CiDRA SONARtrac GVF-100 - Manual (Page 87)

Copyright © 2006 CiDRA Corporation Page 10-11
20675-01 Rev 02
WARNING
For Class I, Division 2 applications, follow established safety
procedures prior to opening transmitter door.
The ‘Alarm Warn Threshold’ and ‘Alarm Crit Threshold’ menu
selections are used to set the flow rate and gas volume fraction alarm
set points. All other parameters must be set using the Configure
menu options in SONARtrac Basic Program.
•
SONARtrac
TM
Filters
The SONARtrac
TM
transmitter has 3 modes of signal output filtering.
These are ‘Damping’ ‘Noise Reduction’, and ‘Spike Filtering’. They
are applied in that order. The filtering affects both the display on the
transmitter and the signal to the current, pulse, alarm and digital
outputs.
‘GVF Damping Filter’ is used to reduce the noise of a signal through
the use of a first order lag filter with a fixed time constant. The time
constant of the filter is set by the user.
- State : Used to ‘Enable’ or ‘Disable’ this option.
- Time Constant : User input range of values that can be applied
are 0 – 600 seconds with 3 seconds as the factory default.
Care must be taken when choosing the time constant for the
damping filter as the response time for the reported measurement
will increase as the magnitude of the time constant is increased.
If the time response of the reported measurement is critical then the
‘GVF Noise Filter’ should be used instead of the damping filter.
‘GVF Noise Filter’ is a filter that has been designed to provide both
steady state noise attenuation and quick transient response. Under
steady state conditions the filter will use a long time constant in order
to attenuate noise on the signal. Once the measurement begins to
ramp up or down, the filter will reduce the filter time constant to allow
the meter output to track the changes with a faster response time.
- State : Used to ‘Enable’ or ‘Disable’ this option. Factory default is
‘Disable’.
- Magnitude : Choices of ‘Low’ or ‘High’. The high setting differs
from the low setting with more damping in both the transient and
steady state condition.
‘VF / GVF Spike Filter’ provides spike suppression capability for
normal operation as well as for the ‘no flow’ condition.
While in the ‘no flow’ condition, this filter requires a user
programmable number of consecutive good readings to be calculated
prior to enabling the display and all outputs of the transmitter. This is