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DFX Engineering Report
Mark Rowan
Senior Project Engineer & DFX Designer
White's Electronics, Inc


Here it is. The finest all-around metal detector. White's new DFX™ is simply unsurpassed in its ability to find treasure older, deeper and smaller items that other metal detectors pass over. DFX™ brings together the ultimate combination of sophisticated microprocessor technology, and "Turn-On-And-Go" simplicity. You're out hunting right away, but there are dozens of adjustable features available if you choose.

Pick your program and GO! Nine "Turn-On-And-Go" Programs including our user designed EEPROM programs you can override with your own custom programs. Listen for the distinctive sound of "treasure," then see what you've detected on the screen. Pull the trigger and DFX™ shows you how deep to dig.

A revolutionary, new multifrequency method. Partnered with the target I.D. you get only from White's metal detectors, now DFX™ uses dual frequency detection to "see through" minerals in the ground and detect coins, jewelry and relics other metal detectors are missing. Hunt in 3 kHz, 15 kHz, or use both together for unequalled hunting. This is concentrated power from the two individually processed frequencies that work best for finding treasure. Detecting together or singly, choose Best Data and the DFX™ displays data from the most reliable frequency. Choose Correlate and questionable targets, including iron, are rejected. All happening automatically, behind the scenes, while you hunt!

The DFX™ (Dual Frequency XLT®) was conceived of as a detector which would maintain the most popular attributes of the Spectrum XLT®, while adding the benefits and capabilities provided by multiple frequencies.

Multiple frequency, for our purposes, refers to a method of detection in which signals at two or more frequencies are transmitted, received, and processed in a more or less simultaneous fashion. We will refer to a detector in which these operating frequencies do not run at the same time, but can be chosen between by the operator, as selectable frequency operation.

The primary intent of adding multiple frequency operation is to enhance performance particularly on the salt water beach. Selectable frequency operation is provided primarily to allow an operator to optimize the detector's performance according to the types of targets he or she is most interested in finding. I will explain these things in more detail shortly.

Keep in mind, although technically more advanced all the features and benefits are available to the "Turn-On-And-Go" PRESET user with nine Factory Set Up programs to chose from, as well as those who like to tailor the features to their exact preferences.

The DFX™ is truly a leap above traditional single frequency models not only in the technical internal circuitry, but in the performance gains and end results, finding more desirable items, in more difficult conditions, digging less trash, and returning home with more prized finds.

Mark Rowan
Senior Project Engineer & DFX Designer
White's Electronics, Inc.

Whites Electronics DFX™ Metal Detector

Operating Frequencies
The choice of operating frequency in a metal detector will have a significant effect on the detector's ability to find certain types of objects. Just as important, it will effect the detectors ability to distinguish between certain desirable and undesirable metal alloys.

White's Goldmaster Series, running at 50,000 cycles per second (50 kHz), is an excellent choice for finding tiny flakes of gold. It would be a poor choice, however, for coin shooting in an environment where aluminum trash rejection is important. It would also be a poor choice for salt water hunting, because the same principles that make it sensitive to small nuggets make it sensitive to salt water. A detector running at 1.75 kHz (like the old Coinmaster V) would have good salt water rejection and good sensitivity to targets like silver coins; but its sensitivity to most gold jewelry, and its ability to distinguish nickels from foil and pull tabs, would be poor.

White's has been very successful building general purpose detectors which run at 6.6 kHz. This frequency was chosen years ago as a standard because it provides both good sensitivity and good discrimination for a wide variety of targets and environments. Still, for jewelry hunters and prospectors it may be too low, while for beachcombers and cache hunters it may be too high. Clearly, providing the flexibility to match the operating frequency with the application is a desirable thing.

The two frequencies available in the DFX are 3 kHz (actually 2.98) and 15 kHz (14.91 kHz). The detector can be configured as multifrequency in two different formats, Best Data, and Correlation, or a conventional single frequency machine at either of those two frequencies. 15 kHz will be a better choice for finding small gold items, including most jewelry. It will provide better sensitivity and more accurate discrimination for targets in the foil through pull tab range. 3 kHz will be preferable for finding copper and silver coins, and will provide better sensitivity improved discrimination in the screw cap through silver dollar range. It will also be less salt sensitive.

