Equinox Transmission & Reception

[Flowdog]

Today is my 50th anniversary. My Equinox 800 is my wife’s gift to me. Tomorrow we brave the snow and head to Lake Tahoe to celebrate. As I get prepared for my first hunt, I have been repeatedly reminded to stick to the default modes. I plan to do just that. 

However, my technical side has a curiosity of its own. It is my understanding that the power of the transmitted field is fixed by battery voltage. Beside changing frequency from Multi to individual frequencies, which settings impact coil transmission properties?

On the reception side, which settings impact signal reception qualities? Do any settings impact both transmission and reception? Do any settings work together in the normal course of tuning and balancing for ground and trash conditions? 

For example, does a change in "Recovery Speed" setting change equally both the number of transmissions and receptions or is processing done only on the reception side? Sensitivity? Iron bias?

What I am unable to find in documentation is a basic guide to all settings affecting transmission only; receiver only; both.

I am enjoying the reading, but there are a lot of places for information to hide. So I apologize if this information is easily found by most, but since I may be near information saturation, I could have easily skimmed by it.

Thanks,

Curtis

 

 

 

[Desert Dawg]

Congratulations on your 50th anniversary, you got 5 yrs on my wife and I. As for the detector question I am sure there will be more informed than me chime in soon,  I do believe transmission is not able to be tweaked period that is fixed in the machine. Its all about the reception where the tweaking comes in.

[Cal_Cobra]

Congrats on your 50th!  

Doesn't Tahoe have like 35' of snow right now?

[Chase Goldman]

Congrats on the 50th here is a DP page with a number of resources that explain the basics, theory, physics and technology behind metal detectors.  HTH

 

Here is the Equinox Essential Information Thread:

 

Here is a link that explains Multi IQ

https://www.detectorprospector.com/magazine/best-of-forums/minelab-multi-iq-technology-details-explained/

Chew on that awhile and if you have more questions than check back.  TBH - As an engineer myself and tech geek, I think you may getting yourself into the weeds too soon on the theory of operation stuff and it appears you might have the wrong mental model of receive and transmit as far as a metal detector is concerned that may be a source of confusion for you.  You are looking at it more like RADAR and it is more closely coupled like a transformer (see discussion below) because we are talking about detecting small changes in magnetic fields not reflected radio waves where there is little influence between the transmitted and received signals.  I would separate your intellectual curiosity about how the detector works from understanding how to operate the detector save for a few basic concepts.  But to delve a little bit into this, the detector is basically acting like a big transformer with a transmit coil (which one "D" the left side of the coil loop) as the primary and a receive coil (the other "D" on the right side of the coil loop) as the secondary and the target acting as the "core" of the transformer and the most "sensitive" region of the coil loop being the center "spine" of the coil loop where the two "D"s overlap in a back-to-back fashion .  Different metallic makeup of the "core" (target) will cause the electric signal passing through the transformer system to be altered in ways that can be measured such that the target shape and electromagnetic properties such as conductivity and inductance can be inferred and passed on to the user as visual and audible target information.  The transformer analogy as I described is incomplete and imperfect but it gets the idea across, hopefully.

Multifrequency helps better cancel/account for ground effects and enable the different transmission and excitation properties associated with different frequencies to be simultaneously applied to the target.  Higher frequencies excite lower conductors like like gold, aluminum, brass, and lead and small targets better but cannot penetrate as deeply into the ground.  Lower frequencies penetrate deeper and excite high conductors like silver and copper and high mass objects  better than high frequencies.  Ferromagnetic targets like iron have different, known. response properties than non-ferromagnetic targets and can therefore be readily identified and discriminated.  There are drawbacks to multifrequency operation, two of the biggest being, minimizing transmission power loss to extent practical (the transmit energy has to be divided between individual frequencies if you are actually transmitting them separately and simultaneously, rather than using more elegent methods such as square waves, pulse width modulation, or other methods to take advantage of harmonics that are produced when two or more signals of different frequencies are combined) and the processing power required to extract the information from the received signal.

