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4 <br />Another way to calculate the amplitude at 80k band is by <br />plotting these same log readings on a semi-log chart. <br />Plot the values for ok Bond and 100k Bond vs. their <br />respective Amplitudes on a semi-log chart - amplitudes on <br />the log scale (y-axis), and bond indices on the linear scale <br />(x-axis). Then, connect the points with a straight line. <br />To estimate the amplitude corresponding to an 80k Bond <br />Index, enter the graph on the x-axis at 8ok bond. Draw a <br />straight line upward until you reach the diagonal line <br />connecting the Ok and look points. continue by drawing a <br />horizontal line to the y-axis. This point on the y-axis is <br />the amplitude correspond_na to an 8ok Bond Index. <br />Using the values from the example above, your chart will <br />look like that shown below: <br /> .a <br /> n <br /> w <br /> v <br /> w <br /> <br /> <br /> w <br /> <br /> <br /> <br />n <br />> <br />; <br />F <br />`J I <br /> <br /> <br />lU <br /> I <br /> <br />F- , <br /> <br />.1 , <br /> I <br /> <br /> <br /> ~ • A ~o w ]~ 10 A U <br />v O '~ <br /> '6 EONO <br />In this example, 30k bond shows an amplitude of 2.4 mV. <br />A convenient way to evaluate the log is t4 draw a line on <br />the bond lag's ampliriad amplitude {SX) track corresponding <br />to the calculated 80k band amplitude. Whenever the logged <br />amplifisd amplitude (SX) curve drops below (to the left of) <br />the drawn line, his indicates a bond of Sot or more. <br /> I <br />1 r I 1 1 <br />I ~ ~ ~ I ~ I <br />~ ~ ~ <br />Dffi BOND <br />81 mV <br /> <br />~ ~ <br />~ i ~ <br /> <br /> <br />100% <br />~ ~ 1 <br />i i <br /> <br /> <br />OND <br />mV <br />I I I I I 1 <br /> <br /> <br />~- I <br />~1 4 mV ~ I <br /> <br /> <br /> <br />i i i <br />I I I <br />~ i , I ~_- I <br />~ 80% BOND I <br />~~ I I <br />~ <br />