Ph4454: Sonar Transducer Theory and Design - Lecture 2

Lecture Notes: drive.google.c...
CONVERSION (TRANSDUCTION) PROPERTIES
Transducers may have some or all of the following desirable properties:
1. Linearity. Output amplitude is proportional to the input amplitude (over some
range of input values). The output amplitude is then determined by the sensitivity in
mV/Pa for a microphone, for example.
2. Flatness. Output amplitude is independent of frequency (over some frequency
range) for constant input amplitude. If the transducer is also linear, then the
sensitivity is independent of frequency.
3. Passivity. Output energy is obtained solely from input energy. (No other
external source of energy is needed.) Sometimes a dc bias is needed, for example
in a condenser microphone, but the power requirement is typically relatively small.
4. Reversibility. Transducer converts energy in either direction.
Property 1 is usually the most important, with property 2 is close behind. Nearly all
transducers are linear and flat over some operating ranges. A hot-wire microphone,
which measures acoustic particle velocity, obeys none of the above properties.