The "Net Kaden" system for monitoring and controlling homes with wireless technology came into being after strenuous efforts by Japanese enterprises to resolve the problems involved.

A chief problem in the development of wireless communication technology linking home electrical appliances (kaden) was electronic "noise."

Toshiba Corp. marketed the world's first full-scale Net Kaden in 2002. But it soon found that the "Bluetooth" wireless communication technology adopted employed almost the same frequency band as microwave ovens.

In the worst case, when microwave ovens are in use, Net Kaden cannot function. Toshiba technicians overcame the difficulty by adopting a communications method using the "opening" of unused microwave frequencies.

A subsidiary of Hitachi Ltd. said wholesale revisions in specifications became necessary when Net Kaden was to be fitted with a remote-control device. "It took two months for dozens of technicians to fundamentally rebuild the software," a technician recalled.