More on Auto vs Manual Sensitivity......long but hopefully worth the read

[Beachcomber]

I spent the day at the beach with the E-Trac today. No gold but some more information about detector operation. With all the discussion about detector depth, Manual Sensitivity, and Auto Sensitivity I took the E-Trac to a beach with little or no mineralization but with sections that had high trash content and areas with very low trash content. When I got out on the beach I did a factory reset to get back to all the default settings. Then I changed it to the Beach Program. I also maxed out tone variablility. The Gain for the beach program is 24 so I left that where it was. I also changed the Audio Mode to Smooth because I never cared for the flutey tones. On the Explorer I used to hunt in Audio Mode 2. The Beach Program also turns both Deep and Fast to Off. It sets the Ground to Normal and the Trash Density to Low. I left all those settings alone. I did a Noise Cancel and started to hunt. When I started the Auto Sensitivity was at 16 but in no time at all it was up to 26 and I was even able to go up to +2 before I got any falsing. I proceeded to hunt this way and was digging quite a few targets some in excess of 12". At this point I decided to switch over to Manual Sensitivity. The machine suggested that I use 22. I decided to try 27 which is one notch lower than I was hunting in Auto. The machine went crazy making all kinds of sounds and falsing like crazy. So I lowered the Sensitivity. The machine didn't settle down until I got down to 23 and was nice and quiet at the recommended setting of 22. I hunted in Manual for awhile and was digging targets without any problems but I like to have as high a sensitivity as I can effectively use when on the beach as depth is king. So I switched back to Auto and kept hunting at 26 +2. I gradually worked my way over to where I knew the trashy part of the beach is located. As I approached the area the machine started nulling as it started rejecting discriminated targets. I kept and eye on the Sensitivity and sure enough it started getting lower and lower. It finally settled into 20+2 in the trash. Now I switched back to Manual. In manual it was still recommending 22 so I sent it to 22 and it worked fine. I was even able to raise it to 23 without any appreciable increase in falsing. At 24 it started getting very noisy so I backed it down again. So now I know for sure that trash levels do in part affect the Auto Sensitivity Setting but NOT the Manual Sensitivity setting recommendation. Also all this is the opposite of what the Manual says when it comes to Beach Hunting. I do have a theory though. In the Manual it states that the E-Trac monitors 3 channels (what 3 channels I haven't' got a clue). It also states that in Auto Sensitivity the detector adjusts the level of sensitivity applied to each of these 3 channels independently of one another to achieve the highest Sensitivity possible while maintaining stability. It also says that when the detector is in Manual Sensitivity that all 3 channels are locked together at the same value and that when we change the Manual level we are changing all 3 at the same time and in step with one another. To me this explains whey the machine was falsing when I adjusted the Manual Level to the same high level as Auto had set. Whichever of the 3 channels that the Manual setting was taking too high the Auto Sensitivity had lowered while raising the others up to 26 and maintaining stability and depth. Since I am pretty much the only one here using an E-Trac on the beach I would be interested in hearing waht happens at an inland location under roughly the same conditions. According to the Manual the best setting for the Beach is Manual Sensitivity and the best setting for inland is Auto. But my own results so far indicate that Auto seems to work better at the beach than manual as least in respect to allowing the machine to run comfortably at higher levels of sensitivity. So since this is the opposite of the manual I am curious to see if Manual is better on land and Auto not so good which again kind of goes against the manual. Who knows maybe they wrote the manual they got ti backwards. Anyway I hope that someone with a fairly low Mineralization and an area that has sections that are both trashy and clean will run a similar test and report on it.

HH

Beachcomber

 

[Chris(SoCenWI)]

Pretty sure the earlier explorer models work the same. Wondering if if is the exact same algorithm in the old ones as the Etrac? Must be close.

Chris

 

[Beachcomber]

My Explorers work the opposite of the E-Trac when it comes to Sensitivity setting for the Beach. In Auto the machine is eratic but Manual works fine. Go figure.

