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Custom Curve Linearization
Easy Programming for
Custom Nonlinear Curve Fits
Applicable to Laureate™
Process, Strain Gauge, Load Cell Meters,
Frequency / Rate Meters, Totalizers
Features
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Achieves exceptional
accuracy with low-cost transducers.
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Extends transducer
operating range on high and low ends.
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Solves application
problems involving non-linear relationships.
- Available with Extended versions
of Laureate digital panel meters, counters and timers.
- Easy setup by entering data
points into a computer spreadsheet, or typing in desired readings for
actual signal inputs.
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Exceptional
accuracy from 0.1% to 0.01% of full scale with few data points, made
possible by curvilinear spline fits.
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Description
Custom curve linearization is
a feature available with the Extended option version of all
Laureate
digital panel meters, counters and timers, excluding only temperature
meters. The latter already include preset linearization for specific
temperature sensors.
Custom curve linearization
can provide exceptional accuracy from low cost transducers, provided
that these are repeatable. It can extend the working range of
transducers on the high and low ends. It can also solve special
application problems where there is a non-linear relationship between
the input and the desired readout.
Linearizing is implemented
for Laureates in the form of 20 nonlinear spline-fit segments, which provide much better accuracy than a
larger number of straight line segments. The typical error will be from
0.1% to 0.01% of full scale, depending on the number of data points used for setup, the
error in the data points, and the severity of non-linearities or
discontinuities.
Easy Setup
Setup of a
Laureate Linearizing Process Meter requires an external PC, which is
connected to the meter via an RS-232 cable, and utilizes linearizing software
furnished by Laurel Electronics. To download, go to our
Software Download Page. A Laureate serial communications
board is required, but can be removed following setup. Three meter programming
methods are offered:
Spreadsheet Method:
Data points consisting of the input signal in Volts or Amps and the
desired reading are entered into an Excel spreadsheet or into a text
file using a space, comma or tab as the delimiter. There can be up to 180 data points. Laurel's software then calculates 20 spline-fit
segments and downloads their coefficients into the meter.
Actual
Input Method:
The meter is hooked up to the actual signal source, and
the user enters the desired readings for different signal levels.
There can be up to 180 input / reading combinations. Laurel's software then calculates 20 spline-fit segments and downloads their coefficients into the meter.
This method automatically compensates for any errors in the transducer.
Polynomial
Method:
The mathematical formula relating the
input to the output is entered into the computer, which then uses this
data to calculate the spline-fit segments. This method is ideal if the
mathematical relationship is knows, for example to calculate the
contents of a tank based on the known geometry of the tank.
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Applications
The ability to apply custom
curve linearization opens many possibilities, including the following:
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Altimeters, since
the relationship between pressure and altitude is very non-linear.
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Rate of ascent
based on successive altimeter readings.
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Volume of
irregularly-shaped tanks, such as horizontal cylinders, based on
measured liquid level or liquid pressure at the base of the tank.
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Non-linear transducers,
such as thermistors or CdS cells.
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Fine-calibration of linear
transducers, since even nominally linear transducers will have
nonlinear components.
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Extending the working
range of transducers, since many transducers become nonlinear at
the low and high ends.
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Compensating for
inaccuracy of low-cost transducers.
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Measuring
tank volume
The Extended Laureate process meter can display the volume of
irregularly shaped tanks based on measured tank level or static pressure
at the base of the tank. An example is a cylindrical tank lying on
its side. The tank can further be tilted to facilitate drainage, as
illustrated. |
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Ordering
Guide
Laureate™ Custom Curve Linearizing Process Meters
Click
on the radio buttons to build a model number with pricing.
| Main Board
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Compatible
Signal Conditioner
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L3 or L4 |
DC, P, SG, WM |
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L7 or L8 |
FR, VF |
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