To Br3098's point, I agree with avoiding "regular" copper wire UBS cables that are more than 3.5m. A longer copper cable would not be within the USB spec and would likely not give you a signal or cause dropouts. But if you use something like the Opticis fiber-optic cable you should be able to go longer than 3.5m meters with no problem. The USB spec requires a limited length wire cable. But Opticis (and other companies that do fiber optic, etc.) have found a way around this with their implementations. Like I said, I have been using a 30m USB cable and a 30m HDMI cable with no problem and no decrease in performance for several years. Wireless is another equally attractive option, but obviously requires a different (maybe easier) implementation and hardware; it depends on how simple you want to go and what best meets your situation.
