E-TRAC Vs. CTX-3030 Side-by-Side - Nail to Coin Separation

Thought it would be interesting to compare the CTX-3030 and E-Trac's ability to acquire a clad penny with a rusty nail nearby. The test was done in the air over the ground. By reducing the horizontal distance between the nail and penny the affect on TID and audio was measured for each detector.

The goal was to see how, if any, the nail would affect the performance of each detector to display the correct TID and audio discrimination. Each detector was in 4TF with the same settings (Everything OFF, Ground Neutral, Trash Density Low). Both detectors were used in MANUAL-24 and swept 2" above the testing board. Each detector was tested at seven separation distances between the nail and coin: 3", 2", 1", 1/2", 1/4", 1/8" and 0" (on top). The nail was oriented either perpendicular or parallel to the DD coil illumination axis. That means, when parallel the coil's long north-south axis and the nail's long axis were both north-south.

In the picture below the 11" DD coil would be swept left-right for parallel testing.


When testing Perpendicular distances - the nail would be oriented 90 degrees as the coil is swept left-right (as below):


When the nail was over the coin at 0", the Parallel testing looked like this (below):


Ans when the nail was over the coin at 0", the Perpendicular testing looked like this (below):


This is the Parallel nail test at 1/8" distance from the coin (not touching):


This is the Perpendicular nail test at 1/4" distance from the coin.


OK then. The philosophy of the testing was only to acquire the penny, the iron nail was not the target. So, all the measurements are above the coin. A 2-Way audio is just that - High Tone signal both left-right and right-left. The given height above the coin is the maximum height that a good High Tone could be clearly heard (without mixing with Low Tones). Of course, in most cases the detectors could acquire the coin higher than this, but it would unlikely to have been a "dig" signal (rapidly changes to mixed or low tones at higher sweep heights; or nulls when in the DISC pattern).

Since this could get confusing, just remember the testing was done 4 times in 2 pattern at 7distances for 56 separate measurements. The next day I redid the test just to verify that the data was not radically different (it wasn't):

1. E-TRAC, Nail Parallel, OPEN PATTERN and DISC PATTERN
2. E-TRAC, Nail Perpendicular, OPEN PATTERN and DISC PATTERN
3. CTX-3030, Nail Parallel, OPEN PATTERN and DISC PATTERN
4. CTX-3030, Nail Perpendicular, OPEN PATTERN and DISC PATTERN

The DISC PATTERN used was my JUST THE GOOD STUFF pattern:


So, what was the result? Did the CTX-3030 blow away the E-Trac? Here is the breakdown of the results in table format:



My overview: As suspected with FBS - when a nail is oriented along the coil's long-axis (parallel) the nail had little affect on the TID and audio. The Ferrous (Fe) TID values do begin to drift downward slightly, in both detectors, otherwise the Conductive (Co) values stay relatively stable. The Two-Way audio became a One-Way audio (only coin-to-nail sweep direction) for the E-Trac when the separation distance was less than 1/2". However, the CTX was able to keep a Two-Way audio High Tone at all distances. The E-Trac did regain its Two-Way audio again - but only when the nail was directly centered over the coin (essentially splitting the non-ferrous target in half. This allowed the High Tone signal to be hard clearly again).

Here are graphs for each detector that shows the Fe and Co (Fe-Co) values received during the PARALLEL test in DISC and OPEN patterns:

E-TRAC PARALLEL NAIL with average Fe and Co results at 3" to 0" separation. Top two traces are Fe results. Bottom two traces are Co results.


CTX-3030 PARALLEL NAIL with average Fe and Co results at 3" to 0" separation. Top two traces are Fe results. Bottom two traces are Co results.


You probably noticed there wasn't much of a difference in TID values measured between the CTX-3030 and the E-Trac. Neither DISC nor OPEN patterns had much impact on how the TID was displayed with a nail parallel to the coil axis. The Co values were more stable than Fe values for both as the Fe values began to down-average a bit - but with no advantage to either detector. The real difference was in the slight depth advantage the CTX-3030 had in maintaining a High Tone. The CTX could obtain the High Tone about 1" further above the coin than the E-Trac (the E-Trac began to suffer at less than 1/2" target separation). This helped the CTX maintain a Two-Way audio at all distances whereas the E-Trac could only get a One-Way audio at less than 1/2" separation (only coin-to-nail direction). Otherwise, they were about equal - overall, advantage to the CTX-3030.

