Xterra 505: Sensitivity/Depth Accuracy Plots

[S505]

These are plots of the data that go along with my post of 1 April 2011. I am not sure if they will post in a real usable form but this will be a good test.

Enjoy- if you can open/zoom them. If it is a failure I may have to try another computer with *real* software.

S505

 

[S505]

Yet another correction: the top plot is not only a very poor presentation of the data but the x-axis units are incorrect. That is a plot of intermediate modified data which should not be there. Since no one has called me out on that I will minimize the use of plots unless they are very clear out of concern they may confuse more than inform. There is a point where too much information is detrimental.

I will try this instead:

In summary, the Xterra 505 indicated depth accurately (within 2 inches) 75% of the time.

Estimating depth by the minimum sensitivity required to detect a target (Depth=Sensitivity / 2) indicated depth accurately (within 1 inch) 95% of the time. This method was accurate within 1/2 inch 80% of the time.

How do you do it? When you detect a target, thumb down the sensitivity while moving the coil over the target until you determine the lowest sensitivity where the target sounds. Divide that number by 2. The answer has been very close to coin's and ring's depths in inches (at least up to 6 inches which is as deep as tests went) .

Note that the 305 and the 705 have different sensitivity scales than the 505 and this equation does not apply.

S505