Minelab Equinox Challenge

[bklein]

spreadsheet file (?)

spreadsheet file attached.

[Skippy]

You seem to have the same issue as Chiv, your uploaded images are very small, just 320 pixels wide. I assume your original pics are several thousand pixels wide, so some excessive reduction has happened. If they were 640 to 1024 pixels wide it would be OK.

CTX and Excal have the same well-documented transmission, which will have strong peaks at 3.125kHz and 25kHz ( 1:8 ratio ) though these can shift by +/- 8% (roughly) depending on the noise-cancel.

Your Equinox spectrum is of a 'Beach' mode, which isn't the same as the Park/Field mode output that Carl posted at the start of this thread. Chiv's tests show Beach mode uses 7.8 / 13 / 18.2 / 39 kHz ( 3:5:7:15 ratio ) which looks a bit like your results , except you have many more peaks, particularly noticeable is the 49kHz one.

It's possibly the use of log scales on the vertical axis that's making it hard to see the wood from the trees, it's making the weak/unimportant frequencies look big.

[bklein]

Park allows use of single frequency as well as multi. I guess we are assuming it was in multi.
Both ctx and excal have such prolific freq content I wonder if the peak frequency matters all that much.
I’ll redo my data and post the data in a text file next time.
The uploaded photos were from a iphone. No idea what the upload as - the site just gives you a total upload size. I’ll try larger files next time. In the photos there are secondary level frequencies that I often didnt measure. If I hold the pickup coil more distant these will drop away and I just pick up the stronger freqs. Which would be preferable?

[bklein]

Better photo Park1

Here's a shot of Park1. I started with 0Khz so the graticule display makes sense.
Frequencies of peaks: 7.75, 10.25, 12.88, 15.50, 18.133, 20.63, 23.25, 25.88, 28.50, 31.13, 33.63, 38.88 (highest), 44.13, 46.63, 49.25
There is ringing in the pickup coil signal - do I need to dampen it or is this info basically ok?

[Skippy]

Your pickup coil should be damped, though I'm not sure how much it would affect the spectrum analysis. It may put a general 'skew' on the amplitudes of the various frequencies, it looks like the higher freqs are picked up stronger with the undamped coil. You may get less noise with damping added, too.
I don't know what equipment you have, but the simplest way to work out a reasonable damping resistor value is trial-and-error. Look at the pickup signal on a scope, (set timebase to 100 microsec/divn, maybe) and choose a resistor that makes the waveform appear the 'most square' , not much obvious over-shoot and ringing, but not so over-damped that the square edges become rounded-off. Likely R value would be 1000 Ohms to 100 Ohms.

Failing that, it's possible to calculate an R value based on coil inductance and self-resonant frequency. The spectrum analyser will tell you the self-res freq, it will show up as a strong peak, probably in the 100kHz - 1MHz range.

Your latest spectrum looks pretty good, though. It compares well with the one I posted earlier in the thread, with the 39kHz the strongest. We are both effectively measuring the transmit coil voltage.

[Riss]

At first sight I did not like the oscillogram on current in TX coil on Equinox...this video confirms my suspicions...in the air this detector registers this coin to more than 45 centimeters ...the soil is of low conductivity ,and very low mineralization -weak reactive component .Electromagnetic disturbances were absent ,at maximum sensitivity only the soil noises are heard...it is clear that the operator it is not with prejudice .
https://www.youtube.com/watch?v=w7yGIfGDLU8

[bklein]

My 800 is not nearly as quiet as the one in that video (too noisy to tolerate sometimes) but in the case of the video the depth of the coin exceeds the capability of the coil for a hard target sound even for an in air test. A single frequency test may actually be superior but who runs the EQ single frequency - almost no one. Try a hard reset on the EQ and you might see a jump in depth like I did.

[BountyHunter]

The question presented by this thread is a very important one for a couple reasons at least. One, for those of us who take the hobby and underlying tech seriously it's important to know how much we can trust what Minelab says a particular machine is doing vs. what it's actually doing. Is it truly giving the edge it is promising or is it in the heads of certain users. Two, from a marketing perspective Minelab's claim of 17 and 28 frequencies was very successful. People continue to repeat it today when discussing whether to purchase a V3i, an FBS machine, or an Equinox etc. Given that the claims of Minelab's Multi-IQ platform have been wildly successful on launch, any company that will compete will need to get to the truth and if it's not as advertised get it out there as part of their own counter marketing strategy. Guys like me countering the myths of BBS and FBS has reversed some of the effectiveness and affected purchase decisions.