Equinox also brings adjustable, fast response to the table (known as recovery speed) which helps with being able to detect multiple targets in close proximity to each other.  But as is true with all aspects of detecting, there is no free lunch.  Run recovery speed too high and deeper target signals will begin to become clipped such that you may not be able to hear them with the practical effect that you are actually reducing detecting depth.  Run recovery too low in an attempt to increase depth, and you risk increasing ground noise because of the need to swing slower to get a good signal whichnis also counter optimal performance.  For the 800, the sweet spot for recovery speed is around 4 to 6 leaning a little on the high side.  There are more in depth discussions of recovery speed on the Equinox Essentials thread page I linked to above.

One of the mantras I use to optimize Equinox setup is to stay as close to the defaults as I possibly can and to maximize the signal to noise ratio.  Avoid doing things that raise the noise floor along with signal sensitivity (like cranking sensitivity too high or lowering recovery speed too low as mentioned previously).

Let me know if you want to go into the different properties of the various modes (Park 1/2, Field 1/2,. Beach 1/2, etc.) and what conditions and targets they are optimized for.

HTH to get you started.

Chase

[Northeast]

2 hours ago, Chase Goldman said:

But to delve a little bit into this, the detector is basically acting like a big transformer with a transmit coil (which one "D" the left side of the coil loop) as the primary and a receive coil (the other "D" on the right side of the coil loop)

On a related but slightly different subject.  Is this perhaps why when swinging the Gold Monster (and possibly the Equinox) people talk about swinging one way and getting a 'ferrous' signal and swinging the other way and getting a 'non-ferrous' signal over the same target.

If the Tx coil passes the target first and excites the target and then the Rx coil passes over it might give a different response to when swinging the other way and the receive coil passes the target first.  Hard for a receive coil to actually receive a signal from a target that hasn't been excited or only gets excited as the receive coil is about to leave the target zone? 

I'm guessing this theory may be full of holes or was it already widely known withing the detecting community  ?‍♂️

[Chase Goldman]

 

21 minutes ago, Northeast said:

On a related but slightly different subject.  Is this perhaps why when swinging the Gold Monster (and possibly the Equinox) people talk about swinging one way and getting a 'ferrous' signal and swinging the other way and getting a 'non-ferrous' signal over the same target.

If the Tx coil passes the target first and excites the target and then the Rx coil passes over it might give a different response to when swinging the other way and the receive coil passes the target first.  Hard for a receive coil to actually receive a signal from a target that hasn't been excited or only gets excited as the receive coil is about to leave the target zone? 

I'm guessing this theory may be full of holes or was it already widely known withing the detecting community  ?‍♂️

I think the physical makeup of a DD coil may contribute to one way signal response.

[Flowdog]

15 hours ago, Chase Goldman said:

Chew on that awhile and if you have more questions than check back.  TBH - As an engineer myself and tech geek, I think you may getting yourself into the weeds too soon on the theory of operation stuff and it appears you might have the wrong mental model of receive and transmit as far as a metal detector is concerned that may be a source of confusion for you.  You are looking at it more like RADAR and it is more closely coupled like a transformer (see discussion below) because we are talking about detecting small changes in magnetic fields not reflected radio waves where there is little influence between the transmitted and received signals. 

Hello Chase,

Thanks for the comprehensive response and for helping to keep me on the straight and narrow.

As I was reading your transformer analogy the flashbulbs went off.  I will get some field time under my belt before I take my curiosity much further into theory just yet. 

 

15 hours ago, Chase Goldman said:

I would separate your intellectual curiosity about how the detector works from understanding how to operate the detector save for a few basic concepts.

What are the "few basic concepts" that you refer to?

15 hours ago, Chase Goldman said:

One of the mantras I use to optimize Equinox setup is to stay as close to the defaults as I possibly can and to maximize the signal to noise ratio.  Avoid doing things that raise the noise floor along with signal sensitivity (like cranking sensitivity too high or lowering recovery speed too low as mentioned previously).

