Pressure Convergence Test
Pressure is set to 0 daPa. The offset pot is checked for a target value of 150, if the
value is in spec., the pressure is set to +200daPa, and the gain pot is checked for a
target value 21. If the value is in spec. the pressure system has converged. If either
of the values is out of spec., the system goes back and readjusts the pressure offset
and pressure gain pots.
Errors:
Corrections:
Cannot converge, too many iterations.
Bad offset or gain pot, Bad Slave micro
Calibrate Microphone
This calibration step sets the speaker so that it is able to generate an 85 dB signal in a
2cc cavity, and then calibrates the microphone gain pot (MicGain pot). The operator is
prompted to connect the B&K 2231 sound meter, which is equipped with a 2cc micro-
phone, to the handle tip. The admittance gain and admittance offset pots are set to
default positions.
Errors:
Corrections:
No tone generated.
Bad speaker gain pot
Tone generated, but not at 85 dB. Bad speaker gain or admittance gain pots
MicGain Pot cannot be adjusted. Bad microphone gain pot
Harmonic Distortion Check
This calibration step will measure the amount of distortion present in the signal gener-
ated by the handle at 85 dB, measuring the amplitude of the signal at different harmonic
frequencies.
Errors:
Corrections:
THD too large.
Bad op amps, bad D/A converter, bad A/D converter
Enter the Barometric Pressure
This step reads the barometric pressure to compensate for the difference between the
days changing barometric pressures and the sea level standard we set the units to.
This is done automatically in units with an automatic barometer.
Admittance Offset POT Calibration
This calibration step calibrates the admittance offset pot. The operator will be prompted
to place a standard 0.5cc cavity on the handle tip. The handle will be instructed to
generate an 85 dB signal by setting the admittance gain pot to the predetermined value
for 0.5cc cavity. Calibration of the admittance offset pot is then attempted.
Errors:
Corrections:
Cannot adjust pot.
Bad admittance gain pot
