Ultrasonic hack notes Sept 28th, 2009
Freed arduino RBBB from old north paw beta electronics. Still works! Programmer dongle has loose connection for power pin.
Wrote code to pulse at 40 KHz.
Created small amplifier circuit to drive ultrasonic transducer from arduino pin.
We tried to listen to the "Ultrasonic Command Console", which looks to be a remote control for household lights, presumably using ultrasonic sound. We can see the speaker inside the box. The red light shines when you press any button, but we can't hear any noise at all. It's possible that it's broken, it's also possible that the noise frequency is higher than the rig is capable of detecting.
Modified code to make small pulses on a regular pattern. We can hear it working, but it's not clear if can hear both the outgoing and the echo incoming.
We tried to compare them on the o-scope, but couldn't get it to show us the bounced sound (reciever) signal. Not sure what the problem was - o-scope seems to not be working on channel 2?
We should run an experiment in determining how small a delay between two sounds can actually be perceived by the human brain (both consciously and unconsciously).