Here are graphs for each detector that shows the Fe and Co (Fe-Co) values received during the PERPENDICULAR test in DISC and OPEN patterns:

E-TRAC PERPENDICULAR NAIL with average Fe and Co results at 3" to 0" separation. Top two traces are Fe results. Bottom trace is Co results.


CTX-3030 PERPENDICULAR NAIL with average Fe and Co results at 3" to 0" separation. Top two traces are Fe results. Bottom two traces are the Co results.


Since the nail is now lengthwise along the board and 90 degrees out from the coil's long-axis, the nail began to have a profound affect on performance. You'll note there is no DISC averaged trace (in red) on the E-Trac perpendicular test graph. At closer than 3" separation the E-Trac went from High Tone to Null (no audio at 2" sweep or TID) in DISC PATTERN. In OPEN PATTERN the E-Trac managed to acquire the penny throughout. However, the penny Fe values were down-averaged to 17-20Fe range (should be 12Fe for a penny) and increasingly were driven south as the nail approached the coin. At less than 1/2" separation the E-Trac TID was erratic and dove deep into iron territory.

Note: To continue to get the audio tone during testing the sweep height had to be decreased (depth/height above target). A coin in the ground would not allow getting closer - so in the real world, in an iron environment, the coin would go undiscovered. This means, with both the CTX and E-Trac, with a perpendicular nail less than 1" away - the coin needs to be near the surface for either detector to provide an audio hit. The CTX will continue to give a TID (red triangle) whereas the E-Trac has gone blank and silent.

At greater separation, the CTX-3030 faithfully reported the penny from 3" to 1", but any closer and the TID/audio was nulled (the TID was displayed as a red triangle within the DISC area on the CTX). The CTX-3030 DISC and OPEN patterns were about equal in obtaining the coin - until the down-averaging drove the TID into the DISC'd zone. The CTX's OPEN pattern produced similar results to the E-Trac's OPEN pattern. Like the E-Trac, the CTX's TID became erratic and the Fe values were down-averaged rapidly at less than 1/2" separation. The CTX did not drop quite as much into iron zone as the E-Trac - about 28-30Fe as compared to the E-Trac's 28-35Fe. Overall, no real advantage to either detector in accuracy of Fe values.

As for Co values, the CTX-3030 performed similarly to the E-Trac from 3" to 1" separation, with Co values around 38-40Co. The penny Co value should be 36-37Co, so this was quite accurate - both detectors had stable Co values between 3" - 1". At less than 1/2" both detectors began to grossly up-average the Co values, to about 44-45Co.The effect of perpendicular elongated iron on both detectors was always to raise the Co and Fe values. The Parallel iron nail had slight or no effect on TID values.

Since the E-Trac's TID checked-out (nulled) in DISC pattern - the CTX-3030 won in providing a reliable cursor display (even a red cursor in the DISC'd area). On the other hand, the E-Trac in OPEN pattern was able to equal or exceed the CTX-3030's High Tone maximum height over the penny. In DISC pattern the audio High Tone max height shrank equally quickly for both detectors, from about 2" above the coin to 1/4" max height at 1/2" target separation. In other words, you aren't going to get much depth with either detector if a nail is perpendicular to to the coil axis. In a nail field you may only get surface coins. In less iron-rich sites, when you change body position 90 degrees and sweep again, then both the E-Trac and CTX-3030 would find the coin again (the CTX has a slight 1/2" to 1" depth advantage in DISC over the E-Trac).


The chart below shows the max heights above the coin. The solid lines are for CTX-3030 and dashed for E-Trac. In most cases the dashed line (E-Trac) was at or below the solid line (CTX-3030). The one time the E-Trac exceeded the CTX, and by a wide margin, was with the perpendicular nail in OPEN Pattern from 3" to 1/2" apart. With a DISC Pattern both detectors were about equal - the E-Trac advantage only occurred in OPEN Pattern. In a heavily infested nail area (less than 1/2" separation) both detectors are about the same again (slight advantage to the E-Trac in tough nail situations where the nails are greater than 1" apart).

Here's a graph of the maximum High Tone heights for each detector in OPEN and DISC patterns:



Lastly, just for fun - here is a plot of the Fe-Co values. Ferrous is the vertical axis and Conductive the horizontal axis - similar to a typical SmartFind display. What you have is essentially the plotted average slope of the DISC and OPEN patterns with both PARALLEL and PERPENDICULAR nail orientations.

