New radio tool to 'whisper' signals to busy channels

Reuters
The new communications tool that 'whispers' on busy radio channels could enable broadband internet services for on-the-go wireless devices or hook-up homes that cannot get fast web access, its inventor said.

xMax is a very quiet radio system that uses radio channels already filled up with noisy pager or TV signals, said inventor Joe Bobier. "xMax is trespassing radio frequencies, although trespassing is not the right word, because we’re allowed to transmit a signal if it doesn’t interfere with other, stronger signals," said Bobier.

The system can emit signals that are too weak to be picked up by normal antennas, but that can be 'heard' by special aerials which know where to 'listen', thus enabling dual usage of the same scarce radio spectrum