I do not yet have the knowledge, experience and tools I see that some of you have. But I would point out that Minelab claims there is a different emphasis or frequency weighting in each mode. In beach mode for example the signal has a low frequency weighting. In Gold a high frequency weighting. Low frequency weighting in Park 1 and Field 1, and high frequency weighting in Park 2 and Field 2. Because of their claims with FBS I have had my doubts about whether 5 are ever used simultaneously, but I have wondered if maybe the best 2 or 3 are used for each mode. Could it be that Beach uses a variation of 5 and 10, that Gold uses 20 and 40, that Park 1 uses 5, 10, and/or 15 etc etc.? I'll keep checking back because this is of a lot of interest to me.

[Skippy]

Your post would probably be more at home in the 'general' Equinox Thread:
http://www.geotech1.com/forums/showt...ineLab-Machine
Carl wanted to keep the "What frequencies Challenge" seperate.

[6666]

it's important to know how much we can trust what Minelab says a particular machine is doing vs. what it's actually doing.

There is only one way to find out and cut through all the BS, buy one and test it yourself, most of what you read about any detector is lies.
Its the old "mine is bigger and better than yours"

I own about 20 commercial made detectors both PI and VLF and do my own testing, mostly they find targets in a very similar way, they either beep or they dont beep.

It just depends on how many bells and whistles they claim to have and you want , and how much you want to pay .

Its not untill you test a machine on your ground , and your environment will you find out if it will detect a target or not, and what good or bad habits that particular machine has.

[BountyHunter]

I have the Equinox. I should clarify that what I meant when I said I do not have the level of knowledge, experience and tools some of you have, I meant engineering. When it comes to actually metal detecting, I have and use many of the best, most pretty proficiently. I've been metal detecting for years. But I want to do more than simply use them. I want to understand what's going on under the hood, and I've become more invested in doing so as time goes on. There are many forums for guys who simply want to use them, but I think one of the purposes of this one is to go beyond that. Do you have to, to be a good detectorist? No, not at all. Your point is well taken. While guys are here discussing how to solve x, y, and z, there are guys out there getting on about the business of actually using x, y, and z even if they can't articulate it, and they are the final arbiters of whether a machine works for their purposes. As for me, I'd always wonder what I'm leaving on the table though. I think having as much knowledge as possible about the underlying technology can make the difference between good, better, and best. I also have an interest in writing about metal detecting and do write for other interests. I apologize if I'm out of pocket posting in this thread. I suppose I got excited that it was being worked on and jumped in the first thread I opened about it. It does matter to more of us than you'd think so I hoped to encourage you guys.

[6666]

I want to understand what's going on under the hood,

Ok , I was responding to your question as to whether you can believe what manufacturers tell you about how great their products are.

[Qiaozhi]

But I want to do more than simply use them. I want to understand what's going on under the hood, and I've become more invested in doing so as time goes on.

I assume you are aware of this book -> Inside the METAL DETECTOR - Second Edition - Published 2015

[Mark-VA]

Imust admit I fell for the Multi IQ from the very beginning and itsold me to an extent I had to have one and bought the 800 model rightoutof the gate.
Insubsequent weeks I tested the Equinox side by side with the FisherF75 LTD and found it extremely hard to get a winner between thetwo.
Butthe Equinox was a quieter running machine in hot ground. Butthat is not exactly the truth, listening very carefully I could stillhere the hot ground but at an extremely lower volume. I feelMinelab might have done a little programming magic to reduce thenoticeable noise to the end user.


Awealth of information has been published on this site.
Askingfor something below:

1. As an overall recap I'd like to see the actual frequencies usedin each program, starting with Park 1 all the way through Gold 2.

2. Then the actual frequency if each is chosen as a singlefrequency, if there is a difference.

[Skippy]

Your question has interesting timing. Until a week ago, it seemed that between this thread and the general Equinox thread:
http://www.geotech1.com/forums/showt...ineLab-Machine
we had confirmed what the machine did. However, very recently, Carl M. posted (on the gold nugget simulation thread) that he has seen different frequencies in use, including only two at once ??? So I too am curious as to whether things have changed, before/after the software update, for example.