What Difference Does 1khz Have On The Equinox From 5khz To 4khz?

[StarVatrex]

..I think Minelab already did the test with v 3.0 by introducing 4 kHz in Nox seies.

The X-Terra Pro in Beach mode runs at 8kHz.

Part of the 'secret sauce' to get hat stability?.

[GB_Amateur]

8 hours ago, phrunt said:

Another vote from me the 4kHz option was a great option to mitigate EMI, 5kHz is pretty terrible around here, 4 runs like a dream.  The Manticore in some of it's modes gets lower than 4kHz so perhaps they worked out 5 was quite troublesome around the world and shifted a bit lower.

I was in a location (former school) and detecting in MultiFrequency.   No problems most of the day.  An older guy (older than I ) came up and said he had been a student at that school some 70 years prior.  He told me a good spot to hunt, where he and others used to play.  It was along the property edge, next to a street and close to some houses.  When I got there the EMI was unbearable so I checked some single freqs.  I was hoping for high conductor coins so started at the low end.  5 kHz was terrible but 4 kHz was dead quiet.  Began searching and found some Lincolns and an Indian Head cent -- best find of the day.  I wondered if the EMI had chased away other detectorists, but without hearing from them (don't know who they are...) I'll never know.  Consistent with phrunt, the VDI's drifted pretty badly as depth increased so I was just digging non-ferrous, but it was better than walking away.

5 kHz minus 4 kHz = 1 kHz doesn't sound like a lot.  But maybe some EMI sources have a spread of frequencies that doesn't follow such a simple relationship.  I.e. suppose it's a more complicated function (logarithm, exponential,...) or depend upon the ratio (i.e. division, not subtraction) or ??  Anyway, in some EMI cases there is a big advantage of 4 kHz vs. 5 kHz on the Eqx 800.  As to why, IDK.

[dave_e]

I have a site that's another example of EMI reduction by moving from 5kHz to 4kHz.

Electric dog fence around the perimeter of a yard.

Neither Impact or Equinox can run at 5kHz.  Completely unusable.  Regardless of frequency shift, noise cancel, or coil size.

I can run the Equinox at 4 though if I noise cancel.

[Digalicious]

1 hour ago, dave_e said:

I have a site that's another example of EMI reduction by moving from 5kHz to 4kHz.

Electric dog fence around the perimeter of a yard.

Neither Impact or Equinox can run at 5kHz.  Completely unusable.  Regardless of frequency shift, noise cancel, or coil size.

I can run the Equinox at 4 though if I noise cancel.

Dave,

In high generalized EMI, 1 khz isn't going to make a lick of difference for EMI noise reduction. So what is the difference between EMI noise and 4/5 khz? Well, it seems that Minelab is experimenting with different algorithms for the 4 khz mode on the Nox. More specifically, a different algorithm for at least the noise reduction aspect in 4khz. If so, the question then begs: Is the EMI noise reduction in 4 khz truly ignoring the EMI, or is the noise reduction merely reducing the hidden gain level?

That question is very important, because if the hidden gain is being reduced, then many hunters would likely switch to around 20khz or higher, which would normally be outside the range of EMI, and also allow them to run the detector at close to, or maximum gain.

 

[Jeff McClendon]

Seven different Equinox 600/700/800/900 owners have reported a difference in overall EMI interference by switching from 5 kHz to 4 kHz. No of these Equinox owners has mentioned a loss of depth, sensitivity or any other change in performance aside from a much quieter single frequency experience when switching from 5 kHz to 4 kHz.

One non-Equinox owner/user is chiming in repeatedly and is telling all of us that there is no way that just switching from 5 kHz to 4 kHz by itself will improve EMI interference.

Are we Equinox owners just full of dog pooh and complete liars????????

[Digalicious]

34 minutes ago, Jeff McClendon said:

Seven different Equinox 600/700/800/900 owners have reported a difference in overall EMI interference by switching from 5 kHz to 4 kHz. No of these Equinox owners has mentioned a loss of depth, sensitivity or any other change in performance aside from a much quieter single frequency experience when switching from 5 kHz to 4 kHz.

One non-Equinox owner/user is chiming in repeatedly and is telling all of us that there is no way that just switching from 5 kHz to 4 kHz by itself will improve EMI interference.

Are we Equinox owners just full of dog pooh and complete liars????????

Wow. Just wow.

Now you have resorted to erroneously implying that I'm calling the Equinox owners "liars". How pathetic.

