I was browsing through Linear Tech's site today, looking for stuff that might help with my VHF/UHF downconverter thing, and came across this cute and fun little app note on acoustic thermometry:
http://cds.linear.com/docs/Application% ... an131f.pdf (http://cds.linear.com/docs/Application%20Note/an131f.pdf)
People usually measure temperature in order to correct the distance determined using ultrasonic transducers. Acoustic thermometry takes the opposite approach - the distance is fixed and the time it takes for an acoustic pulse to make a round trip is used to calculate the deviation from a standard and, indirectly, the temperature.
Why would anyone want to do that? The app note lists a number of reasons, including:
- resistance to environmental extremes (temperature, radiation)
- very quick response
- does not require iso-thermal measurement path
- almost entirely insensitive to pressure and humidity
- makes for an interesting exercise in signal conditioning
I've got a bunch of transducers lying around, as well as an Amani GT that's been lying neglected in my components box and some op amps. This sounds like a nice thing to waste a weekend on. If only i'd have a free weekend or two :/