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Old 07-15-2008, 07:01 PM
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zander10 zander10 is offline
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Location: las vegas, nv
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Originally Posted by Rudy View post
Hi Ray,

Welcome aboard! Glad you found the article on time.

You asked a good question. I don't know why metal detecting has a jargon of its own. It just does Maybe they do it to confuse the uninitiated.
i think you are exactly right Rudy!...

perhaps the term "squelch" is in reference to the observation of one "channel".

"threshold" is a more accurate term to use when a spectrum is the object of consideration. a spectrum is a set of many channels. detectors scan for conductive metal across a spectrum that begins with iron up through silver. each particular class of metal is tecnically a "channel" which is how we descriminate against certain targets.

when we notch out an undesired targets we block it's "channel".

a threshold is what is displayed on our detectors when we are using them if we plot it on a computer. notice that "threshold" sort of imples the edge of a floor, deck or step.

as i mentioned earlier in this thread i perfer the term noise-floor because it is more descriptive. if you plot noise across time you get a sort of ribbon which i call the "noise-floor" because it looks like a floor in a hallway if you plot it graphically on a computer. the point of view of the ribbon is of its leading edge with the observer hovering in space. there are other ways view/display this type of data but this is the one i like. signals look like spikes in the floor of the hallway which is constantly receding in time until it vanishes.

if you set a "threshold" for a signal that tells me you are specifying least-upper-bound for the noise or conversely threshold is a least-lower-bound for signal.

(so threshold is least-upper-bound for noise or least-lower-bound for signal) okay...

the higher the least-upper-bound the more noise you get and vise-versa.

"squelch" and "threshold" are engineering words and "least-upper-boound" and "least-lower-bound" are math terms "noise-floor" is a term we used to throw around in class and everyone seemed to know what was being discussed. i guess "noise-floor" is an engineering term.

-zander... Garrett GTI 2500, Garrett Sea Hunter II (shii), i-detect, Vibra-Probe 570

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