chapter 1 introduction · 2020-03-18 · page 1-1 chapter white’s v3i represents the latest...

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White’s V3i represents the latest technol-ogy in metal detecting. The heart of V3i is ahigh-performance ARM-9 RISC microproces-sor which simultaneously analyzes signalsfrom 3 transmitted frequencies. Those frequen-cies — 2.5kHz, 7.5kHz, and 22.5kHz — werechosen for their diverse responses to a varietyof metal targets, resulting in a superior systemof target analysis and identification.

The face of V3i is a stunning 320x240color display with an easy-to-use menu-driveninterface. Along with three frequencies, thereare three search modes and five analysisscreens which provide more detailed targetinformation than has ever been availablebefore. With a level of simplicity for the nov-ice user, and a depth of configurability thatwill satisfy even the most advanced user, V3i isa metal detector for everyone.

This manual is organized to provide pro-gressive information, a format that attempts tominimize information overload. If you are anew detectorist, the Quick Start chapter willallow you to get a quick jump on using V3i.Then, as you run across new features and wantto find out more, continue reading the manualto get progressively detailed information.

If you are already familiar with high-enddetectors (especially those with a menu inter-face), you might want to read over the QuickStart chapter to get a feel for V3i’s features.V3i’s graphical interface makes the rest easy.

While V3i is easy to use, it does have morefeatures than any other detector before it, andcan appear overwhelming. Don't be intimi-dated! Start with the preset programs and go atyour own pace. There is no need to master allthe features to get excellent performance.

Finally, if you need help, White's Electron-ics is a phone call or mouse click away. Yourdealer is an excellent resource, and the White'sweb site has a V3i help forum for questions &answers, tips, and sharing programs. Go towww.whiteselectronics.com and click on theForum link.

Conventions

In discussing the features of V3i, we willuse Arial-Bold-Caps to distinguish keypad but-tons and menu selections. For example, “pressENTER” means to press the “Enter” key on thekeypad, and “select Enable” might mean toselect the “Enable” menu option, probably byusing the arrow keys to highlight it and thenpressing ENTER. V3i keys and menus work justlike a modern computer graphical interface, sothings are fairly intuitive.

In some cases, you need to use multiplekey combinations, or combinations with thetrigger switch. “Press MENU, ENTER” means topress and release the MENU button, then pressand release the ENTER button. But “pressMENU+ENTER” means to press and hold theMENU button, and while holding it down pressthe ENTER button. Order often matters, soMENU+ENTER is not the same asENTER+MENU. If you find that you have acci-dentally pressed the wrong key or key combo,pulling the trigger switch will usually back youout.

Two of the V3i keypad buttons have dualnames. MENU/TAB is used both as an entry but-ton into the menu system, and to “tab” fromone screen area to the next. This tab method isidentical to how a PC interface uses it. So insome cases we will tell you to press MENU, in

Introduction1

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Spectra V3i Advanced User’s Guide

other cases press TAB. It’s the same button.ZOOM/VIEW works the same way. V3i also hasfour arrow keys, and these may be either calledUP DOWN LEFT RIGHT (or UP DN LT RT) orrepresented with the symbols . Weare free to randomly choose any of these repre-sentations.

Most menus are nested, so instead of tell-ing you to select the Expert Menu, then selectthe Configure menu, then select Live Search

Screen, then select Analysis, then select Sizing,then select Screen Top, we may instead say,select Expert MenuConfigureLive Search

ScreenAnalysisSizingScreen Top. Thismeans to drill down through the stated menupath.

Finally, there is a trigger switch under thepod. It has a normal (center) position, a for-ward position, and a momentary pulled posi-tion. When we say “pull the trigger,” we meanto pull it to the momentary position and releaseit. If we say “Pull/hold the trigger,” then pull itback and hold it there. This might be in con-junction with a key press, such as, “Pull/holdthe trigger and press ENTER,” which is thesame as “Trigger+ENTER.”

Layout

The V3i interface consists of a keypad anda color screen. Below is a picture of the podface with the default layout for the searchscreen.

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The search screen has four major regions:

1. Target information

2. SpectraGraph

3. Status Bar

4. Live Control Bar

The target information includes the VDI num-ber, the depth, and icons representing the likelytarget. SpectraGraph displays signal strengthversus VDI and gives a detailed look at theVDI response. The status bar shows a fewoperational pieces of information, and the LiveControl Bar provides quick on-the-fly accessto operating modes and adjustment parame-ters. All of these will be covered in detail insubsequent chapters.

The Basics of VLF Operation

V3i is a multi-frequency (MF) induction-balance (IB) very low frequency (VLF) trans-mit-receive (TR) metal detector. It has moreuser-adjustability than any other detector in theworld, and in order to understand what allthese adjustments do, it is important to have atleast a rudimentary understanding of how amodern metal detector works.

Metal detectors work on the principle ofinduction, discovered by Michael Faraday in1831. The typical induction-balance metal

detector1 uses a transmit coil to produce amagnetic field, and this magnetic field in turn

produces a small reaction in nearby metal tar-gets. A receive coil is used to detect this smallreaction. A so-called “induction-balanced” coilarrangement prevents the receive coil frombeing overwhelmed by the transmit signal,allowing it to see very small target signals.

Phase & VDI

Practically all VLF-IB detectors operate asphase discriminators. The received signal isconverted to phase, and the phase is a strongindication of what the target might be. The par-ticular phase of a target can vary with the fre-quency of the transmitted signal, so differentdetectors designed to use different frequenciescan report completely different phase results.To keep users from having to learn all thesedifferent phase response scales, White’s haschosen to normalize them all to a standard VDIscale. Therefore, a US nickel detected with a6kHz detector will have the same VDI as witha 15kHz detector. For historical reasons, thestandard VDI scale is based on a 6.592kHzdetector. The standard VDI scale is shownbelow.

1. The first practical metal detector was an induction-balance design, built by Alexan-der Graham Bell in an effort to locate an assassin’s bullet lodged in US President James Garfield. He failed — not enough sensitivity. Ever since then, “more sensitiv-ity” has been the goal of every detector.

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The ability to separate targets by VDI iswhat allows a detector to discriminate. Targetswith a negative VDI are usually ferrous, andtargets with a positive VDI are usually non-ferrous. Small gold tends to have low VDI’swhile thick silver coins have high VDI’s.Other targets like cupro-nickel coins, brass andbronze relics, and aluminum trash can havewildly varying VDI’s depending on their alloy,size, and thickness. This means you need toapply your own discriminator — your brain —in deciding what the VDI responses are tellingyou. We’ll take a closer look at VDI responses,but first let’s look at...

Ground Response

Unfortunately, buried metal is not the onlything the detector sees. Most soil contains fer-ric oxide minerals, and this mineralization

looks like a target1. In terms of VDI, practi-cally all ground mineralization falls in theextreme negative range of the scale, evenbeyond most iron targets. But it can varysomewhat as shown by the gray range in thediagram. At most locations the variation issmall, so you can ground balance at a particu-lar spot and be very close for the entire area.Some locations have significant variations andyou should occasionally re-ground balance asyou hunt, or use automatic ground tracking.

Many locations have enough mineraliza-tion to create quite a strong ground signal,often much stronger than that of amoderately deep target. The VDI dia-gram on the preceding page uses vec-tors to represent specific targetresponses, with the angle of the vectorrepresenting the VDI value. We canalso use the length of the vector to rep-resent the strength of the target

1. In this manual, we’ll refer to the signal resulting from ground mineralization (including salts) as the “ground signal” or the “ground response.”

response, so that a strong ground and weakquarter response would look like:

The detector will see both signals at the sametime, and the combination of the two can berepresented with a third vector as follows:

The resulting signal appears to be a fairlystrong ferrous target instead of a quarter. Thisis the downfall of the old TR-discriminatordesigns. Fortunately, since the VDI responsefor ground is usually far away from theresponse of desirable targets, there are ways todeal with it. In a modern VLF motion discrim-inator, the receiver determines what part of thesignal is the ground response and, using spe-cial filter techniques, normalizes the wholeVDI scale to the current ground signal, result-ing in the ground signal being ignored. Graphi-cally, this looks like:

Any error in the ground balance point willresult in an error in the target VDI response soit’s important to maintain a decent ground bal-ance point.

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Turn On & Go

Although V3i is highly programmable, itincludes several factory preset programs whichprovide good overall performance and allow anew user to quickly start hunting.

1. Press ON/OFF: V3i displays the ownerdetails (if registered) and battery condition;scroll down for information about thedetector and general features.

2. Press MENU: The initial six-block menuscreen lets you easily change basic set-tings. Select PROGRAMS and scroll downto choose a search program:

Tip: Press ZOOM to change the font size

3. Pull Trigger: Squeeze and release the Trig-ger on the handle grip. V3i is now in nor-mal search mode.

Programs and Memory

V3i has 9 preset factory programs:

• Coin & Jewelry - Accepts most commoncoins, along with rings and jewelry.

• Salt Beach - Coin & Jewelry using salt sub-traction mode.

• Relic - Mixed mode, no Tone ID, no VCO.

• Prospecting - Optimized for nugget hunting.

• Deep Silver - Optimized for deep silver.

• Meteorite - Accepts most iron.

• High Trash - Fast recovery response for bet-ter trash separation.

• Hi-pro - Advanced Coin & Jewelry.

• Mixed Mode Pro - Advanced features includ-ing Stereo mixed-mode.

These programs are designed for good perfor-mance under most conditions and provide anexcellent starting point. However, ground con-ditions vary considerably, so some adjustmentsmay be necessary. Changes to factory pro-

Getting Started2


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grams, as well as completely new custom pro-grams, can be saved to memory and recalled atany time. Saving and restoring programs iscovered in the Expert portion of this manual.

