US Telco Support > AT&T > AT&T West > Interesting and major DSL performance problem

Interesting and major DSL performance problem

What modem model do you have? Please use the info in this FAQ to get stats from your modem with the TV both on and off and post them here so we can compare them: »AT&T West FAQ » What information do you need in order to help me with my DSL problem?.

1)Elite (6.0Mbps down)

2)Netopia 3346n-002

3) No additional router is used. (Router is built into the modem).

4) Modem synchs up fine (full speed synch-up with ATT PPPOE user passwords entered into it.)

5) Lights blink normally with data transfer. When there is no activity the lights stay solid green .

6) There are no items plugged into the phone jacks when testing. Just the dsl modem straight into the wall with no filter. No alarm exists for the house that uses any phone jack.

7) Power cycling the modem does not improve the situation.

8) No noises from the phone lines are detectable since nothing is plugged into any phone jacks except for the modem.

9) I will collect the before and after modem statistics and post them in my follow-up post.

Before and after TV data collecting might take me an hour. So please check back. Thanks!!!

reply to ejg1
Most likely your noise margin (SNR) is dropping severely and your CRC rates are very high while the TV is on, but is best to verify this guess. Unfortunately with the Netopia you can't run a DMT chart: »SBC DSL FAQ »How can I check for the maximum attainable sync speeds with a 5100b/4100 modem? to see if there might only be a specific range of frequencies (a notch) that needs to be filtered or maybe the TV is outputting a broad range of harmonic interference.

I have a back-up Speedstream 4100 modem. Would this help? I could swap out if you see benifits.

I have the 4100 online now but I see the firmware is not up to date. It is sitting at 1.0.0.48 and must be upgraded to 1.0.0.53

figuring out where to get the new firmware now...

I found the firmware... installed and verified the modem is now at version 1.0.0.53

reply to ejg1
We should be able to see the frequencies involved on the DMT chart from the 4100 or if the TV is simply spitting out pure impulse noise (I think this is unlikely). Interference frequencies can probably be filtered. It has been done before for a treadmill, but it was quite expensive. I'm not sure if pure impulse noise can be filtered the same way.

I cant see how to produce the chart shown in the link you posted?

Well... I could not figure out how to find the modem ananysis tool.

This data is without the TV on. After rebooting the modem I did three speed tests at speakeasy all returning DL speeds of 5100+ . Then I saved the Technician readout seen in this link: »jiliz.fileave.com/techreadout_noTV.htm

This is with the TV on. After rebooting the modem I also did three speakeasys as above. They resulted in 3015, 3077 and 3084 respectively. Then I collected the Technician readout stats seen in this link: »jiliz.fileave.com/techreadout_after.htm

Whats next?

reply to ejg1

reply to ejg1
NO TV

»/users/deblin/···aph=true

Downstream Current Rate (Reported): 6016
Downstream Maxrate (Estimated): 6024
Downstream Bit Margin (Calculated): 412

Upstream Current Rate (Reported): 768
Upstream Maxrate (Estimated): 982
Upstream Bit Margin (Reported): 96

Bit tones with notches/missing bits:

bit(s) 38:47 163.875 - 207 KHz
bit(s) 118 508.875 - 513.1875 KHz
bit(s) 120 517.5 - 521.8125 KHz
bit(s) 127:132 547.6875 - 573.5625 KHz
bit(s) 141:142 608.0625 - 616.6875 KHz
bit(s) 153 659.8125 - 664.125 KHz
bit(s) 155:161 668.4375 - 698.625 KHz
bit(s) 171:172 737.4375 - 746.0625 KHz
bit(s) 178:179 767.625 - 776.25 KHz
bit(s) 186:190 802.125 - 823.6875 KHz
bit(s) 195:205 840.9375 - 888.375 KHz
bit(s) 208:212 897 - 918.5625 KHz
bit(s) 222:224 957.375 - 970.3125 KHz
bit(s) 229 987.5625 - 991.875 KHz
bit(s) 232:255 1000.5 - 1104 KHz

