I recently upgraded my Time Warner Cable RoadRunner service to the RoadRunner Extreme 30Mbps down / 5Mbps up service. Part of that service upgrade required a new modem to be installed and a technician to come out to validate line quality values. Turns out, I could have done a self install myself and saved the $30 but I wasn’t given that option even after asking.
In any case, while the technician was at my house I noticed on his computer screen power levels and signal to noise (SNR) levels for my modem. Right next to it were the acceptable ranges that Time Warner allows. I asked if I could take a picture of his screen, which he refused, but allowed me to record the values. Here I present them to you for your reference with my values in parenthesis.
Upstream Power -> 33dBmV to 51dBmV (47.7)
Downstream Power -> -10dBmV to 9dBmV (-3.2)
Upstream SNR -> 20dB to 99dB (36.1)
Downstream SNR -> 25dB to 99dB (34.7)
You can get to these stats by going to your modem when you are at home at http://192.168.100.1. Depending on the model and version of software on the modem, you may have to enable a higher level of access on the device to get to the screens with these values on them. Simple Google searches can provide the methods to access these screens for your modem model.