Will The Next Gen Detectors Address Emi ???

[dave_e]

18 hours ago, Mike_Hillis said:

Rutus Altrex has a screen that shows you what freq has the most EMI interference.

The Rutus Atrex EMI preview screen is a game changer.

I use it for both the single frequencies (71 of them) as well as which of the 10 different SMF modes to use.

[Digalicious]

7 minutes ago, dave_e said:

The Rutus Atrex EMI preview screen is a game changer.

I use it for both the single frequencies (71 of them) as well as which of the 10 different SMF modes to use.

Hi Dave.

Can you please explain exactly why you think it's a game changer? The reason I ask, is because automatic noise cancelling scans each channel and chooses the one with the lowest noise. So although the Atrex's preview screen is neat to look at, I'm not seeing why it's a game changer, unless the Atrex doesn't have an automatic noise cancel feature, so you have to do it manually?

The other issue with looking for the channel with the lowest noise, is that in high EMI every SMF channel is usually noisy, because each channel's frequency are so similar to one another. Even a channel that may seem to have a little less noise, will still have a heck of a lot of noise. In addition to that, given the randomness of the EMI frequencies, intensity, and harmonics, that one channel that seemed to have a little less noise, probably won't 10 seconds later.

In SF modes however, there will be frequencies that have very high noise, and frequencies that have almost zero noise. For example, in high EMI, frequencies of up to 15 khz will often be noisy, 20 khz really begins to be outside of the range of EMI noise, and 40 khz is dead quite.

[dave_e]

Auto noise cancel wouldn't let you know whether you should be using one of 10 SMF modes, or whether a single freq. would be best.  It would simply freq shift after you made your choice.

ie.

When detecting next to an old home that has beat up aerial electrical service, I can scroll through EMI preview on all the single freqs as well as the SMF modes, then make the best choice at that moment.

There's also silent EMI that shows up.  Most guys ignore it but it has more of a negative impact than they realize. 

Using my Equinox at this location I can only run it at 15kHz with the sensitivity turned waaaay down.  It's neutered.

The Atrex detector is at another level when dealing with EMI.

I just wish it was waterproof and that the color screen didn't wash out so badly in direct sunlight.

 

[Digalicious]

2 minutes ago, dave_e said:

Auto noise cancel wouldn't let you know whether you should be using one of 10 SMF modes, or whether a single freq. would be best.  It would simply freq shift after you made your choice.

 

 

Ok, but in EMI, all SMF modes are about the same for noise, because the processing is accumulating the noise from more than 1 frequency. As such, each channel in SMF has about equal noise. In general, the majority of channels in SMF will be "ludicrous" noisy, while other channels will be slightly less ludicrous, but still basically unusable. Your example of having to use your Nox in SF at that site shows that. 

SF is almost always less noisy in EMI, because there is no accumulation of EMI noise as there is when using SMF. Although the lower SFs are generally much noisier than the higher SFs.

Silent EMI? That's a whole other can of worms that I was wondering when someone would bring up🙂. 

[dave_e]

EMI aside, I always choose SMF because I'm never just hunting for one specific type of target.

Same example house in my last post, I can run the Atrex in M2, M3, but mainly M4 next to that house.  The other SMF modes have noise.

Much better ID at depth and significantly less falsing than single freqs.

(Post for another day would be me grousing that all these new detectors can't run concentric coils.  I have a 5" cc sniper for the Rutus Atrex and a 7" cc for my Nokta Impact.  They can also be a nice advantage in certain situations.)

[Digalicious]

Dave,

With the 71 SFs, are you able to see a large chunk of those frequencies and their associated noise? If so, that would certainly be much faster than individually selecting most of those 71 frequencies, giving a listen, then moving on to the other 70 frequencies to compare.

[dave_e]

Dig,

Yes.  It looks like a graphic equalizer.  Whatever your current selection is, it shows that in the middle and you can see lower and higher to the left and right.  Then, you can scroll through them all using the + and - keys to move left and right.

Here's a video Tony did...https://www.youtube.com/watch?v=UtgvjZyuGYM&ab_channel=tcDetects

Yes SMF is almost always noisier than single, but I like being able to shift the SMF while staying in the mode I want when possible.

If EMI is too much on all SMF modes then I go single.

This shows interference even when you can't audibly hear it.

[phrunt]

Wow that's amazing, Rutus are well ahead of the pack when it comes to having a user friendly method of EMI mitigation.  I love that its live showing EMI so you can sit and watch it for a while and mentally work out where is best too not just relying on automatic noise cancellation that may have found a good spot at the time but moments later it changes.  This detector really shows how much further they can take the noise cancellation process.  

Targets won't go away while EMI will as you slightly shift frequencies so you would think some smart person would be able to come up with a way to automatically shift away from EMI while you're detecting.  It won't see targets as EMI as targets will come regardless of if it's trying to shift away from them.  It'd probably take quite a lot of processing power but there is nothing saying a detector can't have multiple cores or CPU's.

[Digalicious]

That video was mesmerizing.

Dave,

How much of a frequency range is there? It looks like about 70 channels with a difference of .2 khz between each segment. So a range of around 14 khz?

 

[dave_e]

Phrunt,

I also use the Atrex EMI screen before firing up my Equinox 600 or the Impact and indeed watch for a few min before deciding on frequency choice on those machines.

 

Correct Dig.

Lowest = 4.4kHz

Highest = 18.4kHz