Target Reflection

[Dubulumach]

Anybody know about target reflection? Bob Fitzgerald units have what he calls TRN target Reflection Nullifier. Tim Williams has what he calls TV Target Verify which he says to see if signal is a reflection.

For metal detectors, the process is to cancel a part of the received signal. It's not done during transmission. Anybody?

The reflection component is in real time. Well, I don't know but it seems illogical to be able to cancel something at the exact same time it is sent out. Something does not seem right.

I am waiting to be enlightened.

Big feeding problems same like in cellular phone wireless traffic.

Answers are digital signal processing, high order digital filters, multylayer chirps and narrow band frame windows. Using 24 bit oversampling or interleaving can drastically boost wanted signals while in same time canceling terrestrial wireless feeding.

key word COLD FIRE IN DSP.

[Mike(Mont)]

Mike, you already know my answer. Reflection nullifiers, ghost signals eliminators, weight checks... their all alibis for products that don't work in the first place, and excuses for selling equally worthless add-ons to gullible people who haven't figured out they were taken by the initial sale.

The ME-II TRN is a good example. It's a "feature" that does absolutely nothing. Since the dowsing response is all in the mind, the user might pretend that it does something, by imagining a difference in the dowsing response depending on whether TRN is on or off. But the end result is the same; the ME-II ain't gonna locate anything, TRN or no TRN. Even the battery is optional.

Compare to a metal detector ground balance. Turn it off, and the detector responds to ground. Turn it on, and you can find a setting where the response is nulled. It does something, and that something is measurable and can be agreed upon by everyone who uses it.

But let's suppose for a second that the GB knob was not connected to anything in the metal detector circuit. No matter where you set it, the detector has the same ground response. It would be pretty obvious to any user that it doesn't do anything, because they are using a device that fundamentally works in the first place. With LRLs, all those knobs and switches don't have to actually do anything, and no one would ever know. Very often that's the case.

Hi Carl, sure, you might be right, I mean partially right.

When I first set up the Spectrum Lab i was getting harmonics then when I switched on the TRN the harmonics got closer together. It was like a capacitor was being charged.Could have just been some time delay with the software, I don't know. My brain ain't working too good these days. i can't get it to do that now. I could have damaged something. So don't worry about me, I've pretty much given up on becoming a rich and famous LRL salesman.

[Mike(Mont)]

Dubulumach, I doubt I will ever get it. My spirit has the desire but my brain seems to have a few short circuits. Okay MANY short circuits.

[Mike(Mont)]

Here is the SID antenna and the Mini-Eliminator

[Mike(Mont)]

I've been avoiding mentioning the article I read but might as well throw it out there. I'm not trying to irritate anyone. The title is Metal Detector Basics and Theory. Anyway, the point is when I read it I couldn't help but make a connection with what many people have talked about LRL's. I mean it reads like an LRL sales pitch. All except that they conveniently leave out the part that there is something called a receiver. This can't be a coincidence. Of course to make such a comparison is totally misguided and it just can't be. That was kinda the point of this thread.

[Bill512]

Mike, I think that is hard to see something by connecting a receiver to a spectrum software and walking around from a signal generator.
Remember that the coils, are directional receivers and by moving a coil receiver in the vicinity of a same band TX, you will read an electromagnetic chaos this time.
If you want to use a LRL with a VLF TX/RX, then you need some tricks, like cancelation of the primary TX field.
You see, some metal detector tech concepts, does not apply in LRL's, but some ideas are helpful.
A typical VLF (IB) metal detector has the TX/RX coils is some null, which is roughly at the order of 1 :1000.
This means for example, 10Vpp in to TX , and 5-10mVpp on to RX.
Now, in this type of fully electronic LRL, you will need an order of magnitude "more null" , about 1:10000.
So , you need a TX and RX mounted in same mechanical assembly, (like a hard wooden board).
Then you must cancel out the most of the TX field.
At this point you need to have some super skills in building induction balance coils.
PI metal detectors are popular among DIY builders , mostly because the coils are easy to make. Induction balance coils for VLF's ,are far more tricky.
If you accomplise this, your fully electronic LRL detector will be something like a "rifle detector".
Later , as you gradually understand the concept and at the same time miniaturize the mechanical assembly, you will have a pistol detector...

[Mike(Mont)]

Yeah, this set-up is just to check the output of the Mini-Eliminator II.