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I have been following the mine detector developed at the Siemens Roke Manor facility in England. It is basically very simple. It looks like it would be an ideal metal detector for us THers. Here are a couple of URLs for those interested.
http://w4.siemens.de/FuI/en/archiv/z...l09/index.html
http://www.worldaware.org.uk/awards/...rokemanor.html
Here is the essence of the detector:
Conventional mine and metal detectors usually use a coil to create a magnetic field. A metal object disturbing the field will disturb the current in the coil. Chris Richardson adopted a different approach. In Roke Manor's device, two loops of aerial are printed on a circuit board. The outer loop transmits low-power radio signals. The inner loop, the receiver, is in a figure of eight. Normally, the receiver registers no signal because the two halves of the figure of eight cancel each other out. For the same reason, it gives no signal if the ground over which it is being swept is uniform in character, because the radio signals being reflected to the receiver are then similar. But if the ground under one half of the figure of eight differs from that under the other half, a signal is registered and it is amplified for the operator to hear. The signal also clearly marks the edges of the object located. Results from different radio frequencies can suggest what the object is made of, since different materials respond differently. The task of dealing with a mine remains; but at least it has been located. Tests by the Defence Evaluation and Research Agency found that SPLICE could locate mines five centimetres (two inches) below the surface. It could locate a stainless steel pin less than two centimetres long. Roke Manor is negotiating with two companies interested in manufacturing SPLICE.
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If you read the two articles there is enough info for us to build one of these and test it. One of the things to consider is frequency. Looks like they are using very low power and getting 5 cm for a plastic mine. the 2 cm for the stainless steel pin don't impress me though. Most mines are not buried deep so low power is fine.
Anyone interested? Looks like a very nice innovative detector. AND very simple. Some signal processing on the figure 8 input could probably be used to identify the metal. Plus increase power level for greator depth.
Goldfinder
http://w4.siemens.de/FuI/en/archiv/z...l09/index.html
http://www.worldaware.org.uk/awards/...rokemanor.html
Here is the essence of the detector:
Conventional mine and metal detectors usually use a coil to create a magnetic field. A metal object disturbing the field will disturb the current in the coil. Chris Richardson adopted a different approach. In Roke Manor's device, two loops of aerial are printed on a circuit board. The outer loop transmits low-power radio signals. The inner loop, the receiver, is in a figure of eight. Normally, the receiver registers no signal because the two halves of the figure of eight cancel each other out. For the same reason, it gives no signal if the ground over which it is being swept is uniform in character, because the radio signals being reflected to the receiver are then similar. But if the ground under one half of the figure of eight differs from that under the other half, a signal is registered and it is amplified for the operator to hear. The signal also clearly marks the edges of the object located. Results from different radio frequencies can suggest what the object is made of, since different materials respond differently. The task of dealing with a mine remains; but at least it has been located. Tests by the Defence Evaluation and Research Agency found that SPLICE could locate mines five centimetres (two inches) below the surface. It could locate a stainless steel pin less than two centimetres long. Roke Manor is negotiating with two companies interested in manufacturing SPLICE.
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If you read the two articles there is enough info for us to build one of these and test it. One of the things to consider is frequency. Looks like they are using very low power and getting 5 cm for a plastic mine. the 2 cm for the stainless steel pin don't impress me though. Most mines are not buried deep so low power is fine.
Anyone interested? Looks like a very nice innovative detector. AND very simple. Some signal processing on the figure 8 input could probably be used to identify the metal. Plus increase power level for greator depth.
Goldfinder
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