Vanquish Automatic Noise Cancel On Startup And Sensitivity

[mcjtom]

That sounds like an idea - maybe it internally increases the sensitivity when noise cancelling already? 

Would EMI noise cancel be also related to the recovery speed (I guess the return signal sampling rate)?  In other words, since the modes on Vanquish differ in recovery speed, would noise cancel procedure choose different quiet set of channels depending on the Mode, or perhaps it doesn't matter, but one of the modes (Coins, with the shortest recovery speed?) be the one that would amplify the EMI the most and therefore help to detect and reduce it?

I tried to find some posts related to this at Tom Dankowski's board, but I'm still not quite sure...

[mcjtom]

On 12/8/2021 at 1:26 AM, phrunt said:

You'll never get to understand how it works, just follow the theory of higher gain gives more chance of tuning out EMI as it is affected by more EMI and you should be fine, it's what that article alludes to also.

I've been doing highest sensitivity noise cancel on my VLF's and I think it does a good job.

Looks like the ‘Pascal’s wager’ is the best course of action…

[Chase Goldman]

This is such an in the weeds factor, I would stop trying to wrinkle your brain pondering it, especially in regards to considering the modal nuances.  Vanquish is basically trying to take stab at an auto noise cancel during initialization to ostensibly choose the best operating channel.  Basically it’s the next best thing to doing nothing at all.  Under most circumstances the reality is that several channels will exhibit noise floors that are acceptable so as long as it picks one of those, you are good to go.  If you are not satisfied with the level of chatter after its initialization sequence is completed, then simply cycle the power switch and try again.  If it’s still to chatty, then your only real recourse it to cycle through the modes to see if one is noticeably more quiet, otherwise, you are simply left with reducing sensitivity to quiet down the machine.  
 

Trying to “game” the system by cranking sensitivity and the like is probably not really doing anything because it is not a noise reducer, it’s just picking the least noisy channel by comparing each channel’s noise threshold, so sensitivity doesn’t really matter as long as it is at or near the default setting.

Equinox provides a more sophisticated noise cancellation routine that, unlike Vanquish, IS specific to each operating mode or operating frequency.  GL HH

[phrunt]

that's a very matter of fact post 🙂

It maybe in my head, although I doubt it.  Increasing sensitivity to maximum before noise cancel appears to help.  Give it a try sometime when you're in bad EMI with a Vanquish.  If you have out of control EMI crank that sensitivity right up and power cycle it and then return the sensitivity where you were prior and see the difference.

[Chase Goldman]

Simon - I got rid of my Vanquish so can’t do that experiment, unfortunately.  

Assuming it is doing a channel scan as described (similar to Equinox) it should be doing it from an auto set sensitivity during initialization that is high enough to be able to detect the noisiest channel and eliminate it.  I think ML’s prime objective (especially with Vanquish) is to keep such processes as simple and idiot proof as possible.  All that could be considered conjecture though, so let’s go to the authoritative source of information and see what the Vanquish manual says about noise cancel (p. 7):

Automatic Noise Cancel
VANQUISH Series detectors have an automatic Noise Cancel process that occurs every time the detector is powered on. It calibrates the detector so that excessive noise is not experienced.
For best results, the coil should be held stationary just above the ground until Automatic Noise Cancel is complete (indicated by two large dashes displayed on the Target ID Number field).

If ML thought that the operational sensitivity setting actually mattered as part of optimizing the noise cancel process for Vanquish or Equinox, then wouldn’t it be in ML’s best interest to explicitly instruct the end user to use max sensitivity and not keep that a secret?  It seems they are focused on ensuring the “best results” are achieved as indicated by the explicit instructions about how to hold the coil during the process.  Yet they are silent on anything having to do with the sensitivity setting. Why is that?  I’ve personally concluded it is because it makes no difference to achieving noise cancel “best results”.

By all means, if you perceive a benefit in maxing out sensitivity, then you should definitely do that because it certainly does no harm and I am a firm believer that to be successful you need to have full confidence in the capabilities of your detector.  I simply have doubts as to whether it has any real benefit based on simple logic and cursory technical knowledge on what the machine is doing during the initialization/noise cancel sequence.

If experiencing noise during operation, ML provides the following guidance which basically mirrors what I wrote previously in a prior post:

Excessive Noise
Sometimes, excessive noise is encountered whilst detecting. This can be caused by environmental electromagnetic interference (EMI) from sources such as power lines, mobile phone towers, or other metal detectors.
If noise is a problem, try the following steps in order until the noise is eliminated.
1. Move away from local sources of Electromagnetic Interference (EMI).
2. Restart the detector, and wait for the automatic Noise Cancel process to complete.
3. If restarting the detector does not eliminate the excessive noise, then try reducing the Sensitivity Level.

Nothing about maxing out sensitivity before you cycle power to execute the Auto Noise Cancel sequence.

Anyway, that is just how I see it.  I can’t prove it in a court of law, I suppose.

[phrunt]

You do have a GPX don't you? Try it on that, maximum sensitivity makes a pretty obvious difference in high EMI with the GPX 4500/5000.  The manual doesn't say so, the results do.

I might be right, I might be wrong but I'm not going to tell people they're wrong when I don't know myself.  It certainly can't hurt to do it, and if it does improve things great, if not it wastes a second of your time.  I see a benefit doing it with my Vanquish, so that's good enough for me.  I can stand under power lines with my Vanquish and prove to myself it makes a difference.

