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Donat76
join:2003-01-26
Oelwein, IA

4 edits

Donat76

Member

[Qwest] DSLAM power back off or AM station making DSL modem retrain daily.

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The first 2 pictures are the bit bins numbered 0 - 511. Each bin is 4.3125 kHz wide.
0 - 31 Upstream
33 - 511 Downstream
Bin 220 is AM 950 KOEL
Bin 440 is AM 950 KOEL second harmonic interference. (Thanks Brugar)
Picture 1 is trained during daytime.
Picture 2 is trained at night. Training at night is bad for when morning comes.

»www.kitz.co.uk/adsl/adsl ··· cut_back

1) 5:00pm - AM station decreases power or DSLAM increases power.
2) 5:00am - AM station increases power or DSLAM backs off power. Modem retrains at lower speed.
3) 7:30am - AM staion increases power or DSLAM backs off power yet again. SNRM drops to 3dB.
4) I noticed what happened at step 3 because modem is throwing tons of errors and I reboot modem. Modem retrains at same lower speed but with different bins.

»www.google.com/search?q= ··· back+off

My old modem (PK5000) and new modem (C1000A w/ Updated Firmware) both reset daily around 5am. This started around the second or third of December 2014. This happened when I had either modem synced at my old speed 7Mb/s or 12Mb/s. Here are my speed tests for the last 2 years or so. When the radio station comes up from low power to high power in the morning, my modem logs huge errors and retrains. So the DSLAM sees this as my line being unstable and kicks me down to a lower speed although it could retrain at the full speed just by using different bit bins.

»www.speedtest.net/result ··· 5b&ria=0

This all just started around the 2nd of Demember. Before then my connection was rock solid for over 2 years.

This could be a misconfiguration at the DSLAM since a power back off would make the interference seem stronger across all bands or the AM radio stations are coming up to full power in the morning.

I really would like to know what is going on and why this just started happening around the very beginning of December.

I can't change the interleaving depth since the modem and DSLAM configure that so the modem has around a 6 dB margin. If I train at the highest speed, my interleaving goes up and but the margin is still 6 dB. Even when I was at the lower speed my modem would have aprrox a 6dB margin with very little interleaving depth.

There are some modem comands to increase the SNR margin or lock out certain bit bins but that really shouldn't have to be done and may cause more problems in the long run because it might "confuse" the DSLAM why the modem is doing this and it might see it as more unstable then the interference or "DSLAM power back off" is making it.

Either way, I am ordering a couple of these type 77 ferrite toroid cores to filter out the common mode noise from the AM stations and other interference.

»palomar-engineers.com/fe ··· te-cores
»palomar-engineers.com/fe ··· election

KA0OUV
Premium Member
join:2010-02-17
Jefferson City, MO

KA0OUV

Premium Member

Sunset, Pre-Sunrise, and Sunrise power changes. Schedules for these change monthly for directional AM Stations.

»transition.fcc.gov/fcc-b ··· id=28475

Schedule is squeezed during December and January. You will see the times changes as the days get longer.

They may also have made adjustments to their directional array that laid more power over wiring that feeds you. Telco may have also changed your wiring from the DSLAM and that is affecting you more. Changes in grounding anywhere along the path from the DSLAM to you, seasonal temperature changes, and ground conductivity changes all play in as well.

Sorry I can't point to an exact cause, but I hope I gave you a little more background.

Tim
[KA0OUV]

Ken1943
join:2001-12-30
Brighton, CO

Ken1943 to Donat76

Member

to Donat76
Station must be very close and running high power, 500kw. I was my companies rfi guy for telephone interference. Never heard of rfi with internet wiring though.

w2bdp
Donat76
join:2003-01-26
Oelwein, IA

Donat76 to KA0OUV

Member

to KA0OUV
Thank-you! I just had started looking for the FCC information for KOEL since this just started the very beginning of December after 2 years of rock solid signal with no retrains unless I rebooted the modem. This is exactly the info I was looking for. If it is something KOEL changed, I will find out. If CL / Qwest changed anything, I will eventually track that down too. (Hopefully.)

