Filters And VDI/Depth Changing

[5900_XL-1]

I've noticed this a few times and never made note of it but I found it again and decided to ask a question. Before I start let me say that I've run the 5-Band Pass filter 99% of the time on the V3i.

I have a simple clad quarter buried down at 6 inches in my yard. It's always been pretty solid on the display in Disc and pinpoint, showing close to 6 inches in both modes. Well, I went there today to test for a different situation but in the process, I realized my VDI on the quarter was showing 88-90 and 11 inches. I found the filter was set at 10 instead of 5, I've began using the higher filters for increased sweep speed.

So, I GB-d for sanity, rechecked and it was still reading 88-90 at 11 inches. I then dropped the filter to 7.5, balanced and depth then read 9 inches on this 6 inch quarter.

Not until I went to the 5 band pass filter did I get the accurate depth and 83 VDI and 6 inch depth readings back.

How can simple filter changes make such a difference?

 

[Rob (IL)]

The depth meter is simply a signal strength meter. For your ground the 5 filter gives the stronger signal and therefore reads as a shallower coin. The 5 filter,as a stronger less filtered signal it is more accurate.

 

[5900_XL-1]

Thanks Rob. I've discovered a few things today. I was testing my trustworthy 8x6 SEF, using the 950 coil selection, as I've done for forever. It read fine at 5 Band, then strayed at each higher filter. The 5 Band filter, as you stated, is very forgiving at the fundamentally shallower, but the higher filters skew depending on the setup in the V for a particular coil selection.

Anyway, I was alerted to this today after I thought I still had a problem after installing the 4x6 Shooter. I hadn't changed in setup from the SEF choice of 950. The OEM 4x6, when setup right, was linear. The SEF was changed to 6x10 in coil setup selection, and it was far more linear at all filters. I understand more than I did before concerning setup on these OEMs.