GPZ7000 and GPX6000 Bypolar square Wave

[toolnuts]

Hi All,

What is it about the by-polar square wave design that allows it to
find gold deeper, than the normal VLF designs?

Paul

[Carl-NC]

The GPZ uses a bipolar constant-current square wave which has the advantage that when the current slews polarity there has been ample time for the prior slew to settle out. That is, there is little chance of having reverse-eddy signal reduction issues. I have no idea if the GPX-6k uses this same method or not. I would assume not, that it is a continuation of the MPS/MVT methods used in prior GPX designs.

[toolnuts]

Hi Carl,

How does this all contribute to a deeper detection? Is it cancelling some kind of interference?

Paul

[Carl-NC]

In a std PI you turn on the coil which produces reverse eddy currents in the target. When you turn off the coil the reverse eddies subtract from the forward eddies and reduce depth. In constant-current PI, the coil has no off state; you energize it with current, then energize it with a reverse current. The current has a wicked-fast rise time so there are little or no reverse eddies to reduce depth.

[green]

Hi Carl,

How does this all contribute to a deeper detection? Is it cancelling some kind of interference?

Paul

https://www.geotech1.com/forums/show...501#post270501 maybe the answer is here.

[toolnuts]

https://www.geotech1.com/forums/show...501#post270501 maybe the answer is here.

Green,

Thanks for the link, it really was a good tutorial on the subject.

Carl-NC really knows his stuff.

[gamen83]

In a std PI you turn on the coil which produces reverse eddy currents in the target. When you turn off the coil the reverse eddies subtract from the forward eddies and reduce depth. In constant-current PI, the coil has no off state; you energize it with current, then energize it with a reverse current. The current has a wicked-fast rise time so there are little or no reverse eddies to reduce depth.

Carl, how this differs from square wave VLF? It sounds the same. Bipolar square wave. Am I wrong?

[Carl-NC]

Square wave VLF uses a voltage square wave which produces a triangle wave coil current.
CCPI uses a square wave for the coil current.

[gamen83]

Square wave VLF uses a voltage square wave which produces a triangle wave coil current.
CCPI uses a square wave for the coil current.

OK, I understand. You had a really great topic
Do you plan to continue with a new one? Maybe about the multifrequency VLF? A lot of people will apreciate it

[Carl-NC]

Working on it...

[gamen83]

Cool. I can't wait.

[Altra]

A look inside the GPX6000

https://md-arena.com/razborka-minela...rogoj-novinki/

[dbanner]

A look inside the GPX6000

https://md-arena.com/razborka-minela...rogoj-novinki/

MUX based flash ADC at the front end?

[Carl-NC]

MUX based flash ADC at the front end?

It uses (2) ADS131E08 ADCs, these are 24-bit 8-channel simultaneous sampling. I'm using them in some projects.

[dbanner]

It uses (2) ADS131E08 ADCs, these are 24-bit 8-channel simultaneous sampling. I'm using them in some projects.

Yes, I also saw a bunch of HCT4053 gull wings in a row, plus another row of what I'm guessing might be comparators?