Minelab Equinox Challenge

[ivconic]

Curious to say the least. By the way, that VA software is remarkable, having a blast playing with it. When I click on DAC box, some magic happens which gives me smooth sinus at 14.5 khz(tgs). The spectrum analyser is really cool. And the thing runs in Linux under Wine. Fantastic.

[Mark-VA]

I've not tried Linux, been using Windows 7. But I really like Linux better overall. A lot of software for developers and testers.

[EL NINO]

I made measurements of EquinoX 800 on old 1.5.0 and new firmware 1.7.5:

[EL NINO]

[EL NINO]

[Carl-NC]

Ugh, the sample rate is just awful. Here is what you should see:



Top trace is Beach-MF and bottom trace is Park MF. Here is Prospecting-MF:



Note the 40kHz is slightly modulated at 5kHz.
Here is single-freq @ 5kHz:



The tau of the coil really starts to show up here. If Minelab bumped this up to 7.8kHz as some people claim, it was probably to improve battery life.

[Mark-VA]

Sir, would the sample rate need to be the same for each frequency?
Or does it need to be adjusted to make more visible sense?
I guess, what I'm asking, is there a universal sample rate that will give the best wave, or rather the most truthful looking frequency?

[Carl-NC]

The more you oversample, the more accurate the results. At 1MHz you only get 25pts per 40kHz cycle, I wouldn't go any lower. The scope I used is 1GS/s.

[bklein]

Carl, would an old Tek AM503 current probe be a worthy substitute for your opamp circuit? (Clip on TX)

[EL NINO]

...On my laptop -196 / 24bit Laptop card, I can not get more than 96000s / 35,000 FFTs from the VA program. So my next trip will be buying an oscilloscope ...,. Comparing Park1 / Park2 scans and direct sensitivity comparison of these programs to small things can be said - even beyond the many RX signals operating, a different preamp RXgain per each of the 3 received frequencies ... What makes sense. The low 7.8khz frequency - indeed, it has been chosen for universal targeting, lower power consumption, lighter coil, and better groung balance adjustment.

[Skippy]

ElNino: Your last post of screenshots has errors, 'no attachment' for some of them. Can you repost them, please?

[ivconic]

It is probably my own prejudice, generated through the years of playing with these toys, yet;
i tend to believe in "magic" 5-9kHz range, which gave me the very best of performances overall on all the real terrains, fields, sites... i've been visiting so far.
At the very beginning with the Deus i was amazed with 18kHz and sensitivity on smallest coins.
Some 7 years later i am constantly running it only at ~7kHz.
Why? I guess i don't need to answer why. It is self-explanatory.
Despite my "forum antagonism" towards ML; fact is that those are pretty smart and conversant guys working there.
They do know the job well.
Whether they will disclose everything in white paper; that's quite another thing.

[EL NINO]

...Skippy.. I fixed the last scans 1F ....

[EL NINO]

For comparison, SpectraV3: I give the 3F multi scans :all multi programs are equal in normal/ salt ....So I crowd in Tx normal/TxBost from Whites Spectra V3.
Frequencies for Spectra su Enough-matching-balanced- with Concept Spectra:....Optical Analysis of Signal and Frequency-Based Response Force on 3f-Spectragraph,... 3f-Signagraf,... and 3-fpinpoint by Spectra Detector Users.

[green]

Hi EL NINO
Curious why some of your FFT charts have linear y axis and some have log y axis. Would it be better to use log or linear x or y?