Find's Treasure Forums

Welcome to Find's Treasure Forums, Guests!

You are viewing this forums as a guest which limits you to read only status.

Only registered members may post stories, questions, classifieds, reply to other posts, contact other members using built in messaging and use many other features found on these forums.

Why not register and join us today? It's free! (We don't share your email addresses with anyone.) We keep email addresses of our users to protect them and others from bad people posting things they shouldn't.

Click here to register!



Need Support Help?

Cannot log in?, click here to have new password emailed to you

Changed email? Forgot to update your account with new email address? Need assistance with something else?, click here to go to Find's Support Form and fill out the form.

EMI Question Rob ??

Elton

New member
It reads in several places in the Regular and super manual (I call it that) the sure, and easiest way to over come EMI is a simple offset adjustment.
While holding the trigger in pinpoint mode adjust the offset.Lower Rx if it still is an issue...

How does that work in the REAL WORLD ??..is it effective most times.. It also says turn up TX Boost if you need more depth.. TX Boost is not effected by EMI ( Manual ) ...

If Tx boost ups the coil output 30X how can it not be affected ?? Is the 30 times more concentrated power at full max TX Boost. Or is it going up in steps as you power more Tx Boost. I know this turned into two questions.. Sorry

I guess what I am asking is 30X at full TX boost..or is each step 30X more than what the regular sens would be doing at each step up ??
 
I'm not Rob, but might be able to help.........:shrug:

The manuals are correct about offset and RX reduction to reduce EMI, BUT......... the Boost information is wrong if that is what your information is telling you. Boost increases the coil output voltage from about 10 volts to 30 volts. That is about a 3X increase in TX coil voltage. This does not affect EMI because it is increasing the coil output voltage and EMI is something that affects the receiver side of the V3i. Using Boost usually involves reducing the RX setting which in turn, will reduce the chances of EMI.

Boost is either on or off so you will not have steps in between.
 
I think Larry covered it for you.
 
Thanks I understand now about the TX boost Larry..And I appreciate you substantiating the offset does in fact work as stated in manual..
 
EMI Does seem to be an issue for some however. Steve Hersc bach recently posted on another forum that he gotten rid of his V3i because he couldn't deal with the fact that it was so susceptible to EMI. He tried to use it and would be unable to because of the EMI and finally gave up on the detector which he otherwise liked very much.

What is the experience of others on this Forum?
 
I've yet to not been able to use the V3i because of EMI. The V just gives too many ways to combat it. Oh course you have to know the options.
 
What little EMI I have experienced, the frequency offset has taken care of it, which is the preferred way to handle EMI. For those detectors that do not have frequency shift, reducing the receiver gain will almost always take care of the problem. Those are just two of probably 10 ways the V3i can handle EMI and Rob has a list somewhere of the various ways to handle it.

I have never heard of anyone before, selling their V3i because of EMI problems....... :shrug: I suppose it could happen though.

I would like to see White's automate the frequency offset process to find the best operating frequency which would make most EMI problems go away with the push of a button. Minelab has done this for years and call it Noise Cancel.
 
I read the post.

" I just got tired of tuning it in, trying all the tuning tricks, then putting it back in the truck. It just is not worth the battle when I can just grab another detector that works just fine where the others will not."

So Steve just didn't want to bother, not that the V couldn't handle the EMI. He also dumped some other flagship detectors.

Seems like Elton might also have an EMI problem.

"I'm new to this machine but see right off EMI is a factor........ Hope it can be set to eliminate most EMI. If I see no improvement soon I will move it on..I am in a big city"

Here the post. See if the list gets bigger.
http://www.findmall.com/read.php?18,1960855
 
Rob:

I am seeing some EMI Issues. Hence I asked the questions about offset and TX boost with reduced RX Gain..... It seems like I am able to overcome the EMI.. At least I am now not getting the pulsing sound in my headphones I was getting. Also when I hold waist high and pull to pinpoint mode I am not seeing the fluctuation in the three frequency pinpoint screen. Their stable now that I made some adjustments.
So I'm pretty happy with the setting results........ I feel it is justified to make a comment about what you experience in your area with a machine.. I have some EMI. It would be nice if you posted the way you overcome the issues as you said adjustments did it. Rather than just take a post and highlight the person who made that post.

I have been detecting a long time and know when EMI is causing a problem ..Lucky for me I read and made some of the adjustments so relieved most of the problem.. I plan on doing my best to make this machine work for me as I love, YES LOVE most of the operation and all the toys on it..

Larry is dead on... A noise reduction mode would end the problem and would be easy to have it programmed into the V3i I would think.... I would send mine in for the upgrade for certain..
 
