Tarsos detector vlf turkey

[ledoc]

the "reflection" don t depend of the frequency, but change the phase of the TX signal. After there is different amplitude of the reflected signal in function of the metal. But the size of the objet and the material affect on the same way the dephasage. That why it s impossible to discriminate the big objects even if is the iron.

I would like to know if someone here is happy of is Tarsos detector? ;-) (seriously...)


NB: scs, why do you talk about god?? I don t understand your joke

[Qiaozhi]

NB: scs, why do you talk about god?? I don t understand your joke

Please keep religion out of the forums. This is a place for discussing metal detector technology, not mystical beliefs.

Whatever you believe, or not, should be kept private.

Thank you.

[scs]

"Allah knows better "- writer Anwar 2
Sorry!
For Tarsos-detector: Only with one channel is not possible to achieve simultaneous operation of Geb and Discr.

[scs]

What signals are necessary to operate normally detector

VLF (Very Low Frequency) Transmitter & Receiver Transmitter Inside the metal detector's loop (sometimes called a search head, coil, antenna, etc.) is a coil of wire called the transmit coil. Electronic current is driven through the coil to create an electromagnetic field. The direction of the current flow is reversed several thousand times every second; the transmit frequency "operating frequency" refers to the number of times per second that the current flow goes from clockwise to counterclockwise and back to clockwise again.
When the current flows in a given direction, a magnetic field is produced whose polarity (like the north and south poles of a magnet) points into the ground; when the current flow is reversed, the field's polarity points out of the ground. Any metallic (or other electrically conductive) object which happens to be nearby will have a flow of current induced inside of it by the influence of the changing magnetic field, in much the same way that an electric generator produces electricity by moving a coil of wire inside a fixed magnetic field. This current flow inside a metal object in turn produces its own magnetic field, with a polarity that tends to be pointed opposite to the transmit field.
Receiver A second coil of wire inside the loop, the receive coil, is arranged (by a variety of methods) so that nearly all of the current that would ordinarily flow in it due to the influence of the transmitted field is cancelled out. Therefore, the field produced by the currents flowing in the nearby metal object will cause currents to flow in the receive coil which may be amplified and processed by the metal detector's electronics without being swamped by currents resulting from the much stronger transmitted field.
The resulting received signal will usually appear delayed when compared to the transmitted signal. This delay is due to the tendency of conductors to impede the flow of current (resistance) and to impede changes in the flow of current (inductance). We call this apparent delay "phase shift". The largest phase shift will occur for metal objects which are primarily inductive; large, thick objects made from excellent conductors like gold, silver, and copper. Smaller phase shifts are typical for objects which are primarily resistive; smaller, thinner objects, or those composed of less conductive materials.
Some materials which conduct poorly or not at all can also cause a strong signal to be picked up by the receiver. We call these materials "ferromagnetic". Ferromagnetic substances tend to become magnetized when placed in a field like a paper clip which becomes temporarily magnetized when picked up with a bar magnet. The received signal shows little if any phase shift. Most soils and sands contain small grains of iron-bearing minerals which causes them to appear largely ferromagnetic to the metal detector. Cast iron (square nails) and steel objects (bottle caps) exhibit both electrical and ferromagnetic properties.
It should be pointed out that this discussion describes an "Induction Balance" metal detector, sometimes referred to as "VLF" Very Low Frequency (below 30kHz). This is the most popular technology at the present time, and includes the "LF" Low Frequency (30 to 300kHz) instruments made for prospecting.
Discrimination Since the signal received from any given metal object exhibits its own characteristic phase shift, it is possible to classify different types of objects and distinguish between them. For example, a silver dime causes a much larger phase shift than an aluminum pull-tab does, so a metal detector can be set to sound off on a dime yet remain quiet on the pull-tab, and/or show the identification of the target on a display or meter. This process of distinguishing between metal targets is called "discrimination". The simplest form of discrimination allows a metal detector to respond with an audio output when passed over a target whose phase shift exceeds a certain (usually adjustable) amount. Unfortunately, with this type of discriminator the instrument will not respond to some coins and most jewelry if the discrimination is adjusted high enough to reject common aluminum trash for example pull-tabs and screw-caps.
A more useful scheme is what is called "Notch Discrimination". With this type of system, a notch in the discriminate response allows the metal detector to respond to targets within a certain range (such as the nickel/ring range) while still rejecting targets above that range (pull-tabs, screw-caps) as well as below it (iron, foil). The more sophisticated notch metal detectors allow for each of several ranges to be set for either accept or reject responses. White's Spectrum XLT for example, provides 191 individually programmable notches.
A metal detector may provide a numeric readout, meter indication, or other display mechanism which shows the target's likely identity. We refer to this feature as a Visual Discrimination Indicator, or V.D.I. Metal Detectors with this capability have the advantage of allowing the operator to make informed decisions about which targets they choose to dig rather than relying solely on the instruments audio discriminator to do all the work. Most, if not all, V.D.I. metal detectors are also equipped with audio discriminators.