Will those ferrite toroids I linked to help filter out the common mode noise?
brugar
join:2002-09-16
Las Vegas, NV
·CenturyLink

1 edit

brugar to Donat76

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to Donat76

Re: DSLAM power back off or AM station making DSL modem reboot daily.

ADSL2+ uses 512 carriers (sometimes called bins or tones) at integer multiples of 4.3125 KHz. Some of those carriers fall in the range of frequencies used by AM radio stations. Tone 220 is near the KOEL broadcast frequency at 948.75 KHz. Tone 440 is near the second harmonic of the KOEL broadcast frequency at 1,897.50 KHz.

Your DSL/telephone line uses a twisted pair of wires to provide a what is called a balanced circuit. With a perfectly balanced circuit, your phone line does not pickup 60 Hz power hum or AM broadcast signals. Since no circuit is perfectly balanced, ADSL2+ modems look for interfering signals and avoid using those bins where interference is present. They also dynamically adjust the usage of bins as interfering signal come and go (bit swap).

There may be a corroded splice on somewhere on Centurylink's line which has unbalanced your circuit. A telephone line protector module at your NID may have failed.

The most obvious symptom of an unbalanced phone line: You hear noise when you use your telephone.

CenturyLink will want to know whether the problem is in your inside wiring or their circuit. The Network Interface Device (NID) on the side of your house has a test jack. Your need to connect you modem to the test jack to eliminate your house wiring as the source of the problem before you call CenturyLink to report the problem.

A couple temporary solutions that will probably reduce your bandwidth may prevent modem retraining:

Use the Advanced feature of DSLstats to turn off the bit swap feature after the modem has trained in daytime.

Configure the modem for ADSL operation instead of ADSL2+. Since you mentioned training the modem at 7 Mbps, you may have already tried this.
Donat76
join:2003-01-26
Oelwein, IA

Donat76 to Ken1943

Member

to Ken1943

Re: [Qwest] DSLAM power back off or AM station making DSL modem retrain daily.

said by Ken1943:

Station must be very close and running high power, 500kw. I was my companies rfi guy for telephone interference. Never heard of rfi with internet wiring though.

I don't think AM stations would effect the telephone since that is at a very low frequency but ADSL operates up to 1.1 MHz and ADSL2+ operates up to 2.2 MHz. I only have google knowledge when it comes to those things though.

And yes, those AM radio towers are just across town. DSL (phone lines) are good antennas.

KA0OUV
Premium Member
join:2010-02-17
Jefferson City, MO

KA0OUV to Donat76

Premium Member

to Donat76
If you don't have a whole house DSL filter, I would start with that. The ones CenturyLink (Ex-United Telephone/Sprint-United Telephone/Embarq here) use are very good at helping. There is also a model I used at my mother's house (close to a 1kW/500w Non-Directional AM) that would snap into the Corning Demarcation Box. But keeping DSL separate from the telephone Inside wiring in the house will help.

The Palomar stuff will help as well. They have good resources to help get it installed correctly.

Good Luck!
Tim
[KA0OUV]
Donat76
join:2003-01-26
Oelwein, IA

3 edits

Donat76 to brugar

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to brugar

Re: DSLAM power back off or AM station making DSL modem reboot daily.

said by brugar:

Tone 440 is near the second harmonic of the KOEL broadcast frequency at 1,897.50 KHz

Thanks for the info on the harmonics. That would explain why the interference drops at both areas at the same time.
said by brugar:

CenturyLink will want to know is the problem in your inside wiring or their circuit.

When I first got DSL internet, I got a new NID on the outside of my house and ran some Cat 5e directly to the modem jack. The DSL filter is in the NID.
said by brugar:

A couple temporary solutions that will probably reduce your bandwidth may prevent modem retraining.

I can lock out those channels in my modem and it would still be able to train me at the highest speeds but I would have to do it manually every time I reboot my modem or the power goes out. I also think CL / Qwest is also backing off the power on the lines in my area because of cross talk with other dsl lines. So if my modem is trained at a lower speed, they can still back off the power so I have the 6dB margin and it will still retrain when the station comes up to full power in the morning. This happened when my modem was at the lower speeds too.

