Sending signals through the air may be among the oldest communication methods in human history. It’s practice is not the sole preserve of human species either, as African cave crickets communicate through pressurized rings of air similar to smoke rings. And amazingly this communication method may not be the sole preserve of biotic life for much longer.
The aforementioned insect communication differs from our use of smoke rings. Rather than rely on the visual presence of smoke the cricket:
repeatedly flings its wings forward to create tiny vortices of pressurized air. Like smoke rings, these bursts of air create a low-pressure region around their edges, causing doughnut-shaped rings to form in the air that can travel fairly long distances.
For the crickets, this is their equivalent of giving one another the ‘come hither’ eyes. Amatory matters do not trouble robots, but this communication practice can be co-opted into a binary format, as an engineer at Monash University, Australia, has attempted.
He has created a system wherein a speaker cone can project similar rings of pressurized air to a pressure sensor on a corresponding robot. Using a binary code, the two robots can exchange and decode one ASCII character every four seconds without so much as a peep or a wireless signal exchanged between them.
The signal decay of the air signal is 30cm and is relatively slow but crucially this communication method allows data to be exchanged without a wireless signal or an electrical connection.