Manual Ground Balance

V3i’s automatic ground balance system hasa fast-track mode that attempts to balance thesystem to soil conditions within 20 seconds ofturn-on. If you do not begin searching within20 seconds or the ground is unusually trashy,V3i may not fast-track correctly and you maywant to do a manual ground balance:

• Squeeze/hold the Trigger, then press/holdENTER.

• Pump the search coil over the ground (1-12inches) until the background hum becomessteady (usually 4 to 6 times). Make sure youdo this over an area free of targets.

• Release ENTER, then release the Trigger, andbegin searching.

This manual ground balance sequence canbe done at any time during normal search.Once the initial ground balance is completed,V3i will automatically track to most typicalground mineral changes.

Tip: If you release the trigger before releas-ing ENTER, V3i will lock the screen to pin-point mode. Simply pull the trigger twiceto search.

Tip: If V3i seems to have an erratic audioonly when sweeping the search coil onthe ground, check the ground balance.

Wireless Headphones

If you purchased V3i with wireless head-phones (WHP), then do the following toenable them:

• Turn on your WHP; you should hear a turn-on tone (ta-DA).

• Press MENU, select Audio

• Scroll down and select Wireless Headphone

• If the Enable box is unchecked, the pressENTER to check it. You will see multipleoptions appear:

If Monitor Battery reports a voltage, thenthe WHPs were recognized and are working.If, instead, it reports “Not responding,” thenthe WHPs were not recognized. Try cyclingtheir power. If this does not work, you willneed to do a connect sequence. Simply TAB tothe connect button and press ENTER. You willsee:

Press/hold the WHP power button until it con-nects.


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By default WHPs are set on Channel 4 andPower Level 3. If there is excessive interfer-ence, and especially if you are hunting nearanother V3/V3i user, you may need to try a dif-ferent channel. Each time you change thechannel, you will need to repeat the connectsequence. Turning down the Power Level haslittle effect on battery life so it is best to leaveit at 3.

Electromagnetic Interference (EMI)

EMI can be a problem with any wide-bandmetal detector, whether a multi-frequencyVLF or a pulse induction design. V3i includesa frequency offset to help deal with this. Sim-ply select the Transmit Frequency item on theLive Control Bar to access the Offset control:

There are 5 increments of frequency offset;with the search coil held in the air, find the onefor best stability.

Menus & Controls

V3i is the world's most configurable metaldetector. In order to make this detector bothuser-friendly to a new detectorist, and to sat-isfy the desires of advanced users and tech-heads, there are 3 ways to changes settings:

• 6-Block Menus — Common settings

• Live Control Menus — Live-search settings

• Expert Menus — Complete settings

Tip: EMI is easiest to hear in pinpoint mode(trigger pulled).

Tip: If V3i continues to have erratic audiowith the search coil held in the air, reducethe RX Gain.

By default, when the MENU button ispressed during normal search the 6-Blockmenus appear. These are designed to representthe controls normally found in a high-end ana-log metal detector. Advanced users maychoose to disable the 6-block menu and gostraight to the Expert menus. We will cover allthe menu settings in subsequent chapters.

6-Block Menus

The 6-Block menus contain the mostimportant settings all in one place. Briefly, thecontrols behind the 6-Block menus are:

• Programs — select from a list of pre-config-ured programs

• Sensitivity — receiver sensitivity settings

• Audio — volume, tones, tone ID

• Discrimination — discrimination and filtersettings

• Frequency — frequency mode and settings

• Ground Tracking — tracking mode and set-tings, plus filters

While the 6-Block menu is being accessed, thesearch operation of V3i is suspended.

Live Control Menus

You may want to quickly change settingswhile searching. By default, the Live ControlBar is displayed at the bottom of the Searchscreen and its items are accessible via the left/right arrow buttons. When a Live Control item


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is selected (using the ENTER button), a smallcontrol box pops up with one or more individ-ual controls:

Any available setting in the Live ControlBar performs the same function as any like-named setting in the 6-Block menus (or theExpert menus), but the live controls can beadjusted while the detector is in normal opera-tion. For many of the Live Control items, youcan press the VIEW button to access additionalsettings and controls. Accessing these screenssuspends the search operation of V3i.

Expert Menus

Both the 6-Block menus and the Live Con-trol menus are subsets of V3i's configurationsettings. The complete menu of all possiblesettings is found in the Expert menus. TheExpert menus can be accessed by pressingMENU,MENU from the Search screen (thisbrings up the Information screen), scrollingdown to the bottom, and selecting Expert

Menu.

The Expert menus are very extensive and itis easy for a new user to get confused as tohow all those different controls affect thedetector. We highly recommend avoiding theExpert menus until you get comfortable withthe 6-Block controls and the Live Control Bar.If you explore the Expert menus and want toquickly exit, simply pull the trigger switch afew time.

Controls

V3i uses a variety of different interfacecontrols. Most of them are very similar to

Tip: Press VIEW+DN and VIEW+UP to hideor expand the Live Control Bar.

those found in computer graphical interfacesso they will be familiar to many users.

V3i Displays

V3i has 3 display modes corresponding tothe 3 positions of the trigger switch:

• Trigger neutral — Normal Search

• Trigger forward — Analysis

• Trigger pulled — Pinpoint

Each of these display modes are normally tiedto certain operational modes and can be pro-grammed differently, and even have differentscreen displays. This section briefly describesthe default modes and their screens. A moredetailed discussion of display modes is givenin Chapter xx.

Search mode

Search mode is the normal display modefor V3i. By default, it shows a 3-frequency

SpectraGraph1:

Along the top of the screen are the VDI num-ber, icons, and depth. The majority of thescreen consists of the SpectraGraph display,which provides real-time information on thetarget’s VDI. See Chapter XX for more infor-mation on how to read this display.

1. Some factory programs run in single fre-quency mode, so they will display a single frequency SpectraGraph.


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Below the SpectraGraph is the Status Line,which contains icons for the status of wirelessheadphones, backlight, and transmit boost. Inthe middle of the Status Line the name of theactive Program is displayed, and is occasion-ally overwritten by the ground tracking status.

At the bottom of the Search screen is theLive Control Bar which gives instant access tothe most common settings while V3i is operat-ing.

Analysis mode

The Analysis display mode offers an alter-nate way to analyze the target. In most pro-grams, this mode is set up to display the Sizingscreen. Like the Search screen, the top of the

Sizing screen contains the VDI number, icons,and depth, the middle has the same StatusLine, and the Live Control Bar is at the bot-tom. Instead of the SpectraGraph display, thereis a Sizing display which, when the coil isswept over the target a single time, produces a

graph of the sweep response of each frequency.See the Chapter XX for more information onhow to read this display.

Pinpoint mode

Pinpoint mode places V3i in an all-metalmode and displays the Pinpoint screen:

Again, this screen has the depth (but no VDI oricons), Status Line, and Live Control Bar. ThePinpoint display consists of 3 horizontal mov-ing bars which give the relative signalstrengths of the three frequencies. This can beused to precisely pinpoint the target, and to seewhich frequency is giving the strongestresponse. See the Chapter XX for more infor-mation on how to read this display.

Tip: To lock V3i in Pinpoint mode pull andhold the trigger, press and hold ENTER,release the trigger and release ENTER.V3i will stay in Pinpoint mode until youdouble-pull the trigger.

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This chapter covers some of the basic set-tings of V3i including sensitivity, discrimina-tion, audio, and ground balance. It does notcover any settings which alter the fundamentaloperating mode of the detector. See Chapter 4for operating modes.

Sensitivity

Once you select a basic program you mayneed to adjust the sensitivity settings. Most ofthe V3i programs are set up with nominal sen-sitivities, but some (notably the ‘Pro’ pro-grams) are set up a little hotter.

Most users believe sensitivity should berun as high as possible. In some cases this istrue, but if you find the detector is noisy andfalses a lot you probably need to turn it down.There are three primary sensitivity settings,plus a boost mode. Selecting Sensitivity fromthe 6-block menu takes you to the followingmenu:

Selecting Sensitivity from the Live Control Bargives you this:

Rx Gain

Rx Gain (sometimes called preamp gain)sets the gain of the receiver’s input amplifier.In most cases, you want to set this as high aspossible and still maintain stable operation.

Three things can limit the maximum gainsetting. The first is external noise, such as elec-tro-magnetic interference (EMI) including 50/60Hz mains and RF. EMI typically shows upas erratic operation and noisy audio. Secondly,in highly mineralized ground excessive gaincan cause the input amplifier to overload oroperate at close to overload due to the largeground signal, limiting the available range fortarget detection. Finally, the quality of the loopnull can also push the input amplifier towardoverload. White’s V-compatible loops aredesigned to minimize null limitations, butthird-party loops typically have wide variancesin the quality of the null which can require alower Rx Gain.

EMI affects the lower end of the signalrange, which more directly impacts target sen-sitivity. Both ground signal and loop null affectthe upper end of the signal response range,which usually results in a quicker overload.Ground signal and loop null affect target sensi-tivity only so far as the Rx Gain must bereduced to prevent overload.

Tip: Always address EMI noise by firstadjusting the transmit frequency offset.See the Frequency section for more info.

Basic Settings3


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All-Metal Sensitivity

All-Metal Sensitivity (sometimes calledDC sensitivity) determines the responsivenessof the all-metal channel. Only target signalsabove the threshold cause an all-metalresponse, and a higher all-metal sensitivity set-ting will increase the all-metal audio responserate to targets. This setting affects all-metalmodes including pinpoint and mixed-mode,but does not affect normal discriminationmode. Setting this too high will make the all-metal audio chatter. See Chapter XX for amore detailed discussion of audio responses.