Metal detectors can distinguish metal objects from each other based on the ratio of their inductance to their resistivity. This ratio gives rise to a predictable delay in the receive signal at a given frequency. An electronic circuit called a phase demodulator can measure this delay. In order to separate two signals, such as the ground component and the target component of the receive signal, as well as to determine the likely identity of the target, we use two such phase demodulators whose peak response is separated from each other by one fourth of the transmitter period, or ninety degrees. We call these two channels "X" and "Y". A third demodulated signal, we call "G", can be adjusted so that its response to any signal with a fixed phase relationship to the transmitter (such as the ground) can be reduced to zero regardless of the strength of the signal.
Some metal detectors use a microprocessor to monitor these three channels, determine the targets's likely identity, and assigning it a number based on the ratio of the "X" and "Y" readings, whenever the "G" reading exceeds a predetermined value. We can find this ratio with a resolution of better than 500 to 1 over the full range from ferrite to pure silver. Iron targets are orientation sensitive; therefore as the loop is moved above them, the calculated numerical value may change dramatically. A graphic display showing this numerical value on the horizontal axis and the strength of the signal on the vertical axis is extremely useful in distinguishing trash from more valuable objects. We call this display the "SignaGraph"™.
Ground Balance As previously mentioned, most sands and soils contain some amount of iron. They may also have conductive properties due to the presence of salts dissolved in the ground water. The result is that a signal is received by the metal detector due to the ground itself which may be thousands of times stronger than the signal resulting from small metal objects buried at modest depths. Fortunately, the phase shift caused by the ground tends to remain fairly constant over a limited area. It is possible to arrange things inside the metal detector so that even if the strength of the ground signal changes dramatically--such as when the loop is raised and lowered, or when it passes over a mound or hole--the metal detector's output remains constant. Such a metal detector is said to be "ground balanced". Accurate ground balance makes it possible to "pinpoint" the location of the targets with a good deal of precision as well as to estimate the depth of the targets in the ground. If you choose to search in a non-discriminate, or "all-metal" mode, accurate ground balance is essential.
The simplest form of ground balance consists of a control knob which the operator adjusts while raising and lowering the loop until good balance is achieved. Although this method can be quite effective, it can also be tedious, and some people find it to be difficult or confusing. More advanced metal detectors will perform ground balance automatically, typically by a two-step sequence in which the metal detector is balanced with the loop raised, then balanced once more with the loop lowered to the ground. The most sophisticated ground balance metal detectors will gradually adjust themselves as changes in the composition of the ground occur. We refer to this as "Tracking Ground Balance". A good tracking metal detector allows you to balance once, then hunt for the rest of the day without having to balance again. A word to the wise - many metal detectors which are advertised as having "automatic" or "Tracking" ground balance are actually factory preset to a fixed balance point. Its a little like welding your car's accelerator halfway to the floor and calling it "cruise control".
Motion/Non-Motion Modes Athough the ground signal may be much stronger than the target signal, the ground signal tends to remain the same, or change very slowly, as the loop is moved. The signal from the target, on the other hand, will rise quickly to a peak and then subside when the loop is swept over it. This opens up the possibility of using techniques to separate ground from target signals by looking at the rate of change of the receive signal rather than looking at the receive signal itself. Metal detector modes of operation which rely on this principle are called, not surprisingly, "Motion" modes. The most important example is a mode called "Motion Discrimination". If we wish to isolate the target signal well enough to determine the target's identity, the ground balance alone is not enough. We need to look at the target from a couple of different perspectives, sort of like the way distances can by measured by triangulation if you have more than one viewpoint. We can only be ground balanced from one particular "viewpoint"; the other will contain some combination of target and ground signal. Fortunately, we can use the motion technique to minimize the effect of the remaining ground signal. At the present time, all discriminating and V.D.I. metal detectors require loop motion to be effective. This turns out not to be much of a penalty in practice since you have to move the loop anyway in order to cover any ground.
Once you have located a target in the motion discrimination mode, you will probably want to more precisely locate it for easy recovery. If your metal detector is equipped with a depth meter, you will also want to measure the target's depth. "Pinpoint" locating and depth measurement are done in what is called the "All Metal" mode. Since discrimination is not required to perform these functions, loop motion is not usually required -- except for that motion required to get the loop over the center of the target. More precisely, the speed at which you move the loop is not important. The All Metal mode (also sometimes called the "Normal" mode, or "D.C." mode) is therefore called a "Non Motion" mode.
There are a few potential points of confusion here. Some metal detectors are equipped with a feature called "Self Adjusting Threshold", or S.A.T., which gradually increases or decreases the audio output in an attempt to maintain a quiet but audible "threshold" sound. This helps to smooth out audio changes caused by the ground or inadequate ground balance. S.A.T. may be very rapid or very slow depending on the metal detector and how it's adjusted, but strictly speaking, S.A.T. implies a motion mode of operation. This is why you will hear certain metal detectors referred to as having a "True Non Motion" mode; meaning, of course, an All Metal mode without S.A.T. Another sometimes confusing thing is that some discriminators allow for adjustment down to the point that the discriminator responds to all metals -- in other words, it's a discriminator that doesn't discriminate. This is something very different, however, than the All Metal mode previously described. For this reason we often refer to it as a "Zero Disc" mode.

