Visual Sound Analysis

[IBMe]

The current state of the art is replacing knobs with a computer version.

If sound is the most important thing, how come my detector doesn’t display a full screen color analysis of the sound?

A few decades behind the times?

[Knomad]

I have had similar thoughts.

How about an audio that truly reflects the target by analysis of both sound and coil generated waveform.

A button push to activate analysis, and readout to give probability of different targets, nail, pull tab, dime, large iron, Etc, Reflected in the sound, and trainable as you detect an area and confirm target types, to compensate for ground differences.

 

[IBMe]

It’s been used in the medical field for a long time.

If you swing over a tab and a gold ring, you can clearly hear the difference. So, there’s density and target size information in the tone.

Sound analysis is being used all over the place except where all we have is sound and an ID that may get pulled one way or the other.

Basically, we have a PalmPilot now. Need to move forward.

[kac]

Nexus sort of has that with their color bar.

XP has the XY screen though not in color it is pretty handy at times around mixed signals.

Whites had the frequency responses on the spectrum.

End of the day single tone response of an old analog can still be easier. Sometimes too much information can just add to the complexity of just digging pretty signals.

[IBMe]

Electronics has gone about as far as it can.

Signal analysis used to some extent.

Sound wave analysis, used in medical and industry, ignored.

Might be worth at least a little look.

 

I could be all wrong, but it’s used to tell the life of a bearing. I think it has strong possibilities.

[JCR]

Keith Southern advocated for something similar. He described his idea as a Sonic Picture of a target.

[Digalicious]

Kac gave good examples of detectors that show a visual representation of the raw signal. The question then begs: To what end?

Detectors already do a pretty job of distinguishing coins from trash, but they do a very poor job at distinguishing aluminum trash from gold.  The latter is never going to happen with induction balance. Induction balance is just too crude of a metal detection technology to accomplish that task.

Getting an induction balance engineer to distinguish aluminum trash from gold, would be akin to getting a drummer to create an epic drum solo, while using a spoon and a frying pan 😁

 

[IBMe]

> they do a very poor job at distinguishing aluminum trash from gold

 

Put a gold ring and a tab down. Swing over and over both. Easy to tell the difference. The density of the target is in the sound. But can you hold the tone difference in your head and pick it out of all the noise in the lower band?

 

Electronics isn’t going much further.

Don’t have a Manti, but apparently you can do more with signal analysis.

Medical and industry use sound analysis, but we ignore?

 

I tutted this horn long enough. Basically, just trying to make some noise hopping someone in the MD business would at least do some experimentation. First guy wins the prize.

 

I’m a real old timer. I do a massive amount of sound experimentation because I don’t want to dig unless I am sure there’s a strong possibility.

[kac]

Targets can have similar phase angles resulting in same display responses but nuances are hard to display and even if they do in some sort of graphical means it would take us as users a long time to distinguish what it means.

If your machine has good modulated audio and it's recovery speed is relative to the size of a target then you should be able to hear the difference between a gold ring and piece of can slaw or pull tab. Aluminum will often have a sharper more abrupt sound and signal can carry further than a piece of gold with similar id  numbers.

Where things get tricky is when your looking for chains as they are in the foil range and foil tends to have a softer rounder tone. That is where size of target comes into play. Slow steady sweep of coil and watch how big the area is and in different directions can help determine shape.

[Digalicious]

6 minutes ago, IBMe said:

Put a gold ring and a tab down. Swing over and over both. Easy to tell the difference.

I agree, but that's a controlled test with very specific targets.

In the ground, the various shapes, types, sizes, densities, orientation, and depth of aluminum trash is the major problem. Ditto for gold rings and gold jewelry. As such, the raw signal for gold rings, gold jewelry, and the various aluminum trash, is most often identical and overlapping.

Metal detector engineers have tried for decades to reach that holy grail of metal detectors. If it was possible to do with induction balance, they would have done so by now.