RE: Question for experts / pulse delay and perform

[Anonymous]

The pulse delay is often cited as one of the most important elements to give an idea of the performances of a pulse detector in regard to small items.
But, what is the relationship between the pulse delay and the smallest metallic size a pulse detector can reveal?
In other words, for example, if in the same detector the pulse delay is adjusted at 10 does it hit metallic items that are half sized if compared to when it is adjusted at 20 ? Or what?
Truly appreciate your opinions. Thanks to all.

 

[Anonymous]

Hi Seric,
As you probably know, the pulse delay is the short time that elapses between the switch-off of the transmitter field and the start of the receiver signal sampling. Small objects usually have a fast decay of their signal so, to be detected, the signal decay has to be longer than the pulse delay time. The actual signal decay of an object depends on several factors, of which two important ones are:- a) The conductivity of the metal. b) The mass of the metal. For example, you can have a large piece of a poor conductor which will have the same signal decay as a small piece of a good conductor. Or, two identical size objects of different metals will have greatly different signal decays. A US penny and a Nickel are about the same size, but the penny has a long decay due to the fact that it is made of copper, which is a good conductor. A Nickel has a short decay because it is made of an alloy with a high percentage of nickel, which is a poor conductor. Gold rings have signal decays which very widely due to the purity (carat rating) of the gold and also the cross section and diameter of the ring. The upshot is, that there is no meaningful relationship between pulse delay and object size. It all depends on the type of metal, its surface area, thickness and orientation to the search coil. All one can say is that a detector with a short pulse delay will detect certain classes of small objects better.
Eric.

 

[Anonymous]

Sorry if my question was exposed incompletely. The full question is as follows:
What is the relationship between the pulse delay and the smallest metallic mass a pulse detector can reveal if everything else ,but the mass of the target or the delay, are identical?
For example, if with a pulse delay of 30 microseconds a detector hits a metallic piece of 0,6 gr. at 20 cm. of distance , with a pulse delay of 15 will it hit a metallic piece of 0,3 gr. at the same distance?(Considering identical size