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Threshold Adjustment


TripleT

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Coming from Tesoros I have picked up a NOX 600.  I am use to setting threshold to a barely audible hum.  Then setting discrimination. The quieter the threshold hum, the better discrimination works. Or so it seems.  

So what exactly then does setting threshold do on the NOX?

According to the manual; it is used to notch out an item, like a nickel or penny.

Can someone please explain the differences.  And also explain that if I set the threshold on the NOX to a barely noticed hum what are the consequences?

Thanks

Terry

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3 hours ago, TripleT said:

Coming from Tesoros I have picked up a NOX 600.  I am use to setting threshold to a barely audible hum.  Then setting discrimination. The quieter the threshold hum, the better discrimination works. Or so it seems.  

So what exactly then does setting threshold do on the NOX?

According to the manual; it is used to notch out an item, like a nickel or penny.

Can someone please explain the differences.  And also explain that if I set the threshold on the NOX to a barely noticed hum what are the consequences?

Thanks

Terry

The threshold doesn't disc out anything, but it will allow you to  hear when you run across a target you've disc'd out, by the sound dropping off. I run a barely audible threshold, but, I do not run any disc at all. It functions the same as the Tesoro's threshold. I do not like running the threshold volume too high as it becomes annoying. There really isn't any "consequence" to running a barely audible threshold unless it's so low you can't hear what's going on under the coil.

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With the NOX I have yet to find the threshold of much use.  I guess I am so far missing something that others are hearing that is of benefit in identifying targets.

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Thanks Dan,

So, I guess my next question is: presets are set at "0" and it is recommended to use that setting.  However, the manual recommends that it be adjusted for optimum detection.

I am just a little confused at what appears to be a contradiction...

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From the manual"

Quote
Park, Field, and Beach Modes use a simplified type of threshold
tone, i.e. a 'reference' threshold. It is a continuous background
tone that will blank when a rejected target is detected. Without a
reference threshold, a rejected target detection would be silent,
and you would not be made aware of the target's existence

As stated it's a reference threshold which allows you to hear the nulling out of the audio over rejected targets. That is it's sole purpose, nothing more, nothing less.  Running a slight threshold when in all metal is an old habit I suffer from at times but really serves no purpose on the 800.

On the X-T 705 when used in iron sites I at times notch out the most offending iron number(s) and use the amount of nulling to determine the sensitivity setting. For example if upwards of 90% of iron tones come in at 6 notch it out and if this results in almost constant nulling then lower sensitivity to a level that reduces the deeper/fainter iron responses.  Whether this is useful or not on the 800 with it's ability to adjust iron audio level and iron bias settings I will have to experiment with.

Gold mode threshold is a different animal altogether.  Experienced prospectors spend quite a bit of time tweaking the threshold level to suit the site, their hearing ability and preferred headphones.  Perhaps Steve will chime in with some thoughts or links to discussions on how to set it up. 

 

  

 

 

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Thanks Jackpine,

It must be the new technology that I am trying to understand. Minelab uses threshold adjustment as a feature for users to "not hear" a notched out target (by the sound dropping out)?

Other than that, it's not really needed?

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Sounds like you are overthinking it. The manual does cover it well...

Park, Field, and Beach Threshold
Park, Field, and Beach Modes use a simplified type of threshold tone, i.e. a 'reference' threshold. It is a continuous background tone that will blank when a rejected target is detected. Without a reference threshold, a rejected target detection would be silent, and you would not be made aware of the target's existence.

For typical treasure detecting locations where there is often a large amount of trash in the ground, constant audio blanking may be disruptive.

Minelab recommends using a Threshold Level setting of 0 (off ) for Park, Field and Beach applications, unless you want to hear audio blanking.

25E1F38D-358F-4F6D-9FBA-C09E9BA1ACD2.jpeg

The threshold alerting you to rejected targets is very important when it comes to knowing what the target densitity is, which in turn governs your Recovery Speed setting.

Gold Mode is different and a faint threshold can enhance weak target signals, just like on the Tesoro’s and other units like them.

Gold Threshold
The Threshold for Gold Mode is a 'true' threshold tone that can be adjusted to improve the audibility of faint signals from small gold nuggets. Unlike a 'reference' Threshold, 'true' Threshold allows gold nugget signals to be emphasised in typically mineralised 'noisy' goldfield soils. Greater control of the target audio response may be achieved by adjusting the Threshold and Volume settings together.

Click image to enlarge...

846A4441-7120-4563-A830-562791EFE8EE.jpeg

 

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Thanks Steve,

I was  thinking threshold reference was the same as true threshold.  You put it into perspective when you tied it together with recovery speed. 

Cheers!

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  • 10 months later...

Just found the answer in another post, thanks Steve: "usually by running 50 tones with no items rejected, which means I really do not need the threshold tone since I hear everything. If I reject any items then I need the threshold to alert me to nulling effects"

******************************************** my old question ********************************************

 "Park, Field, and Beach Threshold
Park, Field, and Beach Modes use a simplified type of threshold tone, i.e. a 'reference' threshold. It is a continuous background tone that will blank when a rejected target is detected. 
"

Am I correct thinking that the word rejected in P, F or B mode means only a notched out target ID? And if the coil is swept over a faint target without any notching out, "threshold" blanking would not happen? And is that the difference in reference and true threshold?

 

Thanks!

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I have heard threshold blanking even in AM, so not sure if that is just a really weak target or noise attempting to break the threshold.  The way I read it this should not happen if nothing is rejected because if not in gold mode this is not a "true" threshold. I just ignore it as an anomaly.  Would probably not do that in gold mode, though.

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