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Impulse AQ Testing Results


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It was pointed out to me by my buddy Jim that the AQ runs three different pulse FQ ranges--one for each mode.  These go from highest in A/M (4.02-4.17) to lowest in volcanic. (1.54-1.56).  Tone mode is in the middle at 3.04-3.12.  I've come to recognise that each has its seperate turnng characteristics.  Unlike most detectors--the A/M is easier to tune than  the Tone mode.  With Tone, you have  the "back end" ground noise that warbles in and  out.  If you are overtuned, this will overwhelm your target sounds.  The Tone mode needs to be run closer to preset Gain, with a lower Threshold and Volume.  It also needs a slower sweep speed for deep targets to stand out.  With Tone and Mute, targets sound wider and flatter--especially when you run low delay.  As with any pulse, the low conductor sensitivithy of the low delay settings makes small targets sound bigger.   A setting of 10 uSc or higher makes signals more defined.   So while there are differences between the depth of the A/M and tone modes--the way to reduce this difference is with proper tuning.   As you  increase the Gain in Tone mode, the signal  flattens out--and  target sounds are weaker.   For higher Gain settings, Mute has a lot of potential in that it has no "back end" ground noises.  At the same time it can also be overtuned.   A good way  to become familiar with the responses of the AQ (or any detector) is to start witih the "extreeme" settings and learn to recognize how overtuning sounds in the threshold and target tones.  Oddly enough, athough the REJ control is suppposed  to only be active in tone mode, turning it right down increases the depth. 

Still testing this machine--it certainly has a lot of potential.

cjc

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I would also add  that if you want to use tone as a checker--tune it first.  To just pop over will probably be a lot weaker.   It's effectiveness is also keyed to the target depth so when something is weak in A/M it may not respond  / check accurately in tone.  cjc

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On 8/23/2022 at 8:45 PM, cjc said:

It was pointed out to me by my buddy Jim that the AQ runs three different pulse FQ ranges--one for each mode.  These go from highest in A/M (4.02-4.17) to lowest in volcanic. (1.54-1.56).  Tone mode is in the middle at 3.04-3.12.  I've come to recognise that each has its seperate turnng characteristics.  Unlike most detectors--the A/M is easier to tune than  the Tone mode.  With Tone, you have  the "back end" ground noise that warbles in and  out.  If you are overtuned, this will overwhelm your target sounds.  The Tone mode needs to be run closer to preset Gain, with a lower Threshold and Volume.  It also needs a slower sweep speed for deep targets to stand out.  With Tone and Mute, targets sound wider and flatter--especially when you run low delay.  As with any pulse, the low conductor sensitivithy of the low delay settings makes small targets sound bigger.   A setting of 10 uSc or higher makes signals more defined.   So while there are differences between the depth of the A/M and tone modes--the way to reduce this difference is with proper tuning.   As you  increase the Gain in Tone mode, the signal  flattens out--and  target sounds are weaker.   For higher Gain settings, Mute has a lot of potential in that it has no "back end" ground noises.  At the same time it can also be overtuned.   A good way  to become familiar with the responses of the AQ (or any detector) is to start witih the "extreeme" settings and learn to recognize how overtuning sounds in the threshold and target tones.  Oddly enough, athough the REJ control is suppposed  to only be active in tone mode, turning it right down increases the depth. 

Still testing this machine--it certainly has a lot of potential.

cjc

Hi Clive. I do not think this is entirely correct after many hours of conversations with Eric. Maybe shoot him a mail and see if he saved his results. The manual does reference that tone and mute share the same frequencies but that is not correct. Mute and volcanic share the sam frequencies. That leaves AM and tone as the remaining frequencies. I do believe he is off a bit on the tone mode but your example of tuning is correct. 

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I took my numbers from the manual.  They do seem to make for dramatic differences in turning perameters--I suggest testing a target in Tone to set up the machine.  

cjc

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  • 3 weeks later...

I would also say that with all of its threaded aluminum surfaces (and slightly dodgey coil connector) a tube of Permatech Dielectric Grease is a must.  Apply with a toothbrush to all co-axe jacks and pins--hopefully this will prevent any "wasabe'  from showing up. and the jacks turning  properly.

cjc

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