Discrimination Sensitivity

Discrimination Sensitivity (sometimescalled AC sensitivity) determines the respon-siveness of the discrimination channel. This isa threshold level, so only target signals abovethe threshold cause a discrimination response.Setting this too high will cause noise and fals-ing in the discrimination audio. See ChapterXX for a more detailed discussion of audioresponses.

Tx Boost

Tx Boost is transmit boost. When enabled,it triples the transmit voltage applied to theloop (from 10V to 30V) and increases thedepth. Using this feature has two major draw-backs: it can overload some loops (reduce theRx Gain), and it quickly drains the battery.

There are two common uses for Tx Boost.One is when hunting an unusually “clean” areawhere most targets have been cleaned out, andonly deep targets remain. TX Boost typicallygives about a 1” depth increase. The other iswhen EMI noise is severe. Reducing the RxGain reduces EMI but also reduces target sig-nal strength. Applying Tx Boost increases tar-get signal strength but does not increase EMInoise, so Tx Boost can be used to improve sig-nal-to-noise.

Audio

Selecting Audio from the 6-block menugives this screen:

Selecting Audio Level from the Live ControlBar gives you this:

Target Volume (or just Volume) sets the audiovolume level for target responses (the beeps).Audio Threshold (or just Threshold) sets thevolume level for the threshold tone, which isthe constant “hum” heard in the absence of atarget. In these menus, both target & thresholdvolumes are applied to the audio output youare currently using: speaker, wired head-phones, or wireless headphones. If, for exam-

A note about loops: V3i uses induction-balanced loops which rely on a “null”between the transmit coil and the receivecoil. The quality of the null may determinethe point at which the detector overloads,especially when running Tx Boost alongwith high Rx Gain settings. Null qualityvaries loop-to-loop, so some loops mayoverload at lower gain than others.


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ple, you set the volume while using thespeaker, then plug in a pair of headphones, youmay need to readjust the volume for the head-phones. The advanced Audio menu includesindividual settings for all three audio outputs.

The Tone submenu allows you to changethe individual tone frequencies. We’ll coverthis in more detail in Chapter XX. The Tone ID

selection allows you to turn on/off the multi-tone target response system. By default, ToneID is turned on in the factory programs. TheWireless Headphone selection lets you enableand disable wireless headphone use, plus setoptions. This is covered in Chapter XX.

Discrimination

Selecting Disc. from the 6-block menugives this screen:

For now we will only cover the first item. TheV.D.I. Accept menu item can be used to enableand disable target responses for individualVDI numbers. Selecting this option pops upthe next screen.

This screen lists all the VDI numbers from-95 to +95, each with a selection box. A boxthat is X-ed enables that VDI response, anempty box disables that VDI. This is the pri-mary method of setting up the discriminationpattern for V3i.

Selecting Disc. from the Live Control Bargives you this:

Again, this is a scrollable list of VDI's inwhich you can individually enable (X-ed) ordisable their response.

Other settings will be covered in subse-quent chapters.

Frequency

Selecting Frequency from the 6-blockmenu gives this screen:

The only control we will cover in this chapter


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is Frequency Offset. See Chapter 4 for discus-sion about frequency modes. The FrequencyOffset control provides slight offsets (5 steps)to the selected frequency(ies) and is useful tominimize EMI, especially when hunting nearother detectorists. In general, adjust the offsetup or down to find the quietest setting.

The Live Control Bar version of this con-trol (above) makes finding the quietest offseteasy. Select Transmit Frequency and highlightthe Offset box. Next, with the loop held in theair, pull/hold the trigger to enable pinpointmode. Watch the pinpoint bars and listen to theaudio for noise, and while continuing to holdthe trigger adjust the Offset to find the quietestsetting. Release the trigger and you’re set.

Ground Tracking

Selecting Ground Tracking from the 6-block menu gives this screen:

Selecting Ground Tracking from the Live Con-trol Bar gives you this:

AutoTrac and LockTrac select betweenautomatic and manual ground balance. Auto-Trac is the default in most programs. If youselect LockTrac, the Live Control popup willchange slightly because Soil and Speed areonly valid for AutoTrac:

Ground tracking modes and options arecovered in detail in Chapter 4.

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Chapter 3 covered some of the basic set-tings of V3i, such as sensitivity or audio vol-ume. These are adjustment controls which areused to alter the performance or user prefer-ences. There are other settings which funda-mentally alter the operation of V3i. We willrefer to these as mode settings. Different modesettings might affect completely differentaspects of the detector — such as frequency,tracking, and tone ID — so taken together theyoffer a tremendous amount of flexibility to theuser.

Frequency

The most fundamental of all modes is thatof frequency. V3i is a 3-frequency metal detec-tor, but it has the ability to run in other opti-mized frequency modes. The available modesare:

• 3-frequency normal

• 3-frequency salt compensate

• Single frequency 2.5kHz



The frequency selection screen in V3i lookslike this:

One reason for using multiple frequenciesis that some targets respond better to certainfrequencies than others. Targets that are thinand made of low-conductive metal — typicalof most jewelry — respond better to higherfrequencies, which is why many gold nuggetdetectors are designed to run at much higherfrequencies than most other detectors. Highconductive targets, especially those that arethick, respond better at lower frequencies.Also, ground mineralization has a weakerresponse at lower frequencies, resulting in bet-ter ground penetration in highly mineralizedareas.

The three frequencies — 2.5kHz, 7.5kHz,and 22.5kHz — were chosen because theyoffer excellent target coverage. Note also thatthey are harmonically related, by factors ofthree. This makes waveform processing mucheasier. Though not particularly important tothe discussion, here is what the transmit wave-form looks like:

The received composite waveform and itsthree frequency components look like this:

Operating Modes4


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Three Frequency

The default frequency mode for V3i isstandard Three Frequency. In this mode, V3isimultaneously transmits 2.5kHz, 7.5kHz, and22.5kHz. 3-frequency mode gives the bestoverall response to the broadest range of targetconductivities.

In any frequency mode V3i will plot theVDI responses in the SpectraGraph screen andalso calculate an overall VDI number for thetarget. Under the Three Frequency selectionyou will see an additional selection for theVDI calculation method:

Best Data means that the VDI is taken fromthe strongest responding frequency. Correlate

means that the results from at least tworesponding frequencies must agree in order todisplay the VDI number. Factory programsdefault to Best Data as this typically offersgood VDI accuracy.

Salt Compensate

Salt Compensate mode is the same asThree Frequency mode, except that saltresponses are subtracted out. This eliminatessalt signals while still allowing V3i to trackferrous mineralization. This technique is onlypossible in multi-frequency detectors, which isa second reason to use multiple frequencies.

Trivia: White’s DFX is always in salt com-pensate mode.

The VDI for salt is around +4 to +5 whichis normally the area for bits of foil. However,very small gold nuggets and some jewelry canalso fall in this range, which is why V3i has theadded option to run a normal 3-frequency withsalt subtraction disabled. Some users havereported situations where the salt-compensatemode helps reduce EMI noise.

Like normal 3-frequency, salt-compensateincludes the option of calculating target VDIfrom either best data or correlate.

Single Frequency

With any multiple frequency detector, thetotal transmit power must be divided amongthe active frequencies. V3i offers the ability totransmit only one of its three frequencies. Insingle frequency mode, the transmit waveformis optimized to focus power to the selected fre-quency, resulting in slightly better depth butfor a more narrow range of targets.

When a single frequency mode is selectedyou will also see an option called Normalized:

The VDI responses for targets vary withfrequency, which means that a particular targetwill have completely different VDI numbers ateach of the three frequencies. For example, aUS silver quarter has the following raw VDIresponses:

Trivia: The single frequency modes inWhite’s DFX do not use optimized trans-mit waveforms.


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By checking Normalized, all VDI’s will be nor-malized (shifted) to a common frequency. Thatcommon frequency is, for historical reasons,6.592kHz, meaning the US silver quarter willhave a normalized VDI response of 83.

With Normalized unchecked, V3i willreport the raw VDI numbers for the frequencymode selected. There is at least one situationwhere this is an advantage. At 22.5kHz thelower part of the non-ferrous VDI range isexpanded, resulting in more numerical separa-tion of low-conductive targets. This can help inseparating nickels and jewelry from pull tabs.Here is a table showing the difference in nor-malized versus un-normalized VDI’s for anumber of targets:

This shows there is a significant expansionof the VDI range up to nickels, while the upper

Frequency VDI

2.5kHz 70

7.5kHz 85

22.5kHz 91

TargetNormalized

VDI

Un-normalized

VDI

Ladies ring 2 9

Foil 1 4 14

1 gm nugget 6 17

Foil 2 6 23

Nickel 19 57

Square tab 1 21 59

Pull tab 1 22 60

Pull tab 2 25 63

$2.50 gold 30 66

Pull tab 3 33 68

Men’s band 35 69

Square tab 2 42 73

Minie 47 76

Screw cap 65 83

VDI is actually compressed. The oppositeoccurs at 2.5kHz: the upper VDI range isexpanded at the expense of the lower.

Frequency Offset

This is not a mode, but rather an adjust-ment control. It was discussed in Chapter 3:The Frequency Offset control provides slightoffsets (5 steps) to the selected frequency(ies)and is useful to minimize EMI, especially whenhunting near other detectorists. In general,adjust the offset up or down to find the quietestsetting. One source of EMI that is difficult todeal with are electric fences, including invisi-ble dog fences. It is best to try to have themswitched off when hunting.

The frequency offset applies to all activefrequencies. If you have a single frequencymode selected, then the offset shifts that fre-quency. If you are in a 3-frequency mode, theoffset proportionally shifts all the frequencies.

