim721
join:2014-07-31
Belleville, MI

Jim721

Member

Downstream is getting real weak and all 3 upstream are to high.

Robert
Premium Member
join:2001-08-25
Miami, FL

Robert

Premium Member

Good to know. A few years ago they said that the drop needed to be replaced, but they never replaced it and the service started working again as expected. Not sure if the drop needs to be replaced again, or what the solution to this may be.

Jim721
join:2014-07-31
Belleville, MI

Jim721

Member

With the levels being so out of sync with each other and if you can't remove any more splits then you may need a tech to balance your line. Here is what you want to see when things are correct.

Cable Modem
Status Signal Addresses Configuration Logs Open Source Help
This page provides information about the current upstream and downstream signal status of your Cable Modem.
Downstream Bonding Channel Value
Channel ID 1 2 3 4 5 6 7 8
Frequency 555000000 Hz 561000000 Hz 567000000 Hz 573000000 Hz 579000000 Hz 585000000 Hz 591000000 Hz 597000000 Hz
Signal to Noise Ratio 37 dB 37 dB 38 dB 38 dB 38 dB 38 dB 38 dB 38 dB
Downstream Modulation QAM256 QAM256 QAM256 QAM256 QAM256 QAM256 QAM256 QAM256
Power Level
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
2 dBmV 2 dBmV 2 dBmV 2 dBmV 2 dBmV 2 dBmV 1 dBmV 1 dBmV
Upstream Bonding Channel Value
Channel ID 7 8 9
Frequency 34800000 Hz 27900000 Hz 22600000 Hz
Ranging Service ID 14455 14455 14455
Symbol Rate 5.120 Msym/sec 5.120 Msym/sec 2.560 Msym/sec
Power Level 44 dBmV 43 dBmV 42 dBmV

xj31
join:2005-09-25
Lake Villa, IL

xj31 to Robert

Member

to Robert
Click for full size
Not trying to hijack, but if you are having problems with that, how am I not having problems?

Robert
Premium Member
join:2001-08-25
Miami, FL

Robert

Premium Member

Maybe it's my SNR on the downstream and the PowerLevel on the upstream?

What's weird is that if I have the modem connected to the splitter, it will not fully sync and get online.

However, if I connect the modem directly to the outlet, and wait until it syncs, I can then connect the modem back to the splitter (it never drops the connection) and I can surf the Internet (as I am now).

Jim721
join:2014-07-31
Belleville, MI

Jim721 to xj31

Member

to xj31
Wow good question your signals are jacked up...
xj31
join:2005-09-25
Lake Villa, IL

xj31

Member

that's what I said!!!
I was thinking of calling Comcast and see what they say but since I am not having any problems I don't really expect them to care.
Expand your moderator at work

Robert
Premium Member
join:2001-08-25
Miami, FL

Robert to xj31

Premium Member

to xj31

Re: [Connectivity] Signal Levels

said by xj31:

that's what I said!!!
I was thinking of calling Comcast and see what they say but since I am not having any problems I don't really expect them to care.

If you aren't having any problems, I wouldn't call because them trying to fix it, might just make it worse.

MDA
Auto Negotiating
Premium Member
join:2013-09-10
Minneapolis, MN
Netgear CM600
Asus RT-AC66U B1

MDA to xj31

Premium Member

to xj31
said by xj31:

that's what I said!!!
I was thinking of calling Comcast and see what they say but since I am not having any problems I don't really expect them to care.

What you could do though is buy a 15db forward path amp that has 0 amplification on the return.

I have one from antronix and I know Motorola makes some quality ones too, but that would fix your connection (especially that poor snr) right up.
xj31
join:2005-09-25
Lake Villa, IL

xj31

Member

Thanks for the tip.
BTW, I know for a fact it wasn't always like this. I remember the downstream always was very close to zero. The upstream was always around 40.

MDA
Auto Negotiating
Premium Member
join:2013-09-10
Minneapolis, MN
Netgear CM600
Asus RT-AC66U B1

MDA

Premium Member

said by xj31:

Thanks for the tip.
BTW, I know for a fact it wasn't always like this. I remember the downstream always was very close to zero. The upstream was always around 40.

Then I would (if possible) re-tighten all coax connections to the modem and see if it makes a difference.

If not, then either a faulty splitter, drop line, or pole amp is present in your connection.
xj31
join:2005-09-25
Lake Villa, IL

xj31

Member

Yea I tightened everything the other day when I saw this, even at the ped( I think that's what it's called) where it comes into my yard. Made no difference.

Tobin
join:2003-09-21
Burlingame, CA

Tobin to Robert

Member

to Robert
You do have a pretty high uncorrectable error count on one downstream channel even with the splitter removed. Yay for 700 MHz interference.

Robert
Premium Member
join:2001-08-25
Miami, FL

Robert

Premium Member

I just called Comcast to confirm my appointment for today for 5-7PM, and [not] surprisingly, no appointment was scheduled. The rep I spoke to yesterday did note in the account (per the rep I just spoke with) that an appointment from 5-7 was schedule (I didn't tell him the times, so he definitely did read it in the notes).

Nevertheless, I have some last minute errands to take care of, so it worked out and the Internet is still on despite the same levels. I'll probably call back and schedule another tech later this week.
Robert

Robert

Premium Member

Internet was dead this AM until I removed the splitter and connected it directly to the wall.

I think the upstream PL (@ 50-51) is the problem.

I called CC back and scheduled for a tech this Saturday from 1-3PM. Logged into Comcast.net and it confirmed I have an appointment scheduled, so I'm all set.

Will update after the tech is here.
Robert

Robert

Premium Member

Click for full size
Tech just left. The signal to the house was strong, but throughout the house it started losing signal since my office (where the cable modem is) is the furthest point.

He installed an amp (Commscope?) outside and connected the power inside.

Here are my signals now. They are within spec and should be good to go.
Robert

Robert

Premium Member

Click for full size
In case anyone is interested, here is what my box now looks like from the side of my house.

I don't have any before pictures, but prior to this, I had 1 2-way splitter where the cable modem connected to 1 leg of the splitter, and then the 2nd leg went to a 4 way splitter for all the TVs in the house.

The tech also added new connectors to every cable he touched.

I think I'm good to go now for a while.

Jim721
join:2014-07-31
Belleville, MI

Jim721

Member

I dont know much about these amps i have never used one but how is it powered it looks like the power input port is capped.

EDIT: Ok i see another power in just to the left is that hooked to a power supply?

Robert
Premium Member
join:2001-08-25
Miami, FL

Robert

Premium Member

said by Jim721:

I dont know much about these amps i have never used one but how is it powered it looks like the power input port is capped.

EDIT: Ok i see another power in just to the left is that hooked to a power supply?

It's powered using a power wart inside the house that is connected to a cable outlet:




He split the signal from the TV to the power wart using this:




That outlet is now "electrified", and it corresponds to output #1 on the amp. This is how it powers the amp;

Jim721
join:2014-07-31
Belleville, MI

Jim721

Member

Thanks ! Yeah i never used one of those and was just curious.

Robert
Premium Member
join:2001-08-25
Miami, FL

Robert

Premium Member

No problem. The only thing I am not happy with is that if the power goes out, I lose all cable signal. My modem & router are on a backup UPS, and in the past, when the power went out, the internet stayed on.

Oh well, little things in life we have to forgive for the luxury of others.