Campbell CRVW3, Инструкция по эксплуатации

Страница: 129 / 135

Appendix E. Engineering Output and Calibration
E-2
used will be based on frequency (Hz) and temperature and digits will not be
used.
When UseDigits is True , the form of the calculation polynomial is A *d² + B *d
+ C + D *t² + E *t + F *d*t where d represents digits, t represents temperature,
and the upper-case letters are user-specified coefficients (constants). When
UseDigits is False , the form of the polynomial is A *f² + B *f + C + D *t² + E *t
+ F *f*t where f represents the frequency in Hz, t represents temperature, and
the upper-case letters are user-specified coefficients (constants).
For the proper calculation to occur, you must discern from your sensor
documentation which coefficients of the polynomial are relevant ( A,B,C,D,E
and F ), and set all other coefficients to zero, so that they have no impact on the
output calculation. Do this by comparing your sensor manual’s calculation
equations to the polynomials listed above. Contact your Campbell Scientific
support representative if you require assistance for this step. The polynomial
coefficient schemes have already been determined for the most common sensor
types and these can be shared.
Once you know which coefficients to use, enter their values using
DevConfig
.
To specify the coefficients/constants of either polynomial shown above, use the
following CRVW3 settings:
Use this
DevConfig
Setting To Set this coefficient
Frequency/Digits Squared (second-degree)
Coefficient
A (first polynomial
constant)
Frequency/Digits Linear (first-degree)
Coefficient
B
Constant Term C
Temperature Squared (second-degree)
Coefficient
D
Temperature Linear (first-degree) Coefficient E
Hybrid Temperature Coefficient (Temp*Freq
or Temp*Digits)
F
Please refer to the DevConfig online help topics for the UseDigits and
Calclulate Engineering Output
settings for more information. Relevant help
information is also found in the DevConfig help topics for each coefficient
setting listed in the above table.
Once the settings have been applied and the CRVW3 restarts, the calculated
output in engineering units will be given in the ChanX_EngOut value of the
VW_Data output table, where X represents the channel number or ChanX is
the name you gave to the sensor/channel.
E.2 Calibration of Sensors
To enable in-field calibration on the CRVW3, set the Use Baseline Offsets
setting to
True
, or set the
Use Ambient Pressure Correction
setting to
True
.