Nulling - input needed

[ExpIInut]

Been using my MXT on some old pasture and have hit a baffler of a problem - now correct me if I'm wrong but with the machine in Relic mode - threshold just audible - discrimination on ZERO - and the trigger forward this should (and does) give a low grunt for iron and a high ping on anything else...with me so far?

I have been listening out for the mixed tone signals (no indication on Vdi) that indicate a deep target with some success - but why with the trigger in the central position does the threshold null even though its on ZERO discrim - or do these machines have some built in software whereby it's easier to null than identify

 

[MXTerer]

The way I understand it is with an audible threshold - with a target that is to deep for vdi or audio (high or low)- is that I should get a slight increase in the threshold. This does happen-most of the time-but on occasion my threshold just nulls.
It will be interesting to see what the replies are.

 

[Jeff-TN]

If your ground track is locked, your probably going over a spot of negative ground. For instance if your tracking is locked and the ground gets hotter (more mineralization) when you raise and lower the coil, you'll hear the threshold rise and fall. You probably wont notice it as much with tracking on as the detector corrects itself fairly quickly. I could be way off on this and maybe someone with more technical knowledge can correct me but I think I'm close. I have dug those spots before and there has never been a target found and that's the only thing I can think of. With disc raised up of course it is nulling out discriminated targets. Don't know if I helped or not, but my two cents worth,

Jeff

 

[ExpIInut]

I only notice it after finding a target - I am on some different land today (but still pasture) so will try and keep a record/mental note of what happens - one thing I am going to try is turning the discrim up to full on when the threshold nulls as I have a theory.