said by Johkal:Those limits are high. More realistic ranges would be limits before you see possible issues.
Opinion:
1 channel: 54-55 dBmV
2 channels: 52-53 dBmV
3 channels: 50-51 dBmV
4 channels: 48-49 dBmV
The numbers I gave are the maximum from the DOCSIS specs. Ideally, you'd want to stay 4-5 below them.