Is the new 4 khz frequency in Equinox Update 3 Added to Multi too? Probably Not.

vferrari

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For those of you wondering whether Minelab secretly added the new 4 khz single frequency from the latest Equinox 3.0 update to the multi-frequency modes too, I've got news for you: They probably didn't. Minelab pretty much stated as much when they included the following statement with the new update: "All other single and multi-frequency settings are unchanged in their performance."

Despite whatever confusing/misleading cartoon pseudo technical marketing diagrams Minelab chose to feed us regarding Multi IQ/Single frequency capability upon initial release of the Equinox, the only thing that I can conclude is that they must presume their we are all a bunch of rubes. They tried hard to make it seem like Multi IQ was comprised of the same 5 base frequencies that are used for the single frequency modes. If that was actually the case, that would make for a very poor detector because that means the transmit power would have to be divided across 5 frequencies simultaneously, massively reducing depth capability. Their marketing strategy also backfired because it confused buyers as to whether the 600 had the same multi-frequency capability as the 800 since the 600 only had the capability to operate with 3 single frequency settings. It turns out that the 600 and 800 have identical multi-frequency profiles and Minelab had to actually come out with additional information to clarify that fact. But the Equinox Multi-frequency profiles are not comprised of 5, 4, or even 3 simultaneous frequencies (though there is some debate among those who have done measurements about the latter). Most of those who have done measurements are convinced that the Equinox likely only transmits two frequencies simultaneously and the two frequencies used varies depending on the mode selected (more on that below).

The main advantage of multi IQ, is not so much about what multi-frequencies are used (or how many, for that matter), but it is about how those multi-frequency signals are used. One aspect is to provide target signal optimization and better target ID stability and accuracy (i.e., lower weighted multi-frequency profiles tend to favor larger and/or high conductive targets like silver and copper, higher-weighted multi-frequency profiles tend to favor small, lower conductive targets like gold jewelry, hammered coins, nickels, brass, lead, and, of course, aluminum pieces). Despite these optimizations, since multiple frequencies are used the Equinox tends to have wider target aperture in MultiIQ than single frequency detectors so targets with a wider range of conductivities are able to be detected during a single pass. Multi also provides better ground and salt compensation/cancellation and enables the iron bias filtering to work.

There really is no need to ponder whether 4 khz has been added to multi. Multi IQ is what it is and what is MORE important about Multi IQ is not the individual multi-frequency components but how ML chooses to do the high-end signal processing of the target signals using the varying response from the various frequency components.

Also, adding a new frequency component to Multi IQ is not necessarily better, as mentioned above - Minelab even hints at this in their knowledge base articles that discuss Multi IQ and mention how it is more important to do it with as few base frequencies as possible to minimize loss of transmit power which has to be divided among each individually transmitted frequency. What is more important is the ratio of the two or three frequencies used. While there is some debate on the accuracy and actual numbers used, the most commonly mentioned frequencies are: 7.8Khz/39 khz for the Park and Field modes (the modes are mainly differentiated by how the signals are processed and the user adjustable parameters such as discrimination, tone customizations, recovery speed, and iron bias), 7.8 and 18.2 khz for the Beach modes, and 40 khz and a taste of 5 khz for the Gold Modes (some also say they see 7.8/18.2/39 for the Gold modes). Whatever, the point is it was not 5+10+15+20+40 khz as ML implied on their frequency "cloud" diagram.

So just take that 4 khz for what it is, an additional useful low single frequency setting for Equinox that seems to hit harder on silver (but also tends to up-average most target IDs) and also seems to be able to be run at a slightly higher sensitivity than 5 khz under the same EMI conditions.

I suspect the reason 4 khz behaves so differently than 5 khz in terms of target audio strength and with less noise is that ML is testing a new signal processing algorithm for their next generation Multi IQ detector, perhaps the Multi IQ version of the CTX. Great way to get a bunch people to beta test your software is to make up some mysterious story about Asian hoard hunters. Looking forward to see what ML has up their sleeve.

HTH
 

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smokeythecat

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The 4-5 khz range has been around since the 1970's.
 

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Iron Buzz

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I have kind of suspected this for a while. I also suspect that some of that advanced signal processing you mentioned is very similar to the XP Deus frequency shift/TID shift trick for recognizing bottle caps and other iron bits. I have accidentally run in single frequency a couple of times and wondered why I was suddenly digging more bottle caps before realizing that I had inadvertently switched off MultiQ. In single frequency (I don't remember which but I think it was 40kHx) they rang up just like a quarter, same at the Deus. Once back in MultiQ mode, they rang up at 12-13 as usual.
 

Agent Green

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Great article. Sounds like everyone should double check your sites/holes for more silver to come out of the ground with Nox.
I am so glad I waited for the Nox to come out, what a great machine. Plus the upgrades... win/win.
 

Jason in Enid

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I can promise you that the 4Kz single freq is doing things VERY different from the others. I have areas with EMI so bad I cant get rid of it in multi. Its still a problem in 5, and in 10, and may or may not still be a problem at 15. But at 4, my EQX is so quiet and smooth I would never know EMI existed. It WILL drain your battery at a much faster rate. It's also not nearly as good as dealing with iron garbage and especially crown caps as multi, so its not great in all areas.
 

Donut

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I can promise you that the 4Kz single freq is doing things VERY different from the others. I have areas with EMI so bad I cant get rid of it in multi. Its still a problem in 5, and in 10, and may or may not still be a problem at 15. But at 4, my EQX is so quiet and smooth I would never know EMI existed. It WILL drain your battery at a much faster rate. It's also not nearly as good as dealing with iron garbage and especially crown caps as multi, so its not great in all areas.
I agree.
I just don’t understand the battery drain.
Maybe someone who has ran the 4khz continuous can give an update on that.
Doug
 

Jason in Enid

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I agree.
I just don’t understand the battery drain.
Maybe someone who has ran the 4khz continuous can give an update on that.
Doug

In a different thread, someone mentioned that "the high-power low freq of the Deus will also drain the battery at a faster rate" Maybe its along the same lines and its pumping more power out of the coil in the single 4 freq.
 

samorano

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Great article Vferrari thanks
 

smokeythecat

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V can certainly do the math on how machines work.
 

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