user_daw312's profile

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216 Messages

Thursday, January 12th, 2023 4:24 PM

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Downstream power gone up a lot

My power numbers are usually perfect, I happened to look at the CM2000 modem page, and it's not happy with the downstream. See pictures below, some power levels are very high. Anything I should do other than schedule an appointment? 

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25.5K Messages

1 year ago

... Modem shows green now so the problem appears to have gone away ...

... Ah it's back to yellow/'poor connection' ...

The power levels are a bit odd, showing a "negative tilt" (the higher frequencies are reading higher than the lower frequencies). The last dozen or so are out of spec (too high), see Internet Troubleshooting Tips.

I'd be guided by performance: if the service is working well I'd ignore the modem's complaints and the signal levels. But if there are problems I'd be calling on Comcast to send out a premise tech. If you decide to do that call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit ($70-$100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

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Gold Problem Solver

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25.5K Messages

1 year ago

... CM2000 modem page, and it's not happy with the downstream. ...

The posted stats are not readable. Could you post a readable set? And include the OFDM and upstream stats and the event log?

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216 Messages

1 year ago

Ah, try thuis. Modem shows green now so the problem appears to have gone away. Yet some power looks high still, what do you think? The log is clean - nothing in it. 

tartup Procedure
Procedure Status Comment
Acquire Downstream Channel 601750000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD IPv6 only
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 17 601750000 Hz 3.6 dBmV 42.5 dB 0 0
2 Locked QAM256 14 583750000 Hz 3.0 dBmV 42.3 dB 0 0
3 Locked QAM256 15 589750000 Hz 3.2 dBmV 42.4 dB 0 0
4 Locked QAM256 16 595750000 Hz 3.5 dBmV 42.5 dB 0 0
5 Locked QAM256 18 607750000 Hz 3.8 dBmV 42.5 dB 0 0
6 Locked QAM256 19 613750000 Hz 4.0 dBmV 42.6 dB 0 0
7 Locked QAM256 20 619750000 Hz 4.0 dBmV 42.5 dB 0 0
8 Locked QAM256 21 625750000 Hz 4.4 dBmV 42.6 dB 0 0
9 Locked QAM256 22 631750000 Hz 4.6 dBmV 42.7 dB 0 0
10 Locked QAM256 23 637750000 Hz 4.7 dBmV 42.6 dB 0 0
11 Locked QAM256 24 643750000 Hz 5.1 dBmV 42.9 dB 0 0
12 Locked QAM256 25 649750000 Hz 5.2 dBmV 42.7 dB 0 0
13 Locked QAM256 26 655750000 Hz 5.4 dBmV 42.9 dB 0 0
14 Locked QAM256 27 661750000 Hz 5.7 dBmV 42.9 dB 0 0
15 Locked QAM256 28 667750000 Hz 6.1 dBmV 43.0 dB 0 0
16 Locked QAM256 29 673750000 Hz 6.6 dBmV 42.5 dB 0 0
17 Locked QAM256 30 679750000 Hz 6.6 dBmV 43.1 dB 0 0
18 Locked QAM256 31 685750000 Hz 7.4 dBmV 43.4 dB 0 0
19 Locked QAM256 32 691750000 Hz 7.7 dBmV 43.4 dB 0 0
20 Locked QAM256 34 697750000 Hz 8.2 dBmV 43.5 dB 0 0
21 Locked QAM256 35 703750000 Hz 8.7 dBmV 43.6 dB 0 0
22 Locked QAM256 36 709750000 Hz 9.0 dBmV 43.7 dB 0 0
23 Locked QAM256 37 715750000 Hz 9.5 dBmV 43.8 dB 0 0
24 Locked QAM256 38 721750000 Hz 9.7 dBmV 43.8 dB 0 0
25 Locked QAM256 39 727750000 Hz 9.8 dBmV 43.8 dB 0 0
26 Locked QAM256 40 733750000 Hz 9.6 dBmV 43.6 dB 0 0
27 Locked QAM256 41 739750000 Hz 9.3 dBmV 43.4 dB 0 0
28 Locked QAM256 42 745750000 Hz 9.5 dBmV 43.5 dB 0 0
29 Locked QAM256 43 751750000 Hz 9.4 dBmV 43.2 dB 0 0
30 Locked QAM256 44 757750000 Hz 9.2 dBmV 43.6 dB 0 0
31 Locked QAM256 45 763750000 Hz 8.6 dBmV 43.6 dB 0 0
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 9 5120 Ksym/sec 35600000 Hz 44.3 dBmV
2 Locked ATDMA 2 5120 Ksym/sec 16400000 Hz 48.8 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 46.5 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 29200000 Hz 45.8 dBmV
5 Locked ATDMA 10 2560 Ksym/sec 40400000 Hz 44.0 dBmV
6 Not Locked Unknown 0 0 0 0.0 dBmV
7 Not Locked Unknown 0 0 0 0.0 dBmV
8 Not Locked Unknown 0 0 0 0.0 dBmV
 
Downstream OFDM Channels
Channel Lock Status Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1 Locked 0 ,1 ,2 ,3 33 780000000 Hz 6.88 dBmV 42.7 dB 1108 ~ 2987 30808710 26416462 0
2 Not Locked 0 0 0 Hz 0 dBmV 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
 
Extended Upstream Transmit Power

Contributor

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216 Messages

1 year ago

Ah it's back to yellow/'poor connection' - it must be right on the edge. The power numbers are high. Here is a comparison with Dec 8, which I happened to have a snapshot of:

I don't see a way to call, I have to use the 'Xfinity Assistant'?

Channel 8-Dec 12-Jan
19 5.3 7.3
20 5.6 8.3
21 5.6 8.8
22 6 91
23 6.2 9.7
24 6.4 10
25 6.7 10.1
26 6.7 9.9
27 7 9.6
28 7.3 9.8
29 7.6 9.6
30 8.2 9.5
31 9.2 8.8

Contributor

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216 Messages

1 year ago

OK, thanks @BruceW ! FYI @BruceW , I have always had negative tilt in the power numbers. Maybe there is a reason for it?

(edited)

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