Jump to content

Recommended Posts


  • Replies 136
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

Foreword: For reasons of technological confidentiality, it is obvious that I could not discuss certain technical details. I can only share my knowledge in a relative way in order to give a comprehensi

Hello, I am physicist engineer to Fisher Research Laboratory, I designed the Impulse AQ. Your subject is constructive, so I will read the post carefully and I will try to answer it tomorrow.

The new Fisher Impulse AQ is doing something new with pulse induction discrimination. I think I have a pretty good idea of what the engineers are up to and so want to pass on my thoughts in case it wi

Posted Images

Good question. Platinum rings can read real low, and smaller ones down in the foil range. I would not be shocked if some platinum gets lost with the AQ discrimination setting. The talk focuses on gold for a reason. Like I have mentioned in another post getting our hands on this machine and doing a lot of target testing will be critical to determine where the lines are drawn and if they can be moved at all.

Let's face it, marketing will talk about what the machine does well and will let other stuff go unmentioned. We will have to figure out the details ourselves. In a nutshell, where are the mid-range cutoffs both high and low? And what trash is still going to show up in the mid-range? I have an idea what to expect but only actual use will prove the reality of it all.

There are bound to be people who just freak out over the idea of missing anything. The fact is unless you are using a high power PI and dig every target we all miss stuff. The more discrimination you employ, the more inevitable it becomes. For me it is purely a practical matter involving how much time I have and in some cases how many targets I can physically dig. Moving the odds in my favor by eliminating worthless digs at the cost of some possible good targets missed is one of the most important strategies we employ in metal detecting, and getting it wrong too far in either direction can be costly.

I have often used VLF discrimination to eliminate zinc penny and higher targets while park detecting for rings. People will say "yeah, but some rings read like zinc pennies". Yup, that's true. But rather than fill my pockets with coins I prefer to concentrate on the mid to low range where the odds are better for rings and save a lot of time digging coins I am not looking for. On the very low end I may also pass on the real small foil and can slaw bits. This is what the AQ is also doing.

It sounds like lots of time has been spent optimizing where to put the cutoff points and I am going to trust the testers have chosen wisely. Nothing is perfect. I am all in for a PI that concentrates on the main sweet range while eliminating a lot of deep trash digging, the bane of any PI detector. And if the trash level is low anyway, just switch to all metal and dig it all. Best of all it's not an insane 7 lbs like my old ATX!

I expect the AQ discrimination system will have limits but none that will surprise me and I am willing to accept the limits to get some form of decent discrimination while retaining PI depth in black sand laden beaches. If the machine does as expected I don't see huge benefits for low mineral white sand beach hunters. The main benefit will be west coast and volcanic islands where a PI will shine. And in those areas heading for the trashy places that normally drive PI hunters away will be a good idea.

  • Like 6
  • Thanks 1
Link to post
Share on other sites

Welcome to the forum Alexandre! We are all excited about your new detector and speculating about how the discrimination system works. The goal on this forum is only to help people, so if anything does not seem helpful please let us know.

  • Like 5
Link to post
Share on other sites

The following is a discussion of existing PI detector features that I find to be useful for relic hunting that goes beyond the target discrimination break-point discussion that Steve articulated so well above.  Beside the high mass-high conductor/low mass-low conductor discrimination breakpoint setting - another useful feature implemented in the ML GPX and to a lesser extent (or less successfully, based on my experience) on the Garrett ATX is iron identification, rejection, or blanking.  The GPX implements a blanking function on probable "high" (low tone) corroded iron signals with the peak of the signal tone blanking out.  Not 100% effective as it can also provide "false positives" on non-ferrous targets but it is nevertheless a pretty useful feature.  Similarly, the ATX has an iron grunt check, which is both ergonomically inferior (requires you to engage a separate button during your swing) and I have found it to be less reliable (almost to the point that it is a 50/50 proposition if you do get an iron grunt).  Blanking has it's drawbacks of course.  Besides reliability, iron reject/blanking on the ML can only be utilized with DD coils and can become overwhelmed in thick iron situations. Anyway, Alexandre or Rick (once you get your machine), if either of you can shed light on whether such a feature will exist on any or all iterations of the Fisher Impulse, that would be enlightening. 

