neilo
Sr. Member
- Aug 23, 2005
- 390
- 1
I hear people saying that mono coils go deeper and find smaller items than double d coils this is true but only in a very limited circumstance.In dry sandy soils with very little mineralisation this is a fact. But even in this ideal ground situation finding deep targets can be like finding that needle in the haystack.The shape of the signal being transmitted is the problem its conical, ?meaning that it gets smaller the deeper it goes.
Your coil lets say basketball size sends down a signal which at maximum depth could ?be down to a marble sized area.Whilst a double d coil will send down a signal which is straight and stays at that baskerball sized area to its maximum depth.
The mono coil might be going an inch or two deeper but the area being detected at that depth is very small.What this means is to detect deep targets using a mono coil you have to make many more sweeps ?of your coil to find them.
Example, you want to find coins average depth 10 inches,the area you are detecting is 10 yrds long.your mono coil will go down to 12 inches maximum and your double d will go 11 inches.maximum.Themono coil at the depth of 10 inches would have a signal area of roughly a golf ball,say 2inches across.To cover that 10 yds long area overlapping your sweeps by an inch you would only be able to move forward by an inch per sweep to avoid missing other coins so to cover that 10 yds it would take 360sweeps of your coil .In effect your coil has shrunk from that 11inch basketball size down to a two inch golf ball sized coil. If the double d coil is used withan inch overlapp per sweep of the coil to cover that 10 yds area it would take only 36 sweeps.This is in ideal conditions, when the mono coil has to deal with interference,mineralisation,salt and moisture they fail miserably.The double d excells in these circumstances and will detect much deeper and handle the mineralisation,salt and interference much better.
Then we get back to the situation whats better multifrequency detectors or single frequency detectors.the type of coil fitted to these is another factor.Most single frequency coin machines are fitted with mono or concentric coils which in effect are the same thing.The high frequency machines will detect much smaller items but at the cost of having poor depth and more prone to interference.The low frequency machine will go deeper and are not as prone to interference but cannot pick up small items.This is where once again the multifrequency machines coupled up to a double d coil are the winners.They have the best of both worlds the lower frequencies for depth and the higher frequencies for smaller items allowing a much better target identification with little trouble from mineralisation and interference.
It is easy to see how coins at depth are easily missed when using the mono coils,the shrinking signal size is a problem.
? ? ? ? ? ? ? ? ? hope my explaination isnt too complicated seeya neilo
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Your coil lets say basketball size sends down a signal which at maximum depth could ?be down to a marble sized area.Whilst a double d coil will send down a signal which is straight and stays at that baskerball sized area to its maximum depth.
The mono coil might be going an inch or two deeper but the area being detected at that depth is very small.What this means is to detect deep targets using a mono coil you have to make many more sweeps ?of your coil to find them.
Example, you want to find coins average depth 10 inches,the area you are detecting is 10 yrds long.your mono coil will go down to 12 inches maximum and your double d will go 11 inches.maximum.Themono coil at the depth of 10 inches would have a signal area of roughly a golf ball,say 2inches across.To cover that 10 yds long area overlapping your sweeps by an inch you would only be able to move forward by an inch per sweep to avoid missing other coins so to cover that 10 yds it would take 360sweeps of your coil .In effect your coil has shrunk from that 11inch basketball size down to a two inch golf ball sized coil. If the double d coil is used withan inch overlapp per sweep of the coil to cover that 10 yds area it would take only 36 sweeps.This is in ideal conditions, when the mono coil has to deal with interference,mineralisation,salt and moisture they fail miserably.The double d excells in these circumstances and will detect much deeper and handle the mineralisation,salt and interference much better.
Then we get back to the situation whats better multifrequency detectors or single frequency detectors.the type of coil fitted to these is another factor.Most single frequency coin machines are fitted with mono or concentric coils which in effect are the same thing.The high frequency machines will detect much smaller items but at the cost of having poor depth and more prone to interference.The low frequency machine will go deeper and are not as prone to interference but cannot pick up small items.This is where once again the multifrequency machines coupled up to a double d coil are the winners.They have the best of both worlds the lower frequencies for depth and the higher frequencies for smaller items allowing a much better target identification with little trouble from mineralisation and interference.
It is easy to see how coins at depth are easily missed when using the mono coils,the shrinking signal size is a problem.
? ? ? ? ? ? ? ? ? hope my explaination isnt too complicated seeya neilo
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
