Book Excerpt: Understanding The Heavily Processed Signal""

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3/ Understanding the Heavily Processed Signal 

A heavily processed signal also affects target sounds.  Everything is made to sound more the same.  It’s actually surprising how with the Manticore, when you open up the Ferrous Limits, some spikes and iron come in smooth and “sanitized” just as would a coin or other round small non-ferrous target. 

The relationship between signal tone and threshold is also interesting.  Anything that does not go into this processed “mold” of a response is forced into the background so you have this electronic “cut-off” of a target sound--rather than more of a full, complete dying out of the tone.  This is something to learn to listen for when making quick determinations on iron.

Try this test:

Over normal ground, run the Sensitivity up into the “red” zone--”30+.”  Notice how threshold and target sounds blend together into a series of “clipped” sounding tones.  This is the machine attempting to make sense of basically “too much information” by “flattening” everything out.  In a sense this is how all multi frequency machine process the incoming chaos of these frequencies--by bringing everything down into a heavily controlled threshold.  It’s important to understand that these machines can lose depth and sensitivity without losing threshold.  I disagree with the manual’s instructions to run the Sensitivity “just (down) enough that the false signals disappear” in that this ignores the factor of just how well your actual target sounds are coming though.  At a lower setting there is also more information available in the signal tone.  There is also less chance of overrunning targets due to sweep speed error--something that’s easier to do with the “all or nothing” character of a heavily processed signal.

Understanding what the audio is telling you is the key to learning to hear how the Manticore is performing in relation to the conditions.  With the Equinox the audio had this funny kind of “inverse” quality as this digital reduction took place--even good target sounds were almost delayed by the intense processing taking place.  The “problems” with what was under the coil were all pushed into the sound of the “ramp up / ramp down.”  When the machine was overwhelmed by this processing task due to conditions or tuning error--all targets sounded weak and flimsy--pulled down into this “white noise” threshold.   As someone who runs multiple detectors--coming back to the Equinox was an adjustment every time because of this odd “softness” and latency in the signal tone.  With a larger coil in salt water this “struggling” was even more evident as the signal tone took on this “chattery” hard-to-hear-though processing sound.  The contrast between the two detectors is very obvious as the Manticore handles challenging environments extremely well-with stable audio and full, much more robust signal tones.  At the same time--it’s not invincible--the same limitations and characteristics apply.

The point is that it’s important to understand how machines like the “Nox” and Manticore process and sound off on what is under the coil.  Both are great detectors but the Manticore seems to accomplish this task much more effectively.  However, with either there are consequences to all this processing in that it makes for a detector that is electronically removed from the ground.  You could say that you are hearing something of  a “proxy.” This makes it harder to hear “what’s going on” and to tune accordingly.  The signs that you have set the Sensitivity too high (for example) on this type of a detector are not that obvious and take some practice to recognize. (More on this later).

From: "The Minelab Manticore: Tips, Tricks and Settings" by Clive James Clynick (2023)