WITH TV

»/users/deblin/···aph=true

Downstream Current Rate (Reported): 5728
Downstream Maxrate (Estimated): 5728
Downstream Bit Margin (Calculated): 388

Upstream Current Rate (Reported): 768
Upstream Maxrate (Estimated): 1136
Upstream Bit Margin (Reported): 96

Bit tones with notches/missing bits:

bit(s) 38:42 163.875 - 185.4375 KHz
bit(s) 97 418.3125 - 422.625 KHz
bit(s) 109:115 470.0625 - 500.25 KHz
bit(s) 128:135 552 - 586.5 KHz
bit(s) 139:143 599.4375 - 621 KHz
bit(s) 153:165 659.8125 - 715.875 KHz
bit(s) 170:173 733.125 - 750.375 KHz
bit(s) 178:179 767.625 - 776.25 KHz
bit(s) 185:190 797.8125 - 823.6875 KHz
bit(s) 195:204 840.9375 - 884.0625 KHz
bit(s) 210:215 905.625 - 931.5 KHz
bit(s) 222:226 957.375 - 978.9375 KHz
bit(s) 231:255 996.1875 - 1104 KHz

From the looks of things you have a marginal Elite line to begin with. Those notches caused by the TV might be harmonic interference. Most of them seem to be somewhat evenly spaced. The only thing is that they are there with the TV off and powering on the TV only makes the interference stronger (wider, deeper notches).

I think your TV is emitting interference even when off. The stand by power may be causing your Elite to be marginal.

Everything in the house was unplugged except for the Oven's digital clock. (I was not going to pull the stove out :-/) The fridge was unplugged... everything! Only the modem, desktop, monitor, and power supply to the computer speakers were on. This is how I gathered the OFF data.

Then when I gathered the TV data I only plugged it back in to the 110V, rebooted the router, and ran the speed tests. Then I extracted the tech readout data.

I wonder if it makes sense to go back to the phone box and take some data there?

reply to ejg1
If "go back to the phone box" means the NID, then yes absolutely. I was going to suggest that.

It would seem that your TV is amplifying the interference from some other source. Maybe the TV is broadcasting the the line noise it picks up into that phone jack as you suggested earlier.

What hybrid number is the 4100 reporting in the modem log?: »192.168.0.1/log.htm at the phone jack you normally use? What about at the NID? I'm wondering if your inside wiring has bridged taps that might act as antennas for noise. For example that jack behind the TV is probably an unterminated stub (aka bridged tap).

I am not sure what a NID is but what I am refurring to is the box on the outside of the housewhere the phone comes in off of the street.

I thought I might take some aluminum foil and wall paper over the empty phone jack behind the TV to try and shield it some way. But first I really need a baseline reading so outside I go to gather data at the box.

What time are you off work???

Here is the modem log:
2009/11/03 21:52:23 GMT E |System |=============== SYSTEM UP ===============
2009/11/03 21:52:23 GMT E |System |Current Mode: PPP on the modem (Public IP for LAN device)
2009/11/03 21:52:23 GMT E |DSL |DataPump Version - 01.01.00.00
2009/11/03 21:52:23 GMT E |DSL |State: WAITING
2009/11/03 21:52:25 GMT E |Ethernet |Link 1 Up - 100Base-TX Full Duplex
2009/11/03 21:52:43 GMT E |DSL |State: INITIALIZING
2009/11/03 21:52:50 GMT E |DSL |HYBRID 2
2009/11/03 21:52:50 GMT E |DSL |Link up 1 US 768 DS 5728 (FAST:G.dmt)
2009/11/03 21:53:00 GMT E |PPPoE |tx PADI, id: 0000, ac: (NULL), sn: (NULL)
2009/11/03 21:53:00 GMT E |PPPoE |rx AC Name: 90084080500387-rback7.pltnca
2009/11/03 21:53:00 GMT E |PPPoE |tx PADR, id: 0000, ac: (NULL), sn: (NULL)
2009/11/03 21:53:00 GMT E |PPPoE |rx PADS id: 9161
2009/11/03 21:53:00 GMT E |PPP |LCP neg PAP
2009/11/03 21:53:00 GMT E |PPP |LCP up
2009/11/03 21:53:01 GMT E |PPP |IPCP nak option: 3
2009/11/03 21:53:01 GMT E |PPP |IPCP nak option: 129
2009/11/03 21:53:01 GMT E |PPP |IPCP nak option: 131
2009/11/03 21:53:01 GMT E |PPP |IPCP up ip: 71.146.21.153, gw: 71.146.31.254, dns: 68.94.156.1, 68.94.157.1
2009/11/03 21:53:04 GMT E |SNTP Client |Updated time from Primary server 132.163.4.103

