Visitor
 •Â
11 Messages
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing
I am having exactly the same issue that user_kdseatac2021 had six months ago. As suggested in that post by a customer expert, I'm starting a new topic.
I have a Motorola MB8611 and the modem randomly and several times a day will drop the connection to the Xfinity network. The logs show an error of
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing
Sometimes, after about ten minutes, the modem will reacquire the connections, and sometimes I have to power off the modem to get it to sync. This has been getting worse over the past several months and started while I had a different modem so I don't think it's related to the modem I'm using.
Accepted Solution
EG
Expert
 •Â
110K Messages
3 years ago
Something intermittent is going on. You are going to have to get a tech out as I stated earlier.
Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home. And if the problem is found to be on their side of the demarcation point, there will not be any charge.
Good luck !
0
user_49ba06
Visitor
 •Â
11 Messages
3 years ago
And, since the other posts on this topic have been asked for the error log, here's mine:
Time
Priority
Description
21:44:25
Tue May 3 2022
Critical (3)
Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
21:44:33
Tue May 3 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
21:44:56
Tue May 3 2022
Critical (3)
No Ranging Response received - T3 time-out;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
21:45:03
Tue May 3 2022
Notice (6)
Honoring MDD; IP provisioning mode = IPv6
21:45:17
Tue May 3 2022
Warning (5)
REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
21:49:03
Tue May 3 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
21:49:08
Tue May 3 2022
Warning (5)
MDD message timeout;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
21:49:09
Tue May 3 2022
Warning (5)
DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
22:00:25
Tue May 3 2022
Notice (6)
DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
22:00:28
Tue May 3 2022
Warning (5)
DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:10:02
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 16; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:10:49
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 24; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:11:17
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 16; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:21
Wed May 4 2022
Critical (3)
Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:27
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:27
Wed May 4 2022
Warning (5)
MDD message timeout;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:30
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:31
Wed May 4 2022
Warning (5)
MDD message timeout;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:40
Wed May 4 2022
Warning (5)
DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:41
Wed May 4 2022
Warning (5)
RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:41
Wed May 4 2022
Warning (5)
Dynamic Range Window violation
03:12:43
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 22; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:12:49
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 24; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:13:53
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:13:59
Wed May 4 2022
Warning (5)
MDD message timeout;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:14:04
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:14:06
Wed May 4 2022
Warning (5)
MDD message timeout;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:14:13
Wed May 4 2022
Warning (5)
DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:14:14
Wed May 4 2022
Warning (5)
RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:14:14
Wed May 4 2022
Warning (5)
Dynamic Range Window violation
03:14:19
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 16; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
03:14:43
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 24; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
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0
EG
Expert
 •Â
110K Messages
3 years ago
Please also copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.
What is the exact make and model number of the modem / gateway device ?
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user_49ba06
Visitor
 •Â
11 Messages
3 years ago
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0
user_49ba06
Visitor
 •Â
11 Messages
3 years ago
I have a Motorola MB8611, and before that, I was using an Arris SB6183 and having the same problem.
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0
EG
Expert
 •Â
110K Messages
3 years ago
The upstream power is too high (already out of spec on channel #5) and it may be intermittently fluctuating even higher to out of spec levels. The downstream power is on the weak side as well. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.
In an effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.
Also check the coax cable for any damage such as cuts, nicks, kinks, sharp bends, etc.
If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.
Good luck with it !
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0
user_49ba06
Visitor
 •Â
11 Messages
3 years ago
19:29:57
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 24; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:30
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:30
Wed May 4 2022
Notice (6)
CM-STATUS message sent. Event Type Code: 16; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:34
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:37
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:38
Wed May 4 2022
Warning (5)
MDD message timeout;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:44
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:44
Wed May 4 2022
Warning (5)
MDD message timeout;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:57
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:14:57
Wed May 4 2022
Warning (5)
MDD message timeout;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:15:34
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:15:34
Wed May 4 2022
Critical (3)
Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:15:41
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:15:41
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:15:52
Wed May 4 2022
Warning (5)
DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:15:59
Wed May 4 2022
Critical (3)
SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:16:03
Wed May 4 2022
Critical (3)
No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:16:19
Wed May 4 2022
Notice (6)
Honoring MDD; IP provisioning mode = IPv6
20:16:31
Wed May 4 2022
Notice (6)
DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1.;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:16:36
Wed May 4 2022
Warning (5)
REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:16:37
Wed May 4 2022
Warning (5)
RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=00:00:00:00:00:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
20:16:37
Wed May 4 2022
Warning (5)
Dynamic Range Window violation
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0
EG
Expert
 •Â
110K Messages
3 years ago
Did any of those tips apply ?
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0
user_49ba06
Visitor
 •Â
11 Messages
3 years ago
I went back and looked at my wiring and found that the cable from the street fed into a four-way splitter. It was efficient for space but not good for signal strength. I inserted a two-way splitter with one output going to the modem and the other going to the rest of the house. Unfortunately, there has to be one more two-way splitter in the line to feed my MOCA bridge. I can't see a way to put that anywhere else, given I only have one cable coming into the house to the modem.
Below are the new numbers. It looks like the upstream channels are better, but the downstream numbers look worse with lower SNR. Do I understand this correctly?
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0
EG
Expert
 •Â
110K Messages
3 years ago
Yes that's correct. Up is a tad better, down is worse. Was that a powered splitter / drop amplifier that you removed, or a plain old passive splitter ?
