Complex sentence: With GWEN handling constant voice, teletype and other data traffic, interference was noticed by local power companies on a diagnostic two kilohertz side carrier tone--if the carrier disappeared, the power grid would interpret that as a system fault.
Split into simpler sentences: With GWEN handling constant voice, teletype and other data traffic, interference to a diagnostic two kilohertz side carrier tone was noticed by local power companies. When the carrier disappeared, the power grid would interpret that as a system fault.