Nathanc34's profile

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4 Messages

Wednesday, March 24th, 2021

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OFDM Channel not locked - Downstream light consistently blinking now

Hi there, 

I hope someone can provide some insight on a problem I am having with my gigabit  internet service.   

Last week I was having intermittent service and the downstream light on my Netgear CM1200 modem was blinking.   From what I can tell this would mean that a channel or channels weren't locked.  I tried resetting the modem with no success.

I called cox support and they told me all they could do was look at the signal to my house which of course I was told it was "healthy".   Since they couldn't do much they had a technician come out the next day and have a look at everything.  Long story short nothing was noticed and I was told all my lines looked good. 

I shared my modem information with the tech and he did notice that I did have a few uncorrectable's on my downstream OFDM channel but he said it didn't look too bad. All the other channels looked fine.  After a few other discussions he did say that my modem might be going bad.  

While I didn't really want to buy a new modem since my modem was a little over a year old I went ahead and purchased the new Netgear CM2000 modem the same day and had it set up.      

Unfortunately Its been about 5 days with the new modem and I am still having the same issue.   My downstream light is blinking again so I decided to log into the modem and see if I could see anything different or wrong.   One thing I did notice was my downstream ODFM channel was no longer locked and not even showing a signal.   I called support again but I keep getting the same response that "everything looks fine".   I had to argue with them and explain it was not fine with them eventually agreeing to send someone out again tomorrow.    The downstream light has been blinking consistently now for over 16 hours. 

Would anyone have any idea what would be causing this or what I can do to remedy it?    Here is a copy of my modem status as of this post. 

Cable Connection
Cancel Apply
Frequency start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency
 
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 903000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
 
Downstream Bonded Channels (Partial Service)
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 21 903000000 Hz 1.1 dBmV 41.9 dB 0 0
2 Locked QAM256 1 783000000 Hz 4.3 dBmV 43.7 dB 0 0
3 Locked QAM256 2 789000000 Hz 4.3 dBmV 43.7 dB 0 0
4 Locked QAM256 3 795000000 Hz 4.0 dBmV 43.6 dB 0 0
5 Locked QAM256 4 801000000 Hz 4.1 dBmV 43.6 dB 0 0
6 Locked QAM256 5 807000000 Hz 3.9 dBmV 43.5 dB 0 0
7 Locked QAM256 6 813000000 Hz 3.8 dBmV 43.4 dB 0 0
8 Locked QAM256 7 819000000 Hz 3.8 dBmV 43.4 dB 0 0
9 Locked QAM256 8 825000000 Hz 3.5 dBmV 43.3 dB 0 0
10 Locked QAM256 9 831000000 Hz 3.3 dBmV 43.3 dB 0 0
11 Locked QAM256 10 837000000 Hz 3.2 dBmV 43.2 dB 0 0
12 Locked QAM256 11 843000000 Hz 2.8 dBmV 43.1 dB 0 0
13 Locked QAM256 12 849000000 Hz 2.5 dBmV 42.9 dB 0 0
14 Locked QAM256 13 855000000 Hz 2.5 dBmV 42.9 dB 0 0
15 Locked QAM256 14 861000000 Hz 2.1 dBmV 42.8 dB 0 0
16 Locked QAM256 15 867000000 Hz 2.0 dBmV 42.7 dB 0 0
17 Locked QAM256 16 873000000 Hz 1.9 dBmV 42.7 dB 0 0
18 Locked QAM256 17 879000000 Hz 1.7 dBmV 42.5 dB 0 0
19 Locked QAM256 18 885000000 Hz 1.6 dBmV 42.3 dB 0 0
20 Locked QAM256 19 891000000 Hz 1.4 dBmV 42.2 dB 0 0
21 Locked QAM256 20 897000000 Hz 1.4 dBmV 42.1 dB 0 0
22 Locked QAM256 22 909000000 Hz 1.3 dBmV 42.0 dB 0 0
23 Locked QAM256 23 915000000 Hz 1.0 dBmV 41.9 dB 0 0
24 Locked QAM256 24 921000000 Hz 0.8 dBmV 41.7 dB 0 0
25 Locked QAM256 25 927000000 Hz 1.0 dBmV 41.8 dB 0 0
26 Locked QAM256 26 933000000 Hz 0.8 dBmV 41.8 dB 0 0
27 Locked QAM256 27 939000000 Hz 0.8 dBmV 41.8 dB 0 0
28 Locked QAM256 28 945000000 Hz 0.9 dBmV 41.8 dB 0 0
29 Locked QAM256 29 951000000 Hz 0.7 dBmV 41.7 dB 0 0
30 Locked QAM256 30 957000000 Hz 0.4 dBmV 41.5 dB 0 0
31 Locked QAM256 31 963000000 Hz 0.4 dBmV 41.5 dB 0 0
32 Locked QAM256 32 969000000 Hz 0.1 dBmV 41.3 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 1 5120 16900000 Hz 41.3 dBmV
2 Locked ATDMA 2 5120 23500000 Hz 42.3 dBmV
3 Locked ATDMA 3 5120 29900000 Hz 41.8 dBmV
4 Locked ATDMA 4 5120 36300000 Hz 41.8 dBmV
5 Not Locked Unknown 0 0 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 0 Hz 0.0 dBmV
 
Downstream OFDM Channels
Channel Lock
Status
Modulation /
Profile ID
Channel
ID
Frequency Power SNR /
MER
Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1 Not Locked 0 0 0 Hz 0 dBmV 0.0 dB 0 ~ 4095 0 0 0
2 Not Locked 0 0 0 Hz 0 dBmV 0.0 dB 0 ~ 4095 0 0 0
 
Upstream OFDMA Channels
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Not Locked 0 0 0 Hz 0 dBmV
2 Not Locked 0 0 0 Hz 0 dBmV

Thank you 

Nathan 

Honored Contributor III

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5.7K Messages

4 years ago

Netgear CM1200 is 32×8
Downstream Light:  Blinking Green (Scanning for additional downstream channels)

I don't know why the Downstream would be blinking because you have 32 locked channels.

Your Upstream, however, only has 4 Bonded Channels.  I'd assume...due to gigabit...you should have 8.  Your Upstream Light should be blinking.

dave9  would be the best source but I think the OFDM(A) channels are your overall circuits.  These circuits are then divided into separate channels:  32 and 4.  Therefore the overall circuits wouldn't be individually locked.  I could be wrong and sure I am.

I guess a good question:  why don't you have 8 Upstream channels?

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