E-TRAC Fe-Co Slope for OPEN and DISC patterns


CTX-3030 Fe-Co Slope for OPEN and DISC patterns


The take-away from these two graphs is that the performance of the two detectors is exceedingly similar. Comparing slope-to-slope between detectors yields nearly identical slope patterns. The E-Trac has a slightly more negative slope, meaning it tends toward down-averaged Fe values a bit more than the CTX-3030. But, overall, the difference is very minor.

So, which detector is better?

The CTX-3030 has a very slight advantage over the E-Trac in obtaining audio depth, a more stable Fe value with slightly decreased down-averaging, and due to the stability of the Fe value it tends to avoid nulling in DISC patterns as quickly, and a better Two-Way audio hit around iron. These differences are mostly minor with the one important difference being the E-Trac's inability to keep a TID present when in DISC pattern and confronted with a perpendicular nail. The CTX-3030's provided a red TID triangle which gives the user information while the E-Trac gives no visual clue. The depth response however to the perpendicular nail is identical in both - equally reducing depth to near surface levels on a penny. The visual ID on the CTX-3030 keeps on going even after the audio has nulled, which is a plus.

Overall, the CTX-3030 is the tenuous winner - edging out the E-Trac - but only by a nose. The CTX-3030 is more likely to get that tiny bit more depth, provide that two-way audio hit where the E-Trac may only do a one-way hit; and the CTX will provide a TID after the audio nulls whereas the E-Trac has no more visual or audio information. In fringe areas or nail-loaded ground it might allow the recovery of a non-ferrous target that the E-Trac would only weakly detect or miss. A small difference perhaps - but that's what you get for the extra money.

eXcellent write-up! Very professional presentation.

Thanks for taking the time.

Very good graphs and write up! Thank You!

Where you will see night and day between the two is in the tone I.D.....

The CTX will hear the coin no matter hat you do if you leabve the scren open and break the tone on the nail.....

The Etrac cant do this becasue of the bins even wide open screen..

But as far as patterns and such they are very close yet the CTX is a tad more sure...

I have a feeling the CTX main aim at the tone bin movement was to compete with the more modern unmasker's..

Its all in the tones not the I.D to get the ultimate FBS experience out of the CTX..

The CTX is designed for more user control for unmasking...And Unmasking it does very well...

The CTX in patterns and the etrac in patterns is like apples to apples... the Etrac wide open screen stock tone breaks Vs CTX manipuated tone breaks wide open screen is like Apples to Oranges ....

Thank's for the Info!!!

Very nice graphics

Keith



Edited 1 time(s). Last edit at 07/13/2013 04:09AM by Keith Southern.

Another superb comparison between the E-trac and CTX3030.

Thanks for taking the time for such detailed information.

Detecting since Feb, 2010
E-trac with 18"x15" SEF, 13" Ultimate coil, Pro coil, Minelab 8" coil, 4.5"x7" SEF, Sunray target probe
CTX3030 with 17"x13" DD coil, 11" DD coil

Just a big wow! I have to go through that again and slower.

But a fair question, is the difference as profound in ground?

In my experience it was but only at one spot (a sandy spot) which seems to be more like an above ground test.
In a non sandy spot, the E-Trac was 95% of the CTX. I didn't get as many coins at 9" with the E-Trac but I still got them. I think in the ground matrix, FBS is not too bad on the E-Trac.
In regular ground (but moderately mineralized) I pulled a few more coins with the CTX over the E-Trac. It wasn't startling. My 95% number is actually a bit quantitative.

Thanks,
Albert

Johnny, , , , how could I not comment on this. Your scientific methodology is very good. Keeping variables as a 'constant' ... as much as possible.....(controlled environment) is quite difficult. Yes, there are many, many tests that can be performed; yet, what you have presented is a good/solid base-reference/base-platform unto which additional/amp data can be gleaned/extrapolated.
Having targets at the same altitude....... is indeed a 2-D plane.
Having the nail 1" higher than (yet; still to the side) of the coin... becomes a 3-D (more realistic) real-world scenario. Although this becomes more 'real-world' ..... it also then becomes more difficult for others to duplicate/replicate.
When the 3030 still retains a good VID on a certain desirable target when the audio (now) nulls......... I can hardly see/think this as a attribute. Keeping your eyes glued to a moving LCD screen whilst sweeping detector...... is just simply not possible. Bottom line: Audio is everything.
Kudo's on the elaborate/extensive (labor intense) write-up. (and well articulated).

