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Book Excerpt: False Signals
- Thread starter cjc
- Start date
Clive,
False signals are common if you want to dig those deep coins others have left for you as you have notice. Some of these are easier to tell while others are tougher, but I feel if you don't get a rusty nail or washer once in a while you are missing some deeper coins and coins on edge.I too notice if you are getting quite a few false signals you know the sensitivity is a little high and you have to turn it down a bit as you suggest.
Now where I notice the most if the ground is dry then my rusty bottle caps will read around a nickle signal, but a bit iffy and hard not to dig, I did get them once in the 173 area too on a 180 meter at one site. I also have a few tricks too to help tell some of them and one I have to use on my GT more than any of the other Sovereigns I have used. This is where I get the good signal and move the coil back so I can get the signal right on the very tip of the coil, then being I know where it is suppose to be I come at it from a different angle. Now it is is a good signal it will still be there, but if a iron false then it will be nulling at a different angle or even moving. The other way is doing my 90 degrees pinpoint in all metal then while holding the coil still switch to disc and wiggle the coil a bit and if it goes positive signal it is a good one to dig,but if it null it is a iron null.
The Sovereigns are great detectors as many of you are seeing, but it takes a little time to fully learn these detectors,but once you do you will see some great finds from places others considered worked out.
Rick
False signals are common if you want to dig those deep coins others have left for you as you have notice. Some of these are easier to tell while others are tougher, but I feel if you don't get a rusty nail or washer once in a while you are missing some deeper coins and coins on edge.I too notice if you are getting quite a few false signals you know the sensitivity is a little high and you have to turn it down a bit as you suggest.
Now where I notice the most if the ground is dry then my rusty bottle caps will read around a nickle signal, but a bit iffy and hard not to dig, I did get them once in the 173 area too on a 180 meter at one site. I also have a few tricks too to help tell some of them and one I have to use on my GT more than any of the other Sovereigns I have used. This is where I get the good signal and move the coil back so I can get the signal right on the very tip of the coil, then being I know where it is suppose to be I come at it from a different angle. Now it is is a good signal it will still be there, but if a iron false then it will be nulling at a different angle or even moving. The other way is doing my 90 degrees pinpoint in all metal then while holding the coil still switch to disc and wiggle the coil a bit and if it goes positive signal it is a good one to dig,but if it null it is a iron null.
The Sovereigns are great detectors as many of you are seeing, but it takes a little time to fully learn these detectors,but once you do you will see some great finds from places others considered worked out.
Rick
funkyoldude
New member
I enjoyed reading your excerpt, but although I don't understand your explanation for "falsing", your advice for dealing with it is right on target.
It is my understanding that the receiver coil generates a signal voltage in response to the magnetic field produced by the eddy currents in the target material. The receiver signal is shifted in phase from the transmitted signal depending on the conductivity of the target material: the higher the conductivity, the greater the phase shift, and the higher the meter reading and the higher the tone. The way I understand it, iron has a distinct phase shift, and the Sovereign simply "blocks" (nulls) the signal from the output circuits.
It is also my view that we're not dealing with absolutes here, and in the real world, conductivities don't always match the standard values. For example, I would argue that a new iron wire does not have the same conductivity as an old rusty one. I believe that the shape of the wire will also affect the flow of the eddy currents and hence the phase shift. That's why a disc shaped target responds differently when it lies flat, vertical, or at some angle in between. The signal also varies depending on the way you approach the target with your detector. A coin and aluminum bottle cap may both come in at 180, and the pitch of the tones sound exactly the same, but the two targets will have completely different timbres.
Quite often, I will detect rusty bottle caps that come in around 163 to 169, but I recognize them because they tend to "pop" when the come out of a null. I have never picked up a rusty nail or wire, but we hunt a white sand beach. My wife has a Fisher Impulse (PI) and finds everything. Rusty nails and bits of wire are very rare here, and we don't mind digging them. Aluminum screw caps and beer bottle caps are our Nemesis and populate our beach in the hundreds of thousands!
Thanks for your excellent post. It's been a while since we have had a good technical discussion on this forum.
Good Hunting.
fod
It is my understanding that the receiver coil generates a signal voltage in response to the magnetic field produced by the eddy currents in the target material. The receiver signal is shifted in phase from the transmitted signal depending on the conductivity of the target material: the higher the conductivity, the greater the phase shift, and the higher the meter reading and the higher the tone. The way I understand it, iron has a distinct phase shift, and the Sovereign simply "blocks" (nulls) the signal from the output circuits.
It is also my view that we're not dealing with absolutes here, and in the real world, conductivities don't always match the standard values. For example, I would argue that a new iron wire does not have the same conductivity as an old rusty one. I believe that the shape of the wire will also affect the flow of the eddy currents and hence the phase shift. That's why a disc shaped target responds differently when it lies flat, vertical, or at some angle in between. The signal also varies depending on the way you approach the target with your detector. A coin and aluminum bottle cap may both come in at 180, and the pitch of the tones sound exactly the same, but the two targets will have completely different timbres.
Quite often, I will detect rusty bottle caps that come in around 163 to 169, but I recognize them because they tend to "pop" when the come out of a null. I have never picked up a rusty nail or wire, but we hunt a white sand beach. My wife has a Fisher Impulse (PI) and finds everything. Rusty nails and bits of wire are very rare here, and we don't mind digging them. Aluminum screw caps and beer bottle caps are our Nemesis and populate our beach in the hundreds of thousands!
Thanks for your excellent post. It's been a while since we have had a good technical discussion on this forum.
Good Hunting.
fod