Finally, compared to the Garret ATX, I find that the as you gain experience digging innumerable nails, the tone "shape" of the GPX provides a wealth of information.  For example, the classic "W" double peak high tone (low conductor/small mass target) is often a clue that you are swinging along the long axis of a nail.  Turn 90 degrees and that nail sounds like a sweet high tone indicative of round brass or small lead.  Bent nails, however, are very difficult to ID, they sound great.  Higher mass minie balls give a nice smooth low tone that will not break unlike a large rusted nail or other piece of iron.  The ATX uses more of a processed doorbell high-low/low-high tone, so it cannot convey much additional target information other than the high conductor/high mass or opposite characterization.  So I am interested whether the tone implementation on the Fisher Impulse target audio will convey analog-signal-like target characterization (e.g., irregular or regular shape) information.

Thanks for reading.  Excited to see the Fisher Impulse in action.

  • Like 2
Link to post
Share on other sites

In all this discussion, it ought to be remembered that the AQ is very tightly focused on recovering gold jewelry at salt beaches. That doesn’t mean that it will not be useful for other applications, but to the extent it may prove not ideal for those, the answer will be that tight focus and optimization for a purpose means that other purposes may not be as well served.

  • Like 9
Link to post
Share on other sites

Thanks Rick, your opinions on gold coins on the beach? Will it depend on the size of the coin?. It's the excitement before Christmas!

Link to post
Share on other sites
2 hours ago, Chase Goldman said:

another useful feature implemented in the ML GPX and to a lesser extent (or less successfully, based on my experience) on the Garrett ATX is iron identification, rejection, or blanking.  The GPX implements a blanking function on probable "high" (low tone) corroded iron signals with the peak of the signal tone blanking out.  Not 100% effective as it can also provide "false positives" on non-ferrous targets but it is nevertheless a pretty useful feature.

Long story short this has never been mentioned at any as a potential feature on the Impulse AQ. Perhaps it may be seen on the land prospecting version since the AQ methodology is not very application to ground balanced nugget hunting.

The main problem with the ferrous blanking as implemented in both the Minelab PI detectors and the ATX is it only works on shallow targets, and not on the targets where you need discrimination the most - the really deep ones. I don't mind digging 6" nails, it is the two foot nails that I find annoying. This inability to function at depth made the GPX iron blanking pretty useless for most of my applications where deep ferrous is a common occurrence, whether on a beach or in tailing piles. That, plus numerous instances of my seeing quite large and valuable gold specimens rejected as ferrous by the GPX meant I never used it. It might be acceptable to miss bullets due to improper identification but not $500 gold specimens.

Now don't get me wrong, the surface ferrous blanking function can be very useful for some people and some applications. I can see where it would be a great benefit for relic hunting in particular. I'm just pointing out it has some serious limitations such that most gold prospectors at least never use it except in rare circumstances.

This is typical. This location produced some real nice gold nuggets. I got a bare whisper signal with the GPX 5000. I had a Gold Bug Pro on hand to act as a pinpointer and discrimination tool, but no signal from it until well over a foot. It started reading ferrous but by that time I was close anyway, and wanted the potentially target masking nail to be gone. So after quite a bit of effort in packed rocky soil out comes a large nail at about two feet. That is what I hope the Impulse AQ will help with. On the beach in particular the effort expended goes up exponentially with depth as the hole is likely caving and filling almost as fast as it can be excavated. I have had to dig some huge pits employing a PI in the surf with mask and snorkel only to retrieve a large ferrous item.

steve-herschbach-digging-deep-nails-minelab-gpx.jpg
Heading for China with a shovel

steve-herschbach-digging-deep-nails-minelab-gpx-5000.jpg
And my reward - did not help it was wedged under that large rock in the hole

