Thank you esteban,
I recall now the big difference from zahori and Ivconic's old ion detector is the sample and hold circuit from the cmos switch. A very interesting idea where you could change sample parameters if you want.
It seems to me most of your experimenting works best when you look at the heterodyne mix frequency variations. I presume you find more sensitivity using this method like used in some AM radios instead of direct measuring a signal. This would explain why the carrier frequency would change the sensitivity and range, similar to how a conventional vlf metal detector will use different frequency to optimize different kinds of hunting.
My final question is about what you are sensing.
I don't think any kind of metal detector is able to sense metal. All detectors sense electric fields or magnetic fields, or sometimes capacitance that changes when metal is nearby. So they measure a secondary effect that changes in the signal they are receiving, and we make an inference that metal is causing the signal to change. We usually find we are right that metal is the cause when we recover the target.
In the case of conventional metal detectors, we sense variation in fields that are transmitted, or in induced fields that we measure with a Rx coil. My question is: Do you know what you are sensing in your more recent designs? Are you sensing the same variations in induced fields like a conventional metal detector? Or are you measuring some other phenomena passively without inducing any artificial field?
We have heard about very faint anomalies that could exist at the surface of the ground around a long time buried target. It seems to me that if you are locating these faint ground surface anomalies, then you might be actually measuring something else that is changed where these anomalies exist. Maybe existing electric atmosphere gradient, or existing natural EM frequencies in the VLF or ELF range. Or maybe something else like combined ground currents and atmospheric low frequencies.
Do you know which of these you are measuring with your test LRLs? Or is this still a mystery to you?
Best wishes,
J_P
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