Radio without a transmitter: Stanford sends data using ambient thermal noise
A Stanford team sends data without generating its own radio signal: the transmitter reflects or absorbs natural thermal noise. A radio transmitter can use up to 1,000 times more energy.
Archive image · Photo: Cullen328 / Wikimedia Commons, CC BY-SA 3.0 (cropped and resized)
Researchers at Stanford University have shown how data can be transmitted using ubiquitous thermal noise. The transmitter generates no signal of its own; it switches its antenna between two states, open and short-circuited, thereby reflecting or absorbing background noise. The receiver amplifies the reflected noise and uses it to tell zeros from ones. The study was published in the journal PNAS.
Both devices operated at room temperature inside a shielded test chamber. Using a channel model derived from the experiments, the team increased the data rate 100-fold. “We’ve built a system that others could very easily implement,” says senior author Zerina Kapetanovic. According to Stanford, a conventional radio transmitter can use up to 1,000 times as much energy to send the same information.
The researchers see possible uses in medical devices, environmental sensing and astronomical observatories. Next, the team wants to link multiple transmitters into a network and test the method in noisier environments outside the chamber.