Elton, here is the post that I was thinking of that Rob posted on the various ways to reduce EMI. See what works best for you. http://www.findmall.com/read.php?66,1956709

Rob, your link for EMI in Rob's links goes to a Quartro post........:shrug:
 
Here is what I do.....

1. ground balance
2.. turn down sensitivity
3. freq offset
4. another location
5. cell phone off
6. check connections
7, any other coil (if available)


If it still falses....youve got a bad coil,,,,,almost for sure....only other possibility is the detector


If Ive missed something....let me know
 
I'll try to fix the link ???????

Reducing the Effects of EMI
Smaller coils will help reduce EMI, all the following were performed and validated using the 10"DD coil.

Using Ground Filter and Frequency Offset
1. Hold the unit waist high
2. Go to pinpoint (AM) mode
3. Observe the noise level
4. Select Transmit Frequency from the Live Control
5. Select the Frequency Offset that gives you the quietest operation
6. Select Ground Filter from the Live Control
7. Select the filter that gives you the quietest operation
8. Return to Search mode.

You may still notice some noise. This could be that while quieting one frequency, you may have made another frequency nosier. So, repeat the process in search mode to see if you can improve performance. Since you are generally hunting in the Search Mode, it seems best to do this "touch up" after you've been thru steps 1 - 8.

Using Salt Compensate Mode.
If you can't get the Normal 3 Freq mode quiet, try the Salt Comp 3 Freq mode. Salt Comp employs a salt subtraction algorithm and is inherently quieter, but you give up a bit of depth. However, you can easily get this back by bumping up RXG4. Select Ground Filter from the Live Control

Using a Single Frequency Mode
If you can't find a combination of settings that removes enough EMI in any of the 3 Freq modes, you may want to try a Single Frequency mode. Most EMI generally comes thru the 2.5 KHz frequency. The 22.5 KHz frequency sees smaller targets best but still hits well on gold and all the coins and coin-sized targets. Ground filters and Frequency offset options are still available to further optimize performance in the Single Frequency mode.

Correlate mode
The theory behind correlate is that iron will respond with different phase angles for the different frequencies whereas coins and such will give the correct response across the frequency ranges. So, it is one way to discriminate out iron. The drawback is that potentially you lose depth because the ground affects how the targets come in so they will appear to have the phase difference like iron might and get discriminated out. But, EMI noise would theoretically have an unpredictable response across the frequencies and might be one way to remove EMI too. So, for those that don't want to hunt the deep targets might get an advantage for skipping over the iron targets using correlate. But for those that want deeper, I don't think correlate would be a good option.
Using TXB In Conjunction With RXG
If Ground Filters, Frequency Offset and / or Salt Comp Mode, by themselves or in combination won't eliminate enough EMI to facilitate a successful hunt, or you wish to remain in a 3 Freq mode, try the following:
1. Drop RXG until the EMI effect is negated
2. Turn TXB = ON.
Since the transmitted frequency has nothing to do with EMI signal strength, this technique will improve the target signal return w/o increasing the EMI effect. This technique can be employed in conjunction with any of the previously discussed processes, in 3 Freq Normal, Salt Comp or Single Frequency modes.

1)Switch to a band pass filter as the band pass filters will filter out more noise than the high pass filters
2) Try different frequency offsets
3) Try the various single frequencies
4) Lower disc sensitivity
5) Try correlate mode rather than best data (if in 3 frequency mode).
6) Switching to Salt Compensate helps with EMI if you want to work in 3F mode.
7) Change coils (concentric)
:geek: Try wired headphones

Reducing the Effects of EMI
Smaller coils will help reduce EMI, all the following were performed and validated using the 10"DD coil.

Using Ground Filter and Frequency Offset
1. Hold the unit waist high
2. Go to pinpoint (AM) mode
3. Observe the noise level
4. Select Transmit Frequency from the Live Control
5. Select the Frequency Offset that gives you the quietest operation
6. Select Ground Filter from the Live Control
7. Select the filter that gives you the quietest operation
8. Return to Search mode.

You may still notice some noise. This could be that while quieting one frequency, you may have made another frequency nosier. So, repeat the process in search mode to see if you can improve performance. Since you are generally hunting in the Search Mode, it seems best to do this "touch up" after you've been thru steps 1 - 8.

Using Salt Compensate Mode.
If you can't get the Normal 3 Freq mode quiet, try the Salt Comp 3 Freq mode. Salt Comp employs a salt subtraction algorithm and is inherently quieter, but you give up a bit of depth. However, you can easily get this back by bumping up RXG4. Select Ground Filter from the Live Control

Using a Single Frequency Mode
If you can't find a combination of settings that removes enough EMI in any of the 3 Freq modes, you may want to try a Single Frequency mode. Most EMI generally comes thru the 2.5 KHz frequency. The 22.5 KHz frequency sees smaller targets best but still hits well on gold and all the coins and coin-sized targets. Ground filters and Frequency offset options are still available to further optimize performance in the Single Frequency mode.

