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Ground tracking (old link)
Posted by: Rob (IL)
Date: November 15, 2014 03:35PM
Tracking
All right we covered the correct way to ground balance the V3i. Now that the detector has filtered out the ground signal we need to maintain that balance using the tracking options. Those two options would be Autotrac or LockTrac.
A proper GB should really be done before the AutoTrac is used to maintain that GB. AutoTrac does this by keeping pace with the changes in the ground and then adjusting the set point. The V3i AutoTrac system will eventually get you to that point if you don't ground balance. However, the further off you are, the longer it will take.
There are some settings to consider. I would make sure you have Inhibit - ON, so you won't track out a weak target when you make multiple passes over it. It is defaulted on so that the machine doesn't track when it sees a target. You don’t want the tracking to think your target is a change in ground and track it out.
Another setting is Report. This isn’t a track adjustment. Whether Report is set on or off is a personal preference. If it is on you will see a set of arrows that point left or right to indicate the detector is tracking and if it is tracking up or down. One reason to have it on is the arrows are a good indicator of when you have achieving a GOOD ground balance. You'll see the tracking arrows changing direction as you pump the coil. Also while hunting, if you see tracking come up too often you're alerted that you've wandered into a bad patch of ground, and that a filter change or even a "Track Lock" might be in order. If you don't want to be bothered with the tracking arrows turn Report off.
OK, our only adjustment is tracking speed. This determines how close or fast the tracking follows the ground. You can go too far either way with your tracking. A good tracking speed is one that keeps your threshold steady while you're swing the coil. If you set it too slow your machine may go silent and can cause a loss of sensitivity and lost targets. The tracking is trying to accommodate the mineralization changes in the ground, so too slow will allow the mineralization to generate excess noise. If you set it too fast your machine will try to match every little change in the ground and you'll get overshoot which can also result in noise and lost targets. The optimum tracking speed is the lowest speed that keeps your threshold constant as you're swinging.
Don't worry so much about tracking speed numbers, worry about results. If 20 keeps your machine tracking smooth with your swing speed, then you should use that. You can try dropping the number and if it gets jumpy, go back up. The correct number is the one that works best for you. If you have to err, a little higher number would be better than to err on the low side. Correlate mode seems to need a faster tracking speed than the best data.

Seeing your detector track intermittently is good. If you see excessive tracking your AutoTrac is too fast. Try various settings until you see your tracking arrows reduce to a reasonable number. What's that number? I really can’t say.


Tracking is the process where the ground balance baseline is maintained automatically by a sampling process. As the coil is swept across the ground, samples are taken and compared to the ground balance baseline. If the matrix (ground) signature changes from the baseline, the detector makes the necessary adjustments to the ground balance offset to keep the ground signal neutralized.

If you sweep really fast, you may need to increase the tracking speed to enable the machine to keep up. If you have AT set too fast, you'll hear a threshold "overshoot" as the detector tries to correct for every little change in the ground. If you have AT set too slow, you'll hear the threshold continuously drop out, as the machine can't keep up with the ground changes. "Overshoot" is a positive increase in the threshold volume. "Undershoot" is continuous threshold drop-outs. If you’re not hearing "overshoot" or "undershoot" you are OK.

You'd have to have a really fast tracking speed to cause the unit to miss even a deep target, so long as you have your Recovery Delay, Physical Sweep speed and coil size all working "in harmony". The V3i has the "horsepower" to support a relative fast tracking speed w/o any loss of depth. Bob uses a 50 tracking speed when he designed the Pro program. A "good" tracking speed is one that keeps your threshold steady while you're sweeping. I'd say if you have to err, err on the "high side".
The tracking is accommodating the changing ground conditions. Excessive tracking speed can result in noise and lost targets. Too slow can cause a loss of sensitivity and again, lost targets. Try various settings until you see your "tracking" alerts reduce to a "reasonable" number. I would also suggest that if your ground is so bad that you are continuously tracking, that you use Lock Track.

Tracking Speed, lower numbers equals slower track speed. The V is always tracking as long as auto track is on. The control adjusts the limit of how much it can track at one time. So, (example - numbers are not correct at all - just to give you an idea what's going on), say you have a ground signal that is off by 10,000 from where ground really is. If you have your setting at 10, the detector would track at the most by 20 at one sample. If your ground was off by only 8, then it would adjust by 8 as that's less than the limit. But at 10,000, it will be limited to 10 at that one data sample, whereas, a setting of 20 will track at most by 40 per data sample.
There are a lot of factors that come into play on how tracking is adjusted. Whether it has seen a target recently, how fast the ground is changing, the user adjustable track speed, and how close the ground setting is to the current ground. If the ground setting is close to the current ground, it will track to the current ground faster than if the current reading is far away (might be a target and don't want to track to targets).
The V3 to V3i Tracking fix???
Jeff Foster found that there was an offset when trying to balance for salt water. It was an attempt to get rid of that offset. I think having it with the original was better, and salt water offset could be corrected with the "manual" tracking offset.



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Edited 1 time(s). Last edit at 04/07/2015 12:18PM by Rob (IL).

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