I never once denied that the Nox owners are getting less EMI in 4khz, then they are in 5 khz. My assertion was that the reason for such, could very well be different algorithms in 4 khz than there are in the other single frequencies. Yet, in some sort of bizarre reasoning, you actually twist that legitimate possibility, into me calling the Nox owners liars. Unbelievable.

[Chase Goldman]

3 hours ago, Digalicious said:

That question is very important, because if the hidden gain is being reduced, then many hunters would likely switch to around 20khz or higher, which would normally be outside the range of EMI, and also allow them to run the detector at close to, or maximum gain.

 

6 minutes ago, Digalicious said:

Wow. Just wow.

Now you have resorted to erroneously implying that I'm calling the Equinox owners "liars". How pathetic.

I never once denied that the Nox owners are getting less EMI in 4khz. My assertion was that the reason for such, could very well be different algorithms in 4 khz than there are in the other single frequencies. Yet, in some sort of bizarre reasoning, you actually twist that legitimate possibility, into me calling the Nox owners liars. Unbelievable.

Against my better judgment...

Jeff is saying that you keep bringing up this hidden gain reduction premise, yet no one is reporting target depth loss at 4 khz vs. 5 khz in situations where you can run either at max sensitivity.  

Further, your 20 khz "solution" ignores the fact that there is discrete loss of target detection depth, especially for high conductive targets, by going from 4 khz to 20 khz and unlike your stealth gain reduction conspiracy theory, that's a given performance hit.

[Digalicious]

On 5/2/2023 at 1:22 PM, Chase Goldman said:

ML apparently did something to address EMI and ground handling with the 4 khz "mode" vs. the 5 khz "mode" and it had little to do with the actual operating frequency other than ML probably surmised that if they could make a lower operating frequency mode less susceptible to EMI then whatever they were doing could be used effectively across the board.  Furthermore, they also needed to be concerned about unforeseen consequences such as reduced depth or target sensitivity, hence they left 5 khz alone in the event their "experiment" had unintended consequences.  True, in general there is nothing that makes 4 khz signficantly less susceptible to EMI than 5 khz, but ML must have incorporated some secret sauce to make the added 4 khz mode to be less susceptible or more stable than the existing 5 khz mode.  That extra 4 khz can also make a significant difference on detection depth for large, high conductive targets.

I guess you missed this Jeff 🙄

[phrunt]

I think my T2 video perfectly demonstrates small shifts in frequency can cause big differences in EMI problems. This is shifting .1 of a kHz, the jump on the Nox between 5 and 4 is big compared to this and for me at least fixes any EMI issues I may experience in 5kHz by going to 4kGz.  This first 50 seconds of the video are in disc mode which is filtering some EMI then I switch to all metal to let it really show its ugly face.

FREQUENCY SHIFTING
One disadvantage of a highly sensitive metal detector is its susceptibility to electrical
interference from other electronic devices. If the detector chatters while the search coil is not in
motion, the cause is either electrical interference or internal circuit noise due to a high
sensitivity setting. If the detector chatters or emits intermittent false signals in the field, you are
also probably experiencing electrical interference. If you suspect electrical interference, you
may change the T2’s operating frequency. This is a trial and error method to try to find a
frequency different from the suspected source.

Each actuation will shift the frequency by one value.
The LCD will display the frequency, from F1 to F7. The
default frequency is F4. The T2 will default back to F4 when
the power is switched off

[Digalicious]

17 minutes ago, Chase Goldman said:

 

Against my better judgment...

Jeff is saying that you keep bringing up this hidden gain reduction premise, yet no one is reporting target depth loss at 4 khz vs. 5 khz in situations where you can run either at max sensitivity.  

Further, your 20 khz "solution" ignores the fact that there is discrete loss of target detection depth, especially for high conductive targets, by going from 4 khz to 20 khz and unlike your stealth gain reduction conspiracy theory, that's a given performance hit.

The hidden gain aspect has past precedence. To properly conclude if the gain is being dropped, then depth comparisons would be needed in a manner similar to the test I posted previously.

...and no, I'm well aware of the slight depth loss on high conductors when using a high frequency. I'm also aware that the higher frequencies will have better sensitivity to small targets and small gold. If I had a choice to use 4 khz with a 30% reduction in gain, or 20 khz with no reduction in gain, I sure the heck would choose the latter. 

Do I think Minelab came up with a way to legitimately silence EMI without affecting performance in one way or another? I'm leaning heavily towards "no". Engineers have been trying to do that for what now? At least a decade? To accomplish such a thing would be a borderline game changer. Minelab would have patented the heck out of such technology and advertised it profusely. Now, it would be amazing if they did succeed in such a feat, but there is no evidence to prove that they have done so.