Expert

Re: Cable Modem Reboot due to T4 timeout

 

 This is absolutely out of spec and is a coaxial issue... Throwing modems at it will not fix bad coax....

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4   QAM256   525000000 Hz -4.7 dBmV 37.0 dB 54039680 28489154
5   QAM256   531000000 Hz -9.0 dBmV 33.2 dB 32031083 13387440
6   unknown   537000000 Hz -16.9 dBmV 0.0 dB 22384469 2967420
7   QAM256   543000000 Hz -14.6 dBmV 27.5 dB 512815864 190902370
8   QAM256   549000000 Hz -9.0 dBmV 33.4 dB 420277127 72142734
9   unknown   507000000 Hz -2.8 dBmV 30.5 dB 3683388 2676795

This looks like a "nailed" section of coax, possibly on a splitter or a skinned outside line.

does it run thru trees?

 

Participant

Re: Cable Modem Reboot due to T4 timeout

Yes, it's a long run from the road to my house, and probably 75% of that run is through trees.  LIke I said, we're going to hook the ubee up to the house post using a "clean" piece of coax to hopefully rule out an issue with the inside wiring.  He's suspecting the inside wiring, but I can't think of anything I've done recently that might have damaged the coax in the house.

 

If the problem persists testing with the ubee and the "clean" coax, he'll drop a temporary line from the road to the house and see if that addresses the problem.

Expert

Re: Cable Modem Reboot due to T4 timeout

Trim the trees so the darnesd rodents don't sit up there and chew the line... tree branches rub thru as well , It's your property and you're responsible to keep the trees clear.

 

First tech should of checked the levels, that bump is very bad and out of spec.  Level should have been checked at the pole.

Participant

Re: Cable Modem Reboot due to T4 timeout

Our line is buried from the street to the house.  When you mention rodents, are you referring to voles, etc.?

Expert

Re: Cable Modem Reboot due to T4 timeout

moles, packrats, squirell, etc... or a landscaper... Can you post pictures of the grounding block and the pedestal at the street? somethings corroded or chewed up.

Gotta use imgur

 

Participant

Re: Cable Modem Reboot due to T4 timeout

Latest update: they came out and ran a temp line from the road to the house.  Everything looked AOK for the first 30 minutes or so, but an hour or two later I noticed the power level on 507Mhz  had climbed (dropped?) to -10 dBmV and shortly thereafter my SB6141 rebooted.  From reading, it sounds like the power level needs to be in the +-7 range?

 

I think we've ruled out everything between the road and the house: all the connections at the house are new.  I guess I owe you a picture of the tap at the road.  I'll try to get that tomorrow as it's too dark now.  Assuming the tap is ok, what would my next step be?

 

The tech keeps asking why the SB6141 reboots; a question for which I have no answer.  The  ubee is not rebooting, so I think the inference is "replace your modem", which I don't feel like I should need to do since it's a "supported" modem.  Does anyone know why this particular modem reboots?  Apparently the SB6121 does as well.

 

Thanks for all the advice.

Established Sharer

Re: Cable Modem Reboot due to T4 timeout


johndobs wrote:

Latest update: they came out and ran a temp line from the road to the house.  Everything looked AOK for the first 30 minutes or so, but an hour or two later I noticed the power level on 507Mhz  had climbed (dropped?) to -10 dBmV and shortly thereafter my SB6141 rebooted.  From reading, it sounds like the power level needs to be in the +-7 range?

 

I think we've ruled out everything between the road and the house: all the connections at the house are new.  I guess I owe you a picture of the tap at the road.  I'll try to get that tomorrow as it's too dark now.  Assuming the tap is ok, what would my next step be?

 

The tech keeps asking why the SB6141 reboots; a question for which I have no answer.  The  ubee is not rebooting, so I think the inference is "replace your modem", which I don't feel like I should need to do since it's a "supported" modem.  Does anyone know why this particular modem reboots?  Apparently the SB6121 does as well.

 

Thanks for all the advice.


Because the received signal level is so low that the modem sees it as a T4 error - extended loss of DS - then it resets and starts looking for clocking signals again.  All modems respond the same when there is too little signal for the decoder.  And when that happens the DS indicator on the modem should be flashing to alert you to the problem.

