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@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.....
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