ADS Environmental Services FlowShark QR 775003 A2 - Manual (Page 57)

System Overview 2-15
compensates for temperature using a temperature sensor housed
within the pressure depth sensor.
IS Doppler Velocity Sensor
The IS Doppler velocity sensor (ADS p/n 106194A-35) mounts at
the bottom of the pipe. It emits a wide, omnidirectional sound wave
at a specific frequency upward into the flow. The sound wave
bounces off particles in the flow and returns to the sensor. The
velocity sensor measures the change in the sound wave's frequency
from transmission to reception. This change is used to determine the
velocity of the flow based on the Doppler effect.
The Doppler effect describes the shift in frequency of a sound wave
emitted by a moving object in relation to a stationary point. In this
case, the moving objects are particles in the flow, the stationary
point is the velocity sensor, and the received signal is the reflection
of the sound wave (emitted by the velocity sensor) coming off the
particles.
Doppler velocity sensor sending signals reflecting off particles in the flow