Dynasonics Fusion Water Flow Meter - Manual (Page 28)

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AGC MODE—Automatic Gain Control Mode of Operation
NORMAL - Standard Configuration
MANUAL - AGC disabled
Select the desired mode of operation. A basic understanding of
the AGC logic is required in order to know when to use any
selection other than NORMAL.
When the unit is powered up, there is a delay before the unit
begins transmitting sound into the pipe. During this time, the
signal strength is measured, and a base signal level is obtained.
Typically this is a value of about 20. The unit measures flow by
measuring the Doppler frequency shift. The frequency shift is
approximately 120Hz per foot per second. For every foot per
second increase in velocity, the signal strength should increase
by 1. The unit automatically adjusts the gain and selects the
proper hardware filter for the measured velocity. The control can
be observed when the DISPLAY mode is set to DOP DIAG.
When NORMAL is selected, the unit will automatically control the
gain and front end hardware filter for optimum measurement of
the Doppler signal.
For applications where the flow is constant, but you may need to
tune the unit to filter out extraneous noise, select the MANUAL
mode. Typically, this would only be required at very low flow
rates. When MANUAL mode is selected, the GAIN POT and
FILTER settings are manually set. Automatic control is disabled.
GAIN POT—Digital Gain Pot
0-64
Using the arrow keys, increase or decrease the numerical value
to set the signal gain level. Typically, optimum flow measurement
is made when this value is between 10 and 50. Use the lowest
value that provides an accurate and stable flow reading. This
adjustment must be made in conjunction with the FILTER
setting, and may be an iterative process.
FILTER—Hardware Filter Selection
NONE - No Filter
LOW - (1600Hz Cutoff)