Aalborg Vortex - Manual (Page 44)

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5.3.7.1 Submenu L2 PWM DSP Menu
Digital Signal Processing software algorithm can be set to calculate flow rate
based on five different methods:
a) Auto
b) number of pulses over preset measure interval
c) PWM (pulse width measurement)
d) FFT
e) AWD (Analog Watchdog circuitry, for troubleshooting only)
By default Vortex Frequency source is set to Auto. In this mode flow meter auto-
matically switching source to best suited algorithm.
All methods calculates frequency of the pulses from the flow meter sensor. The
number of pulses over preset measure interval method convenient when pulsating
flow or especially noisy signals are encountered. This method allows to get stable
average flow rate if pulse measure interval is set to values equal or more than 2000
ms. This parameters effects the flow update rate. With higher value of the pulse
measure interval, the and stability of the flow measurement improves, but
response time become longer. A suggested pulse measure interval value of 2000
seconds is a good starting point for most applicable process fluids. With lower
settings the response time of the meter will be shorter, but and stability will
degrade. The pulse measure interval settings are only related to the number of
pulses over preset measure interval method. Pulse measure interval can be select-
ed between 500 and 60000 ms.