question for andy sabish

[wheelbubble]

On the thread that is titled re:gold chains by cody he indicates the exp2,quattro,and sovereigns are p.i. detectors is that a fact?It seems to me that you made mention of this some time ago,but being old I cannot recall where I may have read that or exactly when..Are these machines p.i./Or are they just VLFs on steroids...thank you in advance wheelbubble...

 

[therick]

n/t

 

[wheelbubble]

Well are you right or is cody right..have you read his post on gold chains..and how do you determine that they are not some sort of a p.i. machine..

 

[Cody]

It is not a question of VLF and frequencies but how the detector's transmitter drives the coil and how the data is processed. Not that it makes much difference but that is why we get that great depth and performance from the Explorer and why it has almost no problem with soil minerals. The Explorer is patented as a time domain rectangular pulse drive metal detector (PI). Pulse Induction is used and the Explorer uses time domain instead of frequency domain like some of the other PI machines. Look at the patent numbers for the Explorer and you will see it is patented as a PI and then if you read the patents will see it is a pulse induction time domain process.

Hope this helps,

 

[wheelbubble]

Thank you Cody for the right answer thats what I was looking for...thanks again...Good to have someone in the know!!

 

[Captain Kirk]

Cody,

I have a somewhat different feeling about pulse induction machines. Here is one definition that I found.

"The transmitter circuitry consists of a simple electronic switch which briefly connects this coil across the battery in the metal detector. The resistance of the coil is very low, which allows a current of several amperes to flow in the coil. Even though the current is high, the actual time it flows is very brief. Pulse Induction metal detectors switch on a pulse of transmit current, then shut off, then switch on another transmit pulse. The duty cycle, the time the transmit current is on with reference to the time it is off, is typically about 4%. This prevents the transmitter and coil from overheating and reduces the drain on the battery."

I do not think that is how the BBS detectors work.

HH,
Glenn

 

[Cody]

Pulse induction can be achieved with a square wave Glenn, you know that.

 

[Cody]

Minleab patented the Explorer as a sub-class of a PI because it uses time domain. I am only posting what the patents tell us. Again, I have no original idea about this. If one want to think the Explorer is an SF, TD, FD, CW, or some other machine then what difference does it make? That is what I said in the first place. What difference does it make if we like the detector and it gets great depth and has marvelous discrimination?

I am waiting for your emial on how the transmitter and receiver work!

 

[Cody]

Glenn what you describe is the prior art. The whole idea behind what Candy has done is a new process using pulse induction and time domain. He invented a way to use a rectangular square wave to pulse the coil. The process is what we have discussed many times and that is time domain temporal evolution of data. In doing so he also eliminated the tremendous drain on the power supply using the prior art.

The pulse induction process is covered in the patent. That prior arts for the various detector type is discussed in the first few pages of the patent. However, I should discuss this on the classroom forum so did not mean to get this started here.

 

[Andy Sabisch (SC)]

Since the heart of the BBS and FBS detectors is proprietary software that has NOT been patented, downloading the US patents and trying to analyze how these detectors work is not really going to tell you the whole picture. People have been doing the "patent download" thing for several years now and all claim to have figured out what makes the Minelab's tick; however, knowing a few things about electronics and having had the opportunity to work with the Minelab engineers on a few projects over the years, I know that much of what makes these units different is NOT available from the patent office. If it was really that simple, wouldn't you think that the other manufacturers would have done the same thing; i.e., downloaded the patents, tweaked the circuitry a bit to avoid a patent infringment suit and released their own multi-frequency detectors?

In a nutshell, the BBS and FBS models are NOT using a PI-circuit to operate on.

I guess the key thing is that they work . . . . . . does it really matter how? When you get in your car and turn the key do you want it to start or are you concerned about what gauge wire is used between the key and the starter itself?

Not trying to stir things up . . . . . but for me, as long as I am finding goodies when I go out, then what's "going on under the hood" really has little bearing on my opinions of the detector itself.

Andy Sabisch

 

[cachenut]

I would think a good electrical engineer could examine the chips and software in great detail and learn exactly what is going on w minelab. Its there and it is fixed so not really hidden. Of course it would take a lot of time and skill and anyone with that level of skill could just make their own detector.

 

[staloch]

I dont really care what technology Minelab is using, all i know is that they make awesome machines and i hope they continue to improve on them.

 

[Ralph Bryant]

"Hybrid" would be an accurate description I would think, since there are components of both pulse induction and induction balance involved, not a pure form of either but a combination of both types of technology. It goes beyond just the wave-type being transmitted, and involves much within the receiver circuits in comparative analysis of the target and ground signal. Putting the signal into the ground and getting a response from the presence of metal is not so much the goal anymore, as is the analysis of the target information that is made available. Notice that most of the advancements in the last many years is in the realms of discrimination, not depth of detection. There were machines as far back as the 70s and 80s that will match most high-end machines of today on "depth". But discrimination back then was still very much a future science.

