Answer for PI v MPS? Please!!!!

[nugget]

Hi all, I have'nt recieved any answer RE: the difference between Pulse induction (infinium) and Multi period sensing (minelab). Please will some one with the technical experience answer this question for me. Regards Nugget.

 

[UK Brian]

No technical experience but I'll say what I think it means and it might encourage others to correct me.
MPS and Pulse are the same though some try to deny it. MPS is more sophisticated as it transmits both short and long pulses.
The different length pulses give different decay rates of the signal.
Magnetic ground decay signal is the same for both long and short pulses but not for the items you might be hunting for. So they sample and I assume subtract away the pulses that match ie the magnetic ground, leaving the wanted signal in effect unmasked from the ground signal.

 

[desertdon]

Minelab uses what is call a "Train" of 1 long and three short transmit pulses, the purpose of the short ones is to give sensitivity to small targets. Other Mfgers, just use one pulse and sample from it. It maybe questionable how effective the Minelab system is, I think it may make larger coils more sensitive to small targets than the one pulse. Minelab also uses two channels either separately or mixed, supposedly channel 0ne is more sensitive to small targets. I think the multichannel is also a way they use to ground balance, while the one pulse system does it more differently, either works I think. Don

 

[nugget]

Thanks for the info guys, what you have told me makes sense. I'm an ex stockman (cowboy) so I'm not very technical minded. I have taught myself to detect, through many years of trial and error, I joined a metal detecting club a couple of years ago to learn, but found out that what I taught myself is better than most of the operators in the club. I am getting nuggets where operators with over 25yrs experience cannot score a single nugget. I'm not bragging, in fact it is good to be able to teach people how to do it better. I just don't volounteer info on where I get my gold. These areas have been hammered by every detector known to man. Persistance, willing to dig every signal, and good technique is vital to your success. God bless Nugget.

 

[ferromagnetic]

Brian is this statement correct?
"Magnetic ground decay signal is the same for both long and short pulses but not for the items you might be hunting for. So they sample and I assume subtract away the pulses that match ie the magnetic ground, leaving the wanted signal in effect unmasked from the ground signal."

I thought that the magnetic ground decayed according to the length of the tx pulse(Vo{t}=k/t)ie the ground signal takes longer to decay with a long pulse and shorter with a short pulse? In contrast conductive targets decay exponentially and the decay time is independent of pulse length?
I may have it all wrong.
regards
ferromagnetic

 

[UK Brian]

I think it was a post by Dave Emery that went into this. We could do with him or Eric to clarify. There was also something to do with either the current must or must not be rising at the end of the transmit pulse.

Brian