PGA450Q1

Hello Ayushi,

Yes, crack/flaw detection in metal is possible. We've successfully tested detecting objects through a very thin sheet of aluminum placed immediately adjacent to the transducer. I will follow-up on the availability of the resulting graphs.

Can you further specify the details of the type of metal, depth, size of cracks, etc.?

Part of the ultrasonic signal will reflect back and part will pass through the metal when the signal reaches the metal. Observe the echo data (located in the FIFO RAM) when detecting the metal with and without the crack. If you can see a difference in the echo pattern, then you should be able to develop an algorithm to extract that information.
The settings that you will need to adjust are:
PULSE_CNT_A - number of pulses in a burst, more pulses will send out a higher strength signal, but could cause saturation at shorter distances.
FIFO_CTRL: sets what portion of the digital datapath is stored in the FIFO RAM. Use the lower 8 bits for more resolution, but if you have saturation issues, you can try the mid 8 bits.
DOWNSAMPLE: the ADC samples data every 1us. Use the DOWNSAMPLE setting to control how often a sample is stored in the FIFO_RAM.