This technique positions the probes on the adjacent plate material parallel to the weld axis being examined. TOFD provides a linear “A” scan presentation for when the operator sets up scan parameters and for actual test signal analysis. It provides a sectional view of the weld with a minimum of 64 grey scale levels. Analogue to digital conversion of waveforms shall have sampling rates at least four times that of the nominal frequency of the probe. When digital signal processing is to be carried out on the raw data, this shall be increased to eight times the nominal frequency of the probe.