said by EG: said by flwpwr :
The upstream limit for multiple upstream channels is 54, after that it will drop to one channel which has a limit of 57.
It's not an exact science. Don't forget about accuracy issues.. These figures can be inaccurate by 3-4 dB in either direction than they really are. FWIW, for many years now I have seen connectivity problems with modems that are transmitting at 50-51 dB even with a single 16 QAM carrier.
I have no idea what talking about. You appear to be under the impression there is some real level versus what the modem reports. As a tech, with a meter, that is the case for troubleshooting to and within the plant only, but NOT for DOCSIS negotiating. If the modem says its at 54, it's at 54. Even if the supposed perfect meter says you are at 56. As far as the cmts is concerned you're at 54 and it does not change anything until the modem claims it is at 55 [basically the cmts is not within it's receive specs, for us its -1 to +1, others may be different, if it is not there the cmts will say lower or raise the transmit at this time if it goes out of the appropriate range, things must change.]. If you are having issues at 51 staying with multiple channels this is most likley a config issue with the cmts or a noise issue, and has nothing to do with the modem being off on its transmit value.