PI detection and microprocessors?

[Mullihaka]

Hi!

There's plenty of detectors on the market with LCD, revealing that the device contains a microprocessor as well.

Many detectors have a single coil, which leads me to think that they are PI type.

I'm not aware how discrimination (and other means of selecting, what the user wants to find) in those top detectors work. I have started to think, that all PI based detectros have the same operation principle: the difference comes from the way the detected signals are processed. Isn't it so, that the received signal is always voltage reading in time scale? The processor then takes several samples of the voltage at certain moments, compares them to the characteristics of pre-programmed "finds" in the detector and makes a judgement of the nature of the find, correct?

Unable to make fancy programming with the microprocessors, I have planned to make a simple voltage vs time display. The detector output is fed to the display. Based on the shape and measures of the obtained graph, I could judge the find in my head. That way the processing would be left to the user.

Am I on the wrong track or what?

Is there some other issues the microprocessore takes care of (apart from the operating frequency)?

All hints appreciated,

Andy

[Max]

Hi!

There's plenty of detectors on the market with LCD, revealing that the device contains a microprocessor as well.

Many detectors have a single coil, which leads me to think that they are PI type.

I'm not aware how discrimination (and other means of selecting, what the user wants to find) in those top detectors work. I have started to think, that all PI based detectros have the same operation principle: the difference comes from the way the detected signals are processed. Isn't it so, that the received signal is always voltage reading in time scale? The processor then takes several samples of the voltage at certain moments, compares them to the characteristics of pre-programmed "finds" in the detector and makes a judgement of the nature of the find, correct?

Unable to make fancy programming with the microprocessors, I have planned to make a simple voltage vs time display. The detector output is fed to the display. Based on the shape and measures of the obtained graph, I could judge the find in my head. That way the processing would be left to the user.

Am I on the wrong track or what?

Is there some other issues the microprocessore takes care of (apart from the operating frequency)?

All hints appreciated,

Andy

Hi,
all about right... disc is unreliable on PIs cause mostly you don't know at which distance is the target underground from coil.

If you put several different metal targets near coil at various distances you'll discover that, at various distances, you'll get similar curve shape for different stuff... really unreliable.

In VLF , instead, when signal is strong enough you can actually disc by phase of RX , in an accurate way. though then soil will affect phase too... you need perfect ground balancing to get it work good etc

On micro based PIs you have multiple sampling and a software try to match and existing library of predefined target responses.

There isn't any reliable chart you can use there unless you already know distance between target and coil.

Kind regards,
Max