ADS Environmental Services Model 4000 530017 A0 - Manual (Page 22)

2-10 ADS Model 4000 Manual
The second process involves applying the standards set by the
algorithm in the first sensor firing to process the return echoes and
determine the range actually used to record the depth of flow in the
pipe. The monitor takes 32 analog readings for each of the 12
transducer pairs (384 total firings). The analog signals produce a
greater resolution and accuracy. The monitor applies the range
window to each of the 32 readings and then screens out the signals
outside of that window (data scrubbing). It takes intrapair and
interpair averages, applies the scrubbing routine again, and
produces one final range. To conserve memory, the monitor stores
this single range rather than the four ranges used in the standard
design. However, using the smart depth feature consumes battery
life at a higher rate than standard ultrasonic depth.
Pressure Depth Sensor
The pressure depth sensor typically mounts at the bottom of the
pipe. While the ultrasonic depth sensor can only measure depths
up to slightly below full pipe capacity, the pressure depth sensor
can measure depths greater than a full pipe that might extend up
into the manhole (surcharges).
The pressure depth sensor contains a differential pressure
transducer that transmits an output voltage corresponding to the
difference between the water pressure and the air pressure in the
sewer. It measures water pressure through a port on the underside
of the sensor and air pressure using an integral vent tube running to
the top of the manhole. The monitor calculates the depth of the
flow by reading the difference in pressures. The pressure depth
system also compensates for temperature using a temperature
sensor housed within the pressure depth sensor.
Doppler Velocity Sensor
The Doppler velocity sensor mounts at the bottom of the pipe. It
emits a wide, omni-directional sound wave at a specific frequency