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See Section 5.5, Figure 7 and Section 5.6, Figure 8, Figure 9 for a photo and
schematics showing the position of the on-board barometer in RPM4-AD.
The on-board barometer is a low accuracy sensor used only for measuring
small changes in atmospheric pressure over short periods of time (see
Section 3.2.2). RPM4-AD measurement uncertainty does not depend on the
measurement uncertainty of the on-board barometer.
OPERATION
To view the current reading of the on-board barometer press [SPECIAL],
<7internal>, <1baro>. The display is in the active pressure unit of measure
(see Section 3.3.2). The display resolution is fixed to 0.01 Pa, or its equivalent.
The barometer pressure reading is displayed in the current unit of measure.
If the current unit of measure is airspeed, the barometer pressure reading is
displayed in the default or last selected altitude unit.
barometer in the a desired unit of pressure, return to the main run screen
and use [UNIT] to set the desired unit (see Section 3.3.2).
3.5.7.2
<2R
R
>
EAD
T
PURPOSE
To turn ON and OFF RPM4's automated, rate of change dependent, reading
integration rate feature.
PRINCIPLE
To obtain maximum resolution from RPM4-AD Q-RPT pressure measurements,
an integration time of about 1.2 second per reading is used. In most situations,
maximum precision is needed when pressures are stable so a relatively slow
display update rate presents no disadvantage.
changing quickly, more rapid pressure updates are usually more important than
obtaining maximum precision on individual readings. The RPM4-AD read rate
function automatically adjusts pressure measurement integration time depending
on the rate of change of pressure. When pressure is changing rapidly, reading
rate is increased. When pressure is evolving slowly, reading rate is decreased
and maximum precision is obtained.
When the automated read rate function is ON, three pressure rate of change
dependent read rates are used. The result is three display update rates:
Table 16. READRT - display update rates
RATE OF CHANGE
> 3 % of range span/s
> 0.5 and < 3 % of range span/s
< 0.5 % of range span/s
For situations in which maximum reading precision is desired regardless of
pressure rate of change, the RPM4 automated read rate function can be turned
Page 75
However, when pressure is
PRESSURE
DISPLAY
UPDATE
≈ 0.2 s
≈ 0.6 s
≈ 1.2 s
© 2005-2007 DH Instruments, a Fluke Company
3. OPERATION
To display the
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