Honest question about workings of Multi-Freq.

[sprailroad]

Well Good morning fella's. I have a question about the higher and lower weighted Freq's on let's say Field 1 & 2, of which I most always use. Now I understand in Field 1, it's operation is weighted toward the lower Freq's, best for say copper, silver brass, and of course Field 2, higher weighted, I get that, but my question is just HOW does that work? I only ask because the better I understand the machine itself, the better I might do depending on what I'm looking for. So, is it in Field 1, it transmits in 5, 10 & 15?, and in Field 2, it's 15, 20 & 40?, I doubt that's the case, so if it operates in all 5, Does it somehow send out a stronger signal for the lower Freq's., and a weaker signal for the higher Freq's. in Field 1, and of course just the reverse for Field 2, just how the heck does that work? If I'm detecting in a smaller defined area, I'll go over it in both modes, to kind of cover all my bases so to speak. Guess it's an idle thought early in the morning, but, I do kind of wonder a little bit.

 

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[Rick K]

Minelab is absolutely expert in not releasing any actual technical explanations of such things. The stuff they release is all written by the very talented marketing department, not by their engineering staff.

 

[Treasure_Hunter]

It is transmitting all freqs in Multi-IQ, I imagine it is the algorithm for each search pattern that is different, and Rick K is correct Minelab is very protective of their proprietary info.

 

[vferrari]

Actually, based on some information I have that I can't link to due to forum rules, analysis of the actual transmitted signal output shows that ML is only transmitting and combining two of the 5 frequencies at any one time and the combination chosen is determined by the search profile selection. That makes sense because each of the base frequencies are multiples of the 5 khz fundamental frequency and when you combine them you can generate multiple sideband frequencies.

There is a practical limit to how many frequencies you can generate at any one time because you have to divide transmit power between each frequency. This essentially means you need roughly twice the transmit power to get sufficient ground penetration when you are transmitting two frequencies vs. a single frequency. This is a known engineering design limitation in radio design and is not a big trade secret or anything.

The real secret sauce though is in the post processing of the received signal (i.e., the signal pricessing algorithms) and ML is not giving any of that away to their competition.

Suffice to day that ML is ambiguous enough in their description of Multi IQ if you read it carefully that they can readily imply to the reader that all 5 frequencies are transmitted when in actuality only two frequencies of the five are actually transmitted at a time (with multiple harmonic frequencies generated across the 5 to 40 khz spectrum as a result - hence the frequency "clouds" in their Multi IQ diagram/cartoon). The weighting determined by search profile/mode selection determines which two base frequencies are used.

HTH.

 

[sprailroad]

Thank you vferrari, I was kind of hoping you would weigh in it. Not saying I fully understand it, but it always helps to understand the machine itself. And so, I was kind of right? Not sending all five Feq's at the same time?, but the best two or three out of five depending on the mode, 1 or 2? In a way kind of like the FBS, 28 multi Freq's, but not using all 28 at one time, only the ones best suited for the ground conditions at any given time IF I remember correctly. Either way, I do like the EQ.

 

[Professor of Engineering]

Hello vferrari,

I believe you have it correct!

Interesting side note; the Whites V3i uses three frequencies to "probe" the ground and yes the power is distributed between the three frequencies. Of course, like the Nox a single frequency can be selected. If I've correctly understood the White's method; to transmit 3-frequencies and process 3-frequencies. I am thinking Minelab is similar (2 or 3 frequencies), but I will have to research and study some of my machines.

Doc

 

[Hawks88]

Interesting info. Thanks guys.

 

[smokeythecat]

Well, V, then it should be called "dual frequency", not multi.

 

[rc2125]

Sent an email to Minelab awhile ago inquiring about similar things. Also asked about the particular differences, if any, between field and park modes if All settings/tones/etc are set to be the same. Crickets....

 

[vferrari]

Hello vferrari,

I believe you have it correct!

Interesting side note; the Whites V3i uses three frequencies to "probe" the ground and yes the power is distributed between the three frequencies. Of course, like the Nox a single frequency can be selected. If I've correctly understood the White's method; to transmit 3-frequencies and process 3-frequencies. I am thinking Minelab is similar (2 or 3 frequencies), but I will have to research and study some of my machines.

