Detector design rethink!:nerd:

[Mick in Dubbo]

I guess I must have a bit to much spare time on my hands at the moment. After reading comments on different forums over time and watching the launch of a couple of new models and new detectors, it is interesting to watch how people react to them (just human nature). How often do you see people asking if it will go deeper eta, hoping that something marvelous has just been presented.(This is not a shot at people, it is just how we all react.) Which brings me to my point.
In all the time that detectors have been around, they still continue to use coils. As a line in thinking, with the technology that in now around, has anybody ever thought to use some sort of sensor pad instead (in a similar shape to a coil). I don't know if it is possible to design one that could go deep enough to be effective, even four inches would be good enough, given that that is the depth that you will find most targets. One possible solution to get some decent depth out of a set up like this, would be to think of it in the same way you could think about a radio telescope. In the neighbouring town of Parks, we have one of the largest radio telescope dishes in the world. it is enormous. It was also built in the 1960's. It was built so big so that it could see farther into space than anything else. Today; There are radio telescopes that can do a much better job, and they are a lot smaller. how can they do this. Simple. What they do, is build a number of them in line with each other. I don't know the exact details of how far apart they have to be eta, but suffice is to say, they are linked together in series and make the Parks telescope obsolete. What am I getting at? Simply put; if the senses on this imaginary pad could be linked up in a similar manner, then perhaps it could give you as much depth as you want. The end result, could be a detecting ground interface that can see all targets in the ground at the same time and tell you via a screen, exactly what is under that pad and where exactly it is at any given moment. You would lose a term out of the detecting vocabulary, Pinpointing, as you would never need to pinpoint again. I guess you would call this "Ground Imaging"
I have no electrical knowledge and have no idea if such an imagined idea would be financially viable. What I do know is, that if it is not first imagined first, then it can never be possible.
It is food for thought, and maybe something for R and D unit at Garretts to consider.
Mick Evans.

 

[Spanky]

You may say I'm part ground hog as I do all the underground locates for the company I work for.

I love technology for locating underground artifacts. I have some experience with ground radar imaging which sounds similar to what you are saying. This equipment has identified objects 6 feet below grade surface and will identify large objects very easily but not small items like coins.The equipment is also huge and bulky.The ground radar equipment is used only when the radio detect equipment will not locate what I'm searching for.

Being a water witcher as well I wish I could train that talent to find coins.

 

[khouse]

maybe if there was a small detector say the Ace 250 that had it's regular mode and a high intensity mode with a pad like Mick talked about. In the normal mode you located a target and pinpoint it. now it's the pads turn. you hit the charge button and like the flash on a camera it starts charging. then when you see the green light - push the fire button sending a tremendous amount of energy strait into the ground with the radio wave bouncing strait back to the pad burning an image that pops up on our screen. Garrett would build such a machine and market it for $199.00 with all coils and replaceable pads. Someone wake me up........ I guess it could happen?

 

[Uncle Willy]

Get to work Mick.


Bill

 

[DavHut]

You guys are doing great! Its innovative thinking like that which got men to cross oceans, soar in the skies and leave the boundaries of earth.

 

[jackintexas]

Remember metal detectors used to be large at one time. The guts were carried in a back pack. They were call mine detectors.

 

[John D.]

Yes and they weighed about 35-40 lbs, however I found a lot of CW bullets with one. The only problem was you had to take someone with you to dig, or wear yourself out taking the heavy thing off your back.

 

[Ron from Michigan]

OK,how about a control box smaller than most cell phones with the same battery charging system.The wand and coil asm. fiberglass carbon(light strong doesn't flex) search rod,with a glove type strap built into the handle.The coil also made out of fiberglass carbon which would weigh less than a paper pie plate.Compared with this unit to a Tesoro it would be a lunch box size detector.Ergonomics to an extreme? HH Ron

 

[Mick in Dubbo]

