Summary Explanation Of Fisher Impulse AQ Controls

[Chase Goldman]

In the absence of a manual, a summary breakdown of what the controls do combined with an explanation of the various tone modes (in the same post to avoid having flip around the threads, having trouble interpreting Le Jag’s post) would be helpful when you have a chance, Rick.  Thanks.

[Rick K - First Member]

OK, first the easy ones. Here’s a pic

Fisher Impulse AQ controls

Volume,Threshold and Sensitivity work pretty much like any other metal detector. Note however that this thing has the smoothest threshold I have ever encountered in a PI and that included a TDI with Reg’s mods (I have never used a GPX 5000 so cannot compare there)>

ATS is Fisher terminology for SAT (self adjusting threshold) Lower settings provide more sensitivity to weak signals but require slower swings.

Reject is a control which increases the effect of iron ID in the ID modes of Tone, Mute and Volcanic Sand (more on them later). As you increase this control progressively larger/higher conductivity targets - which have a longer time constant are either muted or give a low tone.

The Mode control has the control choices that it is labeled with.

The Battery position activates the led to the right of the sensitivity and ATS controls. This position also activates the Frequency shift function. With the Mode in Barr/Freq, the Delay/Freq control selects a range of frequencies. to minimize EMI, you would hold the rod horizontal so that the coil is facing the horizon. A sweep while trying the various positions of the Freq control knob will minimize EMI. More on the Delay/Freq control below!

The All Metal mode is the deepest seeking mode with the smoothest threshold. All targets give the same high tone, LE.JAG hunts in this mode by preference and with the ATS set low, listens for faint wavers in the extremely smooth threshold. Although this is an all metal mode, ferrous and especially non-round ferrous targets are usually identifiable by swinging over them at the limits of detection for that target - this will usually cause them to give a double tone. 

The Tone mode causes (depending on the adjustment of the reject knob) progressively longer persisting signals (iron and high conductors) to give a low tone while shorter persisting low conductors give a high tone. Interestingly enough, the two tones have a range of pitches depending on the strength of the signal. I have to admit that my brief time with AQ prototypes never caused me to discover this for myself - but again, I have a tin ear.

The Mute mode depends for its effect in the same manner as the tone mode. ID’d targets signals are completely or mostly muted. 

The Volcanic Sand mode is for really tough mineralization - the kind that makes a gold ring on the surface invisible to any VLF including multifreakers. It’s use combines with increased minimum pulse delay and increased ATS.

The best thing about all the ID modes is that signals from “non excluded” targets still ring out full with their high tone signal - as if the iron, etc, just disappears

Now back to the Delay/Freq knob. It has no stop, you can spin it endlessly. As previously described, when the Mode knob is in the Batt/Freq position it varies the frequency. As soon as you switch the mode knob to all metal, tone, mute or vacancies sand however, it controls the minimum pulse delay in microseconds. Some care is required here. If you adjust the frequency with the mode knob in the batt/freq position, then move the mode knob to any of the operating modes, the minimum pulse delay will be whatever delay is shown on the Delay dial. If, for example you had EMI bothering your threshold and did the freq adjust as described above - and say, you ended up in the “11” position with the knob - when you switch the Mode knob back to an operating mode, your pulse delay would be 11 microseconds - probably not what you want.

About pulse delay. The Delay knob controls the time delay between the abrupt cut-off of the powerful current in the coil and the taking of the first sample of the return signals as the exponential decay of the return signal is occurring. Short pulse delays mean sampling higher up on the decay curve. The minimum pulse delay gives the greatest signal strength. This does at least two things. Targets which give weak returns due to their size, shape or conductivity are more detectable because their signal is still relatively strong because the sample is taken quicker after pulse cut-off. Also, however, ALL signals are stronger, so, for example, a 2 gram ladies ring might be detectable at 14 inches with a 7 microsecond pulse delay, it might only be detectable at a shallower depth - say, for example 10 inches with a pulse delay of 10 microseconds. This increase in depth on all targets is often not appreciated when short minimum pulse delays are discussed.

It is not always possible due to conditions to use the shortest pulse delay - rapidly changing mineralization, highly ferrous and even magnetic black sand, etc may require use of longer pulse delays for smooth operation.

I’ll leave at that for now.

Edit/Addition - Note on coil connector false signals

[Chase Goldman]

Rick - you killed it with that write up.  Excellent info.  Bookmarking that post for future reference.  Thanks so much.  Enjoy putting it through its paces.  Looking forward to your additional reports.

So I see that being able to master the sweet spot between ATS, the Reject breakpoint setting, and pulse delay for the target(s) of interest will be the skill that determines your level of success (unless you just want to go max depth and Dig it All in AM (though ferrous may still give you a telltale double tone)).

[Steve Herschbach]

Superb write up Rick! 👍🏼
 

[cobill]

Wow Rick, everything questioned in our minds was answered...as expected, the Fisher Impulse AQ will be a great tool when used properly. Expect it will be impressive not only in the salt waters, but also on the beach and in the US freshwater lakes and rivers. 

Can't wait for mine to be delivered!

Bill

 

[Rivers rat]

Thanks Rick for the write up !And Happy 2020 filled with Gold finds

 

 

RR

[Rom14]

Thanks Rick, this responded all my questions, happy new year 2020.

2020, impulse year. 

[Joe Beechnut OBN]

Thank You Rick! I like this Forum better Already and only been here for 24 hours.

[Rick K - First Member]

Glad to see you show up here Joe. Imagine the crud which would have flown at me after my write-up on some of the other forums you and I have hung out at!

[Skate]

1 hour ago, Joe Beechnut OBN said:

Thank You Rick! I like this Forum better Already and only been here for 24 hours.

This is the place to be if you want to learn. So many great people whose only agenda is to help others. No snark, no sarcasm, no keyboard cowboys. I know you're a legend OBN and that you know that the treasure is not always what we dig or scoop. Glad you're here.