Patent ID: 8001842

Claim:
An object inspection system, comprising: a transmit and receive section to generate a test signal and to receive a responsive echo signal; a transducer that converts the test signal to an ultrasonic signal, applies the ultrasonic signal to a target object to be tested, receives an ultrasonic echo signal and produces the echo signal for the transmit and receive section; a signal processing circuit coupled with the transmit and receive section for receiving and processing the echo signal, the signal processing circuit including at least two signal processing channels, each channel scaling the echo signal to a different degree, and each channel having a respective analog to digital converter which outputs a respective digitized signal; a selection circuit which selects the digitized signal of the respective analog to digital converter which provides the largest amplification of the echo signal without having overflowed; and a first one of said signal processing channels being coupled directly to the echo signal and comprising a respective preamplifier and a respective clamping circuit for preventing said preamplifier from becoming saturated, and a second one of said signal processing channels being coupled directly to the echo signal and comprising a respective preamplifier and a respective clamping circuit to prevent saturation of the preamplifier of the second one of said signal processing channels, the clamping circuit of the second signal processing channel being configured to maintain a constant input impedance on the echo signal, at least up to a signal level of said echo signal which equals a maximum input range to the preamplifier of the first one of said signal processing channels.