For Carl and the programmers to look at.

[TerryinHawaii]

I want to be able to hunt in parks in the prospecting mode using the 22.5 kHz frequency for the maximum chance of finding gold jewelry. But when I change to the analyze mode, I want to be able to see all three frequencies displayed to help me determine if the target maybe gold. It does not look like that I can do that now. If not, the programmers at White should in the next Spectra V3 software update enable us to hunt using any single frequency but be able to analyze the target using all three frequencies.

 

[TheMarshall]

Terry, your request is possible to create by software modification, BUT don't you think that you are forgetting the realities of metal detecting?

VDI numbers are a product (or summation) of several factors.

For example, ' a gold thing' can have many VDI values, from say, 4 to 40, depending on it general MASS.

The shape / thickness off that mass, and the conductivity of the alloying of the gold with other metals.

Also, VDI's depend on the value of the interrogating frequency, be it 2.5 KHz, 7.5 KHz or 22.5 KHz.

Other non-gold metal/alloy can also fit into that same 4 to 40 VDI category, dictated by similar factors as mentioned.

In simple terms, there is no guarantee that you can detect absolutely by frequency or VDI.

Coins are well defined in size, shape and alloys, so they are more predictable.

That isn't the case for gold jewelery.....approximations, yes, but specifically, not really.

The best you can do, is to accept all targets between 4 and 40, then by experience try and eliminate trash using your Analysis screen......but I think that would be a hard task.

Just consider this....What is the VDI value of a gold coin, the size of a US $..?

What is the expected VDI of a thin white-gold band studded with diamonds?

Now what frequency would best suit those two items?

Thanks for your idea and the chance to explore what's involved..................TheMarshall.

 

[jgedde]

VDI is secondary after a potential digger is identified and ready for analyze mode. The analyze screen just helps confirm it to be what it is expected (hoped?) to be. That said, you're 100% correct about VDI computation. However in the case of the the Spectra V3, VDI on all three frequencies is normalized to the same range. So, that should address the VDI issue regardless of frequency.

Operating in a single frequency mode only gives one trace on the SpectraGraph. That only provides limited information about the "shape" and "footprint" of the object and tells nothing of the material from which the target is made. That's why TerryInHawaii's idea has such merit. One could, in theory, get max sensitivity to a desired target type by running a single frequency, but still be able to get full value of the analyze mode for targets that aren't at the far reaches of the three frequency depth limits.

The main gotcha in my opinion is the need for ground balancing when changing frequencies or running all three. I implement Terry's idea manually: I often run at just 2.5 kHz to get best silver coin sensitivity, then switch to three freq mode to analyze just to avoid digging bottle caps with the 10DD. Since I do the operation manually, often without a ground balance, maybe the experts at White's can figure out a way to "do it right" or to minimize ground balance issues.

All in all, I LOVE TerryInHawaii's idea. The best of all worlds if White's could pull it off.

I suggested to Carl a "two frequency mode" to balance analyze vs sensitivity for a given target type, but Terry's idea is better. I hope they listen!

John

 

[ak_1234]

How about if you have 2 programs (one next to the other in the program list). In the first program, you have single frequency and signagraph information showing on the search screen. In the second program, you have 3 frequency and analyze showing on the search screen. To switch modes, you'd be switching programs using the program live control rather than toggling the trigger switch. (You can set up the analyze screen to show in the trigger released position).