This doesn't seem right Downstream Errors

About a couple of weeks ago i noticed that whenever i download a file 300+ MB, i get these downstream errors, sometimes no more than 20 on a few channels, but other times i get these insane amount of errors, is this some sort of throttling? been with TWC for almost 3 years now and i've had my issues before but this is crazy,  its to the point where i have to reset my modem after i download a file to have a lagg free connection.


Edit: My TWC supplied modem is a SB6183, with the coaxial cable running from the modem straight to a utility pole between my back yard and my neighbors.


1LockedQAM2569567000000 Hz2.4 dBmV42.6 dB6942618
2LockedQAM25610573000000 Hz2.3 dBmV43.2 dB1208361457
3LockedQAM25611579000000 Hz2.3 dBmV43.1 dB19365100158
4LockedQAM25612585000000 Hz2.2 dBmV42.7 dB19130101393
5LockedQAM25613591000000 Hz1.8 dBmV42.8 dB1483377737
6LockedQAM25614597000000 Hz2.1 dBmV42.4 dB25992137355
7LockedQAM25615603000000 Hz1.8 dBmV42.6 dB19685101086
8LockedQAM25616609000000 Hz1.8 dBmV42.6 dB469721255
9LockedQAM25617615000000 Hz1.6 dBmV42.2 dB1154960094
10LockedQAM25618621000000 Hz1.3 dBmV41.9 dB1559878391
11LockedQAM25619627000000 Hz1.1 dBmV41.4 dB1560580146
12LockedQAM25625663000000 Hz0.5 dBmV41.1 dB176755
13LockedQAM25629687000000 Hz1.5 dBmV41.2 dB1522978137
14LockedQAM25630693000000 Hz1.3 dBmV41.3 dB24276123262
15LockedQAM25631699000000 Hz0.7 dBmV41.2 dB1266461405
16LockedQAM25632705000000 Hz0.8 dBmV41.5 dB24425123354



Upstream Bonded Channels

ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA925120 Ksym/sec37000000 Hz42.8 dBmV
2LockedTDMA892560 Ksym/sec18500000 Hz41.5 dBmV
3LockedATDMA905120 Ksym/sec23300000 Hz42.5 dBmV
4LockedATDMA915120 Ksym/sec30600000 Hz42.8 dBmV

Re: This doesn't seem right Downstream Errors



I'm a bit new to this forum, but i'll try my best to help.


First off, what cable modem you have? I just want to know so I can check if this has an Intem Puma 6/7 chipset. These chipset(s) are known to have a lag issue.


Secondly, go to where your cable comes in from your road, and connect your modem to where it first comes in. Post your levels, and if there are any errors. Run speedtests as well.


What speeds are you getting? Before and after this issue?

I usually like to see levels in the negative areas, but those downstream levels are fine.





Re: This doesn't seem right Downstream Errors

A modem wouldn't give corrected/uncorrecteds like this simply due to being a Puma 6 based modem. I have a 6190 and that isn't normal.  What does the upstream look like? Are you actually having slowdowns or dropouts? Connecting the modem to the incoming line before any splitters and hard wiring a laptop to the modem to test is the best way to narrow down where the problem is occurring.


Re: This doesn't seem right Downstream Errors

i've edited the post to give you a few more details.

Re: This doesn't seem right Downstream Errors

Chances are:

a) Your modem is failing.  I doubt it is but you never know. I do see this isn't a Puma 6 Chipset modem, the only reason I asked is because you said it lagged, so I didn't know if it could be related to the chipset or not.


b) the coaxial cable is broken somewhere, or has been tampered with. Is your line buried or is it still out in the open? If it's not buried, trace the cable back to where it's connected to your pole. Look to see if it's been broken somwehere.


Hope you can fix your issue! I'm used to messing with DSL stuff, not cable, but I do know some things.

Proven Sharer

Re: This doesn't seem right Downstream Errors

Your modem levels in both directions are right in the middle of the desired ranges.  The DS (also called DownStream or Receive) level should be between -10 and +10 dBmV on every channel, with no more than 3 dBmV difference from the lowest to highest value.  The US (UpStream or Transmit) level should be in the +30 to +50 range, with +51 dBmV as the highest allowed. 

You commented on the HUGE number of uncorrectable errors since the modem's counters were reset during the last power cycle.   You also noted that your delays go up after downloading large files.  The cause is usally interference coming from any of several sources to the DS signal on the cable.  Here's what happens:

Every time your modem detects and cannot correct an error in the incoming data packet it tells the far-end host to stop and resend the corrupted data packet before going on any further with the file transfer.  Meanwhile the receiving  modem holds the incoming data (starting with the errored packet) in its receive buffer. 

Unfortunately the NoAck message is received at the host end several DS packets later, so the replacement data arrives out of sequence and has to be reassembled in order before the modem poasses it on to yiour data device.  Obviously these steps take time and add to any other delays you might be experiencing during file transfers.  It's the same process that can cause programs to stutter on your cable TV channels, except that those are being displayed in real time. 

Your installation does experience extremely high error counts, pointing to an abraded or loose cable shield or cable connector nut, among other things.   Don't worry about changing your modem until the errors stop increasing beyond a few hundred after any power cycle.  THEN if you still have problems you can look at buying a replacement modem.


Re: This doesn't seem right Downstream Errors

You are having ingress issues due to chewed up/ corroded line, loose connectors or opensplitter ports.

 The skipped channels is a dead giveaway When you add in the high corrected/ uncorrecteds.