Preset Starting Programs
The selection of "turn-on-and-go" programs has been greatly expanded. Preset Programs let the detector do the work for you selecting the most desired options for the application. The standard Preset Programs; COINS, COINS & JEWELRY, JEWELRY & BEACH, RELIC, and PROSPECTING can be chosen. In addition to that there are four EEPROM (Electronically, Erasable, Programmable, Read, Only, Memory) Custom Programs that are set up at the factory when the first five Preset Programs are installed. EEPROMs contain more advanced settings that experienced hunters have found useful.

DFX main menu screen

The four EEPROMs can be overwritten to hold one's own custom programs. Or one of the standard Preset Programs can be modified and saved in one of the EEPROM positions. In other words the first five standard preset programs are permanent. You can modify them for temporary use, and/or copy past those modifications of that program to one of the EEPROM positions by SAVING and/or NAMING it, for future use. However, the first five standard Preset Programs will always revert to their original factory settings upon battery changes and/or fresh start up procedures. Once any modifications have been SAVED in an EEPROM position, they will remain during battery changes and fresh start up procedures until manually overwritten with a new program and that program SAVED in that position.

You can SAVE and continue using that EEPROM position with the same name, or select NAME and manually NAME & SAVE at the same time allowing you to type in a descriptive name for your special program.

The Display
The DFX provides a wealth of information on the LCD display.

VDI (Visual Discrimination Indication): provides a reference number for all alloys and sizes from -95 to +95. Assigning a VDI number for each target type allows the DFX to selectively accept or reject like targets. The chart painted on top of the control box references VDI numbers and common targets.

VDI number

Target Icons: Along with the VDI number, a representation of common targets within that range are displayed providing a quick and easy on the eye reference.

SignaGraph: Along the bottom portion of the display the SignaGraph provides a conductive/magnetic signature of that alloys characteristics. Magnetic irons are easily identified by their magnetic signature (to the left of center) where as alloys of the non-ferrous precious class pattern to the right of center and tend to provide narrower taller patterns.

Status Indicators: The battery check is automatic upon turn on. If the battery gets low during searching LOW BAT appears on the display. The Multi Frequency mode of operation is also indicated in the center/bottom portion of the display. Best Data (automatically chooses the best frequency for the target range), Correlate (compares both frequencies), or individual frequencies 15 kHz or 3 kHz.

Depth Reading: Once a good target has been located, squeezing and holding the Trigger Switch on the handle changes the display to indicate the depth of the coin sized target in inches and provides a non-motion pinpoint mode for zeroing in on the exact spot to dig. Once the Trigger is released the DFX returns to the search mode.

What does the display tell me?

DFX Screen Data

1. V.D.I. Visual Discrimination Indication ("target reference number") In the upper left hand-side of the display there is a V.D.I. number that corresponds to the V.D.I. SCALE painted on the top right-hand side of the control box. It also corresponds to the Discriminate Edit feature allowing you to reject or accept targets based on their V.D.I. reference number. There are "+" numbers for nonferrous (not of iron) targets, and "-" numbers for ferrous (iron) targets. Rejected V.D.I. numbers may not appear if the VISUAL DISCRIMINATION feature is ON. Reasonably consistent V.D.I. reference numbers (± five digits), in a desirable area of the chart is a vote for digging the target.

2. Possible Target Identities ("Probable or most likely target") To the right of the V.D.I. number, possible target identities will be represented graphically. These graphics are called ICONS. A fairly consistent indication of a desirable target is another vote to dig the target. One or two possible target icons may appear. There is significance to which icon appears first. The first target to appear is always the most likely, the second is another possibility, slightly less likely than the first.

3. SignaGraph® The SignaGraph® at the bottom of the display provides a final vote as to whether or not the target should be dug.

