ADS Environmental Services Model 4000 530017 A0 - Manual (Page 20)

2-8 ADS Model 4000 Manual
Ultrasonic depth sensor sending signals to flow surface to determine range
Quadredundancy
Each ultrasonic depth sensor contains four ultrasonic transducers.
Taking readings with four transducer pairs gives 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.
Data Scrubbing
Flow conditions and internal structures introduce many potential
obstacles to obtaining accurate flow data in sewer systems and
manholes. Some of these obstacles may include noise, turbulent or
wavy flow, a foamy flow surface, side connections, rungs, broken
pipes, or drop connections.
To minimize these effects, ADS uses a process of eliminating
erroneous data called data scrubbing. Initial data scrubbing occurs
routinely in the following way as the monitor takes readings:
The monitor fires each sensor and averages the multiple
readings.