What a read,... my brain is still trying to take some of it in,.... LOL

You have measured to a certain extent what our gutt feeling is, when we switched over from an e-trac to a ctx.
The designers probably have similar test beds for evaluating new "ideas".
TOP NOTCH !

I hung on to my e-trac for quite a while untill the CTX became comfortable.
I frequently took the E-trac to the beach, so was extremely happy when they revamped it into a CTX3030,... with indeed more options, more detecting capability.

Took me a while to brand my CTX3030 with it's first Scoop of sparkling approval,... thank you Minelab!

Most interestingly reported by your analysis is the fact that indeed ferrous and non ferrous in very close proximity will drag visual and audio TID down into ferrous range.
My unscientific, but curious in the field diggings led me to the same conclusion.

Which resulted in steel core coins and very few bottlecaps.

HH
Johnb

Nice work.

Ok, so the bottom line in all of this is you must run an open screen on a CTX if you don't want a null in iron. Disc will null a non-ferrous target on a CTX?

Awesome report. Many hours of work went into that presentation of information. Thanks for sharing.

Tip of the hat on that one....testing extremely well done.....

When you use DISC on the E-Trac and encounter iron (nails), which is common, the perpendicular nails will cause the TID to stop displaying (if the non-ferrous target is less than 3" apart), as the cursor is driven into the DISC'd area immediately by the presence of iron. However the audio report will give a two-way High-Tone (for a penny target) until the target separation is about 1/4", then silence. In testing, in order to still get the two-way High-Tone to report the target separation must be decreased so that at 1/4" separation between the nail and coin the sweep height must be under 1/8" above the coin.

In the real world we don't get to bring coins closer to the coil when searching. So, for the E-Trac with DISC pattern, with a sweep height of about 2" above the coin-nail, you will lose both the TID and audio at closer than 2-1/2" target separation. You'd never know there was a non-ferrous target present just 2" under the ground with one single nail present (forget about a dense nest of them). Now, with the E-Trac, if a single nail is allowed only to be parallel to the sweep, then you get different results: The TID remains functional (Fe numbers drop some but hold between 12 and 15) which allows the cursor to show a penny is present and the High-Tone audio is present with each sweep (mostly 2-way tone) at 2" above the coin until the coin-nail combo is less than 1/4" apart - at which point the High-tone breaks up or goes silent. That's a big difference. Parallel nail masks the coin when closer than 2-1/2" apart and a perpendicular nail does the same but not until they are about 1/4" apart. Masking is greatly reduced depending upon the orientation of the nail.

So, in a randomized bed of iron nails with a non-ferrous coin present - the chances are good that at least one nail (all it takes) is within 2-1/2" of the target - which means it is entirely masked at 2" depth. By changing your sweep angle (90 degrees) you may make a perpendicular nail appear more parallel and get some broken high chirp, but my testing indicates it is doubtful.

The CTX behaved as if it were the E-Trac2, same family. With the same DISC pattern, the CTX loses the audio at closer than 2-1/2" nail-coin separation at a 2" sweep height with a perpendicular nail. Just like the E-Trac the audio goes bye-bye. However, unlike the E-Trac which loses the TID, the CTX displays the TID until about 1" coin-nail separation (the E-Trac TID is gone if closer than ~3"). This is because the CTX has a more stable Fe value, less down-averaging by adjacent iron than the E-Trac. The CTX also displays a red triangle to show that there is a target in the DISC'd area while the E-Trac gives no hint a target is under the DISC'd area. Likewise, in the Open Pattern, the CTX keeps a more stable and reliable Fe value.

You might think the CTX would ID better at a greater distance above the coin, since it's newer and more expensive ... but not really. In fact, oddly, the E-Trac in Open Pattern was able to give a nice High-Tone at 2" above the coin-nail at close as 1" coin-nail separation but the CTX in Open Pattern wasn't able to give a High-tone when less than ~ 4" coin-nail separation. Obviously an Open Screen helps limit masking problems as the down-averaged Fe values still provide a TID. So, the E-Trac with Open Screen when dealing with the difficult Perpendicular Nail problem - will give a Two-Way High tone on the coin at greater depth and/or at smaller coin-nail separation than the CTX (CTX consistently gives a Low-Tone audio (iron)).