A. Sweep the loop over the target several times and look at the SignaGraph®. The SignaGraph® automatically clears itself (FADE RATE) so that it doesn't fill the screen with information from past loop sweeps. An operator has limited time to look at the SignaGraph®. If you want to look at the information again, sweep the loop over the target several more times. The fading of the SignaGraph® information can be slowed or speeded (FADE RATE) to operator preference. This is completed in the PRO OPTIONS under DISPLAY. Automatic AVERAGING and/or ACCUMULATING of SignaGraph® information is also available (See PRO OPTIONS).

B. Valuable targets will show up on the positive side of the graph. The positive area of the chart is the section located to the right of the zero.

C. Look for consistency. In ideal conditions, coins and jewelry produce one or two bars to the right of zero. Trash produces several bars, sometimes on both sides of zero.

D. In less than ideal conditions, coins may produce a wider pattern of bars. Most trash targets produce a recognizably different pattern than valuable targets.

E. One of the most visual benefits of the SignaGraph® is the ability to show a smear pattern on iron targets that often fool the other methods of identification. An iron target will likely show definite bars on both the negative and positive sides of the SignaGraph®, often smearing all the way across the entire chart. Valuable targets should not produce such obviously wide patterns. In very bad ground conditions, a good target may have a few small bar segments in the negative area due to mineralization. However, the pattern will show mostly positive bars, in a fairly narrow tall group.

Signal Processing
Within the DFX™ circuitry, the identification and discrimination of targets are performed by the same proven basic techniques used in the XLT®. Bandpass filters are used to remove most of the slowly changing ground signal, while allowing most of the more rapidly changing target signal to pass through. In the XLT®, this filtering is done entirely with analog hardware. Each signal channel passes through two stages of hardware filtering. In the DFX™ , the second stage is accomplished by a digital filter, which is entirely under software control. This allows for a greater degree of user adjustment, including a less aggressive filtering mode (two filter/three filter) similar to that found in many popular lower-end machines.

We have upped the microprocessor clock frequency from 6.75 MHz (XLT®) to 14.32 MHz (DFX™ ). You will immediately notice a result of this in the form of "snappier" display response.

All the MENU items are tied together so that the ARROW up and down controls scroll through every adjustment screen. If you continue to press the ARROW down you can go beyond the last BASIC ADJUSTMENT (View Angle) and into the PRO OPTIONS. If the ARROW up control is pressed after VOLUME, you will be scrolling backwards through the options starting with the end of the Preset Programs, then the MAIN MENU, then the end of the PRO OPTIONS.

An important feature of the ARROW controls; If a BASIC ADJUSTMENT has been made (for example Volume) and the trigger has been squeezed and released to return to a search mode, you can return to the volume adjustment simply by pressing either of the ARROW controls. This shortcut returns to the last adjustment that was made thereby allowing an operator to switch directly from a search mode to the adjustment currently being fine tuned. This feature is desirable as you start using BASIC ADJUSTMENTS or PRO OPTIONS that are located further down the menu listings, or any adjustment that may require some trial and error to find the appropriate setting.

If care is taken to use a desired adjustment screen last (just prior to squeezing and releasing the TRIGGER for a search mode), Custom Programs can use this ARROW RETURN feature to allow quick easy access to the most used feature. Use that feature (adjustment screen) last, just prior to squeezing and releasing the TRIGGER for searching. Then during searching, press either ARROW to return directly to that adjustment screen.

"HOT KEYS" will save time as they allow easy access, from the search mode, to the most needed adjustments. They are painted on the bottom of the control box for field reference.

NOTICE: "HOT KEY" shortcuts will not function from a cold start (batteries just installed). To function from a cold start the DFX™ must be turned on and air/ground balanced in any mode, then turned off. "HOT KEY" shortcuts will then function.

DFX New Features

Ground Filtering
Motion discrimination is based on the fact that the signal received from the ground tends to remain the same, or change very slowly, while the signal received from a metal object buried in the ground tends to change much more rapidly as the loop is swept over it at a reasonable speed. We are thus interested in the rate-of-change of the signal more than we are in the magnitude of the signal itself.