When making offset adjustments, put V3iin pinpoint mode (by pulling the trigger) andwatch the pinpoint bars, like this:

Along with the audio, the pinpoint bars willhelp you find the quietest offset. In some situa-tions, you may not be able to find a quiet offsetfor all three frequencies at the same time. Payattention to the pinpoint bars and see if one ofthe frequencies tends to run quieter than theothers. If so, run in single frequency modewith the proper offset. A stable single fre-quency mode is usually better than an unstable3-frequency mode.


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Ground Balance

In Chapter 1 we briefly covered howground balance works, and how automatictracking can compensate for varying groundconditions. V3i offers both automatic tracking(AutoTrac™) mode and the ability to lock theground balance when needed (LockTrac).

Whether you are using AutoTrac or Lock-Trac, it’s important to know how to check ifV3i is properly ground balanced. As you arehunting, test the ground balance occasionallyusing these steps: lift the loop a foot off theground, pull the trigger to put V3i in pinpointmode, then lower the loop to the ground, mak-ing sure you are not over a target. In mostground, the pinpoint threshold level shouldremain constant (unless you have implementeda track offset) as the loop is lowered to theground. In severe mineralization, a lift-offeffect can cause an abrupt threshold change inthe last inch or so, and this is difficult to bal-ance out.

AutoTrac™

AutoTrac mode automatically tracks thephase of the ground signal. This is the defaultground balance mode for most programs and isthe recommended mode except in certain con-ditions. There are several parameters whichcontrol automatic tracking:

The Report selection determines whetherthe tracking status is displayed to the screen.

When enabled, you will see

<<< Tracking <<<>>> Tracking >>>

occasionally pop up on the status bar wheneverV3i is changing its ground balance point. Atstart-up, it may say Fast Track instead. If youdon’t care to see this information, simply un-check the option.

Ground tracking is adjusted whenever V3isees a change in the overall RX signal phase.Targets can cause a phase change as well, butfar more radically. The Inhibit option tells V3ito inhibit tracking when it goes over a fastground anomaly.

The tracking Speed selection adjusts therate at which ground tracking is allowed tochange. A faster speed (higher number) is use-ful for ground that varies a lot over short dis-tances, but can also be more subject to errors,especially in high-trash areas. Generally, usethe lowest setting your ground allows.

How do you determine a proper trackspeed? Occasionally check the ground balanceusing the test several paragraphs back. If youfind that the balance is often off, then increasethe track speed. However, if V3i seems to benoisy as the loop is swept over the ground andyou’re sure it’s not due to targets, then thetrack speed may be too high.

Some users prefer to use a slight amount ofoffset in their ground balance. If the Offset

control is set to the positive side, then a prop-erly ground-balanced detector will still give apositive response to mineralization. If the Off-

set control is set to the negative side, then aproperly ground-balanced detector will have a“null” audio response to mineralization. Thelatter is usually undesirable because it canmask faint target responses. Conversely, giv-ing the ground balance a little bit of positiveoffset can prevent masking. The default settingis 0.


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LockTrac

There are some uncommon situationswhere AutoTrac does not work well. Inextreme ground that has a lot of variability, orwhen a lot of trash targets are present, auto-matic tracking may result in excessive noiseand tracking errors. High levels of electromag-netic interference can also cause problemswith automatic tracking. In these situationslocking the ground balance at one value mayprovide better performance. Keep in mind thatwhen tracking is locked, V3i will only be prop-erly ground balanced for one type of ground.As the ground varies, there will be errors in thebalance point, so there may be some compro-mise in depth. But LockTrac may allow hunt-ing an area where AutoTrac does not.

The selection screen looks like this:

The only parametric setting is for Offset,which is identical to the Offset control in Auto-Trac. In LockTrac, using a slightly positiveoffset can help compensate for variations inmineralizations and keep the balance pointfrom going negative.

Soil Type

V3i includes a 3-frequency mode calledSalt Compensate, which literally subtracts thesignal response from salt. This techniquewon’t work in single frequency mode, so a dif-ferent method is included to allow the use ofsingle frequencies in wet salt sand. V3iincludes a Soil Type selection for choosing aNormal or Salt tracking range:

As explained in Chapter 1, ground trackingis normally restricted to a region of VDI’swhere mineralization is found. However, wecan open up this range to include salt, so thatV3i will ground balance in any combination ofsalt and mineralization. This technique doesnot work as well as true salt subtraction, butdoes allow the practical use of single frequen-cies in salt environments.

In some areas such as mineralized beaches,there can be extreme variations in the compos-ite ground VDI in very short distance, such asswinging over black sand streaks, or across thetransition to wet salt sand. It may be necessaryto increase the tracking speed to deal with this.

One of the advantages of using the salt soilsetting is in extremely noisy environments.There are cases where, in 3-frequency mode, aquiet frequency offset cannot be found, but a

quiet single frequency setting can be found1.Another case is when using a single frequencymode in highly alkaline soil such as fields thathave been fertilized for years, or some pros-pecting areas. In general, if you are havingproblems with either EMI or ground noise, tryusing the Salt setting, possibly with a singlefrequency mode.

1. There have been a few reports from users that simply switching to ‘salt soil’ in 3-fre-quency improved noise rejection. This is likely due to the fact that salt mode notches out a small portion of VDI responses.


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Audio

V3i has the most extensive audio systemever offered in a detector, including four audiomodes and complete user-customization.Because of the extent of the audio system andthe number of options, it will be presented inits own chapter.

Discrimination

A primary mode of practically all detectorssince the 1970’s has been discrimination. V3iis no different. Discrimination, of course,allows us to accept or ignore certain targetsbased on their phase (or VDI) response. Inanalog detectors, this is accomplished with aknob that sets the threshold point of discrimi-nation; everything below the threshold isrejected, and everything above is accepted.

Modern digital detectors take discrimina-tion to a higher level, allowing the user toaccept and reject narrow VDI regions. WhileV3i has a discrimination resolution down to thesingle VDI number, there are several ways toset up the discrimination. The basic Discrimi-nation menu is:

Visual Reject

Visual Reject is a preference setting for dis-playing rejected VDI numbers. If it is un-checked, then the VDI numbers for targetswhich are discriminated out will still be dis-

played. If you don’t want to see the VDI num-bers of rejected targets, then check this option.This option does not alter the audio responseor the SpectraGraph response for rejected tar-gets; they are controlled separately.

Bottle Cap Reject

The next control is Bottle Cap Reject

(BCR). Bottle caps are difficult targetsbecause, as the search coil is swept over them,they look both ferrous and non-ferrous. Thiscan fool the discriminator into deciding onnon-ferrous and reporting a good target, andcan be further exacerbated by DD coils. BCRcontrols how aggressively V3i attempts tobreak up the audio on bottle caps, makingthem produce a distinct “chatter.” A higherBCR setting breaks up the audio more. BCRcan be fooled by an iron target buried adjacentto a good target, and a higher setting can alsomake faint targets falter as well. Set this as lowas you can stand.

Hot Rock Reject

Hot rocks are mineralized rocks that usu-ally fall in the normal mineralization trackingrange, but being rocks they have a very quickrise-and-fall signal response. Technically, hotrocks have a VDI higher than the currentground balance point, while rocks with a lowerVDI are often called “cold rocks.” We won’tbother to distinguish. With Hot Rock Reject

(HRR) turned on, when V3i identifies a targetas a hot rock it automatically assigns it a VDIof +95. With HRR turned Off no VDI reassign-ment is done.

Normally, +95 is rejected so that a hot rockhas no audio response. However, if +95 isaccepted then the HRR number controls howthe audio is altered. More positive numbersincrease the audio response, negative numbersdecrease it. Setting HRR=0 means the audio isnot altered.


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VDI Select By

The next item in the menu, VDI Select By,is where the discrimination is set. There arefour ways to set up the discrimination:

Level

This control works just like the traditional dis-crimination knob on an analog detector. Every-thing below (and including) the setting isrejected, everything above the selection isaccepted.

Icon

Discrimination can also be set to accept orreject predefined icon ranges. Icons can beuser-defined to certain VDI ranges, such as aUS nickel to +18 to +23 (see Chapter XX).Then, using VDI Selected By Icon, that iconrange can be wholly accepted or rejected.When this method is selected, an Edit boxbecomes available, and each icon range islisted with a check box. A checked range isaccepted, an un-checked range is rejected. TheEdit box looks like this:

VDI

The most detailed method of setting the dis-crimination mask is by individual VDI num-bers. When this option is selected, thefollowing Edit box is available:

Each VDI number is listed with a check box; achecked VDI is accepted, an un-checked VDIis rejected.

Graph

The final method of setting up a discriminationmask is by using the Graph. When selected, thefollowing Edit box becomes available:

Tip: There are 191 VDI numbers, and set-ting each one individually can take a longtime. There is a short-cut: when you pressthe ENTER button to check or un-check aVDI, continue holding down the ENTER

button, then press the or button torapidly set a range of VDI’s to the samesetting.


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The displayed number shows the VDI numberyou are editing. Also shown are the icons thatare set for that VDI. Use the and buttonsto move left and right through the VDI range,and the and buttons to accept and reject(respectively) the selected VDI.

The final entry in the Discrimination menuis the Icon table. It is as follows:

Tip: As with the prior VDI edit method, thereis a short-cut: when you pressthe or button to check or un-checka VDI, continue holding the button, thenpress the or button to rapidly set arange of VDI’s to the same setting. There are three pre-defined icon tables for

Park, Relic, and Prospecting. These are shownin tables below. There is also a Custom selec-tion for setting up your own icons. This is cov-ered in detail in Chapter XX.

