Coil Swing Speed

JONATHAN PORTER

Not everything to do with successful detecting is as cut and dried as we would like it to be. I can remember the first time I listened to the audio of an SD 2000; using the standard issue earphones it sounded so smooth and stable, yet when I returned with a louder grittier sounding headphone to an area that I had had considerable success, I found even more gold.

Coil swing speed can be a useful tool in an observant prospector’s repertoire; this is something that requires experience; however you can start to become experienced once you are aware of its existence. Every gold target that is in situ in the ground (undisturbed) has a unique signature all its own, the way it presents itself to your detectors magnetic field will affect the way your detectors circuitry responds.

A pulse induction detector pumps large amounts of energy into the ground trying to break through ground minerals; the detectors electronics have to then read the resultant reflected energy at many thousands of times reduced levels to determine if indeed there is a target present. This is all done with timing, a burst of energy is transmitted into the ground then the transmit is turned off and the receive is turned on to capture any returning signals which is then sent to the processor which converts any probable targets into an audio response for you to hear. This process is happening at incredible speed all the time whilst the detector is turned on.

I have noticed that when working in variable ground the speed of your coil can determine the amount of success you have. We have all been the recipient of the good advice of low and slow’s the go when detecting and in most cases this will be so, however sometimes this is not the case. For example: in shallow ground you can receive a crisper signal response on small shallow gold targets if your swing is sped up. Try reducing the width of your swing when doing this as it will decrease the amount of ground your detectors processor has to cope with. Pay particular attention to rapid changes in threshold; this could be all the information you will receive in your headphones. Once conversant with this detecting style, small changes will become obvious compared to any hot ground or hot rocks.

Hot rocks will generally be much larger in size for the given response compared to a similar signal generated by a gold nugget eg: a one gram nugget will give a positive response on the surface yet a hot rock will have to be ten times bigger to generate a similar sounding response. If the coil is moved briskly in relation to the target the hot rocks response will be reduced but the gold nugget will stay almost the same.

This same method can also be used in deep ground chasing those elusive bigger pieces. There is no set speed for your coil, I feel this is why a person can come into an area just left by someone else and score more gold (none of us swing at exactly the same speed). Depending on your coil speed in relation to the targets present will determine how much success you can generate. If you are aware of this then you will constantly adjust your speed when receiving signals.

More often than not, most detector operators will operate their coils at too fast a rate, this is fine in shallow ground, but if the ground deepens or becomes too mineralised then the electronics and your ear will fail to cope with the changes, by applying steady changes in swing speed you can create a better more obvious signal than if you were using a set speed. Most experienced operators do this automatically without even realising it.

If a faint signal is received try slowing down your swing to see if there is an improvement; assuming it is a good target the signal will give a better sounding response at a set speed. If you can’t get the signal to improve then the chances are it might be ground noise, I say might because there are always exceptions to every rule. When using the coil swing speed technique incorporate it into coming at the target from different directions (90 degrees so on).

All these techniques are primarily designed to decrease the amount of time spent chasing false signals and also improving your chances of success on deeper gold normally left in the ground for someone more experienced. If you can increase your efficiency by using less physical effort and more brain power, you will spend more productive time in the field whilst getting closer to that moment we all wait for, the sound of a solid nugget rattling in the jar.

* For more detecting tips & techniques, be sure to view Jonathan Porter’s newest 3-hour video: The Outback Prospector - Unleashing the GP Series (available from Arizona Outback).