They may have just reconfigured or lowered the DSLAMs power output recently to the bare minimum to squeeze more people on DSL in my neighborhood and that isn't having a desirable effect. That however is just conjecture although there is notation of cross talk on my line. I will be checking my brothers modem and my friends modem but it is hard to monitor theirs as they have no Broadcom a/xdslctl commands, only a GUI and no advanced logging.

Would a feritte toroid filter and attenuate the DSL single if it has become "unbalanced" from bad wiring whereas a line with no wiring issues, it would only attenuate the common mode noise from the AM station.

Ken1943
join:2001-12-30
Brighton, CO

1 edit

Ken1943 to Donat76

Member

to Donat76

Re: [Qwest] DSLAM power back off or AM station making DSL modem retrain daily.

Great to learn something new to go along with the cable tv frequency in the two
meter ham band. I worked around the New Jersey Meadowlands with plenty of radio stations running power. One clear channel station took some heavy filtering or strange things to get out of some telephone systems
Donat76
join:2003-01-26
Oelwein, IA

Donat76 to KA0OUV

Member

to KA0OUV
said by KA0OUV:

f you don't have a whole house DSL filter, I would start with that. The ones CenturyLink (Ex-United Telephone/Sprint-United Telephone/Embarq here) use are very good at helping. There is also a model I used at my mother's house (close to a 1kW/500w Non-Directional AM) that would snap into the Corning Demarcation Box. But keeping DSL separate from the telephone Inside wiring in the house will help.

The Palomar stuff will help as well. They have good resources to help get it installed correctly.

Thanks Tim. I'm ordering three of their Type 77 Mix Ferrite Toroids tomorrow morning.
Donat76

1 edit

Donat76 to brugar

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to brugar

Re: DSLAM power back off or AM station making DSL modem reboot daily.

said by brugar:

There may be a corroded splice on somewhere on Centurylink's line which has unbalanced your circuit. A telephone line protector module at your NID may have failed.

I don't know if this is what you meant by line protector... I haven't really used my house phone in 2 years although I still have it. And although I mentioned the line conditioner which puts a small current through the line to keep it from corroding. The line tech that took the one bridge tap out last Friday told me he has never heard of such a thing, even though I tried to explain what it does. (My friends neighbor used to work for Alliant energy and he serviced the DC power that had to be fed through the gas lines to keep them from corroding.) They must not use them around here although the probably should on naked DSL or on lines like mine where the phone is for backup only.

My NID has no electronics, just the DSL filter that works similarly to the one inside.
brugar
join:2002-09-16
Las Vegas, NV
·CenturyLink

2 edits

brugar

Member

Line protection modules are located in the Telco side of the NID. Each has three connections: tip and ring wires of a phone line and your building ground. It provides over voltage protection to minimize damage to telephones from voltages induced by lightning.

I have CenturyLink Pure Broadband service. I have dial tone on my DSL circuit, but I can only make outgoing calls to 911. I can receive incoming calls. The standard voltage on telephone circuits is -48 VDC. The voltage is negative to prevent corrosion of the copper wires.

What does your modem report for overall Signal to Noise Ratio (SNR), Attenuation, and Power for both upstream and downstream signals during day and night?

My modem reports:
Down Up
SNR (dB): 10.9 13.3
Attn(dB): 37.0 18.9
Pwr(dBm): 19.8 12.6

My ADSL2+ service trains to 11774/894 Kbps.
Donat76
join:2003-01-26
Oelwein, IA

4 edits

Donat76

Member

Mode: ADSL2+ Annex A

Down Up
SNR (dB): 10.1 23.4
Attn(dB): 28.5 15.1
Pwr(dBm): 19.3 10.8
AgR: 13976.76 896.26

The signal to noise ratio can be effected with the amount of interleaving. I can get it up to 10 dB while synced at 15,384 if I tweak the interleaving higher by adjusting the SNRM but it won't hold between reboots. The max my line can get fluctuates between 18,000 during the day and 21,000 at night. The modem and the DSLAM will negotiate the lowest interleaving it can get away with while maintaining a 6dB margin. If manually change the margin to have a 9dB margin, the interleaving goes up to 384 but that gives me more room if the SNR suddenly drops. If the required margin was set to 9dB by the DSLAM instead of 6dB, the interleaving could go up to 511? and my line would probably be stable when the radio station kicks on in the morning even without filtering. But the DSLAM prefers low interleaving first. The radio station causes exactly a 3dB drop or rise in SNR.