reply to ejg1
I don't work for AT&T.

Probably some IW bridge taps: »SBC DSL FAQ »What do the hybrid numbers mean and what do they tell you about your line?

How old is your home phone wiring? Newer homes have Cat5e runs back to a punch down block and these seems to have the highest chances of hybrid 2 or 3 readings in the modem. The older daisy chained wiring might only have hybrid 1 or 2 readings if the total length of all the stubs is fairly short (say less than 100').

You might be able to disconnect the wire run to that jack off of a punch down block if you have a newer home.

my home was built in Oct 1999. It was given provisions for an alarm system that I would not pay for to turn on, then the only people who monkeyed with the lines were the phone company

I am putting data together for you now...

ok here is my setup to show you what I am doing. I have abandoned the desktop computer and am using my laptop. It is easier to carry around. This means the power plugs were also pulled for the desktop and any peripherals. I cant think or find of a single item in the house that is plugged in.

One thing I wanted to mention is a month ago the power company installed a Smart Meter right next to my phone box. The gas company did the same thing but that is out of the picture and about 6 feet away. The Smart Meters supposedly communicate remote data back to the company. I don’t know how they are doing it.

You can see how I have run my own line off of the box and around the corner to the garage. Only the modem is plugged in and the laptop is off battery.




After booting up the modem, the three speakeasy tests gave: 5142/655, 5139/653, 5137/654. What I really like about this is the speedometer needle pegs to look rock solid. There is no wavering at all. A good sign.

Then I logged into the modem, downloaded the technician readout, and plugged it into the graph tool:



Downstream Current Rate (Reported): 6016
Downstream Maxrate (Estimated): 8564
Downstream Bit Margin (Calculated): 476

Upstream Current Rate (Reported): 768
Upstream Maxrate (Estimated): 1136
Upstream Bit Margin (Reported): 96

Bit tones with notches/missing bits:

bit(s) 38:41 163.875 - 181.125 KHz
bit(s) 130 560.625 - 564.9375 KHz
bit(s) 141:142 608.0625 - 616.6875 KHz
bit(s) 155:163 668.4375 - 707.25 KHz
bit(s) 186:189 802.125 - 819.375 KHz
bit(s) 198:201 853.875 - 871.125 KHz
bit(s) 211 909.9375 - 914.25 KHz
bit(s) 222:223 957.375 - 966 KHz
bit(s) 234 1009.125 - 1013.4375 KHz
bit(s) 242:246 1043.625 - 1065.1875 KHz
bit(s) 255 1099.6875 - 1104 KHz

Time to digest this I guess...

reply to ejg1
Look at the difference in that maxrate as compared to the two I posted before. There is something in your house that is injecting noise into your phone lines and the interference frequencies seem like they are harmonic (evenly spaced).

This might be something like a motor or some other triac-controlled device or perhaps an outside CFL light bulb controlled by a photocell.

I am going to do this again. I forgot to flip the power switch on the desktop computer and monitor. The only things that will be on are the power supply for this laptop, the modem power supply, and the two 3 foot long florescents for the garage light.

Absolutely nothing else on.