Doc

Doc - you got it right on the V3i. It uses 3 frequencies simultaneously. The detector design expert that posted the info said 2 or 3 simultaneous frequencies is optimal. Above that number there is little benefit gained versus the further diminished transmit power capability. BTW, the CTX and other ML FBS machines also only combine two frequencies from the 28 base frequencies they can generate except the 28 frequencies top out lower than the top two high high bsse frequencies of the Equinox Multi IQ. ML discovered less (i.e., 5 base frequencies of Multi IQ) is more as it reduced complexity in programming and enabled the higher frequency weighting that gives Equinox superior mid-conductor (e.g., gold) performance vs. CTX, eTrac, etc.

 

[vferrari]

Well, V, then it should be called "dual frequency", not multi.

Nah. There are multiple 2 frequency combos applied depending on the mode chosen, plus other manufacturers like Nokta/Macro and even Garrett call or claim their detectors are multifrequency because they have multiple selectable single frequencies or use pulse induction (a completely different technology than VLF).

Bottom line is that all the manufacturers play the features marketing game so there is no point trying to put the toothpaste back into the tube.

Besides, most consumers don't care about, don't want to know, or can't grasp the underlying technology beyond the marketing doublespeak so its not worth the energy holding the manufacturers accountable. It all really comes down to whether you can find stuff or not with the detector, i.e., performance. If it's a sham, a loser design, or unreliable resulting in bad finds results or wasted time, then folks will get the word out quickly and eventually vote with their wallet regardless of whether they understand the underlying tech and the loser designs will fall quickly by the wayside.

The Harry Potter Magic wand folks are starting to wake up to reality and will either jump to the next bright shiny object or go back to what they are/were comfortable with. While those who had more realistic expectations of what Equinox brings to the table (primarily versatility) appear to be satisfied with Equinox, for the most part. There are machines out there that will outperform Equinox in specific situations, but none that I know of that will outperform Equinox at everything it can do from salt surf/beach, to playground, to park, to plowed field, to backwoods, to lake, to desert gold field.

 

[67GTA]

I've seen several claims that Park 2 is deeper, but shouldn't it be a little shallower in theory due to it being weighted towards a higher frequency? Anyone have info on which two base frequencies are being used for each mode?

 

[Happa54]

I've seen several claims that Park 2 is deeper, but shouldn't it be a little shallower in theory due to it being weighted towards a higher frequency? Anyone have info on which two base frequencies are being used for each mode?

Good question...It would be good to know which frequencies are dominant in the various modes. ie; is park1/field 1 best for high conductive targets and/or mid-conductors in park2/field 2.

 

[vferrari]

The folliwing are true most of the time - i.e., YMMV when variables such as soil moisture, mineralization, target orientation deviate from ideal:

The "2's" (Park 2/Field 2) are deeper on mid-conductors and small profile targets than the "1's" (Park 1/Field 1) due to their high frequency weighting.

Conversely, the "1's" are deeper than the "2's" on larger targets and high conductors due to the lower frequency weighting.

All things being equal, in mild ground, the "1's" will detect the deepest high conductive target deeper than the "2's" will detect ANY target including the mid conductors they are optimized for due to frequency dependent transmitted signal attentuation (i.e., higher frequency transmitted signals cannot penetrate as far as lower frequency signals).

The Beach modes are a different animal because they are designed to cancel out salt which overlaps with small gold, but that doesn't mean the won't detect gold, they are just not optimal for it (that's the tradeoff for stability on a salt beach). Beach 1 for wet salt sand, Beach 2 for surf/submerged salt water hunting.

Gold/Prospect mode is the hottest mode which means it will be best a detecting small gold in hot soil, but will not be anywhere as deep on silver on as Park/Field 1 and perhaps even the 2's.

Multi IQ enables all modes to detect the whole spectrum of targets from iron to platinum to gold to aluminum to brass to nickel to lead to copper to silver and everything else in between at some depth though perhaps at very shallow depths for the non-optimized targets for the given mode depending on the target and soil characteristics.

Finally, its anyone's guess whether Park 2 is deeper than Field 2 and whether Park1 is deeper than Field 1 and is subject to endless debate.

Field 1 is the red-headed stepchild of the Equinox modes, no offense to red-headed stepchildren...or to those who prefer the simplicity and elegence of 2-tones.