Preset Icon Tables

Park Relic Prospecting

-97 to -57 -97 to -57 -97 to -57

-56 to -27 -56 to -27 -56 to -27

-26 to -1 -26 to -1 -26 to -21

+0 to +12 0 to +17 -20 to -1

+13 to +16 +18 to +23 0 to +16

+17 to +24 +24 to +37 +17 to +24

+25 to +50 +38 to +40 +25 to +50

+51 to +54 +41 to +44 +51 to +57

+55 to +57 +45 to +55 +58 to +75

+58 to +68 +56 to +60 +76 to +80

+69 to +75 +61 to +70 +81 to +86

+76 to +80 +71 to +75 +87 to +90

+81 to +86 +76 to +78 +91 to +94

+87 to +90 +79 to +82 +95 NONE

+91 to +94 +83 to +86

+95 NONE +87 to +90

+91 to +93

1

CH

AP

TE

R

In Chapter 4 we discussed several operat-ing modes of V3i. The audio modes are exten-sive enough for their own chapter. The V3iAudio menu is as follows:

This is a little different than the audio menupresented in Chapter 2, which was accessedfrom the 6-block menu and was limited to sev-eral audio settings but did not include audiomodes. This more extensive Audio menu isaccessed by selecting the Audio level/tone item(or the Search Audio item in some programs)on the Live Control Bar and pressing VIEW.

All of the audio modes are accessedthrough the Search Audio selection of this

menu. The remaining selections are for settingvarious user preferences. We will cover themodes first, then proceed through the varioussettings, not necessarily in the order of themenus.

V3i Audio Response: A Graphical Look

V3i has a lot of audio adjustments, andsome of them tie in with other non-audio set-tings. To help tie together the various settingsand better explain them, we’ll take a graphicallook at what’s going on.

Let’s start with a block diagram of V3i,shown below. The Rx Gain setting (in the Sen-

sitivity menu) is applied to the raw input signalfrom the coil. The signal is then split into twoprocessing channels, one for all-metal and onefor discrimination, and these channels havetheir own audio responses. You can listen tothe all-metal signal, or the discrimination sig-nal, or both of them combined (mixed-mode);the audio can be sent to a standard speaker, apair of plug-in headphones, or wireless head-phones.

Audio Basics5


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Note that the various settings apply only toone or the other processing channels (audiomodes). It’s important to remember which set-tings affect which mode, and that’s not diffi-cult once you understand what the settings do.

V3i Audio Modes

V3i has the following four search audiomodes:

• Discrimination

• All-Metal

• Mixed-Mode

• Stereo Mixed-Mode

Discrimination mode produces audio onlyfrom the discrimination channel, and All-Metal mode produces audio only from the all-metal channel. The two mixed modes combineaudio from both channels, but in slightly dif-ferent ways:

• Normal mixed-mode puts both the all-metalaudio and discrimination audio on the leftand right channels. However, due to a hard-ware limitation, both audios cannot sound atthe exact same time, so as the discriminationaudio comes in, the all-metal audio cuts out.

• Stereo mixed-mode puts the all-metal audioon the left audio channel and the discrimina-tion audio on the right audio channel. Thisallows both audios to sound continuously.

All-Metal Audio

The all-metal channel simply detects and

indicates metal targets. It does not care whatthose targets are, nor does it attempt to tell youwhat they are. The all-metal audio channel isalso used during pinpointing.

In this channel, the All-Metal Sensitivity set-ting is basically an additional gain settingapplied to the all-metal signal above andbeyond the Rx Gain setting. The followinggraph shows a signal with both a low setting(black trace) and a high setting (gray trace).

The higher sensitivity setting improves targetsignals, but it also increases the amount ofaudio noise and can make V3i more “chattery.”This is especially true when EMI is present.

All-metal audio can be presented in one oftwo ways: VCO, and non-VCO. This selectionis found at AudioSearch AudioAll Metal

VCO:

Tip: In the all-metal mode, SAT (self-adjust-ing threshold) is applied so if you hold thesearch coil steady over a target, the audioresponse will fade away on its own. In pin-point mode, SAT is not applied so you canhold the search coil steady over a targetand the response will remain steady.


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If VCO audio is disabled then the all-metalaudio response will be a fixed tone, and anincreasing signal level creates an increase in itsloudness:

In other words, as the search coil is passedover a target, the all-metal audio will begin at alow volume and progressively rise in loudnessas the target signal gets stronger, peaking whenthe search coil is directly over the target.

If VCO audio is enabled then an increasingsignal level creates a rising audio tone or pitch:

In other words, as the search coil is passedover a target, the all-metal audio will begin at alow tone and progressively rise in pitch as thetarget signal gets stronger. The highest pitch isachieved when the search coil is directly overthe target (strongest target signal) and then theaudio falls in pitch as the coil moves off thetarget. As with non-VCO audio, loudness alsorises and falls.

Both VCO and non-VCO audio methodshave user settings for the tones used. In VCO

Tip: The human ear is more sensitive tochanges in pitch than to changes in loud-ness. Therefore, deep targets that pro-duce only a very slight all-metal signal willbe easier to discern using VCO audio.However, some people just don’t like VCOaudio or have hearing problems, so theoption to turn it off is also provided.

mode, the threshold tone is the lowest tone atwhich the VCO response begins; that is, thetone heard when there is no target present. Atarget signal will then increase the audio abovethe threshold tone. Its setting is found atAudioToneVCO Threshold:

In most programs the VCO threshold is set to amid-level tone of 128.

Non-VCO audio has a fixed threshold tonefound at AudioToneFixed Threshold:

This is the same threshold tone that is used forthe discrimination channel.

Tip: A low VCO threshold (such as 50 in theMixed-Mode Pro program) will make theVCO start out at a low growl and some-what increase its f sensitivity to deep tar-gets.

Tip: The VCO Threshold tone does notaffect non-VCO audio, and the FixedThreshold tone does not affect VCOaudio.


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Finally, the target volume controls moveall response levels (both all-metal and discrim-ination) up and down in loudness:

Discrimination Audio

Unlike the all-metal channel, the discrimi-nation channel does not treat all targets alike.Discrimination uses the phase response of thetarget to determine how to respond. It is possi-ble to assign different tones to different phaseresponses, or to completely ignore targets withcertain phase responses.

Threshold

In this channel, the Discrimination Sensitiv-

ity setting determines a threshold level abovewhich you will hear target responses. In manydetectors, this setting is simply called Thresh-old, but V3i has separate adjustments for eachchannel. The following graph shows the rela-tionship between the threshold level and thedetection signal. Only detection signals that

exceed the threshold level (shaded in gray)will become audible target signals. Otherwise,you will only hear the threshold tone.

Increasing the Discrimination Sensitivity

setting lowers the threshold, making V3i moresensitive to weak target signals. Like All-Metal

Sensitivity, this can also increase the amount of

audio noise, and can make V3i more chattery,especially when EMI is present.

The discrimination threshold level canhave a tone associated with it, so that you cancontinuously hear the threshold level and listenfor perturbations that indicate a target. You canthen select the tone for the threshold by access-ing AudioToneFixed Threshold:

This setting also controls the non-VCO all-metal tone.

The loudness of the discrimination thresh-old tone is set in the AudioAudio Threshold

menu. The volume can be independently setfor speaker, standard headphones, and wirelessheadphones:

The balance control adjusts the left-right bal-ance in stereo headphones, which allows youto compensate for hearing imbalance. The onecontrol affects both types of headphones.

Setting the threshold volume all the way tozero will result in silent-search (no thresholdtone). The Discrimination audio selection also


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has an option for enabling and disabling thethreshold tone:

This selection also affects the all-metal thresh-old tone (including pinpoint mode).

Target Volume

AudioTarget Volume adjusts the volumefor the target response (that is, the target beep)in discrimination mode. V3i has separateadjustments for speaker, standard headphones,and wireless headphones:

The Target Volume setting cannot be lessthan or equal to the Audio Threshold setting ortargets will not be heard. V3i attempts to main-tain a minimum 8dB loudness separationbetween them. That is, if you try to increasethe Audio Threshold setting too close to a cor-responding Target Volume setting, the Target

Tip: Silent search can also be achieved bysetting the AudioToneFixed Thresholdtone to 0, but this will also kill the non-VCO pinpoint tone, which shares this set-ting.

Volume will automatically increase in order tomaintain an 8dB loudness difference.

As with Audio Threshold, the balance con-trol adjusts the left-right balance in stereoheadphones, which allows you to compensatefor hearing imbalance. The one control affectsboth types of headphones. It also can be usedas a poor-man’s stereo mixed-mode by puttingthe Target Volume in one ear and the AudioThreshold in the other. However, true StereoMixed-Mode audio does a better job of this.

Modulation

AudioSearch AudioModulation allowsyou to enable target audio modulation and toadjust its effect. Modulation is a techniquewhere progressively deeper targets have a pro-gressively weaker audio response (the beep).A shallow target produces a loud response, anda deep target produces a soft response. If mod-ulation is disabled, then V3i attempts to pro-duce the same response loudness regardless oftarget depth.

With modulation enabled, you can alsoadjust the Range setting, which affects thestrength of the modulation. A low settingmakes shallow and deep responses more simi-lar in loudness, and a high setting makes themodulation more pronounced.

Tone

The AudioTone selections allow you toset up several common tones. We’ve alreadycovered two of the tone controls: Fixed Thresh-

old and VCO Threshold. V3i tone settings gofrom 1 to 255, which roughly corresponds to afrequency range of 5-1000 Hz. A setting of 0

Tip: Modulation is most effective when youwant to distinguish between deep andshallow targets of similar type. For exam-ple, if shallow coins are likely to be cladand deep coins are likely to be silver, thenmodulation will give you that informationin the audio response.


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results in no tone.

