Signal Level Check for Xfinity Connected CM1200

Downstream and upstream power levels are important when determining if the cable line that is connected to your cable modem or modem router is receiving sufficient power. Good Downstream power levels are within -7 to +7 dBmV. Good Upstream power levels are within 38-48 dBmV.

DarrenM

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.

Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 

You'll not see anything much over 900Mpbs on ethernet speed test due to the connection rate of the RJ45 ports being 1000Mpbs max. 

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ITGL72 wrote:

I have a tech from xFinity coming to my house to look over my setup. I've complained of slower speeds not near the 1200 Mbps package. I never expect to maintain that speed but I've seen it dip down to the 200's. I'm using a Nighthawk CM1200 Modem. Below is information on the signals. Would someone be so kind as to have a look and see if anything stands out that I need to bring up with the tech or tech support?

 

I pasted it below but also linked to it here:
https://pastebin.com/ex03QtSw

 

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
0

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 501000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)

Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 5 501000000 Hz 0 dBmV 41.3 dB 0 0
2 Locked QAM256 1 477000000 Hz 0.3 dBmV 41.3 dB 0 0
3 Locked QAM256 2 483000000 Hz 0.2 dBmV 41.4 dB 0 0
4 Locked QAM256 3 489000000 Hz 0.2 dBmV 41.3 dB 0 0
5 Locked QAM256 4 495000000 Hz 0.1 dBmV 41.3 dB 0 0
6 Locked QAM256 6 507000000 Hz 0.1 dBmV 41.3 dB 0 0
7 Locked QAM256 7 513000000 Hz -0.2 dBmV 41.3 dB 0 0
8 Locked QAM256 8 519000000 Hz -0.1 dBmV 41.2 dB 0 0
9 Locked QAM256 9 525000000 Hz -0.2 dBmV 41.2 dB 0 0
10 Locked QAM256 10 531000000 Hz -0.3 dBmV 41.2 dB 0 0
11 Locked QAM256 11 537000000 Hz -0.4 dBmV 41.1 dB 0 0
12 Locked QAM256 12 543000000 Hz -0.8 dBmV 41 dB 0 0
13 Locked QAM256 13 555000000 Hz -0.9 dBmV 40.9 dB 22 90
14 Locked QAM256 14 561000000 Hz -0.5 dBmV 41.1 dB 48 63
15 Locked QAM256 15 567000000 Hz -0.6 dBmV 41.1 dB 23 0
16 Locked QAM256 16 573000000 Hz -0.4 dBmV 41.2 dB 0 0
17 Locked QAM256 17 579000000 Hz -0.4 dBmV 41.1 dB 0 0
18 Locked QAM256 18 585000000 Hz -0.3 dBmV 41.2 dB 0 0
19 Locked QAM256 19 591000000 Hz -0.2 dBmV 41.3 dB 0 0
20 Locked QAM256 34 453000000 Hz 0.9 dBmV 41.6 dB 0 0
21 Locked QAM256 35 459000000 Hz 0.6 dBmV 41.5 dB 0 0
22 Locked QAM256 36 465000000 Hz 0.5 dBmV 41.4 dB 0 0
23 Locked QAM256 37 471000000 Hz 0.3 dBmV 41.3 dB 0 0
24 Locked QAM256 38 423000000 Hz 1.2 dBmV 41.8 dB 0 0
25 Locked QAM256 39 429000000 Hz 1.1 dBmV 41.8 dB 0 0
26 Locked QAM256 40 435000000 Hz 1 dBmV 41.8 dB 0 0
27 Locked QAM256 41 441000000 Hz 1.2 dBmV 41.8 dB 0 0
28 Locked QAM256 42 399000000 Hz 1.5 dBmV 41.9 dB 0 0
29 Locked QAM256 43 405000000 Hz 1.3 dBmV 41.8 dB 0 0
30 Locked QAM256 44 411000000 Hz 1.5 dBmV 41.9 dB 0 0
31 Locked QAM256 45 417000000 Hz 1.2 dBmV 41.8 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 1 5120 Ksym/sec 35600000 Hz 44.5 dBmV
2 Locked ATDMA 2 5120 Ksym/sec 29200000 Hz 44.8 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 44.3 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 16400000 Hz 42.8 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 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 Locked 0 ,1 ,2 ,3 33 690000000 Hz -1.4 dBmV 40.0 dB 1228 ~ 2867 318477801 295038727 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

Extended Upstream Transmit Power
Enable Extended Upstream Transmit Power

Current System Time:Thu May 06 14:30:49 2021
System Up Time:21:26:18

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