Correlate mode
The theory behind correlate is that iron will respond with different phase angles for the different frequencies whereas coins and such will give the correct response across the frequency ranges. So, it is one way to discriminate out iron. The drawback is that potentially you lose depth because the ground affects how the targets come in so they will appear to have the phase difference like iron might and get discriminated out. But, EMI noise would theoretically have an unpredictable response across the frequencies and might be one way to remove EMI too. So, for those that don't want to hunt the deep targets might get an advantage for skipping over the iron targets using correlate. But for those that want deeper, I don't think correlate would be a good option.
Using TXB In Conjunction With RXG
If Ground Filters, Frequency Offset and / or Salt Comp Mode, by themselves or in combination won't eliminate enough EMI to facilitate a successful hunt, or you wish to remain in a 3 Freq mode, try the following:
1. Drop RXG until the EMI effect is negated
2. Turn TXB = ON.
Since the transmitted frequency has nothing to do with EMI signal strength, this technique will improve the target signal return w/o increasing the EMI effect. This technique can be employed in conjunction with any of the previously discussed processes, in 3 Freq Normal, Salt Comp or Single Frequency modes.

1)Switch to a band pass filter as the band pass filters will filter out more noise than the high pass filters
2) Try different frequency offsets
3) Try the various single frequencies
4) Lower disc sensitivity
5) Try correlate mode rather than best data (if in 3 frequency mode).
6) Switching to Salt Compensate helps with EMI if you want to work in 3F mode.
7) Change coils (concentric)
:geek: Try wired headphones
 
The link works now. Odd I used the same link???? Thanks Larry.

Sorry I made you mad Elton. I guess it's easy for me to do. Nothing was intended. The post was referred to and your comments were in the post.You mentioned having EMI problems with more detectors than the V. You may have a unique area concerning EMI. My EMI experience has been in Illinois, Indiana, Iowa, Texas and Missouri. I've haven't hunted in your neighborhood.

As far as settings those above are about all I know.
 
Some Fishers were right at the top of EMI in my loaded with cell towers and schools every neighborhood that have electronic teaching communication satellite dishes.
 
You know Larry a long time ago you said if I would give the V3i a chance and learn the operation it was a pretty awesome machine. I am finding you were correct.. It can detect just about anywhere with some good results.. It's fun too and that is important to me. I do this for a hobby and not really just for the great finds. ( Thought I do like those too) it has put the fun back and made it possible to just enjoy detecting.
Some machine require an all serious approach. And one forgets it's the hobby we all love and not just the Silver & Gold.. The V3i has so much to view and some great alternative screens it makes all fun to play with them..
 
You are catching on fast Elton and you seem to have a good understanding on the most important things now. Your next step might be to learn how to set the tones how you like them and then you are ready to put in into cruise control and go out and have fun on a regular basis. :biggrin:

It is easy for some to forget that the V3i is the most advanced metal detector on the market and although it is ready to go right out of the box, it does take a lot of learning to get the best from it. I think you have a keeper :thumbup:
 
It's the Rx that is adjustable...... It per Whites should always be set at the highest level that allows quiet interference free operation.. ( Note some of us know this feature as Pre-amp Gain. Today I had to turn Rx down. I then turned TX Boost on and in the school I was detecting this did work for me. EMI was cut way down. Not 100% but it was workable. The next place I detected I could go up two notches from the preset on RX Gain ..But had to turn TX boost off. I was getting overload on every third or 4th swing... Salt compensate setting did nothing.. Special note. It seems salt compensate is really just a form of discrimination. It takes out some lower foil and small ring potential VDI's and other things you might hit. So it removes those in areas on the Scale so you do not get the interference that is susceptible to that particular wave length., or accepted targets area might be a better word. The DFX worked in salt compensate all the time.. Hmmmmmmm I did not know that. DID YOU ??

As stated first site was a school..Though closed today the Micro feeds must have been on.. Really bad interference

Second site was a corner park with loads of trash. No EMI but constant target chatter TX boost on.. Just to much coverage power with TX Boost on. Detector was seeing every small piece of stuff in the ground..

I did switch to coin mode..My V3i has that in the programs along with coin and Jewelry ..that really quieted the targets......... I found a 6" Rosie mixed in with lots of junk stuff...
 
Salt compensate is helpful on salt beaches and farm fields that have been fertilized, yes it does reject the small foil area because that is where salt would read as a target. Yep, knew that about the DFX.....:biggrin:
 
With the advent of tight-footprint elliptical DD coils...... requiring a high order-of-magnitude engineered gain settings to achieve acceptable depths...... comes EMI issues.
 
Top