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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Accepted Solution

BruceW

Gold Problem Solver

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24.5K Messages

2 months 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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BruceW

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24.5K Messages

2 months 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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user_daw312

Contributor

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208 Messages

2 months 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

Enable Extended Upstream Transmit Power (this is checked 'on', not sure why it doesn't show that way here)

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user_daw312

Contributor

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208 Messages

2 months 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

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user_daw312

Contributor

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208 Messages

2 months 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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Your Home Network

user_daw312

Downstream power gone up a lot

BruceW

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BruceW

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user_daw312

user_daw312

user_daw312

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