• Fixed Threshold This setting is the tone that will be used for

the background threshold in the discriminationaudio, as well as the all-metal threshold whenVCO mode is disabled. A value of 195matches the frequency used in older White’sdetectors.

• VCO Threshold This is the tone that will be the starting

point for the all-metal response when VCOmode is enabled.

• Target Tone

This is the frequency that will be used forthe discrimination target response when Tone

ID is disabled (single-tone response). See Tone

ID below.• Overload Tone

When an unusually strong target responseoverwhelms the receiver circuitry, V3i willemit an overload tone, determined by this set-ting.• VDI Tones

If Tone ID is enabled then this selectionspecifies how tones are determined for the dis-crimination target response. See Tone ID

below.

Tip: The Mixed-Mode Pro program uses anunusually low threshold tone coupled withan equally low VCO threshold to give it aBFO-like growl response.

Tone ID

Any modern discriminating detector has atleast a rudimentary audio method of distin-guishing accepted targets from rejected ones.This may be as simple as an audio response foraccepted targets and no audio response forrejected targets. More advanced detectors havea tonal identification system where differenttones represent different target ranges (phaseresponses).

V3i has the ability to produce a differenttone for each VDI number, and it is fully user-customizable. But it can also produce a simplebeep/no beep audio for those who want to keepit simple. If the AudioSearch AudioTone ID

selection is unchecked, then all accepted tar-gets will respond with the same tone as set inthe AudioToneTarget tone control. If it ischecked, then the target response will corre-spond to the tone ID method selected by theAudioToneVDI Tones setting:

V3i offers three tone ID methods: Stan-

dard, Shifted, and Custom.

Setting up a custom tone ID audio isclosely related to setting up a custom discrimi-nation mask. All of these will be coveredtogether in Chapter XX.

Mixed-Mode Audio

V3i has two mixed-mode options: standardmixed-mode and stereo mixed-mode. Withoutmixed-mode, you can hear either the all-metal


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audio or the discrimination audio. The all-metal channel doesn’t tell you anything aboutthe quality of a target; the discrimination chan-nel only signals on accepted targets, and rejecttargets do not cause an audio response (orcause a null in the audio).

Mixed-mode lets you hear both audiochannels. The advantage is that you can hearthe responses of all targets, even those that arerejected by the discrimination system. This canhelp in target separation, especially in trashyareas, and can also help in pinpointing targets.On the other hand, the increased targetresponses can be overwhelming and createaudio fatigue.

Standard Mixed Mode

Standard mixed mode equally applies boththe all-metal audio and the discriminationaudio to the speaker or headphones. In theabsence of targets, or for targets rejected by thediscrimination channel, the mixed-mode audiooutput will be the all-metal response, and youwill hear the all-metal threshold plus the all-metal response of rejected targets. When anaccepted target is detected, the discriminationaudio will take over and you will hear the dis-crimination tone for the target. Due to a hard-ware limitation, both audios cannot sound atthe exact same time, so as the discriminationaudio comes in, the all-metal audio cuts out.This is illustrated below.

Mixed-mode has several settings that arethe same as we have seen in the all-metal and


All-metal Audio

TargetBeep

discrimination modes:

See the previous sections for descriptions ofTone ID, Modulation, and VCO.

Stereo Mixed-Mode

As the name implies, stereo mixed-mode isonly for stereo audio (headphones). It appliesthe all-metal response to one ear and the dis-crimination audio to the other ear. This methodgets around the hardware limitation mentionedbefore so that both audios are continuous:

Because the all-metal response is presentthroughout the discrimination response, targetseparation and pinpointing is further improvedbeyond the standard mixed-mode audio.

Stereo mixed-mode has several settingsthat are largely the same as we have seen in the

Tip: In Stereo Mixed-Mode, the Balancecontrols found in Target Volume and AudioThreshold have no effect.


All-metal Audio

TargetBeep


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all-metal and discrimination modes, with theaddition of two new options:

See the previous sections for descriptions ofTone ID, Modulation, and VCO. Balance letsyou choose which audio goes to which ear.Audio Boost compensates for the loss in appar-ent loudness when a given audio signal isapplied to only one ear instead of both ears.

Pinpoint Mode

Although technically not one of the fourmajor search audio modes, pinpoint audiocould be used for searching if you pull andhold the pinpoint trigger switch. Pinpointaudio is identical to all-metal audio with oneexception: all-metal has SAT applied to it, andpinpoint does not. That means the all-metalchannel requires loop motion or the target willget “tuned out,” but pinpoint does not requireloop motion.

Pinpoint audio has the following options:

VCO is the same as with the all-metal searchmode, and shares the same VCO Threshold andFixed Threshold settings depending on whetherVCO is enabled or disabled.

Rachet is an method whereby the pinpointaudio is automatically narrowed on successivesweeps of the target. Many detectorists do thismanually during pinpoint, by resetting the pin-point trigger switch to desensitize the targetresponse, which has the same effect as creatinga narrower audio response as the coil is sweptacross the target. This significantly helps zeroin on the target, especially shallow ones. Anillustration of rachet pinpointing is as follows:

Speaker and Headphones

V3i provides three ways to listen to audio:

• Speaker

• Plug-in headphones

• Wireless headphones

There are obvious limitations in using thespeaker. None of the left-right balance controlsdo anything, and Stereo Mixed-Mode will notwork properly. The same is true when usingplug-in mono headphones.

Tip: When rachet pinpointing (either manu-ally or automatically), the target can “dis-appear” if you over-rachet, then slightlyraise the loop.

Tip: For plug-in headphones, stereo modelsare recommended. Many headphones aremono/stereo switchable, so if somethingseems amiss with the audio check thatthe headphones are in stereo mode.

Sweep Left Sweep Right Sweep Left


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When you plug in a set of headphones, thespeaker is disabled. When wireless head-phones are enabled and connected, both thespeaker and plug-in headphones are disabled.Basic wireless headphone connection was cov-ered in Chapter 2. We’ll cover it again here,with more detail.

Wireless Headphones

V3i is available with optional wirelessheadphones (WHPs), which are designed touse a world-wide available 2.4GHz ISM band.To enable and connect WHPs, access the WHPmenu at AudioWireless Headphones:

Once you enable WHPs, the menu willexpand to include a number of options:

Below the menu of options are two buttons forConnect and Exit. Connect synchronizes theWHPs with V3i; press the TAB keypad buttonto highlight the Connect button, then press

ENTER. A pop-up balloon will prompt you topress and hold down the WHP power button:

When you follow this procedure, the WHPswill produce a pair of “ta-DA” jingles; the firstsignifies “power on,” the second signifiesproper connection. Upon connection, V3i willpop up another balloon signifying that:

Why is there a “connect” ritual? It’sbecause the WHPs may need to search for andfind the right channel to operate on. With theChannel control, V3i lets you select one of 76channels (4-79), allowing multiple V-users tooperate in close proximity. By default, channel4 is selected, both in V3i and in the WHPs. Soright out of the box, you can probably turn theWHPs on and they will work fine. But if youchange the channel in V3i, then the WHPsneed to know that, hence the connectsequence. If you never change channels, youshould never need to “connect,” just turn themon and go.


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Multiple channels are provided for dealingwith noise and interference from other V3iusers. If the WHP audio seems excessivelynoisy (cutting in and out) or you seem to bepicking up audio from another V3i, try a differ-ent channel. Pay attention to the reception barwhen selecting a channel; choose a channelthat has a maximum green and minimal redresponse.

The next control is Power level which setsthe RF transmit power. A high setting mayinterfere with another V3/V3i user on the samechannel, and a low setting may cause the sig-nal to drop out, especially in high EMI. Werecommend leaving it high, and using differentchannels to avoid interference.

V3i gives you the option to synchronize tosingle or multiple WHPs. Multiple is useful fortraining purposes. Select the Multiple head-

phones option, then TAB to the Connect button

Tip: There are 3 ways to tell if you need torun the connect sequence once the WHPsare turned on:One, look at the search screen; the WHPicon will have a red slash through it if theWHPs are not properly connected.Two, look at the title bar of the WHPmenu; if it says “Working,” then the WHPsare connected. If it says “Off?” then theyare not connected.Three, look at the battery voltage report inthe WHP menu; if it says “not responding”then WHPs are not connected.

Tip: If you run the connect sequence at thesame time as another nearby V3/V3i user,you may inadvertently connect yourWHPs to the wrong detector.

and press ENTER. You will get the usual pop-up balloon prompt to press and hold down theWHP power button. But once the first WHPsare connected, V3i will prompt you again:

Continue connecting WHPs until you aredone, then press ENTER to engage what is nowthe STOP button.

If you are only connecting to a singleWHP, then select Single and V3i will also readback the battery voltage, as well as the versionof software in the WHPs. Single also has aSpeaker option which, when selected, auto-matically switches audio over to the speaker ifthe WHP battery dies, or the WHPs are turnedoff.


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Summary

A lot of material has been covered, and a sum-mary will help reinforce what we’ve covered:

Select the Search Audio mode you want:

Discrimination

• Select Threshold if you want an audiblethreshold, or not for silent-search

• Use Fixed Threshold to set the all-metaltone

• Select Tone ID if you want multiple toneresponses, or not for single-tone responses

• Select the VDI Tones method to use —see Chapter XX for details

• Select Modulation if you want the targetresponse loudness to vary with signalstrength, or not for all loud responses

• Use Range to set the variation in loud-ness

All-Metal

• Select VCO mode or not

• For VCO mode use VCO Threshold to setthe base VCO tone

• For non-VCO mode use Fixed Threshold

to set the all-metal tone

Mixed Mode

• Select Tone ID, Modulation, and VCO modeor not

• See above for options

Stereo Mixed Mode

• Select Threshold, Tone ID, Modulation, andVCO mode or not

• See above for options

• Select the Balance method to determinewhich side is all-metal and which side isdisc audio

• Adjust the audio boost to a comfortablelevel (8 is recommended)

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V3i is the only metal detector with fullycustomizable audio and discrimination. Thischapter will cover the methods for setting upcustom audio tones and discrimination masks.

