Ultrasonic Test System Basics PC-Based

Ultrasonic test systems can take several forms, but the most common for automated test is immersion testing. To have good acoustical impedance matching between the couplant and the UUT and free range over the entire surface of the UUT, many test systems use an immersion tank filled with water.
These test systems use one or more ultrasonic transducers, which are moved over the surface of the unit under test (UUT). As the transducer is moved over the surface, it is pulsed and receives echoes from various surfaces. This process is repeated many times a second — sometimes over 50,000 times per second (>50 kHz). There are several pieces of the test system that must work together to get expected results. The following list includes the steps, and the accompanying hardware and software pieces, required to get one pulse and the subsequent echoes:
Application software – The user interacts with the application software to set up the test and presentation parameters.
Motion control – The ultrasonic transducer is moved over the appropriate area over the UUT.
Communication – The pulser/receiver operation parameters, such as pulse energy, pulse damping, and bandpass filtering, are set. The communication path is typically RS-232 or USB.
Pulser/Receiver – This device generates the high voltage pulse that is required by the ultrasonic transducer.
Ultrasonic Transducer – The transducer is pulsed, sending out an ultrasonic wave. The subsequent echoes generate a voltage in the transducer, which is sent back to the pulser/receiver.
Pulser/Receiver – The analog signal from the ultrasonic transducer is amplified and filtered before it is sent back to the digitizer within the PC.
Digitizer – The waveform sent from the pulser/receiver is converted from voltage to bits using an analog-to-digital converter.
Application software – Data from the digitizer is processed, analyzed, and presented according to the user-defined parameters. If there are multiple transducers that are coupled with one digitzer/pulser/receiver combination, switches much be used.There are several hardware and software components that must interact effectively for even the simplest ultrasonic test system to work properly. When assembling your custom ultrasonic test system, there are several factors to consider for each component of the system, including how well the components interact with one another. The Ultrasonic Transducer section describes each component of the test system in detail as well as the important features required for ultrasonic testing.