[ledoc]

ouah! long and detailed descriptions, i ll read that with interest. Are you the author?

[Anwar2]

Friend, do not mention the name of God in our human problems.One is God, it has many prophets and messengers to the Earth.

my friend dont be a fright Im not terrorist this is our language in arabic when we start or fnish some thing we politly respect gods majesty this is our habituation Im not pushing the religion to forums
any way we are here to learn and teach some thing good

[Anwar2]

I would like to know if someone here is happy of is Tarsos detector? ;-) (seriously...)

no ledoc Im not happy with my its dosent discrime between metals

[scs]

Authors

ledoc
Junior Member
Join Date: Aug 2012
Posts: 11



ouah! long and detailed descriptions, i ll read that with interest. Are you the author?

Authors-Mark Rowen and Bill Lahr of Whites Electronics

[ledoc]

here my project! to wrap correctly the coils
I ll give you more details next week, i m gooing to holidays this afternoon ;-)

[Anwar2]

to SCS

whats Tarsos RX&TX exact frequency and voltage

[Anwar2]

here my project! to wrap correctly the coils
I ll give you more details next week, i m gooing to holidays this afternoon ;-)

hi ledoc its done in microstation or other program Im too master in Microstation
good design

[Anwar2]

HI ledoc this one side.....but think how u will join with tow coils its wil be up and down

[scs]

"I think it"

I think it search in ground Tarsos is not good . I want to not anyone offend .Greetings to neighbors.

[Anwar2]

thanksssssssssssss

[ledoc]

HI ledoc this one side.....but think how u will join with tow coils its wil be up and down

yes one up and the other down, but if you have an idea. post a draft I will try to draw it.

I used AutoCAD, but I realized is not possible to export in .obj or .3ds , formats asked on the website to print them. so I ll have to try other program.