Because both the audio responses and thediscrimination settings are based on VDIs, it

will be useful to review V3i’s VDI1 scale. Interms of raw signals, VLF detectors attempt toidentify targets based on their phase response.But different frequencies result in differentphase responses for a given target, so the VDIscale was created to present a normalizedresponse, such that detectors of different fre-quencies would have consistent outputs. Thatway, users don’t have to remember a lot of dif-ferent response scales.

The White’s VDI scale (see Chapter 1 forprior discussion) is based on a 6.192kHz scale:

Negative numbers generally represent ferrous(iron) targets, positive represents non-ferrous.This can be redrawn in a linear fashion:

1. “VDI” stands for Visual Discrimination Indicator,” and was originally created for metered responses. When varied tonal responses were added to later models, the tones also followed the VDI scale.

Ferrous Non-Ferrous

-95 +95

0

Normal soil

Sal

t

US Quarter

US

Nic

kel

Nail

-95 +950Ferrous Non-Ferrous

Soil Nail Salt US 25cUS 5c

Low positive numbers correlate to thinner andless conductive targets. Gold nuggets, smalljewelry, and foil will often fall in the range of0 to 20. Medium-sized cupro-nickel coins canfall in the 20-50 range. Silver and large coinsgenerally show up above 70.

Many modern detectors visually report thetarget VDI. This might be done as a VDI num-ber, or as a group of segments which representgroups of VDI ranges. Additionally, manydetectors assign varying audio tones to differ-ent VDI ranges; for example, a 4-toneresponse might divide the non-ferrous rangeinto four sub-ranges and assign increasingtones to them. The pitch of the tones and theranges they are assigned to are normally fixed;V3i lets you change both.

Custom Audio

From the Live Control Bar, highlight theAudio level/Tone selection and press VIEW.Select ToneVDI Tones:

Trivia: Exactly why ±95 was chosen forthe VDI scale is uncertain. In somecases other manufacturers haveadopted this scale, while others cameup with their own.

Custom Audio &Discrimination6


Page 6-2

VDI Tones offers 3 selections. Standard

assigns increasing tones to every VDI number,starting with tone = 65 at VDI = -95 and end-ing with tone = 255 at VDI = +95. The tone-vs-VDI response would look like this:

Shifted assigns one tone to all negativeVDI numbers and increasing tones to everypositive VDI number. This mode adds twoselections:

Negative tone lets you select the tone that isused for all negative VDIs. Reference tone letsyou select the tone that corresponds to VDI =0; the tones will then increment with each sub-sequent positive VDI. For the numbers above,the tone-vs-VDI response would look like this:

+95-95 0VDI

Tone

65

160

255

+95-95 0VDI

Tone

120

214

255

+41

Notice that tones increase from 214 (VDI =0) up to 255 (VDI = 41) and then remain at 255for all higher VDIs. That’s because 255 is thehighest tone setting.

Finally, we get to the fully custom tonemode. Custom offers a single additional selec-tion, Edit:

Selecting Edit pops up a small window whichcontains a list of VDIs, and each VDI has aslider for selecting a tone number from 0 to255 (roughly 5 Hz to 1000 Hz):

At this point you can go through each ofthe 191 possible VDIs and set the tone for eachone. However, most people will want to use a

Tip: When any tone selection slider isactive, you can hear the tone by flip-ping the trigger switch forward.

Tip: A setting of ‘1’ is about 5Hz; a set-ting of ‘0’ produces no tone at all, andis equivalent to discriminating thatVDI.


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single tone for small groups of VDIs; forexample, one tone for the iron range, one tonefor a foil range, etc. There is a short-cut for set-ting multiple VDIs to the same tone:

1. Move to the first VDI in a desired tonerange.

2. Set the desired tone for that VDI.

3. Press/hold ENTER, then press to set thesame value to subsequent VDIs. Thisworks in either direction, so you can alsostart at the last VDI and press .

As an example, the Mixed Mode Pro pro-gram has custom tones set up as follows:

Notice that the ferrous region (-95 to 0) iscompressed compared to the non-ferrous side.

Custom Discrimination

In metal detectors, discrimination is theprocess of accepting some types of targetswhile rejecting others. In many designs, this isa simple linear adjustment that sets a singlerejection threshold. In more advanced designs,rejection can be selected across multiple dis-crete ranges. V3i allows discrimination at theindividual VDI level, and the resulting patternis called a discrimination mask.

From the Live Control Bar, highlight theDisc. selection and press ENTER. This pops upa small window which contains a list of VDIs,and each VDI has a checkbox next to it:

VDI+95-95 0

Tone

80

100

240

120

140

160

180

200

220

20 40 60 80

An “X” in the box means the VDI is accepted,otherwise it is rejected.

At this point you can go through each ofthe 191 possible VDIs and individually settheir acceptance. However, as with audiotones, most people will want to accept andreject VDIs in groups; for example, reject theiron range, accept a cupro-nickel range, etc.There is a short-cut for setting discriminationfor multiple VDIs:

1. Move to the first VDI in a desired discrange.

2. Check or uncheck that VDI.

3. Press/hold ENTER, then press to set thesame setting to subsequent VDIs. Thisworks in either direction, so you can alsostart at the last VDI and press .

As an example, the High Trash programhas the following discrimination mask:

Again, the ferrous region (-95 to 0) is com-pressed compared to the non-ferrous side.

Additional methods

The method just described is availablefrom the Live Control Bar. There are addi-tional methods of setting discrimination whichare accessed in the more advanced Discrimina-tion menu. From the Live Control Bar, high-

Tip: For all factory programs, +95 isalways rejected. This is the VDI thathighly questionable signals — usuallyfrom hot rocks — are assigned.

VDI

Rej

Acc

+95-95 0 20 40 60 80


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light the Disc. selection and press ENTER;scroll down to the VDI Select By entry, whichcontains four methods for setting up discrimi-nation masks:

Level replicates the simple Disc knob found onmany detectors. Everything below and includ-ing the setting is rejected, everything above itis accepted.

Selecting IconEdit pops up a small boxcontaining a list of all the currently definedicon ranges. We haven’t covered icons yet, butany given program can have them defined,either using factory default ranges or customranges. Once icon ranges are defined, you canaccept or reject those ranges in their entirety.In the example above, the foil/ring range isrejected, as is the cap/zinc-cent range. Theother ranges are accepted.

Tip: This method may seem superflu-ous but, as an example, it allows youto quickly toggle discrimination for thefoil region without having to rememberwhat the VDI range for foil is.

Selecting VDIEdit pops up a small boxwhich contains a list of VDIs, and each VDIhas a checkbox next to it. This method is iden-tical to the pop-up box on the Live ControlBar, already covered.

Selecting GraphEdit creates a small dis-crimination mask graph that you can visuallyedit. The large number represents the currentVDI at the cursor (the arrow); the symbolbelow the cursor tells acceptance ( ) orrejection ( ) for the current VDI; the iconsshow what icon range is currently active, perthe defined icon ranges. Use the and keysto move along the graph, and the and keys to set acceptance & rejection. As before,you may press/hold the ENTER key and “drag”a selection for faster editing.

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So far, everything we’ve done has beenaccessed from either the 6-block menus, orfrom the Live Control Bar. A lot of features areavailable at these levels, but as we move intomore advanced features, we will need to beginaccessing the Expert Menus. The ExpertMenus are the third level of the user interfaceafter the 6-block menus and the Live ControlBar. Every setting for V3i, bar none, can befound here.

Info/Configuration Screen

Before we jump to the Expert Menus, let’stake a look at the Information/Configurescreen, which we have to pass along the way.Press MENU,MENU (twice); this will take youto the Configure screen:

The first selection is for Language. V3isupports 6 languages: English, Spanish,French, German, Russian, and Turkish. Alloperational screens for V3i have been trans-lated; however, all Quick Reference screensare English-only.

Next selection is for Metric units. Checkthis if you want depth readings reported in cminstead of in.

The Backlight slider adjusts the screenbacklight brightness from OFF to 20. V3i uses atransflective LCD screen which has good visi-bility and contrast in full sunlight, so the back-light should not be needed in normal daylighthunting. If you are going in and out of shade,then a low backlight setting may be needed.Keep in mind that a higher setting draws morejuice from the batteries.

Loop Selection allows you to tell V3iwhich loop you are currently using. V3i willuse this to adjust target depth readings to com-pensate for loop size. If you are using an after-market loop, select the factory loop that isclosest in size.

We’ll skip Quick Reference and Owner reg-

istry for a second and point out the Battery

readout. If the batteries get below a criticalvoltage, V3i will simply shut down. Exactlywhere this occurs can vary between machines,but it could be as low as 4.5 volts; however,there is no guarantee that V3i is performingwell with this low of a voltage.

Typically 12 volts is fully charged, andaround 8 volts or so you should be thinkingabout replacing the battery pack. Any White’s12V slide-in pack will work: NiMH, NiCAD,or alkaline. As the voltage drops below 8 volts,all current settings will be saved so when youreplace the batteries, your program will be justas you left it. There is a chance that if youmade a change just prior to instant batterydeath, that change may not get saved.

Tip: If you turn on your V3i and thescreen flashes and immediately shutsdown, suspect the batteries.

Info, Config, &Expert Menus7


Page 7-2

Quick Reference™

Quick Reference is the entry point into theon-line help system. Selecting this optionbrings up the following screen:

If you scroll down (press/hold ), you willsoon reach a list of help topics:

From here you can peruse topics; press ENTER

to select a topic, and use the and keys tomove backwards and forwards through yourcurrent history of viewed topics.