Expert

Re: Cable Modem Reboot due to T4 timeout

Need to see the signal level pages...

modems need to be in the -8 to +8 range these days.. The -15 to + 15 mfg spec has NEVER worked reliably, it is under lab, not real world conditions... sorry.Woman Sad.

 

Participant

Re: Cable Modem Reboot due to T4 timeout

Here are the current signal levels.  They don't look as bad as they have, but they vary.  Last reboot was about 9 hours ago.  Expect I'll have another shortly.

 

Downstream Bonding Channel Value
Channel ID10 11 13 14 15 16 
Frequency507000000 Hz 513000000 Hz 519000000 Hz 531000000 Hz 537000000 Hz 543000000 Hz 549000000 Hz 
Signal to Noise Ratio38 dB 36 dB 33 dB 30 dB 34 dB 36 dB 37 dB 
Downstream ModulationQAM256 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
0 dBmV  -2 dBmV  -7 dBmV  -9 dBmV  -5 dBmV  -2 dBmV  -1 dBmV  

 

Upstream Bonding Channel Value
Channel ID
Frequency37000000 Hz 19400000 Hz 30600000 Hz 24200000 Hz 
Ranging Service ID388 388 388 388 
Symbol Rate2.560 Msym/sec 2.560 Msym/sec 5.120 Msym/sec 5.120 Msym/sec 
Power Level42 dBmV 40 dBmV 42 dBmV 40 dBmV 
Upstream Modulation[3] QPSK
[1] 16QAM
[2] 64QAM
 
[3] QPSK
[2] 16QAM
 
[3] QPSK
[1] 16QAM
[2] 64QAM
 
[3] QPSK
[1] 16QAM
[2] 64QAM
 
Ranging StatusSuccess Success Success Success 

 

Signal Stats (Codewords) Bonding Channel Value
Channel ID10 11 13 14 15 16 
Total Unerrored Codewords1556734351 1122785463 699415581 1544180117 1555945146 1555944949 1555949691 
Total Correctable Codewords18332 32355499 83165655 11763395 1664 13 
Total Uncorrectable Codewords2286 25674558 146166611 4870 2647 1289 1510 
Participant

Re: Cable Modem Reboot due to T4 timeout

Here are the signal levels from the ubee, which the tech added off of a splitter to see if the ubee rebooted like my SB6141 does.

 

Startup ProcedureProcedure Status Comment

Acquire Downstream Channel597000000 HzLocked
Connectivity StateOKOperational
Boot State  
Configuration FileOK 
SecurityEnabledBPI+



Downstream Bonded ChannelsChannel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables

1 QAM256 597000000 Hz1.9 dBmV39.7 dB240
2 unknown 513000000 Hz-4.6 dBmV40.0 dB2202371443746589
3 unknown 519000000 Hz-11.0 dBmV23.9 dB1134106713657372
4 unknown 525000000 Hz-15.1 dBmV0.0 dB49093391
5 QAM256 531000000 Hz-8.5 dBmV31.7 dB21660
6 QAM256 537000000 Hz-3.7 dBmV36.2 dB00
7 QAM256 543000000 Hz-1.3 dBmV38.1 dB00
8 QAM256 549000000 Hz0.0 dBmV39.0 dB00
9 QAM256 555000000 Hz0.6 dBmV39.2 dB00
10 QAM256 561000000 Hz0.9 dBmV39.5 dB00
11 QAM256 567000000 Hz0.8 dBmV39.4 dB00
12 QAM256 573000000 Hz1.5 dBmV39.5 dB00
13 QAM256 579000000 Hz1.5 dBmV39.5 dB00
14 QAM256 585000000 Hz2.0 dBmV39.8 dB00
15 QAM256 591000000 Hz1.9 dBmV39.7 dB00
16 QAM256 507000000 Hz0.4 dBmV35.2 dB88711635792

 

Total Correctables Total Uncorrectables

3474502057439844



Upstream Bonded ChannelsChannel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power

1 ATDMA 5120 Ksym/sec24200000 Hz40.3 dBmV
2 TDMA 2560 Ksym/sec19400000 Hz40.0 dBmV
3 ATDMA 5120 Ksym/sec30600000 Hz41.0 dBmV
4 ATDMA 2560 Ksym/sec37000000 Hz41.3 dBmV