Let me know if you want to go into the different properties of the various modes (Park 1/2, Field 1/2,. Beach 1/2, etc.) and what conditions and targets they are optimized for.

HTH to get you started.

If I can see open ground and I am not in violation of hotel beach rules, my plan is to stick to FPs and to follow Minelab's basic instructions: select mode, perform noise reduction and if necessary, ground balance, go hunt. Get my new spade dirty so I can begin to relate what I may uncover to what the sounds and meter are saying. As for your offer to clarify the properties of the various modes, I will surely touch base with you after I have had a chance to reassemble my thoughts along the lines you correctly steered me, coupled with some real time experience. Thanks again for your generous post. I am obliged and a bit overwhelmed that you would take as much time as you have to lend a hand. 

Curtis

[Chase Goldman]

17 hours ago, Flowdog said:

What are the "few basic concepts" that you refer to?

Primarily understanding how the varous metals you will encounter fall across the spectrum of target IDs and how that is primarily (but not soley) related to the conductivity of the metal, the target shape  (irregular or symmetric like a coin), the target size (footprint), the target mass, and whether the target is ferromagnetic.  Corrosion, depth, nearby metals, soil condition will also have an effect.  All of these things play a role into developing a target ID.  Having a fundamental understanding of that aspect is important to helping you make dig decisions because the metal detector can be easily fooled into giving you, for example, high numbers for iron targets that SHOULD be ringing up low and other anomalies.  Understanding how that can happen can make you a more skilled detectorist down the road.  So I recommend, setting up a test garden so you can train your ear and get used to the typical target IDs common targets such as various types of coins and jewelry and nails and aluminum trash will ring up as.

In a nutshell, iron will typically fall in the -9 to 2 range; brass, nickel, aluminum, and gold can ring up anywhere from 1 to the 20's but will typically fall in the teens; nickels will typically show up around 13; pull tabs will surround the nickels, zinc pennies around 19-20, copper pennies slightly higher, dimes in the mid 20's, larger high conductive (silver and clad) coins will ring up in the high 20's and low 30's and so on.

Speaking of ears, it will be natural for you to heavily rely on just the screen numbers to decide to dig, make sure you pay attention to the audio tones too because ultimately you will realize there is a lot more information and clues about the nature of the target in the audio nuances than in some digits flashing on the screen.

Know this also, there are no "givens" in metal detecting save for you won't detect the target unless you get your coil over it.  Also, no free lunches.  The reason is because the variables that affect detectability are too numerous for any machine or human, for that matter, to fully account and compensate for.  That is also why you should be wary of test videos that purport to conclude the absolute truth about the best detector or best settings.  Likely, there is no one answer and the best answer usually is, "it depends". 

The key to detecting is patience, getting swing hours in so you can gain the experience you need to know your machine, balance all the tradeoffs and improvise as necessary, and most of all, enjoying the unpredictable nature of the hobby.  Finally...

Have fun!

[Northeast]

9 hours ago, Chase Goldman said:

Primarily understanding how the varous metals you will encounter fall across the spectrum of target IDs and how that is primarily (but not soley) related to the conductivity of the metal, the target shape  (irregular or symmetric like a coin), the target size (footprint), the target mass, and whether the target is ferromagnetic.  Corrosion, depth, nearby metals, soil condition will also have an effect.  All of these things play a role into developing a target ID.  Having a fundamental understanding of that aspect is important to helping you make dig decisions because the metal detector can be easily fooled into giving you high numbers for iron targets that SHOULD be ringing up low and other anomalies.  Understanding how that can happen can make you a more skilled detectorist down the road.

Great post Chase.  Especially the cut and paste piece above. Well done  ?

 

[midalake]

For whatever it is worth [signal transmission aside]  In saltwater and light black sand conditions, I get way more accurate  target ID numbers hitting the all-metal button and re-sweeping the target. 

 

Dave