The Quick Reference system is context-sensitive, so anytime you need help with a fea-ture simply highlight the menu item and pressMENU+ZOOM. Here is an example of the QuickReference screen for AutoTrac speed:

Short-cut: Quick Reference screensoften have “jump” points embedded.Press MENU+ or MENU+ to jumpahead or back.

Notice that the Quick Reference entryincludes a list of related topic hyperlinks. Atany Quick Reference screen you can also pressENTER and a list of related topics will pop up.

In addition to the Quick Reference system,V3i also has pop-up help balloons, which canbe activated by flipping the trigger switch for-ward:

Obviously the Quick Reference system hasmore detail and includes hyperlinks to addi-tional help topics, but the pop-up balloons mayhave all the information you need.

Owner Registration

The last item to cover in the Configurescreen before we get to the Expert Menus isOwner registry. Selecting this option brings upthe following screen:


Page 7-3

Owner registry is for personalizing your V3iwith name and contact information, in caseyour detector is lost or stolen. It does not regis-ter the detector for the purposes of warranty.

If the screen has “Unregistered” in red,then the detector has not been registered. Pressthe TAB button to highlight the Register button,then press ENTER. At this point you will see ascreen with a 4-character password:

If you choose to Continue registration, youMUST write down this password if you everwant to change the registration in the future;this password will not be shown again. How-ever, you can opt to bail out of the registrationprocess by TABing to the Cancel button, orsimply pulling the Trigger switch.

Assuming you have chosen to continue(and you wrote down the password!), TAB toContinue and press ENTER. Here is the nextscreen:

You may now enter your name, press TAB, andenter your contact details. Use the and keys to select characters, and the and keys to move backwards and forwards in theedit window. You may also press ENTER toaccess the V3i Keyboard Editor, which is cov-ered in detail in the last part of this chapter.

A completed registration screen might looklike this:

Tip: Contact details may contain multi-ple lines, created by using a semico-lon: 1011 Pleasant Valley Rd; Sweet Home,OR 97386; (541)367-6121

Tip: Should you decide to transfer yourV3i to another owner, be sure to givethem the registration password sothey can replace your information withtheirs. If you have misplaced the pass-word, you (not the new owner) willneed to contact the factory to get itreset.


Page 7-4

Expert Menus

Finally, we have reached the Expert Menuselection and, selecting it, get the followingscreen:

Many of these are recognized as topics wehave covered in previous chapters, but theExpert Menu categories may have additionalsettings.

The only parts of these menus we will lookat in this chapter are the Configure and Infor-

mation sections. If you expand the Information

section you will see:

Quick Reference and Owner registry were cov-ered in the previously in this chapter. Battery

simply reports the current voltage level.

The Configure menu has some familiarentries: Language, Metric units, Backlight, andLoop selection, plus a number of additionalentries we have not yet covered:

Color theme gives you a number of screencolor schemes to choose from:

• Chestnut• Dusk• Fireside• Pine• Sunshine

Most programs use the Sunshine scheme. Inaddition to the 5 standard color schemes, youwill notice that two programs — Hi-Pro andMixed Mode Pro — are also in the list. That’sbecause these two programs have their owncustom color schemes. There are also entriescalled Custom and Custom Edit; we will coverhow to create custom color schemes in ChapterXX.

The Sound Effects section lets you selectoptions for key clicks and the key limits tone:


Page 7-5

Key Click is the short tone you hear every timeyou press a keypad button; you can disable itby unchecking the option. Tone lets you selectthe click tone; Balance adjusts the stereo bal-ance for the effect. Key limits is the short toneyou hear when you reach an option’s limit; youcan disable it by unchecking the option. Tone

lets you select the limit tone; if Stereo isselected then the low limit is sent to the left earand the high limit is sent to the right ear. Vol-

ume sets the sound effects volume.

Live Search Screen is the entry point forsetting up all the options for the various searchscreens. This will be covered in Chapter XX.

Live Controls is for setting up the optionsand contents of the Live Control Bar. This willbe covered in Chapter XX.

Menu contains the following options:

Out of the box, V3i has the 6-block menusenabled and easily accessed, while the ExpertMenus take several key strokes to enter. Asyou gain experience using V3i, you may wantto replace the 6-block menus with the ExpertMenus. The above option Expert Only doesthis; when you check this option, a press of theMENU key during normal search will bring upthe Expert Menus instead of the 6-blockmenus.

The Size option let’s you choose the fontsize used in the menus. You can also press theZOOM key any time you are accessing themenus.

Normally, when you scroll down to the endof the menu list the selected item will stopthere. With the Wrap option enabled, theselected item will jump up to the top of themenu list.

Normally when you exit the menus (backto the search mode), re-entering the menu willput you right back where you left off. Check-ing the Reenter at top option will reset themenus, and put you at the top upon re-entry.

Quick Reference has a check box optioncalled Topics which, when selected, enablesthe hypertext links to “other topics.” Uncheckthis option if you don’t want the hypertextlinks.

Battery has the following options:

With Battery type you can select which batterypack you are using, and V3i will slightly tweakthe battery graphic on the splash screen. How-ever, for most people this is not an importantconsideration so leaving the battery type set toa single entry is fine.

Auto Power Off, when enabled, will auto-matically shut down V3i after a period of inac-tivity. The inactivity time is set by Inactive

Limit, which is in minutes. “Activity” isdefined by a key click or a trigger pull, not justscreen activity. Therefore it is possible to huntfor an extended period of time where, if younever use the pinpoint trigger, V3i could auto-shutdown. You will know when this happensbecause it plays a short piece of (our interprre-tation of) Beethoven’s 5th.


Page 7-6

The V3i Keyboard Editor

The owner registry requires that you createtext entries, and there are other features in V3ithat also require text entries. V3i includes apop-up keyboard editor. When a text entry isactive (such as Owner’s Name in the Owner

Registry screen) press ENTER to access theeditor:

Use to move around the keyboard;press ENTER to “type” the selected key; whenyou are done, pull the trigger switch to exitback to the registry screen.

Because of the limited keypad on V3i, it isdifficult to provide an easy way to backspace,delete, and even move the cursor back & forth.Fortunately, there are some key short-cuts, anda “Special Operations” alternate to the pop-upkeyboard. While in the pop-up keyboard, sim-ply press VIEW to switch back & forth betweenthe keyboard and the special ops view:

The first three entries are:

• Position — use the and keys to movethe cursor backwards and forwards in theedit window text.

• Delete — the and keys to highlight textin the edit window, then press ENTER todelete the highlighted text.

• Overtype — check this to switch the editmode to overtype mode instead of insertmode.

These functions operate just like most anycomputer text editor. If you scroll down thespecial operations selections you will also seeentries for the six supported languages:

At any time you can switch keyboards andenter text in the selected language.

Finally, there are a number of keyboardshort-cuts:

• ENTER+: spacebar (add a space)

• ENTER+: backspace (delete preceding)

• MENU+: move right

• MENU+: move left

• ZOOM+: move to the end of the text

• ZOOM+: move to the beginning of the text

• ENTER+ZOOM: toggle between insert &overstrike

The Keyboard Editor is also used in Pro-gram file operations, covered in Chapter XX.We will refer back to this section on how touse the Editor.

5


Ground Tracking

In order to better handle variations inground mineralization, many detectors nowincorporate automatic ground tracking(White’s uses the trademarked term AutoTrac).The detector attempts to determine what partof the signal is due to ground and continuouslytrack the phase and strength of that signal, andeliminate it. One trick is to limit the range ofVDI’s for normal ground (the grayed area inthe VDI scale) and consider anything else atarget. This works for most soils, with twocaveats.

Besides “normal” ground mineralization,some areas contain rocks or small pockets con-sisting of material with slightly different min-eralization than the surrounding ground. Thedifference in VDI between these anomaliesand the surrounding ground isn’t enough toconsider them a true target, but they are smallenough to act like a target to the detector’sground filters. These so-called “hot rocks” cancreate annoying responses in many detectors.

Another situation concerns soils with sig-nificantly conductive salts. A pure saltresponse lies all the way in the non-ferrousregion of the VDI scale, roughly in the midstof foil. Some salt-water beaches are close tohaving a pure salt VDI, while other beachesinclude black sand mineralization that createsa composite VDI that can land anywherebetween pure ferrite (VDI=-95) and pure salt.Other areas, like fertilized fields with residualsalt ions, can also have a composite ground

response. Many deserts have a layer of surfacesalts that have been leached from the soil; thisis generally not a problem as long as it is dry.

Frequency

Metal detectors are produced using a widerange of transmitted frequencies, from 1kHzup to around 100kHz, though the vast majorityfall in the VLF range of 3kHz - 30kHz. Lowfrequencies usually favor thicker targets andmetals of higher conductivity, while high fre-quencies favor thin and low-conductive tar-gets.

Low frequencies also do a better job pene-trating ground mineralization, including salt.High frequencies tend to generate strongerground and salt signals which can limit theability to distinguish weak targets. Obviously,when trying to detect thin low-conductive tar-gets (like nuggets and jewelry) in harsh ground(like wet salt sand or black sand) there arecompeting frequency requirements, so a com-promise is necessary. With the ability to run 3simultaneous frequencies or any one of themindividually, V3i has the ability to deal with awide variety of conditions.

Interesting Experiment: Thickness mat-ters because of a phenomenon known asskin effect. To demonstrate this, cut sev-eral identical flat squares (say, 1”x1”) ofaluminum foil. Test the VDI response of asingle square, and see how the VDI variesas you stack more squares (tightly)together.

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