Connect the modem directly to the PC. Unplug the power cable, then plug it back in. Immediately see if you can get to the 192.168.100.1 modem admin page. On it you will see the signal levels. You have to do this quickly before all 4 green lights become solid (it gets sync) cause it will lock the page (shaw prevents you from getting to it when they have their file loaded).
You'll see something similar to the 3rd post on this page:
http://www.broadbandreports.com/foru...ng-config-file
Record the two power levels and SnR.