you can log into the modem it self and see the signal strength, unless of course if they did not lock it out.
When we had cable and we had our own modem, I frequently logged into it and used it as a signal meter. Now, I do ths same with Ceton tuner, which is even better, since Ceton can do signal strength on dividual channels, not just pre-set frequency, like most meters.
6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!