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This paper investigates various types of coded waveforms that could be used for air-coupled ultrasound. These are needed because of the low signal-to-noise ratios that are found in many air-coupled ultrasonic NDT measurements. The various algorithms are described, and their performance in the presence of noise demonstrated.
Pulse compression is often practiced in ultrasound Non Destructive Testing (PDF) systems using chirps. However, chirps are inadequate for setups where multiple probes need to operate concurrently in Multiple Input Multiple Output (PDF) arrangements. Conversely, many coded excitation systems designed for PDF miss some chirp advantages (constant envelope excitation, easiness of bandwidth control, etc...
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