Journal of AE, Volume 23, 2005 (ca. 43 MB) - AEWG

10S/N 1 to 20-1010S/N 1 to 1Displacement, pm0-10100-1010S/N 2 to 1S/N 4 to 10-100 30 60 90 120 150Time, sFig. 4 Typical examples of S+N signals for case 2793 at four different S/N ratios.the same sequence of noise signals (multiplied by a different factor to create a different S/N ratio)was added respectively to the noise-free signal to form each “set” of S+N signals. WTs ofthe S+N signals were then carried out for each case for the different S/N ratios, and the appropriatearrival times were obtained. Figure 4 shows examples of the S+N signals for case 2793 atfour different S/N ratios.5. Effects of Electronic Noise on WT-Determined S+N Signal Arrival Times (at a propagationdistance of 180 mm in the zero-degree radiation direction)For each case (AE source type, source depth and S/N ratio), a total of 50 arrival times at themode and frequency combination(s) (shown in Table 1) was obtained from the WT results. The50 arrival times represent the effect of the random variation in the noise. Table 2 shows a statisticalcharacterization of the arrival times as a function of the S/N ratio for one source type anddepth (case 2793; see Fig. 4). The table provides the average arrival time, maximum time,minimum time and sample standard deviation (SD), as well as the noise-free arrival time. Even6