To be honest, I'm not exactly sure how or why the interleaving effects the SNR the way it does. This is just my experience trying things I read. At this point, I just want things to work without tweaking the settings manually.

If the DSLAM didn't lower my speed. It could retrain every morning at 15,384 and all would be good for at least 24 hours. The modem and the DSLAM just can't handle such a change in interference without retraining. With the modem bit swapping to the interfered bins at night, it runs into trouble in the morning when those bins are now interfered with by that AM station and it retrains. Filters will be on the way tomorrow.
Donat76

1 edit

Donat76

Member

Re: [Qwest] DSLAM power back off or AM station making DSL modem retrain daily.

Pretty disappointed in CL right now. The DSL splitter / filter in my NID is bad. I know this because when I use my home phone, the CRC / FEC errors shoot through the roof, to the point that my modem almost loses sync.

In under 30 seconds while phone off hook...
20,000+ FEC
9 CRC
2 ES (error seconds) (Too may of these will make it retrain at a lower speed.)

Normally...
100 - 1000 FEC every 15 minutes
0 CRC in 24 hour period
0 ES (error seconds) in 24 hour period

I set a ticket up to get it replaced and the tech didn't show up or even bother calling. I wasted 2 hours waiting around. The note said "Line tested fine".

Well of course the DSL signal is fine unless I try to use my phone. A note was put on the ticket to call me and said specifically what was wrong but this is what I get. Not very happy right now.

I set up another ticket. They will probably just close that one out to without even calling or reading the notes on the ticket. I have seen another thread on this forum about the techs lack of communication and it doesn't give me much faith in their technicians.

No way of contacting the technician or his boss, so I am stuck making tickets until they bother to read the notes or call me.

Terrible customer service.

KA0OUV
Premium Member
join:2010-02-17
Jefferson City, MO

KA0OUV

Premium Member

CTLJoey used to frequent this forum. Might want to search for his username. I think he recently posted information as to how to get help for stuff like this.
Donat76
join:2003-01-26
Oelwein, IA

Donat76

Member

said by KA0OUV:

CTLJoey used to frequent this forum. Might want to search for his username. I think he recently posted information as to how to get help for stuff like this.

I messaged the CL account at DSLReports. And they flagged my new ticket so a field supervisor will watch the progress of the ticket. The notes on the last ticket were sufficient enough to explain the problem. I don't want to upset the tech by being persistent but I wasted time off work waiting for him to show up and lost that money.
Jeffg7
join:2001-07-27
Colorado Springs, CO

Jeffg7 to Donat76

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Just curious what application did you use to graph out the bit tones? Ive used a few others but their graphs are small and hard to see details...
Donat76
join:2003-01-26
Oelwein, IA

2 edits

Donat76

Member

said by Jeffg7:

Just curious what application did you use to graph out the bit tones? Ive used a few others but their graphs are small and hard to see details...

»www.s446074245.websiteho ··· e.co.uk/

I use the C1000A with new firmware. This modem is much more responsive and stable after the firmware update. I wouldn't of bought this modem without knowing there was a firmware to fix all the issues the C1000A had. Not I consider it one of the best CL branded modems.

I just wanted to add that the tech stopped by today and replaced the filters in the NID and the DSL leaking over to the phone side is now not an issue. I no longer get tons of errors when the phone is off the hook.

I think there was a miscommunication over what the issue was and that is why the tech originally closed the first ticket after just checking to make sure the DSL signal was good. The tech was a really nice guy and we chatted a bit while he repaired things. So I am much more happier about my experience today then I was yesterday.

My ferrite toroids should be arriving tomorrow. They are mix / type 77 which are designed to take out common mode interference at 1 MHz much better than other generally available.
CenturyLink
join:2009-03-09
Boise, ID

CenturyLink to Donat76

Member

to Donat76
Hello,

If you're still having troubles please reply with your account & contact information, email to talktous@centurylink.com.

Thank you very much,

Tom
Social Media Manager
Customer Advocacy
Consumer/Small Business Sales and Care
talktous@centurylink.com