Detectors are nothing more than relatively simple computers, whether analog or digital, intailing the usual "garbage in - garbage out" philosophy. Still, there are manufacturers today who seem intent on designing and programming detectors to "think for the operator". Others are content to produce older technology designs that assist the operator in "thinking for himself". There can be productive advantages either way......

Ralph

 

[Cody]

We need you Ralph as you nailed it.

Cody

 

[Ralph Bryant]

SUMMARY OF THE INVENTION

The subject of this invention is a pulsed, discriminating, time domain conducting metal detection apparatus utilising rectangular transmitted pulses.

----------------

Pretty much speaks for itself as to the general transmitter process used. From a purist's perspective, you either have CW (constant wave) or PW (pulsed wave) on the TX end, regardless of the waveform used or the amplitude (strength) or frequency(ies) involved. If you envision a bent string lying across the floor to represent the radio wave, it is either solid or broken. The only other option is no string (wave) at all. The differences are primarily in how the TX waves are manipulated and how the RX or receiver end of the circuit interprets the incoming data or signal. Older PI technology consisted primarily of true pulsed (on-off) signals and "eddy current detection", and little else, thus no discrimination beyond relative decay rates. Minelab technology goes beyond pushing that envelope, and breaks through to new processes of "pulsed constant wave transmission" (for lack of a better term), or a combination as it were of both modified pulse and constant wave technology, and interpreting the vastness of information contained in the received target signal through time domain sampling involving new processes of discrimination and ground effect elimination through the use of multiple sampling points/times and comparative analysis.

My appologies for the edits, but that first version didn't sound quite accurate......

Ralph

 

[Cody]

You might consider the following but at any rate I will drop this and go with hybrid.

We might consider the following from Minelab Patent 537,041 for the Explorer. These are direct quotes from the patent.

Title of Patent:

 

[MattR]

Hi Cody!

I was perusing the Explorer forum and noticed the discussion on Explorers and Pulse Induction. I was intrigued by Andy Sabisch's comments on the subject

Because of his claim to knowledge of electronic principles, AND to have worked with the Minelab engineers on some projects, then why does he express the opinion that the Explorer does NOT utilise pulse induction?

I respectfully enquire of Andy's professional knowledge on this subject, to justify his statement?

Here is my 'two-cents-worth'.

The Minelab Sovereign, etc. Explorers ARE INDEED PULSE INDUCTION detectors, regardless of how they subsequently function.

How Minelab PROCESS the returned signals from the PULSED TRANSMISSION is the basis of their patent, and not the manner in which the target is interrogated, i.e. by a train of PULSES.

IT IS BY USING PULSED TRANSMISSION THAT THEY CAN CLAIM THEIR SYSTEM INVOLVES 28 FREQUENCIES. (HARMONICS of two fundamental frequencies)

The success of the Minelab detector is a combination of their utilisation of PULSED transmission, 'Double D' search-head, digital signal processing and a unique computational algorithm for the signal evaluation...........

The PI detectors of yesterday were primitive and simple analogue mode units. Eric Foster of the UK did produce a hybrid form of discriminating unit, but it was relatively 'stone-age' principles compared to the Minelab approach. (No disrespect to Eric, for I have two of his units. His machines have found thousands of mouth-watering artefacts for beach detectorists here in the U.K.)

The Minelab Explorer and the White's DFX are two fine examples of present day PULSE induction transmission mode detectors.(Hence 'multi frequencies')

------------------------

Cody !!! It's good to say "Hello" again...MattR.UK

 

[Cody]

MattR, I have no idea how the comments posted square with not understanding advanced PI art. I don't recall when I have been more baffled when taken in context of your enquiry. I think I would have understood if not for your comments below.

I am sure Andy will be glad to explain his comments and how BBS and FBS have anything to do with the Explorer being advanced time domain pulse induction.

"Because of his claim to knowledge of electronic principles, AND to have worked with the Minelab engineers on some projects, then why does he express the opinion that the Explorer does NOT utilise pulse induction?

I respectfully enquire of Andy's professional knowledge on this subject, to justify his statement?"

I was wondering when some of the engineers on the forums were going to challenge those remarks and thought about you in particular as a semi-retired engineer. You have kept me straight on several points and I really appreciate it in my overall understanding of detectors.

 

[Cody]

MattR, I forgot to say good to see you posting. I have wondered what you have been doing. I thought as a semi-retired electronic engineer you might be on another project. I very much enjoy you book by the way. I have never read a post of yours that some light did not go on and another piece of the puzzles falls into place.