What I am suggesting, is only a new way for the detectors that we now have to pick up metal objects under the the ground. I don't think that the detector needs to go super deep, so I don't see a need to change them to much.Actually, the Infinium is the best detector on the market at the moment that can discriminate between different types of metals at the greatest depths. The reason that I say this, is because most coins are found close to the surface. The other reason, is that it is a given that once you start producing coil much bigger than 15 inches, they start to have problems seeing objects as small as coins and jewellery.
The main problem with coils, is they only put out one large signal and see only one target at a time, which makes them quite unweilding in thrashy ground. The current only only solution is use a small coil, which still only sees one object at a time.
The reason that I"m thinking along the lines of a sensing pad type of format, is that you can have something that has a series of senses that are small enough, yet hopefully still powerful enough to see a lot more than one target at a time and therefore show you on a simple screen where each object is under the pad and what is it's inductiveness. The more senses you have, the higher the resolution of that information
If you think vertically and have the individual senses built like a standard coil, then the depth would be hopelessly inadequate, however using the radio telescope allegory, and have the transmit and receive senses separate and far enough apart from each other, then you can overcome the depth problem hopefully from using such small sensing devices. I personally think that something like this is doible and practical.
It is something worth pondering.
Thanks to all with your ideas, suggestions and funny one liners.
Mick Evans.
Mick Evans.

 

[Spanky]

Interesting thought....in this day and age this should be do able. In fact it may be worth putting a paton on the idea as a first step.

 

[JB(MS)]

Lawrence Livermore National Laboratory developed a hand-held, lightweight detector for detecting land mines that uses micropower impulse radar technology. It provides three-dimensional images of the underground and permits objects to be identified by size, shape and a mixture of microwave frequencies. It uses a small waist-mounted computer for acquiring and processing data and a heads-up display that shows images of underground objects beneath the coil. Unlike ground penetrating radar, at least according to LLNL literture when it was being developed, it's capable of seeing small objects. Price might be a consideration.

<img src="http://www.boomspeed.com/cleotus/microimpulse.jpg">

 

[DavHut]

We have radio pulse detection already - its called PI.

Anyway you shake it, you must "illuminate" a metallic object in the ground with SOME sort of EM energy.

 

[Paul(NWO)]

the radio telescope might not be the right analogy. The transmit part of the scheme is the the object in outer space and all the dish is doing is capturing the signal. The metal detector transmits and receives while penetrating the soil beneath. The signal is somewhat reflected back to the pickup coil after being distrubed by the metalic object in the ground. The concept seems great though and would be more practical with a multi frequency detector such as the Infinium. You could set your small sensitive pick-up pads in an array with multiples of pads sensitve to specific or multi frequencies. It would seem that you could have them arranged so that you could not only tell depth and size but with with proper circuitry be able to tell shape. Reading the date might be a bit much though. This would mean a whole new chip for the circuit board and lots of built in ram. You're thinking Mick. You're on to something. Don't give up until you find the why's and why not's.
HH

 

[DavHut]

[size=small]The term 'sensor' is alas, rather skewed in its use here and I feel compelled to throw a wet blanket on the party.

Sensors do one of two things

1. Sense energy in one form or another
2. Sense the presence of something in proximity.

Number one can be further divided thus:
1A. The energy you are sensing has to be disturbed in one way or another by the item you wish to sense. You see this in beam sensors, like the ones's that generate the "bing-bong" sound you hear when you enter a store - as you cross the threshold, you break a beam of light with your body and you, the target, are sensed and announced.

1B. The item being sensed must present its own energy, either intrinsic or reflected. The radio telescope is a good example of the former and the metal detector as we know it of the latter.

In number 2, the item you wish to sense has to be close enough to the "sensor" so as to disrupt an EM field intrinsic to the sensor itself. This type is known as a proximity sensor and typically has a very narrow field - you gotta be real close, like within 5-8MM.

The current state of "sensors" doesnt allow for the passive sensing of say, metallic objects within a matrix, at anything other than very close distances. Obviously not going to work on a dime at 6".
We are therefore forced to iluminate our targets with some form of EM energy and then "sense" their reaction to it.

But, who knows, maybe someone will change the universal laws of physics and we'll soon have some sort of Star Trek scanner gadget.[/size]

 

[Paul(NWO)]

only I didn't want to rain on Mick's parade and used it in a generic sense because the man was thinking and his sensors would have to act like a minaturized but super sensitive coil as we know them. As I was saying about the chip, this whole idea would require new technology but it should be achievable. In one of Charles Garrett's books he has a picture of military detectors which some don't have a coil as we know them but look like the end of a polo mallet. He said our type of metal detector would set off modern mines. I hope I didn't offend. I see from previous posts that you are well acquainted with electronics and have the insights into what must be to accomplish the task. Thanks for the input.
HH

 

[DavHut]

No offence at all and I hope I didnt do the same. I wasnt speaking directly about your posts, but about the whole concept as its being discussed here, in general.