An electronic device which is sensitive to the rate-of-change of a signal is known as a differentiator, or, alternately, as a "high-pass filter". A single high-pass filter is often used in the all-metal channel to provide what we call S.A.T., or "Autotune". For discrimination purposes, one high-pass filter is not usually good enough. We need at least two Ń which is the origin of the term "two-filter detector". A potential point of confusion here is that discriminating detectors need at least two signals, or channels, commonly called X and Y (or X and R). White's high-end detectors use three channels. But in any event, each channel needs at least two high-pass filters which is the origin of the term "four-filter detector".

Detectors in the 6000 - Eagle - XLT® line have three high-pass filters per channel. In addition, a "feedback" technique is used to increase the gain for fast changing target signals, which in some sense is like adding yet another, forth high-pass stage "four-filter machine". Our experience has been that this additional filtering provides superior depth and discrimination in ferrous mineralized ground, however, with it some compromise responding quickly to targets near to each other.

In the DFX™, the first two high-pass filters are implemented in hardware. The third high-pass, and the feedback element, are implemented in software with what is known as a digital filter. The digital filter is easily adjustable, requiring only the change of a few numeric constants in the microprocessor. Here is a summary of Ground Filter settings:

2- digital filters disabled - hardware filters only (quick "two-filter" response)
3- third high pass enabled; no "feedback"
4- feedback enabled (XLT®-like response)
5- additional feedback (more filtering than XLT®)
6- maximum feedback (maximum ground filtering)

Use a lower setting for faster recovery between targets, and for greater freedom to sweep fast or slow without losing depth. Use a higher setting for better ground rejection.

Sweep Speed
The digital filter can be tuned so that it is more sensitive to a faster sweep, or more sensitive to a slower sweep. When Ground Filtering is set to 2, the digital filter is disabled and so the Sweep Speed adjustment has no effect. Use higher settings of Sweep Speed to quickly move through an area with few targets, and lower settings to move more slowly through areas in which you need to get in between the trash.

Bottlecap Rejection
This feature has changed compared to the XLT®. It has been pointed out for some time that setting this control up beyond 4 or so wasn't very practical in the field. A lot of people wished they could turn it down below 1. So, the range has been shifted. A setting near mid-scale should give you fairly good and familiar results. Turning it down will provide a little more depth on coins at the expense of poorer iron rejection. Turning it up should provide some useful reduction in the iron trash you dig.

The range of this control has been shifted by a considerable amount. While there is not a direct conversion factor to equate XLT® settings with DFX™ settings, our intent was to make a setting of 10-12 (in the DFX™) about equal to a setting of 2-4 in the XLT®. Since most of the Preset Programs have BOTTLECAP REJECT set to 4, we are actually running at reduced levels in DFX™, when compared with XLT®. While the effect is most pronounced on bottlecaps and similar iron targets, this control will have some impact on all aspects of the discrimination performance.

Hot Rock Rejection
Setting or clearing +95 in the DISC Editor (on the XLT®) can have a pretty dramatic effect. So, we have provided an adjustment to allow for more "shades of gray" between the extremes of simply accepting or rejecting this number with the DFX™.

A setting of 20 with the DFX™ does the same thing as selecting +95 to reject regarding XLT® models. Turning it all the way down to 0 makes it a "hot rock accept" control Ń like making +95 an accepted target did previously with the XLT®. A setting of 10 means that the detector will neither accept nor reject the target; it does nothing. Other settings give greater or lesser degrees of acceptance/rejection.

+95 in the disc editor controls whether the number is displayed, but has no effect on the audio response.

Remember that +95 in the DISC editor now only controls the Visual Discrimination of those readings. Audio Discrimination response to +95 readings is controlled by HOT ROCK REJ. A setting of 20 is the same as setting +95 to reject in an XLT. Setting to 0 is the same as clearing +95 to accept. A HOT ROCK REJ. setting of 10 means that the reading will have no effect on the audio Ń it will neither accept nor reject the target. Other settings give various degrees of acceptance or rejection.

