Dynasonics DXN Portable Ultrasonic Measurement System - Manual (Page 60)

In Figure 76 flow data falls outside the flow hysteresis window but does not reach the minimum time specified in the bad
data window. When data appears that is outside the hysteresis band and shorter than the bad data window time the data is
rejected.
±10% Hysteresis
Limit
Flow Outside
Hysteresis Limit
3 Samples Outside
Hysteresis Limit
Bad Data Rejection
Window
Flow
1 2 3
Flow Outside
Hysteresis Limit
3 Samples Outside
Hysteresis Limit
±10% Hysteresis
Limit
Bad Data Rejection
Window
Flow
1 2 3
150
100
50
0
110
90
Sample
Limits
Figure 76: Bad Data (Rejection)
The flow rate is again outside the original ±10% hysteresis window but the data exists for a time period greater than the Bad
Data Window. In this instance the meter interprets the data as a new valid flow rate and moves the hysteresis window to
correspond with the new established flow rate.
DXN Portable Ultrasonic Measurement System
Page 60 February 2013