So, if you are in a field of iron nails, the best pattern is an Open Screen. The E-Trac will probably down-average the Fe values more than the CTX but the E-Trac will handle the Perpendicular nails better - giving the High-Tone whereas the CTX will only give a Low-Tone. The E-Trac will continue to give the High-Tone until the nail-coin separation is about 1" apart whereas the CTX needs about 4" separation to give a High-Tone (with both detectors sweeping a coin 2" deep). Again, we can't move the coin closer to the coil to regain a High-Tone (dig signal) under normal search methods. A coin in a bed of nails has a better chance of being heard with the E-Trac than with the CTX (it'll sound like iron which isn't likely to gain attention with all the other iron sounds).

So, overall, the CTX had better TID values - more stable and more accurate, and a bit more depth. However, it wasn't able to compete in the Perpendicular nail arena against the E-Trac - only in Open Screens. With DISC the two detectors up against a Perpendicular nail were about equal. And in DISC with parallel nails the CTX was superior.

If you only had the E-Trac or the CTX-3030 to choose from - the CTX would probably be the better choice. The one thing the CTX has that the E-Trac doesn't is the Combined Mode - which allows the audio to be programmed in audio bins. This allows the operator to use zero DISC and set the bins more intelligently than any audio patterns given on the E-Trac (like TTF or 4TF). Neither the E-Trac or CTX is very apt in a nail-strewn area - that isn't their forte. If you hunt those kinds of areas a lot then the F75SE/T2SE, Deus, GMP, Omega, Vista Smart, or a some other detector would be best (to include searching for gold jewelry along the beach or tot-lots - neither FBS detector had affinity for light gold rings/jewelry - again, not its strong suit).

One other note for those trying to decide - the CTX is about unviewable in sunlit areas - the screen washes out. In fact - I've become a better all audio hunter simply because the CTX screen is nearly impossible to see. I have no idea where the cursor is hitting, but the audio bins are fairly clear what it going on. The E-Trac black-n-grey screen had problems too - but was still viewable. Yes, the CTX is easier to swing due to the improved balance - but it's still heavy (actually heavier than the E-Trac). If you make many small sweeping motions to inquire over a target and do that often enough (such as in an iron littered area with a lot of falsing) the reversing of momentum will eventually tire out your arm/shoulder. The FBS machines are more like touring bikes made for the open roads (i.e., open fields).

The Fe-Co screen matrix is a great aid in fixing the identity of targets - in my opinion this is one of the FBS machine's best features. If I had to use a linear VDI again it would be only under protest. Both FBS machines have great depth and TID ability especially in mineralized soil that weakens the TID of most VLF machines. But it's all a trade-off between good, average, and poor features/performance that you'd have to think honestly about the type of hunting you would do. I would say the FBS machines are a good all-arounder for relic hunting, coinshooting, and in bad dirt - but then not the best even at these depending upon the circumstances.

What this all means is - if you are buying a detector - just buy something (don't fret about it endlessly comparing and watching videos and testimonials until you go insane). If you don't like it (try it for at least 100 hours to get accustomed to it and learn it) then sell it and move on. Detectors are like shoes - you need different ones for different purposes, most do the job pretty well, but sometimes they just don't fit your current needs.

Again...... exceptionally good report! Engineering level data. And this is the kind of data that separates performers from non-performers..... especially in site-specific applications.

Hi,,Hey Johnny that's a nice report you put together there, complete with charts etc.....I'm sure you put a lot of time,effort and thought into this....I may be wrong but it appears that you used a zinc penny? and not a copper penny?....Most of the machines I run in the field would want to kinda reject both targets at any angle of approach....Iron Vs Zinc not Iron Vs Copper........Perhaps the roundness and density is at work here and not so much the conductivity of the target..... Thanks for taking the time to do this informative report ....JJ

Way over my head but thanks I think dirt is a very important factor for me it is what is in the ground leaching, water, dry ground, heat, but it all together and it changes everything..

LowBoy

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Nice scientific test . A copper penny or silver dime might give better results with both machines ..... Of course a small gold coin would do worse I suspect.

All in all a fine report with ballpark results at best..Just tough to simulate objects that have been in the ground for years as leaching for one would effect the results just as an example and imagine learned forum members could add some more effecting factors.