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Ultrasonic Non- Destructive Testing (NDT) is the most popular method used to detect defects and flaws in the materials. Ultrasonic C-Scan is used to pictorially visualize the detects present. Echo signal contains information regarding the flaws and cracks. The duration and amplitude analysis of echo signal reveals the information of defects. The Radio Frequency (RF) echoes received are ana-lysed in time and amplitude domain. Envelop contains information of peak and time duration of echo. Envelop detection is the method used to extract information form signals. It can be done by wavelet transform and Hilbert transform. This article describes the developed envelop detection technique to extract information from echoes. Transducer radio frequency data of reflected signal is obtained into computer using data acquisition card (Gage Applied Razor- CSE1222). This raw data contains all points of echo signal with the frequency component related to the frequency of trans-ducer. Generally, amplitude and time duration of echo are only useful for estimation of defects. The classical approach for envelop detection is the use of analog filter circuit which removes the radio frequency content of the echoes. The drawback of this method is that the change in transducer fre-quency needs change in hardware components of time constant of filter. This becomes cumbersome for the users and limits functionality of system for manual mode only. In order to provide improved and versatile features and software based selectivity. The entire software was developed in visual C++ platform and using C Sharp. In this article, the functionality of the developed software for envelop detection has been described. Finally, the obtained results have been compared with the envelop detection capability of commercially available instruments. The absolute values of echo signal have been taken and develop a software based logic for digital Low Pass Filter (LPF). In LPF a certain cutoff frequency is assigned to obtain proper envelop of the signal. Two parameters, cutoff frequency and sampling rate defines proper reconstruction of signal. Cutoff frequency of low pass filter limits transition rate of signal and smooth envelop is obtained. It was observed that estimated envelop can track the entire signal to provides desire outcome of signal.
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