VDI Normalization
When a target is analyzed and a VDI number computed based on signals acquired at 3 kHz, the results will not be the same as the familiar numbers we see in a 6.6 kHz machine. The microprocessor, though, can easily compute what the result would be at 6.6 kHz when given 3 kHz data. We call this process "Normalization". Similarly, the 15 kHz VDI results can be normalized to 6.6 kHz units.

There are several reasons for performing normalization. First is the fact that many people have already committed the 6.6 kHz VDI scale to memory. Second is the fact that it would be extremely annoying to have to edit your discriminator every time you changed frequencies. Finally, normalization makes it possible to do the dual-frequency discrimination techniques mentioned below.

Here is a chart showing the non-normalized, and normalized, data for some familiar targets:

space 3 kHz VDI # 6.6 kHz VDI # 15 kHz VDI #
Salt 0 2 2
Foil 7 8 15
Nickel 15 20 46
Pulltab 21 31 63
Zn Penny 43 63 80
Dime 63 78 88
Quarter 77 84 91
Dollar 87 92 93

So, why would you want to turn normalization off? Notice that you get much more "spread" between foil and pulltabs at 15 kHz; this means better VDI resolution, which might make it easier to identify rings. The same applies to the spread between Zn pennies and dollars at 3 kHz. Normalization is forced ON when either "Best Data" or "Correlate" are selected. Only in the single frequency 3 kHz or 15 kHz modes can normalization off be used.

"Best Data"
The DFX transmits, receives, and processes data continuously at both frequencies. When you pass over a target, the processor looks at the magnitude and phase of both signals, and decides which one is more likely to give an accurate VDI result. It then computes the VDI at that frequency, normalizes, and reports the result to the LCD as well as using it to perform audio discrimination. Thus you should get good results on nickels and rings (where 15 kHz is the frequency of choice) as well as on deep silver coins (where 3 kHz is likely to be selected by the processor).

When Best Data is selected, the all-metal signal (both for pinpointing and searching with the discriminator off) will also be derived using both frequencies. The 3 kHz signal will be factory balanced to reject salt; same with the 15 kHz signal. The resulting salt-balanced signals will be highly sensitive to ferrous ground, as well as to most metal. We combine these two signals in the correct proportions in order to achieve ferrous ground balance. We now have an all-metal signal which is balanced to salt, balanced to ferrous minerals, and still sensitive to metal objects.

When the normalized VDI results from each of the two frequencies do not agree, we can be pretty certain that the target response at one or both of these frequencies is too weak to be useful, or that one or both signals have been corrupted in some way - by interference or ground noise. If the agreement is excellent, we can feel pretty confident in reporting the result to the operator, both visually and audibly. This is what Correlation does; when the two results are the same or nearly the same, the target is treated as valid; when they don't agree, the results are ignored. Early indications are that iron targets do not correlate well, and thus some improvement in iron trash rejection may be had by selecting "Correlate".

Single Frequency Modes; 3 kHz, 15 kHz
These two modes should be fairly self-explanatory. Both disc. and all-metal data comes from the frequency you select. Use 15 kHz for small gold, nickels, jewelry etc. Use 3 kHz for copper and silver coins, larger objects, etc.

External Interference
Experienced White's users are familiar with the types and the severity of interference which impact the performance of those products operating at 6592.5 Hz. Since the DFX operates at two less familiar frequencies, new interference issues are sure to arise. One such circumstance which we are aware of has to do with interference from power lines. In general, power line interference is stronger at lower frequencies Ń thus we expect to see more significant power line related interference at 3 kHz than we do at 6.6 kHz or 15 kHz. To operate nearer to power lines the single 15 kHz frequency is suggested.

