frequencies?

[daddyflea]

Or you could buy a Whites V3i that transmits and displays 3 frequencies at the same time displaying them in color coded lines.

 

[hunter_46356]

This thread has got me thinking. The Etrac allows auto and manual noise cancelation, choice of 11 different channels. Done automatically with the coil held a foot off the ground the unit chooses the best channel in regards to the local EMI. With the coil off the ground I assume the trac can't tor doesn't est the mineralization of the ground along with the EMI. While in auto sensitivity the Trac sets itself according to the ground. This function only changes the sensitivity not the channel. From what I've read high conductive targets are better located with lower frequency operating detectors. This is an assumption cause I don't really know it's just what I've read. If this is true and you are specifically looking for silver coins (high conductive targets) wouldn't it make sense to choose a channel that transmits a lower frequency as long as the EMI is low or reasonably acceptable? I have no idea what frequencies the available 11 channels transmit and not sure this info is even available. But if it is and you are looking for specific high conductive targets and can choose the best frequency to be able to do this. Wouldn't this give you a bit of an advantage? My test garden sucks cause I didn't clear enough of the trash targets in the area. Not sure an air test would give you solid answers to this question either. I guess best test would be to try changing channels on a relatively sure target in the field and see if there are any of the available channels that respond better. Is Noise cancelation a specific function of EMI only or can it choose the best channel for ground conditions as well? If you are in a low EMI area why couldn't you hold the coil to the ground to allow the Etrac to choose the best channel according to the mineralization? If it would work like this Etrac owners would theoretically have a multi frequency detector with 11 available channels. Any thoughts on this or am I just dreaming.Too good to be true I bet.

 

[Larry (IL)]

The E-TRAC and Explores have automatic ground balance and the CTX 3030 has both automatic and manual.

Noise cancel is just that, the E-TRAC is automatically cycling through many SLIGHT frequency change combinations looking for the least EMI. It is a process that is manual on other detectors. One example is the Tesoro Cibola where it has a switch and you can chose 14.3, 14.5 or 14.7 KHz. The primary is 14.5 and the others are called offset frequencies. Your E-TRAC may have a primary of 1.5 KHz and offset frequencies may be 1.6, 1.7, 1.4 and 1.3 KHz. The second Primary frequency might be 2.5 KHz with offsets of 2.4, 2.3, 2.6 KHz. and so forth. A channel is just a combination of any of the operating frequencies like 1.6 and 2.4 or it could be 1.3 and 2.6 or 2.3 and 1.7......... endless combinations but Minelab thinks 11 channels are enough.

If you really want to know how metal detectors work, a very good read is Inside the Metal Detector by George Overton and Carl Moreland.

Another great two page read on multi-frequency, is the first two pages of the owners manual of the V3i written by Carl Moreland.
http://www.whiteselectronics.com/media/downloadable/files/samples/s/p/spectra_v3i_instruction_manual_1.pdf

 

[NiagracountyNY]

I tested a handful of gold rings /ear rings /and chains between my ctx 11 inch coil(FBS ).....E-trac 5 inch excelerator coil(FBS) Nokta Fors cor 11 inch coil(induction vlf). The ctx and the E-Trac missed the ear rings and the chains.The e-Trac could get them if i rubbed them right on the coil...just get them. Now the Induction vlf For's cor picked every item up ..even the tinest ear ring from 6 inches air test np.The Fors core uses 17.5 khz i believe. So for small gold and chains u may wanna have something in your arsenal other than fbs. I think 4 detectors are needed for my personal taste depending on the hunt. CTX for water and cherry picking.The fors cor is super fast like the dues...I use it in heavy iron for the extreme seperation speed.Im still shopping for my Deep seeker ( blisstool v.5 or Makro cf77--Both vlf machines 15 khz i think).And a gold machine which i also don t have yet lol..(Not much gold in NY state in the raw form).....I currently have several machines...need to start selling them off i guess...CTX 3030,E-Trac,Nokta fors cor,Garret GTI 2500,AT pro,Ace 250. Not worth selling them for a loss tho.Good for friends and the grand kids i figure.

 

[hunter_46356]

Larry thanks for the info and reading material. Will take a look at it. Ironsight and I had a similar discussion and his explanation of channel shifting /splitting was similar if not the same. Guess my interest regardless of how or what make this tick is can it be used to improve finding coins. Trying different channels in the field should give some clue ......or not. Thanks

 

[Larry (IL)]

Of those who have tried manual noise cancel channel selection, most say no difference in depth. There are some who differ but there are also those who think a sugar pill makes them feel better too.......

 

[ironsight]

Hunter, if you're going to try the experiment thing with noise channel vs. the best coin detection, i'd recommend burying the coins instead of air testing. Its important the test bed is located in an area that has no EMI interference which would skew the test results for some channels likely rendering the whole exercise useless.

As i indicated earlier, some swear certain channels are deeper seeking for specific targets and/or soil but i haven't seen that albeit never actually tested for it.
I would think you'll find little to no difference as i don't know this for a fact but i suspect the xmit frequency bandwidth doesn't shift enough to make a gigantic difference in depth or specific target ID.

The most important thing to consider with noise channels, is to use a channel that is the quietest especially in a high EMI area. I typically AUTO noise cancel in hi EMI areas and call it a day. The quietest channel in those areas will give the best depth and IDs regardless of target or soil conditions.
The reason for raising the coil during AUTO noise cancel utilizes the fact that for a lack of better words, the coil can act as a defacto 'radio' antenna to better receive and process any EMI radiation in the area to be detected.
Ground canceling on the other hand is a function of FBS technology. While i can half way see how changing xmit frequency bandwidth could affect ground canceling for some soil conditions i think the effect would be minimal, barely or not perceptable to the user. Again i never experimented with this, just guessing.

If you go ahead with some testing we'd all appreciate posting the test description and results. Who knows, maybe some of us will be surprised!
IMO, the only time you can manually pick and choose a noise channel is in a very low to no EMI area then have at it sugar pill or not.

 

[hunter_46356]

Ironsight, I realize air testing would not be the best test. In fact I have a problem attempting air test since my home and yard is situated in a subdivision as such that I can't get away from EMI. What I did do last Thur. was to manually choose a several different channels and run over my test garden anyway to see what I could come up with. Auto noise cancel came in on channel 9 and as it should it was the quietest channel. Like I said EMI interference should be terrible as I have a transformer and main power line to home that crosses my backyard. I have been plucking around this yard for almost four years. other than the three coins I've planted. I was certain I found any and all coins that could possibly have been back there. Hunted it with BH 505, AT Pro and my Etrac. Sensitivity set to manual 19 (Auto also choose 19) Deep On, Fast Off. Multi/Co.The thought was to find a lower channel assuming maybe a lower freq. I checked several channels on the test bed and channel 6 seemed to be able to handle the EMI and run pretty stable. My back yard is very small and have a fare amount of trash targets. Mostly foil, bits of aluminum from siding, nails and typical trash found around most homes. Surprisingly within 15 min. I dug one wheat, three zincolns and two clad quarters. Wheat was about six inches the rest were shallower. There is no way I should have missed these before. I do understand that this could all be a fluke and not getting super excited but something made a difference. Will try this manual channel changing in the field when I find a "for sure" coin target. Don't think any of this is going to increase depth but it may just improve separation in trash. Who knows.