Automatic sensitivity adjustment apparatus for calibration of a non- destructive inspection instrument

摘要

The present invention is an automatic sensitivity adjustment apparatus for calibration of a nondestructive inspection instrument with a reference standard. Calibration is performed by setting the gain of a variable gain amplifier while a reference standard containing a standard flaw is passed before the sensing means of the instrument. A discriminator circuit connected to the sensing means detects when the output of the sensing means exceeds a predeterminedlevel. A hold time controller sends a sampling enable signal to a peak hold circuit which is also connected to the sensing means to cause the peak hold circuit to sample the sensing means output. The hold time controller senses the peak in the response of the sensing means and causes the peak hold circuit to hold that peak value. The output of the peak hold circuit is applied to the input of a variable gain amplifier. A comparator compares the output of the variable gain amplifier with a reference voltage produced by a reference voltage setting means. The output of the comparator is connected to the gain control input of the variable gain amplifier in order to control the gain of the variable gain amplifier so that the output level equals the reference voltage. Switching means disables the automatic sensitivity adjustment apparatus with the gain of the variable gain amplifier thus set during the ordinary operation of the non- destructive inspection apparatus.