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0
user_49ba06
Visitor
 •Â
11 Messages
3 years ago
It was a plain old passive splitter. I have to assume either the two-way splitter or the cable I added to the circuit must not be very good to eat away the loss of the other taps in the four-way. The Xfinity tech that was here a few weeks ago said that they don't like to have amplifiers in the circuit, and I can understand that view. I may have to add a second cable through the wall and outside to where the other cables originate so that I can isolate the internal MOCA network from the incoming signal. Still, I'm not convinced that will make any difference. As I understand it, they operate in different frequency bands and can't interfere with each other.
Can you recommend a source for good patch cables and splitters?
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0
EG
Expert
 •Â
110K Messages
3 years ago
Here are some quality brand splitters that Comcast actually uses in different market areas
Antronix CMC2002H 2-Way Splitter: http://www.amazon.com/Antronix-CMC2002H-2-Way-Splitter/dp/B001E4OH1E
Regal 2 WAY 1 GHZ Splitter: http://www.amazon.com/DIG702867-Regal-WAY-GHZ-SPLITTER/dp/B0018BQMUM/ref=sr_1_2?s=electronics&ie=UTF...
Extreme Broadband BDS102H 2-Way Digital Coax Splitter: http://www.amazon.com/EXTREME-DIGITAL-PERFORMANCE-CABLE-SPLITTER/dp/B007YV0UQW
Holland 2-way horizontal splitter 5-1000 MHz with ground. http://www.3starinc.com/holland_2-way_horizontal_splitter_5-1000_mhz-w-ground.html
Sv-2g 2-way Splitter 5-1000mhz: http://www.amazon.com/Sv-2g-2-way-Splitter-5-1000mhz-Sv2g/dp/B003TH36CK
Amphenol or Belden makes very good quality coax cable ! RG6 Quad Shield is preferred for fairly short runs.
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user_49ba06
Visitor
 •Â
11 Messages
3 years ago
This is going to be a long post. Here's the modem information this morning:
Most of the channel SNR is around 30 dB.
Here's the modem information from yesterday afternoon:
Startup Sequence
Startup Step
Status
Comment
Acquire Downstream Channel
399000000 Hz
Locked
Upstream Connection
OK
Operational
Boot State
OK
Operational
Configuration File
OK
Security
Enabled
BPI+
Connection Status
System Up Time
0 days 02h:36m:20s
Network Access
Allowed
Downstream Bonded Channels
Channel
Lock Status
Modulation
Channel ID
Freq. (MHz)
Pwr (dBmV)
SNR (dB)
Corrected
Uncorrected
1
Locked
QAM256
1
399.0
1.3
42.1
2549
703
2
Locked
QAM256
2
405.0
1.5
42.1
1927
1121
3
Locked
QAM256
3
411.0
1.7
42.2
8411
13856
4
Locked
QAM256
4
417.0
0.6
41.9
8415
11488
5
Locked
QAM256
5
423.0
0.6
41.9
7481
8911
6
Locked
QAM256
6
429.0
1.2
42.1
7691
12318
7
Locked
QAM256
7
435.0
-0.2
41.8
7971
13685
8
Locked
QAM256
8
441.0
-0.2
41.7
7644
14492
9
Locked
QAM256
9
453.0
-0.4
41.7
2937
4229
10
Locked
QAM256
10
459.0
-0.9
41.5
18662
21756
11
Locked
QAM256
11
465.0
0.2
41.8
6660
16507
12
Locked
QAM256
12
471.0
-0.5
41.5
7354
15995
13
Locked
QAM256
13
477.0
-1.4
41.3
28782
24214
14
Locked
QAM256
14
483.0
-0.3
41.6
7245
12960
15
Locked
QAM256
15
489.0
-0.2
41.6
7285
11984
16
Locked
QAM256
16
495.0
-1.5
41.2
8780
14001
17
Locked
QAM256
17
507.0
0.1
41.8
6921
13205
18
Locked
QAM256
18
513.0
-1.1
41.5
7635
16366
19
Locked
QAM256
19
519.0
-1.1
41.5
5118
15775
20
Locked
QAM256
20
525.0
0.7
42.1
7761
15602
21
Locked
QAM256
21
531.0
-0.4
41.8
7151
15656
22
Locked
QAM256
22
537.0
-0.5
41.6
8369
15931
23
Locked
QAM256
23
543.0
1.2
42.0
7912
13384
24
Locked
QAM256
24
549.0
0.5
41.9
6484
11283
25
Locked
QAM256
25
555.0
0.0
41.7
7592
14351
26
Locked
QAM256
26
561.0
1.2
42.1
7303
14150
27
Locked
QAM256
27
567.0
1.1
42.0
6955
13865
28
Locked
QAM256
28
573.0
0.1
41.6
4071
5711
29
Locked
QAM256
29
579.0
0.9
41.9
5474
6638
30
Locked
QAM256
30
585.0
1.3
42.0
6068
12800
31
Locked
QAM256
31
591.0
0.3
41.5
6044
12529
32
Locked
QAM256
32
597.0
0.3
41.5
6987
13012
33
Locked
OFDM PLC
159
690.0
-2.2
40.1
14193482
6805
Upstream Bonded Channels
Channel
Lock Status
Channel Type
Channel ID
Symb. Rate (Ksym/sec)
Freq. (MHz)
Pwr (dBmV)
1
Locked
SC-QAM
1
5120
35.6
48.3
2
Locked
SC-QAM
2
5120
29.2
48.3
3
Locked
SC-QAM
3
5120
22.8
47.8
4
Locked
SC-QAM
4
5120
16.4
47.3
5
Locked
SC-QAM
5
1280
39.6
48.3
Most of the channel SNR are around 40 dB. Nothing inside the house has changed.
0
0