USB EMI Problem - Losing communication with webcam - How do I suppress noise in USB?

[[email protected]]

Here's my problem. I've got a USB webcam which keeps losing
communication with my PC. The USB cable is running alongside an AC
power cable which is turning on and off repeatedly to turn a pump on
and off. Each time the pump is turned on and off, the PC drops the
webcam, and then reconnects. I am fairly certain that the USB cable is
picking up electrical noise generated by the sudden rushes of current
in the power cable. When the cables are seperated from eachother, the
problem goes away. But I have no option but to keep the cables
together.

What is the best way for me to suppress the noise in the USB signal? I
have observed the USB signal on an oscilloscope, and it appers that
every time the pump is turned on and off, there is a spike in the
voltage.

So far I have tried installing a snubber across the live and neutral
lines of the power cable, and I have also placed a toroid on the USB
cable, but with no luck.

Any help is much appreciated. Thanks

 

[dholsop]

Try applying a number of ferrite beads. You can get ones to apply to existing cable or built-in by the mfg. If you have any Hubs between your USB devices and the PC, try running them directly to the PC, bypassing the hub. The hubs appear to be sensitive to noise.