HH

Beachcomber

 

[Jim upstate NY]

I noticed that on the explorer, the deep targets would thump in auto, like it was trying to see the target but adjusting at same time.. never ever used auto on the explorer.. I havent noticed that thump on the etrac, but maybe the etrac just lowers it more so you dont.. I know I refuse to hunt in sens 4 I havent seen a target yet that reads in auto and not manual.. I hunt iron slow anyway.. and as long as you go slow you will hit on the same targets and better in my opinion.. I have switched to auto and had signal decrease but not totally lose it yet either.. but I am not getting many targets to test in the first place,

 

[Beachcomber]

I think you are right Jim. If you are in trash and mineralization it is probably adjusting way too low and in that case setting it manually will do a much better job for you!

HH

Beachcomber

 

[Charles (Upstate NY)]

Do you think its backing way off the small gold sensitivity? That's what spooks me about this auto adjusting three channels independently. If its throttling back the high frequency channel I could see the machine being more stable, but then who knows where the small gold high frequency sens is, maybe its 10.

 

[Beachcomber]

Hi Charles,

They don't go into much detail about what the 3 channels are so I don't know if they are 3 different frequencies or something else like the noise channel or ground channel...only Minelab knows for sure I don't think they like us to know too much as then it would be too easy to set the detector for best performance But to answer your question i was still digging a lot of small targets like brass washers, the tab part of a pulltab, and other small pieces of metal. Both hoop earrings in the pix were open when found so just appeared as a piece of wire to the detector and were easily detected. The small post earring in the far right of the pix has very little metal to it but able to be detected so it didn't appear to have lost sensitivity to small targets with the Sensitivity set to Auto. Based on what land hunters link yourself have found using Manual Sensitivity and what I am finding out on the beach with Auto vs Manual Sensitivity I think the manual got it backwards and that you need to use manual sensitivity when land hunting in trashy mineralization areas and on a Saltwater Beach with Low Mineralization and not a lot of trash run in Auto Sensitivity. As with anything in detecting there are no hard and fast rules. Things are different from site to site and you need to learn to set the detector to the best settings for that particular location. It's always an on going learning process. I know you were doing great on fairly small gold and chains with the SE last Winter and I hope that this machine turns out to be as good as the SE in that department as well as in overall depth as you were pulling out some very deep targets with that SE of yours. I have only used the XS and the II but never had an SE so I can not make comparisons of depth or sensitivity to gold compared to an SE. You will be the better judge of that.

HH

Beachcomber

 

[Jackpine Savage]

or just make it noisy? Also, does the gain setting effect what auto will run at. ie: if you lower the gain will auto run higher?

Tom

 

[Chris(SoCenWI)]

n/t

 

[Beachcomber]

n/t

 

[Chris(SoCenWI)]

n/t

 

[digitrich]

because my ETrac doesn't seem all that much of an improvement over my SE's. Of course I am talking about a machine I just mailed off to Minelab My SE's always seemed pretty stable and well behaved around EMI. I have one site in particular where the farmer has an electrical fence sending out random low electrical pulses. It made both my SE's absolutely unusable in that area, when I get my ETrac back, if it works there, then I will be incredibly impressed. I doubt it though, my F-75 couldn't deal with it either.

 

[jbow]

for those who just happen to read this post and may miss the other, there was this about the three sensitivity channels...

Q: What are the three sensitivity channels? Are they three frequencies?
A: They are not frequencies. As described in the Instruction Manual (page 54), the E-Trac has three dedicated sensitivity channels for small, medium, and large signals. These channels are essentially seperate hardware circuits. During operation, when the Auto sensitivity mode is selected, the E-Trac algorithms calculate the "optimal" sensitivity value that guarantees optimal detection of all three signal types. This "optimal" sensitivity is presented to you as the "Suggested Sensitivity". By default, the value of the Suggested Sensitivity will ensure stable operation. The user has a choice to make the Suggested Sensitivity more "aggressive" by selecting +1, +2, or +3 options.
Manual Sensitivity on the other hand, sets detection thresholds for all three target channels to your chosen value and is locked.

J

 

[jbow]

My understanding is that the three channels are new to the ET.

J