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legend power output
- Thread starter sargojim
- Start date
Odanscoils
Well-known member
My understanding at this time.
Fcc doesn't regulate below 1 mghz.
I want my copper sparkplug wife's back.
Still run em on the tractor.
Fcc doesn't regulate below 1 mghz.
I want my copper sparkplug wife's back.
Still run em on the tractor.
Gord (Tecumseh)
Active member
So what you are saying is that if it is 30dbd it is legal and if it is higher output it is illegal.
The Coin Magician
Well-known member
Yes it would be illegal.
Thats the way I understand it also, and I would think if there was anything wrong with the power the Legend is putting out the FCC would have caught it before it was okayed to sell
Picketwire
Well-known member
Do a search for "Riddle me this!" on FMDF. Carl NC will give you the lowdown.
dbs isn't a thing. dB is a ratio measurement, and you need to identify what is being measured. The standard for power is milliwatts (dBmW or dBm). 20dBm is about 100mW which seems a bit low by itself, but if you add in the unit processing and display it's probably accurate.
dBd is a measurement of gain, typically used in an antenna. It would make sense to apply it to a metal detector, but knowing the output would be dependent on knowing the input. You cant just say "this detector outputs 20 dBd, THAT TOO MUCH POWER!" because it could be a lot, or it could be nothing
I would think that it would be easy to over power the ground to the point where you would hear nothing but noise…The real deal the way I see it is how well everything is tuned, and how good the machine is filtered, all in the design of the machine… Sorta like building a hot rod….A high hp motor is only part of what makes the car fast…Gearing, suspension, tires, etc all come into play..
The Coin Magician
Well-known member
Eventually in many years from now most detectors will move away from VLF as we know it. I am guessing imaging systems will show what is under ground. I think pulse induction will be become more advanced too.
The ultimate in discrimination is to see with your eyes what the target looks like. 2023 and a modern detector can't tell the difference between a tab and a ring. These things advance snail pace with metal detectors.
Your right about the power , the ground really limits how much power can be used and we are at those limits and have been for decades.
I'm not super smart on metal detector physics, but I remember some of the EE courses I took many decades ago.
Seems to me detectors do two types of detecting. Time phase for depth and frequency phase for identification. The biggest issue here is that differences in cross section can have as much of an impact as material differences and can affect both. Not to mention multipath becomes an issue.
I think PI reduces multi-path, and having a more "fixed depth of detection" could help identification a lot. For instance a coil in the shape of a rounded pyramid with isolated tx/rx loops on each side. Each tx loop a different frequency, and the rx loop on the opposite side only looks for the frequency on the other side. When all rx loops receive a strong signal it should be within a very narrow depth (or be massive in size). Put in a gyro (like in your kids game controller) to detect swing speed / spatial relation and you could accurately measure the size and shape of the reflective surface(s) of the item. If you have an accurate idea of shape and depth, then the already pretty decent identification process can be much more accurate.
The issue of course is the fixed depth. Could possibly be addressed by having you detect with a pumping motion, or just set your angles based on expected target depths (the tighter the more accurate results).