In a PI MD, does the tx pulse width affect target response?

[Atul Asthana]

In a PI MD, does the tx pulse width affect target response?

That is, will the target response differ if tx pulse width was changed from 15 microsec to 25 microsec? And all other conditions remaining same for both transmissions and receptions.

[rajesh]

oi md

In a PI MD, does the tx pulse width affect target response?

That is, will the target response differ if tx pulse width was changed from 15 microsec to 25 microsec? And all other conditions remaining same for both transmissions and receptions.

yes atul you know that a pi md to need a low frequency and high pulse rate and very low samling delay.............rajesh

[Rudy]

In a PI unit, what matter is that the Tx pulse be wide enough to allow the current flow (and thereby the magnetic field) to build to maximum. Then the Tx current is shut off quickly to let the Tx magnetic field collapse as fast as possible.

For target detection purposes what matters is the delay from the field collapse to when the signal is sampled.

So no, assuming no limits in the electronics, the repetition rate of the Tx pulse doesn't really matter. Though if too low, you might miss targets depending on coil sweep speed. If too fast, you drain down the batteries much quicker than necessary.

[porkluvr]

How much energy a target can absorb mainly depends on its size, shape, and chemical composition.

At 25us your gold ring may have already absorbed all the energy it's going to, and so a longer pulse would be mostly a waste of energy. But a large coin (or that buried automobile, if you're car hunting ) could very well absorb much more energy.

Some PIs (Minelabs SD2000 for instance) use a pulse train consisting of low PRF (Pulse Repetition Frequency) long pulses, interleaved with high PRF short pulses. The best of both worlds is theoretically obtained because your deeply buried coins will respond better to the longer pulses, but small gold nuggets are more easily detected with the multiple short pulses.

To have the same relative amounts of energy transmitted during the two different PRFs, there needs be more short pulses than long pulses, as is the case in the SD2000. The frequency of the transmitted pulse is not so important to the target's responding - except that more pulses equals more energy and a better chance of detection.

For small targets it does no good to bang harder - what you want to do is lightly bang it many, many times.

[rajesh]

pi md

porkluvr ithunk all manufacture built pi locator coin shooter .coin shooter has a limited rang .but we shold be modifing hemmarhead while using a 1meter /1meter coil 400uh becouse 9volt making a low mgnatfied......