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Where is DOCSISWAN Table on XB8?

misc9700
I'm here a lot

Hello,  I just received my new XB8 modem after signing up for a self-install.  My home had Rogers some 8 years ago.  The existing setup from the previous install had a 3db attenuator on the coax  before entering the old Hitron Modem.  I would like to know whether to keep or discard the attenuator when plugging in my new XB8 Modem.  I am looking for the coax signal strength charts (DOCSISWAN tab) on my new XB8 modem but can;t seem to find the option anywhere.  Any suggestions?  Thank you.

 

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Re: Where is DOCSISWAN Table on XB8?

misc9700
I'm here a lot

Located.  Thank you.

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Re: Where is DOCSISWAN Table on XB8?

misc9700
I'm here a lot

Located.  Thank you.

Re: Where is DOCSISWAN Table on XB8?

@misc9700 note that the Comcast XB6, 7 and 8 modems use the traditional Quadrature Amplitude Modulation type signals and the much newer Orthogonal Frequency Division Modulation (downstream) and Orthogonal Frequency Division Multiple Access (upstream) signal type.  

 

The OFDM and OFDMA channels use thousands of low power sub-carriers for data carriage, compared to the traditional higher level QAM signals.

 

Traditionally, previous modems using QAM only would run with a zero dBmV target on the downstream side and 36 to 40 dBmV target on the upstream side.  

 

While that is generally still applicable to the XB6, 7 and 8, Rogers has been cranking up the signal levels at the neighbourhood nodes in various places, so, if you happen to have a steady increase in signal levels across the board to some ridiculous level, don't be surprised.  That is what I have from my neighbourhood node, a 9 dBmV increase from the lower to upper frequencies.  So, not only is there an increase in the signal levels, the signal tilt, which is a steady increase makes in generally impossible to use a signal attenuator to bring the signal levels back down to a reasonable level.  That is due to the OFDM channel which usually exists in the 350 to 447 Mhz range and the possibility of an upper OFDM channel in the 900 Mhz range.  If you bring down the upper OFDM channel, there's a good chance of dropping the lower OFDM channel down to a signal level that impairs its use.  So, that is signal tilt and overall signal level dependant.  Just pointing this out due to the low signal level data sub-carriers in the OFDM and OFDMA channel coupled with the possibility of extremely high signal levels, which is an attempt to transmit the data sub-carriers at a level that their actually received by the downstream modems.

 

Fwiw.....

Re: Where is DOCSISWAN Table on XB8?

misc9700
I'm here a lot

Hi Datalink,

 

Thank you so much for your insight.

 

Before reading your response, I went ahead and hooked up the new XB8 modem, using the 3db attenuator that was in place for my previous Hitron modem.  Below are the results that I obtained.   Do you recommend that I remove the 3db attenuator?

 

Thank you ever so kindly in advance!

 

Channel IDLock StatusFrequencySNRPower LevelModulation

Downstream
Channel Bonding Value
9
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
621 MHz
279 MHz
579 MHz
585 MHz
591 MHz
597 MHz
603 MHz
609 MHz
615 MHz
633 MHz
639 MHz
645 MHz
651 MHz
657 MHz
663 MHz
669 MHz
675 MHz
681 MHz
687 MHz
693 MHz
699 MHz
705 MHz
711 MHz
717 MHz
723 MHz
825 MHz
831 MHz
837 MHz
843 MHz
849 MHz
855 MHz
861 MHz
350000000
920000000
39.6 dB
39.3 dB
39.6 dB
39.6 dB
39.8 dB
39.7 dB
39.8 dB
39.8 dB
39.0 dB
39.4 dB
39.5 dB
39.5 dB
39.5 dB
39.3 dB
39.1 dB
39.2 dB
38.7 dB
39.5 dB
39.5 dB
39.5 dB
39.5 dB
39.5 dB
39.5 dB
39.6 dB
39.6 dB
38.8 dB
38.8 dB
38.8 dB
38.7 dB
38.7 dB
38.6 dB
38.4 dB
38.7 dB
38.2 dB
9.0 dBmV
9.7 dBmV
9.3 dBmV
9.2 dBmV
9.4 dBmV
9.4 dBmV
9.2 dBmV
9.4 dBmV
9.1 dBmV
8.9 dBmV
9.0 dBmV
8.9 dBmV
8.9 dBmV
8.6 dBmV
8.6 dBmV
8.6 dBmV
8.8 dBmV
8.8 dBmV
8.8 dBmV
8.8 dBmV
8.9 dBmV
9.0 dBmV
8.9 dBmV
9.1 dBmV
9.2 dBmV
7.2 dBmV
7.1 dBmV
7.0 dBmV
6.8 dBmV
6.7 dBmV
6.4 dBmV
6.2 dBmV
9.6 dBmV
7.4 dBmV
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
OFDM
OFDM

 

 

Channel IDLock StatusFrequencySymbol RatePower LevelModulationChannel Type

Upstream
Channel Bonding Value
1
2
3
4
10
Locked
Locked
Locked
Locked
Locked
21 MHz
25 MHz
32 MHz
38 MHz
42 MHz
2560
5120
5120
5120
0
33.0 dBmV
34.0 dBmV
34.5 dBmV
36.0 dBmV
32.0 dBmV
QAM
QAM
QAM
QAM
OFDMA
TDMA_AND_ATDMA
ATDMA
ATDMA
ATDMA
TDMA

 

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