Much can be done, from within the industry, as new advances come along. 2 examples are the effects that low power/low noise circuitry and microprocessor control has wrought.

Id like to see a detector that clips to you belt and operates wirelessly, so the only thing you have in your hands is an "S" pole to mount a printed elliptical coil.

As to the mines, I find it hard to believe that the amount of powere emitted by the now current detectors could trigger a mine. Unless, of course, if some clever Russian designer hadnt developed a mine that could detect when it was being detected, and go off. Long life batteries and a tiny bit of circuitry little larger that a digicam would do it. I pulled a lithium memory retention battery from a controller 2 weeks ago that had been in service for 15 years and had only JUST died. It was a single AA size.

 

[Mick in Dubbo]

Thanks to all for replying. This has been quite educational.
After I wrote the last post, I started thinking about the Infinitum as well as small coils.Firstly small coils. In essence, like all coils, a small coil sends out a signal with one part of the coil and receives with the other part. (I'm too ignorant to remember which part sends, and which part receives.The fact that it works is good enough for me.) What I have been thinking about, is how too shrink it enough, so that you can have more than one coil operating at a time. The primary reason for this would be to overcome the fact that what we have at the moment can only put down one signal, which means that if more than one object is in the detecting field, the the detector won't cope. The more mini coils you can have, the better. There may only be a need to have 3 or 4 of these mini coils in concert with each other, depending on whether you set it up to detect one signal for each object that could be under the coil at that time; or whether you set it up in such a way that it can send signals from different angles and thereby set up something like a 3D picture of the target or targets that are passing under the coil and prevent the detector from getting swamped by the targets.
Second. The detector itself. In order to allow a system like this to work, you need to be able to send out multiple signals that won't inter fear with each other.Thinking about the Infinitum(as well as the 2500 with the imaging coil and the Minelab explorer with it's 3 signals sent into the ground at the same time, I presume, to give the optimum depth at each given moment with a byproduct of giving ferrous/conductive two digit readings.)and thinking about the term, pulse induction, if you can send signals on the same frequency, but in pulses from the different transmit points in rapidly alternating bursts, could be one solution.Another, would be to send out signals at the same time on different frequencies, or a combination of both ideas.
What is interesting, is that both Garrett's and Minelab have already started to head down this road a bit, but with narrow thinking insomuch as to be thinking how to see a single target better.Garrett's use the imaging coil (which I confess to know little about) that helps to size a target. Minelab, with their multi frequency approach, which helps to give a targets ferrous/conductive reading, so as to be good at I.Ding exactly what it is detecting.
What I am suggesting here, is to apply the technology that we already have and apply it differently. All the manufacturers are all still only thinking how to best figure out how to see one and only one target at a time.If you have more than one target under the coil at a time, then you can quickly see the limitation of this sort of approach. A coil in this situation becomes like trying to use a chainsaw to make a cut that would really need the precision of a surgeon's scalpel.Instead, if research was done in how to set up the above mentioned approach, then I think we could see a quantum leap in what a detector is capable of.If set up in this type of fashion. The possible new abilities could be to 1)be able to see exactly what the target is that is under the coil (because you can see it from multiple angles) and 2)You should then be able to see every target (if there is more than one under the coil at a time)and not have the detector's discrimination getting overloaded.
From some of the replies, I can see that I must have given the impression that I was talking about some real you beaut ground X-Raying detector. All I am suggesting, is that the current technology is used in a different manner.This could be a practical and affordable way forward. As it stands, I don't think detectors are going to move forward mush farther as they are. They don't need to go any deeper. The main 2 paths foreword for them from this point, is discrimination, and reducing their weight, which Tesoro have already done.
I have had a good laugh at some of the comments and It would be nice if these posts have inspired anybody in the industry to think a bit differently in how to improve them.
Mick Evans.