Ray Seidel

Hello Rege-PA; and the “detectorprospector” community; allow me to expand a little on my previous response to you and put it into context. I apologize in advance for too many words, however. Several years ago, I was involved and enthusiastic about Gold Detector design suitable for highly mineralized Gold fields in Australia’s “Golden Triangle” our primary objective was a project called “Titan Pulse Induction Detector”. I worked with “Finders” in Dunolly Vic/Australia. I wrote the patent ( https://www.google.com/patents/WO2006037176A1?cl=en ) for this machine which involved Constant-Current-Coil-Drive and separate core and anus peripheral field illuminations; this was a technique to achieve real time Ground Balancing.( ie a view along the bore-sight view where the target “is” and an annulus view around the periphery where the target “is not”). The audio used subtle white noise (slaved to the annulus view) to describe the general ground mineralization, which gave way to a monotonic tone that pierced through the soft quiescent white/pink/brown background “hiss noise” to announce a target was on central bore-sight axis. This was meant to invoke a mental picture of a conductive target being revealed. The use of white noise was that it proposed to be less annoying to listen to while searching; with its variable spectral colour (bandwidth) it was conveying some idea of the changing soil mineralization. As a separate product that might have helped finance the Titan Project, I designed a “retrofit audio enhancer” for the popular Minelab SD-Detectors. This was the “SuperFix” and while it had some innovative processes, which dissembled, processed then reassembled the classic Minelab’s “cook/coo” audio, it was my mistake to do it at that time. As events unfolded, it’s premature release plus my attempt to be too clever and also some manufacturing difficulties coupled with the variability of the machines it was to parasite on, then it failed as a product. In hindsight, as a business solution it was a risk for R&D finance that could not afford failure. It failed. Still, from my viewpoint it taught me a valuable lesson in “Signal processing Latency” i.e. how long it takes for a signal to propagate through a filtering process. It also enabled me to test some of the minor audio concepts of the Titan. For those few who mastered the use of the Superfix, they would notice the high or low monotone (as determined by metal type), now occurred when the target was under top-dead centre of a mono coil; To achieve this we had to simulate travelling “back in time” as the incoming Minelab being a frequency modulated tone which is simultaneously amplitude modulated by the silhouette of the detected video waveform. (An issue that causes the straight through Minelab and raw Superfix audio to appear long after the sweeping coil has moved on. Positional confusion) The fact that Minelab use differentiation of the Detection envelope, followed by Low-pass filtering (which delays its output by many milliseconds) then invoking the combination of Voltage controlled oscillator (to which the ear is sensitive), then amplitude modulating (to quiet the drone of the base tone while searching) the desired consequence is that no detection DC drift is apparent. Unfortunately for the operator he cannot easily pinpoint the target as the “cook/coo” appears after the target has been wiped over. This Minelab mechanism is now too well accepted, to say the target is “somewhere here – dig a big hole to retrieve it” ... it works, but we tried to mine the MineLab audio to better announce a target and endure acoustic fatigue for long time searching and then rarely find the target. The Titan coil was unusual in several matters, it used inverted conical winding to focus the emitted transmitted field (and by reciprocity the returning induced target signal). The second feature was to be a stainless steel focusing shield (much like a torch reflector) ... the aim being to drive the available illuminating power burst into the soil and also mitigate against outside Radio-Wave type interference. The final coil structure was bulky, like a biscuit tin on a stick ... however, we saw it as the next stage of evolution for detector coils, one-day it may yet come. Finders closed and I left to work in “Low Frequency Electronic Animal Eartag Readers”. The issues that this offered had much similarity to Pulse Induction Detectors. Both are Half Duplex systems, ie Transmit then quickly receive, noise mitigation and controlling directivity (Reflectors) and much more. So when I chanced on your request for any help/advise on detection interference “from” a pain/pacemaker. I should have been more forceful to you that the problem is what the detector might do to you, do you agree the problem is better voiced in reverse ... be careful, I have no good answer for you. This is an interesting forum. As for gold, I got to see and handle several >300 oz nuggets, quite a thrill, but I had to hand them back. Kind Regards Ray

Hello Rege-PA, I recall an alarming incident when a visitor walked past our experimental RFID (Radio Frequency Identification Device “Transmitter”) ... ie 50 millisecond burst of 134.2Khz of very intense magnetic field, used for Electronic cattle ear tag detection. He had an under-skin Pain Blocker Transplant that had leads threaded up his neck to trick his brain into “mitigating” random pain episodes (he is war veteran when vehicle rolled over onto him). As he approached the alternating magnetic field emanating from the 1.5 metre diameter, resonant detector coils caused him to respond in increasing pain ... somehow the interference was causing “mis-firing” of the electronic pain blocker. There is a slight similarity here to your desire to use a pulse Induction detector. However my suspicion is the detector coil would need be very close to the (your?) implant to cause “harmful interference”, though, for a more common heart pacemaker death may be possible. I chanced on this forum and your thread in particular and advise you be careful and seek more scientific studies... this is a tip of the iceberg problem.