Emi Vs Smf

[midalake]

9 hours ago, Chase Goldman said:

Agree, Dave.  But let’s not forget that the original topic of this thread was how to combat EMI.  Any recommendation on reduction in sensitivity setting (at least on my part) was solely focused on mitigating EMI, not ground noise

Ya, what I wrote was not pointed at you. I was skimming and just decided to tell it how it works in the Black Sand playground. 

As someone who noise cancels in front of every hotel/building. You either have EMI or not. Yes, some detectors are better. Sometimes I noise cancel if there is a difficult target.  Nothing earth shaking but sometimes I think there is a better look at that target after a noise cancel reset. 

I was never a big proponent of onsite testing. When the D2 arrived, everything changed. I will never run a new detector without fringe testing. Even then> test again, after tweaking settings after a few months. Happy holidays, Hugh.  

[Chase Goldman]

35 minutes ago, midalake said:

Ya, what I wrote was not pointed at you. I was skimming and just decided to tell it how it works in the Black Sand playground. 

As someone who noise cancels in front of every hotel/building. You either have EMI or not. Yes, some detectors are better. Sometimes I noise cancel if there is a difficult target.  Nothing earth shaking but sometimes I think there is a better look at that target after a noise cancel reset. 

I was never a big proponent of onsite testing. When the D2 arrived, everything changed. I will never run a new detector without fringe testing. Even then> test again, after tweaking settings after a few months. Happy holidays, Hugh.  

Thanks.  Happy holidays and happy hunting, Dave.

[HardPack]

Ain’t Christmas yet. Headed out tomorrow morning with my notes in hand. What’s fringe testing?

[midalake]

1 hour ago, HardPack said:

Ain’t Christmas yet. Headed out tomorrow morning with my notes in hand. What’s fringe testing?

It is just knowing the max depth of a detector in your conditions.

WITH settings that work in your location. 

It encompasses the range of the detector past normal TID depth.  [my definition]   

[JCR]

12 hours ago, midalake said:

It is just knowing the max depth of a detector in your conditions.

WITH settings that work in your location. 

It encompasses the range of the detector past normal TID depth.  [my definition]   

@HardPack This is the dedicated approach to what I suggested.  If on your bad EMI site, you have to go down to “10” or whatever low number of Sensitivity to run stable enough to detect;  know what that low setting will achieve. Then hunt with confidence.

[HardPack]

Took the ML EQX 900 back to EMI site today. The powerhouse and overhead high voltage towers could be seen four miles north across canyon from the site. Modern trash: brass shell casings & lead bullets.

Set the ground balance to tracking (GB 40’s), volume 22 for all tests. Starting in search mode Park 1, noise canceled with Sensitivity 0, Tone 1, Recovery 0. Adjusted the Sensitivity until the EMI level became audible at Sensitivity 10. Adjusted Sensitivity to 16 then increased Recovery to 4. The EMI audibles were spaced, intermediate but workable in Park 1.  Switched tones from 1 through 3, 5 & At with no observed change in EMI level. Stayed in At-All Tones for the remaining tests. Started detecting adjusting to Sensitivity 18 and Recovery 5 with noise cancels with each setting change. EMI audibles were closer together but still workable. Throughout the day cycled through search modes Park 2, Field 1 and Field 2 at Sensitivity 16/18 Recovery 4/5. EMI audibles were workable in all search modes above. At Sensitivity 20 & Recovery 4 or 5 EMI levels were at the edge but still workable; Sensitivity 22 and above EMI levels were not workable. Did not search for any length of time in Gold 1 & 2, EMI audibles were very close, loud, difficult to hear targets. EMI levels may have been lower when the coil was sweeping near the ground but the EMI audibles could still be heard.

Target depths for non-ferrous ranged from near surface to 4 inches (brass & lead); 3-4 inches ferrous square nails; 6 inches for 3 square inch ferrous (cast iron), did not dig rusted cans. Soil depths varied from tight/shallow on the flats to loose/deep hillside soils. Bedrock: black slate. Coil: 10x5 Nox Coiltek. Headphones: none.

Find of the day a 40 caliber lead ball.  Thank you all for the suggestions.
 

[HardPack]

Returned to detect the  EMI site today. Started the day with Park 1 in the single frequencies, recovery 3, iron Bias 1. From 4kHz, 5kHz, 19 kHz & 15kHz. The EQX 900 was quiet. Had to switch to All-metal to make sure the detector was “On”. Did hear a few false positive signal in Discrimination. Ran the Sensitivity to 26 before picking up any EMI. At 20 kHz had to back off the sensitivity 22, at 40kHz the EMI was loud and clear Sensitivity 18. Did notice the EMI stopped with the coil in motion. Ground Balance 40, coil: 10x5 Coiltek

Detected the remainder of the day in Multi-Frequency, Sensitivity 24, Recovery 4, Iron Bias 2. The EMI was jumping but decided to run hot. Ran through Park 1, Park 2, Field 1, then settled on Field 2. Again the EMI stopped when the coil was in motion. Plenty of false positive signals over iron. On the hillside picked up 8 intact 40 caliber (10mm) lead balls, 1 intact 44 caliber (12mm) lead ball, a piece fine wire and 2 half inch square pieces of metal which were not magnetic, pewter maybe, several modern lead bullets 22 to 30 caliber. Depth varied from 4 to 6 inches. Ground balance 40, Coil: 10x5 Coiltek

[JCR]

Sounds like progress.

[HardPack]

8 minutes ago, JCR said:

Sounds like progress.

Yeah, I’ m trying the EQX 900 stock 11 inch coil on the old tent flats later today. Lots of down trees and brush. See how it handles the EMI. Been searching the web for a 40 caliber percussion cap rabbit gun. No luck so far. 

[Digalicious]

13 hours ago, HardPack said:

Did notice the EMI stopped with the coil in motion. 

 

It is for that exact reason, that I learned to live with SMF / EMI, instead of switching to a SF with notably less target ID accuracy.

 

13 hours ago, HardPack said:

 

Iron Bias 2. Plenty of false positive signals over iron. 

Was that low iron bias deliberate for some reason, or do you normally run the IB as high as necessary to avoid iron falsing?