In the future, we hope that a global army of open-source code developers, students and other experts in digital signal processing, as well as citizen scientists willing to lend their intelligence to our exploration, will have access to the same technology and join our quest.

CNN: What if there's somebody else out there?

Pulse-code modulation is simply a way of representing the analog electrical signal, in digital form.

ENGADGET: Primed: digital audio basics Mobile

They could be used to make cheap radio-frequency identity tags in essence, printable bar-codes that transmit an identifying code in response to a pulsed radio signal.

ECONOMIST: Just press print