GrievousAngel

I agree of course.

I was relating to the -3db frequency point of a given target (assuming all other being equal, e.g., shape, orientation, size, conduction value, etc. ). As I understand it, the target's reflected signal is maximum at the ~ -3db frequency level. This is assuming the transmitted frequency is also set to the target's frequency -3db level point. This happens to be the r-component of the signal, which is defined at it's  half-power point.

For example, with everything being equal, a given target has an optimum single frequency, yielding maximum reflected r-signal level to be analyzed. I would tend to think this has a lot to do with Multi-IQ design and resulting algorisms. 

Anyone expand on this? Am i somewhat correct on this?

Thanks, Billy

On 11/15/2017 at 9:26 AM, Steve Herschbach said:

From http://www.detectorprospector.com/forum/topic/4488-minelab-equinox-multi-iq-technology-part-2/

“* 20 kHz and 40 kHz are not available as single operating frequencies in EQUINOX 600. The Multi-IQ frequency range shown applies to both EQUINOX 600 and 800. This diagram is representative only. Actual sensitivity levels will depend upon target types and sizes, ground conditions and detector settings.“

Access to the Gold Mode and therefore the 20 kHz and 40 kHz single frequencies is limited to the Equinox 800.

“Gold Detecting Mode - Gold Mode operates the high single frequencies of either 20 kHz or 40 kHz to detect gold nuggets in mineralised soils.”

In another thread I mentioned my interest in the -3db Half-Power Level. I noticed it was discussed in one of the articles on this site (written by Andy I think).

I have used ‘half power’ points many times in electronic subjects dealing with analog audio signals, eg., audio amplifiers as typically used in studio settings.

Anyways, generally quoting a few statements that grabbed my eyes:

‘For -3db frequencies. . . 
Examples given: a dime and a penny -3db freq is ~2.7kHz. Silver dollar -3db is ~800Hz. Nickles ~17kHz. Thin rings and fine gold are usually higher still.x
These results are based on a VLF detector with max Sensitivity and positioning the transmit frequency directly on the target’s -3db frequency point.’

I often asked my self, what is the better single frequency for a given target? I suspected something like this but . . . the catch is someone has to determine each target’s ideal center frequency, ie., I think of it as the target’s center of gravity if you will.

Please expand on this topic.

Thanks, Billy
 

On 4/7/2018 at 7:21 PM, vive equinox said:

I want To know that for the multi IQ . 

I suspect park 1 ,field 1 , beach 1 and 2 .

To no run in 40khz in his multi.

So i dont understand why minelab tell the 5 frequency run in multi ? 

I wonder what are the combination?  

2? 3 ? 4 ?  Frequency?  And wich frequency? 

Now i think some people must know that.  It can be helpful for choosing the good mode. 

Anyone have an idea ? 

Without Minelab’s white paper articles, it’s difficult to be sure so we all tend to apply educated-guesstimates. For keeping it simpler, just consider the Nox800. 

Since v3.x, the lowest single freq is 4kHz (3.7kHz). 5Fx8 is not accurate. I suggest using 3.7 [not 4] to determine ratio or range. IMHO, range ratio is 11, therefore marketing icon might be 6Fx11.

Y’all agree?

What interest me more is the use of -3db Half-Power Level for determining the exact preferred frequency. I assume it is used in terms of single and Muli-IQ frequencies.

I will finish this thread below on Andy’s reply.

Thanks 
 

That’s how I took it as well but I didn’t want miss a concept. 
Thanks

Thanks for the greetings.

I'm from Statesboro, GA near Savannah, about 3-4 hours south of ATL. I spent sometime in the Eagle River Valley near Beaver Creek in Avon, CO (near Vail).

I am a retired EE of ~20 years. I enjoy projects in most all areas, ie. electronics to wood to metal, etc. I enjoy most all outdoor adventures from fishing to hunting to canoeing to travel. History and related treasure like modern coins & jewelry to relics to gold has always been an interest of mine, and of course, metal detecting is a great pathway to venture into. I am located very close to many Atlantic beaches (60 miles), ie. Tybee Island, Hilton Head and a few others, so beach detecting works.

I did a introductory video years back for post-graduate course, so it's attached. It may be off-topic, but hopefully a little entertaining. I played music from early high school through university study as well as engaging in related technologies.

Looking forward to sharing with y'all soon.

BTW: I tried to attach video but failed. Is there a way to upload a video for sharing?

Refer to page 48 in Minelab Equinox Manual:

Am I missing something or is the instruction wrong or a type-o?

Manual states: "The non-ferrous setting can not be a higher number than the ferrous setting."

Should it not read: "The non-ferrous setting can not be a lower number than the ferrous setting."

Of course it may have 'flew over my head' . . . I've spend some time attempting to clarify the statement but it still appears like a type-o.

What's the verdict?

While on this subject: Are t1(50Hz) and (t2)500Hz fixed in terms of pitch or frequency? I would think they are permeably set. Just curious.

Thanks, Billy

I have browsed & ‘lurked’ around this site for a while now as it has become my ‘go to’ detecting magazine & forum! So I signed up today and looking forward to hanging out.with y’all. 

I have used Garrett Land & Sea but recently moved into an Equinox 800 w/ the Minelab Coils plus Coiltek NOX 5x10 and a NOX 15. I gave my grandson the Garrett L&S as it is an excellent ‘dig everything’ PI detector. It needs a strong back to swing…

IMHO, the NOX 800 is a ‘top drawer’ detector that does what Minelab claims with authority.

See y’all around town,

Billy