Pulser-receivers (also referred to as pulser/receivers) generate ultrasonic pulses, which are propagated into materials for nondestructive testing (NDT). The pulser generates short, large amplitude electrical pulses (pulse voltage) when its trigger is actuated. These electrical pulses are transmitted into an ultrasonic transducer, which converts the electric pulses into short ultrasonic pulses. Most pulser sections have very low output impedance to better drive the transducer. The receiver then converts the ultrasonic pulses into electric pulses by mean of an ultrasonic transducer. In the receiver section the voltage signals produced by the transducer, which represent the received ultrasonic pulses, are amplified. The amplified radio frequency (RF) signal is available as output for display or capture for signal processing.
Pulser-receivers have a number of control aspects. When in action, the pulser section may apply a number of attributes to the pulses being transmitted. It may lengthen or dampen the pulse depending upon the needs of the application, and the amount of time that the pulse is applied to the transducer. The pulser can also vary the pulse voltage generally within a specified standard range.
The receiver section of the pulser/receiver can be for a number of control aspects as well. The receiver is designed to boost the signal (amplification) or gain, as well as filtering the signal to cut down on impedance and unwanted interference. Additionally, the receiver can function as a signal rectifier, to attune the RF signal into a full wave, or break it down into positive or negative half waves.
Pulser-receivers function in a number of specified modes that help to determine how they generate pulses. The two most common modal types for pulsers and receivers are pulse / echo and through-transmission. In pulse-echo mode, the transmitting transducer receives the echoes that are reflected back from the interface. In through-transmission mode a second transducer is used to receive and convert the ultrasonic pulse. Another less common operating mode is external pulser.
Pulser-receivers are used in material characterization work measuring sound velocity or attenuation, which in turn can be correlated to such material properties as elastic modulus or grain orientation. In conjunction with a stepless gate and a spectrum analyzer, pulser-receivers can also be used to study frequency dependent material properties or to characterize the performance of ultrasonic transducers.