ADS Environmental Services FlowShark QR 775003 A2 - Manual (Page 55)

System Overview 2-13
Ultrasonic depth sensor sending signals to flow surface to determine range
Quadredundancy
Each ultrasonic depth sensor contains four ultrasonic transducers for
taking readings to give the sensor quadredundancy, which ensures
greater sensor reading reliability. To take a reading, one transducer
transmits a sound wave while a second transducer listens for the
returning echo. Each transducer has its own electronic circuitry and
dedicated wiring for true redundancy.
Ultrasonic Depth Processing
The standard method for processing ultrasonic depth involves firing
the sensor once to take readings for predefined transducer pairs.
The monitor performs a detailed analysis of all the returning echoes
that involves amplifying the good readings and attenuating the false
and multiple echoes representing noise and other erroneous
readings. It then discards the questionable data, averages the good
readings to arrive at a final reading for each of the designated pairs,
and logs the final readings in the monitor memory for availability
during data collection activities.