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Our objective was to investigate the accuracy of metal detecting for the application of finding land mines. Variables:
Method Number One: We tested the accuracy of the metal detector by, first one person placing several pieces of metal attached to pieces of dowel (called targets) just underneath the sand with the metal at the bottom. Another person would then sweep the sand field with the metal detector, making sure not to miss any ground. Once the ‘sweeper’ found a target the other person would start the stopwatch. The ‘sweeper’ would keep sweeping until they thought they had found the exact location of the targets and then the ‘timer’ would lay down a marker where the sweeper thought the target was and the ‘timer’ would then stop the stopwatch. A metal crosspiece would then be laid over the area where the marker was and then a marker on the crosspiece was slid across so it was over the initial marker. The initial marker is then taken away and the ‘timer’ would search the area of sand underneath, for the target. Once located, the distance from the marker on the crosspiece to the target was measured, in relation to the X-axis and Y-axis. The information of the target number, how long it took from the first detection the more accurate positioning and where the target really was in relation to the X-axis and Y-axis was then recorded in a table of Results. Method Number Two: The second method involved hiding the targets, sweeping for then and starting to time when a target was first detected, but then scanning from side to side until you have found the two points on the sand field when the area of detection stops (see diagram). We would than turn so that we were 90° to thew original sweep and try to detect the top and bottom of where the target detection starts and ends. We would place a marker at each of these points (4) and then use the crosspiece to take measurements from centre of where all the markers line up to. Discussion and Conclusions: There is a lot of variability in the results I have compiled, which makes it hard to identify and trends or patterns in the results. These tests would need to be done many times to get more accurate results. One of the main problems is the number of variables. The conditions are not always the same for each test, many times the battery may be at a lower level of power, and the sensitivity, threshold and ground balance may all be different for each set of testing. I feel that the results also heavily depend on the user of the metal detector. I found that gradually throughout the testing the user of the detector became more accurate because they had a feel for how the detector works and you have a better understanding of where the target would be. Even though it is not totally proven, I feel that the one marker system is the more effective method from the point of view of accuracy and the amount of time it takes to find the target. I found that you gained no more accuracy from using four markers rather than one and placing four markers down takes longer. Jacob Doogue |
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