CiDRA SONARtrac PW VF-100 - Manual (Page 161)

20834-01 Rev 04 Page 8-17
8.3.7 VF & GVF Spike Filter
The VF & GVF Spike Filter is used when the transmitter is in a “No
Flow” condition displaying dashes and when outputting flow (GVF)
data.
The VF & GVF Spike Filter menu can be used in conjunction with the
‘Flow (GVF) Spike Flt Adv’ filter menu where additional items are
selectable.
8.3.7.1 State
State is used to ‘Enable’ or ‘Disable’ this option. Factory default is
‘Disable’.
8.3.7.2 No Flow (GVF) Length
No Flow (GVF) Length is us ed when the device is in a “No Flow” (“No
GVF”) condition displaying dashes. It defines the required number of
consecutive measurements with good quality before a measurement
is deemed valid and displayed. This will eliminate spurious spikes that
sometime occur during process non-flowing condition due to noise.
8.3.7.3 Length
Length defines the number of bad quality readings that are allowable
before the transmitter goes into a “No Flow” (“No GVF”) output state
and displays dashes on the transmitter display (-------). Prior to going
into this state the output will “Hold” the last valid value.
Note: This can be used with the ‘Flow (GVF) Spike Flt Adv’ settings
as discussed below. For example, if the measurements with bad
quality are not consecutive then more than
‘Filter Length’
measurements with bad quality are required to force the ‘No Flow’
(‘No GVF’) condition. The actual number depends upon the values for
the ‘Up Count’ and the ‘Down Count’ and the number of
measurements with bad quality compared to the number of
measurements with good quality. For more information see the
definitions of ‘Up Count’ and ‘Down Count’.
8.3.8 Flow (GVF) Spike Flt Adv
Flow (GVF) Spike Flt Adv menu provides additional spike filter menu
selections.
8.3.8.1 Up Count
Up Count is used in conjunction with the ‘Down Count’ parameter and
is used when the device is ‘Holding’ a previous measurement due to a
new measurement with bad quality. Each time a measurement with
bad quality is made, ‘Up Count’ is added to an entity called the quality
counter and each time a measurement with good quality is made
‘Down Count’ is subtracted from the quality counter. If the quality