


                               Factory Calibration          10-22-91 -med


        Factory calibration is similar to manual calibration except that 
        the control of the audiometer is performed through the RS232 
        computer interface rather than via the front panel. 

        The front panel is disengaged by using the computer command to 
        do so. See the Set Control Panel Registers command.

        The Set Calibration Flags command is used to enable the 
        calibration mode. The calibration is then done by using the Set 
        Control Panel Registers command to select the desired mode and 
        the Get Calibration Data and Set Calibration Data commands to 
        adjust the calibration. 

        When the calibration is completed, the Write EEROM command is 
        used to store the new calibration table in the EEROM. There are 
        four tables that are saved in the EEROM. For field calibration 
        only the first two tables are updated. For factory calibration 
        all four tables must be written. Each table is simply a duplicate 
        copy of the calibration data.

        The above method assumes that computer controlled calibration 
        equipment is available to perform the calibration. To update the 
        factory calibration tables you must at least have a computer with 
        an RS232 interface, the RS232 option installed in the audiometer, 
        and the appropriate software to update the table. The calibration 
        itself does not require computer control test equipment. The 
        manual calibration method can be used, after which the computer 
        can update the factory calibration tables by reading in the field 
        calibration table, then writing the values to the factory 
        calibration tables. 

        It is recommended that a manual factory calibration not be used 
        since it may be less accurate than the fully automated factory 
        calibration method.

        Since speaker calibration varies significantly depending on the 
        environment  in which the speakers are placed, the  speakers  are 
        not calibrated directly at the factory. Instead a default average 
        value for the speakers is preloaded into the calibration tables. 
        If the speakers will be used in a sound room, a field calibration 
        can be done to adjust the speaker calibration to the specific 
        environment.

        For further information on using the RS232 computer interface 
        with the audiometer, see the RS232 option manual.

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