Also Phil Beck from Minelab did this Treasuretalk on the very point of discussion, although it was with the GPX.

https://www.minelab.com/community/treasure-talk/four-tips-to-help-your-detector-auto-tune-or-noise-cancel

Info for the GPX seires.

Change settings to enhance noise if required. If operating at a lower gain or in Cancel mode it may be advantageous to increase the gain, or switch to Mono or Double D mode. Similarly changing the Motion setting to a faster setting will allow any noise to be more easily located by the detector. You can safely switch these settings back after the Tune is completed.

Enhance any difficult noise sources. If you are still able to hear some remnant interference after an Auto Tune then you may need to move the coil to enhance those signals either by turning around to face the noise source or by tilting the coil away from horizontal. Remember that large signals will be located and avoided easily. It is the small and intermittent signals that are difficult to locate.

You'll also note Nenad in the comments at the bottom of it pointed out cranking the gain up helps, although Phil had already indicated that in his article.

The manual for the GPX doesn't mention this.

[Chase Goldman]

1 hour ago, phrunt said:

You do have a GPX don't you? Try it on that, maximum sensitivity makes a pretty obvious difference in high EMI with the GPX 4500/5000.  The manual doesn't say so, the results do.

I might be right, I might be wrong but I'm not going to tell people they're wrong when I don't know myself.  It certainly can't hurt to do it, and if it does improve things great, if not it wastes a second of your time.  I see a benefit doing it with my Vanquish, so that's good enough for me.  I can stand under power lines with my Vanquish and prove to myself it makes a difference.

Also Phil Beck from Minelab did this Treasuretalk on the very point of discussion, although it was with the GPX.

https://www.minelab.com/community/treasure-talk/four-tips-to-help-your-detector-auto-tune-or-noise-cancel

You'll also note Nenad in the comments at the bottom of it pointed out cranking the gain up helps, although Phil had already indicated that in his article.

The manual for the GPX doesn't mention this.

That great info, Simon.  Thanks for the link.

But please take the time to read my response carefully.  I am NOT telling anyone not to do it. I never told people they were “wrong”.  In fact, I explicitly said do it if you think it does make a difference because it does no harm.  So please, do not imply I ever wrote that people should not do it or that people who disagree with my position on the subject are wrong.  I'm simply putting my thoughts out there and stating my case with my reasoning and folks can take it or leave it.  It’s really not a "he’s right and she’s wrong" issue unless someone from Minelab weighs in explicitly on the Vanquish.

Again. I personally think it’s a down in the weeds thing and with my GPX have had no issues with channel scan in very high EMI environments keeping my sensitivity at my desired operational setting.  For noise cancel, regardless of detector I use, the feature doesn’t have to select the quietest channel, it simply has to get me to an acceptably quiet channel consistent with the gain setting I plan to use while detecting, and that is almost never Max sensitivity.  I personally do not think it is good practice to max out gain for the purpose of a channel scan because I believe it is an unnecessary extra 2 steps (which is especially cumbersome on the GPX user interface) and because I rarely operate at max gain, run the risk of not readjusting gain back to the desired operational setting before setting out causing more delays or potential missed targets due to saturation.  But perhaps I am missing something and not getting my GPX optimally set up to the gnat's eyelash so I will look into the info you provided.  I do think that if it DOES matter, ML instructions should be more explicit/complete and I also think comparing a $4000, ultrasensitive PI detector to a $350 VLF is somewhat apples and oranges but appreciate the situational similarities in your GPX vs. Vanquish example. 

Anyway, moving on because I’ve spent more time typing on this subject than I’ve cumulatively spent in the field obsessing over noise cancel.  So I need to go back and introspectively reassess my priorities.  

[phrunt]

All good, EMI is something I have a lot of trouble with and have to deal with constantly and mostly why I upgraded my GPX in the first place to the GPZ is it is far better in high EMI areas, I have a 4500 and 5000 and find the 5000 reasonably better for EMI than the 4500.  I've found the Vanquish works very well in high EMI, and I've done what I need to do for it to work well for me in these EMI areas which is my noise cancels in highest gain so I'm talking from someone dealing with the issue regularly, not speculating or educated guessing.   I find the Vanquish to be excellent in higher EMI areas, the elliptical coils may help but often I struggle less with it than the Nox.

With the GPX I run it as close to maxed out on sensitivity as conditions permit as I'm chasing tiny gold so every notch on that gain control makes a difference. 

I would say based on personal experience people should go to highest sensitivity before doing noise cancels if they're in a troubling area for EMI to try give themselves the best chance of mitigating it.  With the Vanquish and Nox I run them maxed out or one segment off maxed most the time anyway so I don't need to do any extra fiddling.   Similar to my GPX and GPZ, it's usually right up near max if not maxed out so I guess Its easier for me to do the high gain noise cancels than someone that hunts in lower sensitivity.

[DSMITH]

I have been away from the site for quite a while now and have been reading through some of the post started reading through this post

phrunt turning the sensitivity all the way up on the vanquish before noise canceling is impossible to do, the same for the gold monster unless it stays on the last setting that you may have used not sure if the Vanquish reverts to the last setting you were on or not but on the vanquish and the GM 1000 the vary first thing either of those machines do upon power up is the noise cancel and then you are able to make the other adjustments that is the way I understand the start up procedure of the vanquish and the GM 1000 someone please correct me if what I state is not correct

[phrunt]

yes you're wrong, well you're wrong and right.  All you do is have the sensitivity on either the GM or Vanquish on maximum when you turn it off, when you next turn it on it's still in maximum sensitivity thereby doing its noise cancel while in maximum sensitivity.  Both detectors retain their settings when switched off.