Physical Descriptions
General looks have not changed from the earlier XLT® to the DFX™ . It has the same S-handle framework and lightweight yet rugged design for long hours in the field, without fatigue. You will also notice that, although the size of the coil is the same 950, it is now the Wide Band Multiple Harmonic coil and not interchangeable with the XLT®. The display or meter is mounted at the top of a comfortably padded handle, with the trigger switch near the index finger for quick and easy pinpointing and non-motion, all-metal detection. The armrest sits at elbow position over a control housing that is noticeably smaller than White's boxes of just a few years ago and therefore much lighter. The sides of the box read, "White's DFX™ Spectrum E-Series," with start-up procedures and a VDI (target ID) scale painted on top of the box, and the "Hot Key" control shortcuts on the bottom. At the back of the box is a hinged door to remove the battery pack, and a 1/4 stereo headphone jack. The internal speaker is on the top. White's has continued with this well thought-out design.

Feature Index
If you are a beginner, don't get "tech freaked" when you read the following list of features. Remember that the machine can automatically set everything, unless you want to set a few or as many as you want yourself. White's has the features divided into sections. First on the visual display screen is the Main Menu with the prompt pointing to enter the Preset Programs, ARROW down to the Basic Adjustments, or the Pro Options, and continue ARROW down to find the Custom EEPROM Programs. A Preset Program should be selected as a base or starting point. If not, the DFX uses the standard COIN settings.

Preset Programs
The starting point for selecting a base program most likely needed for the days hunt. Nine programs are available to choose from. The four EEPROMs can be used or replaced by storing your own programs for future use. Let the detector do the work for you and SAVE preferred settings.

Basic Adjustments
These are the typical features and controls found on high end models.

1. TARGET VOLUME - How loud a target beeps when detected.

2. AUDIO THRESHOLD - The slight hum or background sound heard continuously during searching.

3. TONE (AUDIO FREQUENCY) - Selects the frequency or pitch of sound the detector produces.

4. AUDIO DISCRIMINATION - The ability to reject trash, different sounds for different types of targets.

5. SILENT SEARCH - The ability to operate without the threshold or background hum.

6. MIXED-MODE - DC All-Metal non-discriminate mode, working simultaneously with AC discrimination mode.

7. A.C. SENSITIVITY - Degree instrument is responsive to signals in the discriminate (motion) modes.

8. D.C. SENSITIVITY - Degree instrument is responsive to signals in All-Metal non-discriminate (non-motion) modes.

9. BACKLIGHT - Used in dark conditions to light the display improving visibility.

10. VIEWING ANGLE - Adjusts the display for low or high temperature visibility.

Pro Options
These are the more detailed options one should study in the manual prior to experimentation.


Pinpoint feature, automatically de-tunes for center of target location.

2. S.A.T. SPEED - Self Adjusting Threshold or Auto-tune, automatically maintains threshold.

3. TONE I.D. - Assigns each V.D.I. target number its own special tone or sound.

4. V.C.O. - Pinpoint or All-Metal non-discriminate feature, increases pitch or tone with target strength.

5. MODULATION - Motion modes produce the same, or different volume, based on target depth.


Automatically updates Ground Balance during searching.

7. TRAC VIEW - TRACK appears on right side of display during AUTOTRAC® adjustments.

8. AUTOTRAC® SPEED - Dictates when (how quickly) AUTOTRAC® adjusts Ground Balance.

9. AUTOTRAC® OFFSET - Positive or negative AUTOTRAC® (over or under kill).

10. TRAC INHIBIT - Prevents tracking the ground during target detection.

11. COARSE G.E.B. - (Manual Ground Balance) Coarse viewing, or overriding automatic.

12. FINE G.E.B. - (Manual Ground Balance) Fine viewing, or overriding automatic.


13. DISC. EDIT -
Change V.D.I. (target reference numbers) accepted (detected), or rejected status.

14. BLOCK EDIT - Speeds EDIT by dragging ACCEPT or REJECT with ARROW controls.

15. LEARN ACCEPT - Target samples can be used to show or teach ACCEPT discrimination.

16. LEARN REJECT - Target samples can be used to show or teach REJECT discrimination.

17. RECOVERY SPEED - Speeds target responses, so close together targets each respond.

18. BOTTLECAP REJECT - How strongly the instrument rejects or breaks up on iron.

19. HOT ROCK REJECT - Degree the instrument is responsive to signals in the +95 (hot rock) category.

20. SWEEP SPEED - Adjust signal sampling width thus the ideal loop/search coil sweep speed.

21. GROUND FILTERING - How much circuitry (high-pass filtering) used to separate ground/trash signals and targets.


Rejected V.D.I. numbers and ICONS do not appear on display.