  • Like 7
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Similar Content

    • By tvr
      Hunted mostly in tone mode. Set up reject with a small paper clip. Delay 7.5, Reject 6, ATS 7, Sensitivity 7, Threshold 4, Volume max.
      I did not play much with ATS. I am in brackish water in a pretty well protected environment so the water was flat. Did have a boat go by and the AQ was not affected by the 6 inch or so wake that washed over with the detector fully submerged and coil on the bottom. The threshold did have a little bit of warble from the boat. Changing freq did not seem to help. When the guy shut the engine down at his dock, the little bit of warble went away. I'm thinking his ignition system is transmitting the noise.
      I was surprised how quiet the AQ is in the water. I could run any delay. If sensitivity was higher than 7 there was some sounding on coil movement that was reduced when sweep was slowed to a crawl, but at 7 it was pretty quiet.
      As for the sounding when the connector dips in and out of the water; it does, but not any where near as bad as I had imagined from watching and listening to a couple of the posted videos. Would I pay more for a stainless connector with a reduction in the effect? Sure, but after actually experiencing it, I am kind of ambivalent about it. It retunes quicker than I would need if I were in waves that were at the connector level, so if I have a little cut close to shore on an ocean trip, I could deal with a wave hit at the connector and hunt between waves. How much the higher salinity at the ocean would change how it acts? Not sure.
      Coil does have a little float to it. Not bad, but would be nice to have it not float.
      I gave up with back pain at almost exactly 3 hours of running the AQ; battery was still going.
      The edge of the coil does help with pinpointing. I hit a few old pull tabs that were deep and took several scoops to dig out. Also got some small sinkers that were several scoopers.
      Moving the scoop close to see a tone break is kind of tricky. There is a very narrow window between getting a target tone break and the scoop being a greatly overwhelming influence. It is going to take some practice and some more ear learning.
      Overall, I'm very happy with the AQ so far. Most of the targets are right in the range I'm looking for. Even got one small ring, although it is a junk eaten up copper one.

    • By Steve Herschbach
      Fisher Impulse AQ Ltd Owners Manual - Download Here

    • By PPP
      The site http://fisher-impulse.com  is going to become annoying every time I visit it in hope of  some update or information or something about AQ and you see the ''COMING SOON'' sign. Please put at least a picture of the AQ in there!!!

    • By Rick Kempf
      With this weeks output, 8 units the last two weeks. Hope the trend continues and increases.
       
    • By cdv
      Approximately  3 hour hunt (one battery), about 2 hours in the water in the Gulf. Water was almost flat with a slight current, bottom was rippled. This particular beach doesn't get many tourists and is somewhat out of the way, I didn't expect a lot of targets.
      Since I still have loads to learn on the machine, I didn't spend a whole lot of time with any specific setting as I was trying to see what adjustments did what. Hunted in all metal the entire hunt.  I found you really need to hunt slow to avoid any rising threshold due to swinging into deeper water. Sensitivity adjustments and delay adjustments helped. The machine was more than useable in the water with the exception of the coil connector when it enters/exits the water. Odd thing on that was I thought I was shallow enough but the connector sticks out a good ways.....
      The tent stakes, sinker, and bottle caps were from the wet sand. The few other targets were from the water waist to chest deep. The dime seemed to be the deepest target at about 3 scoops deep give or take. There was no mistaking the ring as a target, it wasn't a whisper at all.....got it with the second scoop.
      Pinpointing the target prior to digging was easier with the 12" coil then I had thought it would be.
      Balance on this machine is really good for wet/dry hunting, however, it did take a few adjustments to my typical hunting style to have good coil control in the water, it does show you how "bad" your normal coil control may be....
      You sure don't have to worry about when the battery is getting low, it lets you know when it is time to change batteries or go home!
      All in all, I'm liking this machine so far....
      Cliff


    • By jimpugh
      Getting ready to ramp up......what’s better than a AQ...... hmmmmm ....Two AQ’s
      Happy Trails
      jimpugh


×
×
  • Create New...