Campbell AVW1, Инструкция по эксплуатации

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AVW1/AVW4
3-2
TABLE 3.2-1. Calibration Data for Sensor 3998
G age Factor Temp. Coeff. Zero Rdg. Period Temp. Baro.
(psi/digit) (psi/oC) (digit) (usecond) (oC) (in Hg)
0.0151 -0.0698 9431 325.6 24 29.51
The equation to change the CR10's output into
pressure (psi) exerted on the sensor is given
below:
P = [M * X] + B 3.2-1
where P is the pressure in psi and X is the
result of measurement Instruction 28 in kHz
2
( =
1/T
2
where T is the period in milliseconds). The
multiplier (M) and offset (B) are determined by
equations 3.2-2 and 3.2-3.
M = -1000(digits/kHz
2
) * Gage Factor 3.2-2
where M is the multiplier in psi/(kHz
2
) and the
Gage Factor is found on the Calibration Sheet
in psi/digit.
B = Po + [Gage Factor * Zero Reading] 3.2-3
where B is the offset in psi and Po is the
pressure in psi at the time of calibration. For
vibrating wire sensors not vented to the
atmosphere, Po is the barometric pressure
["Baro."(in Hg) * 0.49116 (psi/in Hg)] at the time
of calibration. For the vented sensors, Po is 0
psi. The Gage Factor (psi/digit) and Zero
Reading (digits) are found on the Calibration
Sheet.
Example: Using sensor number 3998, the
multiplier, offset, and equation for pressure
would be:
M = (-1000 digits/kHz
2
) * 0.0151 psi/digit
M = -15.1 psi/(kHz
2
)
B = 0.0 psi + (0.0151 psi/digit * 9431 digits)
B = 142.4 psi
P = [-15.1 psi/(kHz
2
) * X (kHz
2
)] + 142.4 psi
3.3 SWEPT FREQUENCY, START AND
END
The AVW1 and AVW4 were not designed for
use below 1000 Hz.
In general, the starting frequency of the swept
frequency for this sensor should be just a bit
lower than the frequency at the Full Scale
pressure of the sensor. A rough rule of thumb
would put the starting frequency at two thirds
that of the ending frequency. Almost always the
starting frequency should not be lower than half
of the ending frequency.
Start Freq. < ([Full Scale Pressure - (Gage
Factor * Zero
Reading)]/M)0.5 * 1000 Hz/kHz 3.3-1
Start Freq. < ([50psi - (0.0151psi/digit *
9431digits)]/
[-15.1psi/kHz
2
])
0.5
* 1000 Hz/kHz
Start Freq. < 2474 Hz or 24 hundred Hz
In general, the ending frequency of the swept
frequency for this sensor should be just a bit
higher than the frequency at Zero Pressure.
End Freq. > ([Zero Pressure - (Gage Factor *
Zero Reading)]/M)
0.5
* 1000 Hz/kHz 3.3-2
End Freq. > ([0.0psi - (0.0151psi/digit *
9431digits)]/
[-15.1psi/kHz
2
])
0.5
* 1000 Hz/kHz
End Freq. > 3071 Hz or 31 hundred Hz