Campbell CR3000 Micrologger, Руководство оператора

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Section 8. Operation
399
effect is caused by dielectric absorption of the integrator capacitor and cannot be
overcome by circuit design. Remedies include the following:
•
Program longer settling times
•
Use an individual instruction for each input terminal, the effect of which
is to reset the integrator circuit prior to filtering.
•
Avoid preceding a very small voltage input with a very large voltage
input in a measurement sequence if a single measurement instruction
must be used.
TABLE: Offset Voltage Compensation Options
(p. 349)
lists some of the tools
available to minimize the effects of offset voltages.
Offset Voltage Compensation Options
CRBasic
Measurement
Instruction
Input Reversal
(RevDiff =True)
Excitation
Reversal
(RevEx = True)
Measure
Offset During
Measurement
(MeasOff = True)
Measure Offset
During
Background
Calibration
(RevDiff = False)
(RevEx = False)
(MeasOff = False)
AM25T()
  
BrHalf()
 
BrHalf3W()
 
BrHalf4W()
  
BrFull()
  
BrFull6W()
  
Resistance()
  
TCDiff()
 
TCSe()
 
Therm107()
 
Therm108()
 
Therm109()
 
VoltDiff()
 
VoltSe()
 
Input and Excitation Reversal
Reversing inputs (differential measurements) or reversing polarity of excitation
voltage (bridge measurements) cancels stray voltage offsets. For example, if 3
µ
V offset exists in the measurement circuitry, a 5 mV signal is measured as 5.003
mV. When the input or excitation is reversed, the second sub-measurement is –