 

[sprailroad]

OK then, it pretty much clears it all up for me, and again a thank you to vferrari for laying it out there in a way that even I could grasp. Whether I'm correct or somewhat off, the way I will approach my hunting with the 800 will be that in the "one" modes, it operates in say 5 & 10 Khz. and in the "two" modes, 15 & 20 Khz. So then I'm guessing that in prospecting mode, it might operate in 20 & 40Khz. I am very OK with that. When I bought the X-Terra 70, it was because that I could go to a 3Khz. if I were really looking (or hoping) for copper, silver & brass, or go to the 18.75Khz for it's own reasons, and the "stock" coil of 7.5Khz? for all around hunting. I can do all that with the EQ in a "single" Freq. IF I so choose. So OK, it does not operate in all five simultaneously as I first understood. Again, I'm fine with that, it's a really good all around machine. Changing from lower Freq's to higher and back again, only by pressing a touchpad, is so much easier, as opposed to changing coils, and operating in "dual" Freq's as opposed to one. The Safari, using FBS (28) Freq's, would "select" one of 11 possible "sets" between upper & lower limits by pressing noise cancel. Was always a quiet machine (chatter). I've little doubt that with the advancement of tech. Minelab and others have somehow improved even on that. In a "defined" area such as a parking strip, I go over it in a "2" mode, then over it again in a "one" mode. Tromping around in woods or fields, a "one" mode. It's worked well for me. I now like to think that perhaps I better understand just "How" the EQ operates, and I feel good about it. I've pushed it hard the last couple of days, I think the 800 and I will stay home and take a nap together today. Thank you for the feedback fella's.

 

[rc2125]

Finally got a response from Minelab last night. They just forwarded a picture of the different mode defaults thats from the user manual and said to watch the blog videos about multi IQ. Gee, thanks.

 

[vferrari]

Yep. It’s competition sensitive so don’t expect them to hand out any secret sauce recipes.

 

[pulltabfelix]

I am trying to recap and digest this information.

It is pretty clear now the 800 in the multi mode, is only actually transmitting in 2 frequencies because adding more frequencies being scanned at the same time would affect power and depth.

Frequency weighting means the detector is operating in two specific frequencies per mode and can and are different for the 1's, 2's.


in the 1's mode (park1 and field1) we suspect or do we know it is operating in 5 & 10 Khz?
in the 2's mode (park2 and field2) we suspect or do we know it is operating in 15 & 20 Khz.

beach and gold 2's would probably be 20 & 40
beach and gold 1's would be what?

so do we know this for a fact or are we just making good educated guesses based on what the modes are supposed to be weighted for for those types of hunting and listing the two most logical frequencies to obtain that hunting goal?

Just maybe I am getting a little closer to my higher education in understanding the 800 thanks to great guys here who take the time to share information with us. Please point out if I am digesting some of this info incorrectly I don't want to learn incorrect info on the 800. I know vferrari is always doing a great job of helping us, but sometimes I need some more clarification on his detailed points.

 

[cudamark]

I wouldn't lump the Beach modes in with the Gold modes. They work quite a bit different. I suspect the Beach 1 is more likely a lower Khz similar to the Park and Field 1, or maybe a 5 and 15 mix with a higher iron bias, whereas Gold 1 would more likely be the 20 and 40 Khz. Beach 2 is similar to Beach 1 but with a different mix to account for water salinity changes and a reduction in transmit power. Gold 2 uses a slower recovery speed than Gold 1 that is supposed to help deeper targets in more mineralized ground. At least, that what I get from reading and experimenting.

 

[vferrari]

The frequency combos are only a part of what makes up Multi IQ. The other part is the received target signal processing. ML is not revealing the frequency combos (though some detector designers have gotten some o scope measurements fwiw) nor the signal processing algorithms and without that information speculation just causes confusion, dissemination of false information, and frankly not sure how useful or relevant all that Geek stuff really has on how you use the detector. Think about it - does knowing whether Park 1 is 10 + 40 khz or 5 + 15 khz really matter in how you use the detector? How are those two frequencies combined to create harmonic sidebands? Square or sine waves? All of those unknown but important factors dictate performance yet it's all really irrelevant to the end user, IMO.

My recommendation is to follow the broad guidance in the manual for the optimal targets and conditions associated with each mode combined with your real world experience with those modes and focus on learning how the things you do have control over (i.e., the user settings for sensitivity, disc, tones, recovery speed, and iron bias) and site selection affect your ability to find targets.