5.2.USB Cable Shielding Standard USB cables always connect both ends of the cable shield to the shell of the USB connector. On most systems, this will interconnect the grounds between USB nodes, turning the shield into a current carrying conductor if there is a difference in voltage between the two grounds. If the shield is allowed to pass a significant amount of current, it can radiate noise into the signal wires. Most instrumentation cables are designed so that only one end of the shield is terminated so as to avoid turning the shield wiring into a noise inducing source when it is forced to pass current. Disconnecting one end of the shield wiring can often significantly reduce USB communications problems.
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