Pulse Hunting Basics And The Impulse AQ

[cjc]

New Fisher Impulse AQ pulse induction metal detector

Ive listened to a lot of hunters scoff at the simple basic skills I promote in my books. However as these machines become more powerful—with more telling audio and more heavily processed signal—the more important these basics become. The Fisher Impulse AQ is a good example of this. The only way to describe this detector is to say that it’s “a beast” very deep and powerful—on a par with any not-gold -specific pulse out there (SD / GPX/Z Series). I also own a waterproof TDI Pro and the AQ’s performance characteristics resembles this machine quite closely. For one thing with each—as you turn them up—it’s harder to hear any detail in the response. The lower Sensitivity settings go almost as deep but let you hear the weak responses of junk or the elongated tone of a hairpin better. The “maxed out” settings can come later. As well, with both, when a target has some steel in it as do many bottlecaps, this shows up at the ends of the tone. This is especially true of the Impulse AQ in “Tone” mode. A good way to demo this is to get a clean non- ferrous signal then move your scoop in closer to hear the tone change. This sound is one of your primary weapons in trash. As well—the simple basic of listening for a narrow peaked tone will help you to zero in on the non-ferrous targets. With any detector—a peaked sound means something that’s distinct from the ground. There’s a lot to becoming accurate with a pulse and it takes time. What helps is to have a “language” of signal characteristics to pair with your digs:

-wide / narrow.

-overall size.

-consistency on the cross-sweep.

-peaked / drawn out.

-single or double tone.

-how does it respond when you raise the coil? (Faint or dropping out altogether)?

-overall correlation (size / strength / depth make sense).

-smooth or sharp tone ends.

-signal tone itself as relates to an optimized pulse such as the Anchor Electronics Barracuda or the Pulsepower Developments Aquasearch.  (With this type of a PI--the "cleanest" sound you hear will be gold). 

 

These are some of the target characteristics that--if you pay attention to them will make you a more accurate pulse hunter. I’ve been hesitant to get out with the Impulse AQ because the sites near me are so full of trash. The hunt I did today in this type of conditions showed me that it is possible to use a pulse in dense trash but to dig random targets is a recipe for frustration. When you begin to use the above basics it’s possible to become more accurate—just as you can using a VLF in All Metal mode.

I also found the Impulse AQ’s iron rejection modes to be interesting and effective tools although I’ve a lot to learn about how to best use them. From observing Alexandre’s tuning video the sense I get is that setting the AQ is about working with combinations of Sensitivity, ATS (re-tuning speed) and Rejection. The amount of Delay used also plays a role here too in that longer Delay settings will reduce the machine’s response to weak targets such as foils and hairpins. What I’ve seen so far makes me think of a comment of Eric Foster’s in describing the effects of the Aquasearch’s adjustments (Delay, SAT and Threshold) as being “nonlinear.”  I think this will be an important part of understanding the Impulse AQ. 

 I  also noticed that the adjustments Alexandre made were small but produced dramatic changes.  This points to a detector with a lot of fidelity--a versatile machine. 

With the TDI Pro, the challenge for me has been learning to turn it down enough to have a stable threshold in fast salt and stay off the “micro conductors”--but to still get more performance than say--a Dual Field.  This was important in that the Dual Field is more stable in fast salt--so why have an erratic machine with the same usable performance range? What I found was that the TDI needed to be run up at 12 uSc—same as the Dual Field.

While I’ve yet to run the AQ in salt—the overall performance in fresh water and black sand seems to indicate that it will be more stable than the TDI Pro. This would be a huge gain in and of itself--TDI Pro depth—with more stability at the lower Delay ranges.

Can’t wait!

cjc

[Steve Herschbach]

Great post Clive - thanks!

Clive’s Book Store

[tvr]

Good to hear you chime in. From a previous post, I know you have been busy. Hope you get a chance to do more with the AQ soon!

[King-Of-Bling]

Great post on the idiosyncrasies of the pulse machines you use and the dynamics. Much is still to be learned , but this is a step in the right direction. Many people disagree or can't fathom that you can actually discriminate with a PI machine. It's beyond them. On a very heavy , trash infested beach , it is challenging but can be done. Back in the day , it was mainly VLFs , then pulses , now MFs. In the way of a double-edged sword , I'm glad there AREN'T more people using them.... I am one of those that also enjoy your books with some great information  that has helped me see things in a slightly different perspective in my quest for treasure.

[cjc]

Thanks for your reply, Bling. That's been my experience--you pick up a tip here and a setting there, and eventually you have a whole lot of "things to try."  Then, once in a  while you manage to "hit the nail on the head...".  I've been six years learning how to hunt with accuracy using the TDI Pro--but now--its an incredible tool that gives me a huge advantage--over even other pulse hunters.   All those challenges are worth the journey.  

I've finally come up with a reply for those pesky "should I dig everything?" guys:  "Yes---if you have no other skills whatsoever...!"

cjc