23. ICONS - Graphic display representation of metal targets, ON/OFF.

24. V.D.I. SENSITIVITY - Response intensity to produce a display indication & 3rd V.D.I. digit@ 86 and higher.

25. D.C. PHASE - Measurement of ground, or metal target, during pinpointing.

26. GRAPH AVERAGING - SignaGraph® information collects over multiple loop passes.

27. GRAPH ACCUMULATING - Emphasizes common or predominate SignaGraph®.

28. FADE RATE - Clears or fades noncurrent SignaGraph® information (bars).


29. PREAMP GAIN - Selects the intensity of the signal received from the loop.


Transmits and processes at both 3 kHz and 15 kHz frequencies (salt eliminated). Automatically chooses data from the most reliable frequency (based on both magnitude and phase) for each specific target.

31. 2 FREQUENCY (CORRELATE) - Transmits and processes at both 3 kHz and 15 kHz frequencies (salt eliminated). Compares data at 3 kHz and 15 kHz. Target signals that do not provide reasonably predictable information at both are automatically rejected. Iron typically doesn't compare predictably between frequencies, improved iron rejection can be expected.

32. V.D.I. (NORMALIZED) - 2 Frequency modes (Best Data and Correlate) automatically have V.D.I Normalized ON as it is required for these modes to operate predictably. Differences at 3 kHz and 15 kHz skew the well known traditional (6.59 kHz) V.D.I. chart/numbers painted on the top of the DFX control box. Normalization recalculates signals for this traditional V.D.I. number chart. OFF expands/compresses portions of this V.D.I. scale (depending on the 1 frequency used).

33. 1 FREQUENCY (3 kHz) - Operates at 3 kHz providing for superior high iron mineral use (no salt present) particularly for high conducting silver/copper alloys. Normalized ON maintains traditional (6.59 kHz V.D.I. chart/numbers. Normalized OFF significantly expands higher end of V.D.I. chart/numbers compressing lower end of the scale.

34. 1 FREQUENCY (15 kHz) - Operates at 15 kHz providing in lower mineralized areas (no salt present) particularly for lower conducting gold/nickel alloys. Normalize OFF significantly expands lower end of V.D.I. chart/numbers compressing higher end of the scale.

Only one of the four available multifrequency methods, BEST DATA, CORRELATE, 3 kHz, and 15 kHz, can be "ON" at any one given time. For example if BEST DATA is "ON", the remaining three multifrequency options are automatically "OFF". To turn BEST DATA "OFF", requires the selection of one of the three remaining methods. In other words, an operator never turns "OFF" a multifrequency method, they simply select the desired method and turn it "ON", all other methods are automatically turned "OFF."

The MULTIFREQUENCY selection in use appears continuously on the bottom of the LCD display during searching. The ideal multifrequency or single frequency setting will depend on many different factors such as the amount, degree, and type, of ground mineralization, the types of metal alloys most desired, as well as personal preferences. No one setting will be ideal for all situations. A user should first trust the factory preset settings for the general types of searching and then experiment to find the most ideal settings for that particular area and type of search. Generally multifrequency settings are better suited to areas that have both magnetic (iron) and conductive (salt) components. Inland areas may vary in this regard with the soils moisture content. For example dry soil may present mostly iron type characteristics possibly making one of the single frequency modes a better choice. The same area when the soil is wet may exhibit conditions similar to a combination of both iron and salt due to nonferrous metallic type mineralizationŐs greater electrical activity when wet. For example soils containing silver, copper, or nickel oxides/nitrates react differently in conditions from wet to dry. These soil traits can occur naturally and are typical of areas with mineral springs or volcanic origins. However, be particularly aware of this wet/dry phenomena in farming areas where the soil mineralization is likely altered for agricultural purposes.