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Beware digital interfaces can introduce signal anomalies
- Thread starter dirtdog
- Start date
Ralph Bryant
New member
"Can"..."could"..."might"..."possibly"..."potentially"..."may".
But "WILL" they ?
Inquiring minds want to know more.....
Ralph
But "WILL" they ?
Inquiring minds want to know more.....
Ralph
Ralph, I got a good morning laugh at that statement. Anyhow I thought you might think about this and comment.
A coil is designed to be tuned to the operating frequency of a detector as we know. If we apply a sine wave to the TX coil and look at the RX coil when a target is passed through the electromagnetic field we see a target signal. The coil can be fine tuned so the signal in the RX coil is best which is what I think we are seeing with the smart coil.
A detector operating at 7.5khz with a properly designed coil should be tuned to that frequency. There are some variations in the frequency that is tolerable such as if the frequency drifts to 7.8khz and with a little loss in effectiveness. I guess we could express that as a plus or minus tolerance so if the frequency drifted to 7.2khz we have a + or - .3khz variations that should work within specifications.
However, if we want to take advantages of the higher frequency operation then we need a coil that is tuned to that frequency. The difference between 7.5khz and about 18khz would cause signal degradation that is unacceptable. We notice that the physical and or electrical parameters can be varied to keep the coil fine tuned to the transmitter for most effective operation.
The chip in the smart coils for the X-50 should keep the coils tuned to the operating frequency as the attribures of the coil change. These can change due to aging, being bumped, cold and hot weather, etc, so if we keep the coil fine tuned to the transmitter we have an advantage.
A factor in keeping the coil fine tuned is to drive the coil with a clean sine wave that is very stable. A nice clean 7.5khz drive to the coil and then keeping the coil fine tuned to that frequency is going to be an advantage.
Multiple frequency detectors do not use a sine wave drive but a square wave to drive the coil. I don
A coil is designed to be tuned to the operating frequency of a detector as we know. If we apply a sine wave to the TX coil and look at the RX coil when a target is passed through the electromagnetic field we see a target signal. The coil can be fine tuned so the signal in the RX coil is best which is what I think we are seeing with the smart coil.
A detector operating at 7.5khz with a properly designed coil should be tuned to that frequency. There are some variations in the frequency that is tolerable such as if the frequency drifts to 7.8khz and with a little loss in effectiveness. I guess we could express that as a plus or minus tolerance so if the frequency drifted to 7.2khz we have a + or - .3khz variations that should work within specifications.
However, if we want to take advantages of the higher frequency operation then we need a coil that is tuned to that frequency. The difference between 7.5khz and about 18khz would cause signal degradation that is unacceptable. We notice that the physical and or electrical parameters can be varied to keep the coil fine tuned to the transmitter for most effective operation.
The chip in the smart coils for the X-50 should keep the coils tuned to the operating frequency as the attribures of the coil change. These can change due to aging, being bumped, cold and hot weather, etc, so if we keep the coil fine tuned to the transmitter we have an advantage.
A factor in keeping the coil fine tuned is to drive the coil with a clean sine wave that is very stable. A nice clean 7.5khz drive to the coil and then keeping the coil fine tuned to that frequency is going to be an advantage.
Multiple frequency detectors do not use a sine wave drive but a square wave to drive the coil. I don
Ralph Bryant
New member
Hi Cody,
Hope you and yours had a nice Christmas.
The first machine that comes to mind for me (obviously) is the Nautilus DMC-IIb with its R&C coil tuning capabilities. I think the ability to fine-tune the coil according to variations caused by some of the reasons you mention is very important. Too many times we think of our detectors and their capabilities all lying within the circuitry of the control housing, and don't pay near enough attention to the coil. We assume that the coils are tuned to their "optimum" level, when in fact that is rarely the case. And having that ability to fine-tune the coil I think is one of the major advantages of the Nautilus and likely why most relic hunters who use them consider them as the "best" machines on the market for that purpose with an apparent ability to signal on fringe range and fringe sized targets that others cannot. I'm not sure if other machines have this "coil-tuning" activity being performed to some degree "automatically" within the circuitry as a matter of design or not. I would suspect though that most machine to coil "tuning" is more a matter of just manufacturing the coils to "tolerances" as you suggest. I know Tesoro for instance claims compatability between all of their uMax land machines and coils, even though they have units operating from 10 kHz up to 12 kHz, plus any individual unit tolerances + or - those frequency specifications. That is a pretty wide tolerance to cover with a coil that is "tuned" to the operating frequency, but they seem to be "functional" (as Monte would put it
) from experience. But how could they possibly be tuned for optimal performance with such wide tolerances ? At detectable depths, maybe it is not quite as important......with the term "detectable depths" being a little more than vague terminology. Either it can or it can't..... 
I think the suggestion (by Matt) that the Minelab Xterra coils have what amounts to a digitizing function at the coil RX point is a matter of which is easier or "cleaner" to transmit from that point back to the main circuits via the coil cable, analog information or digital data.
In any case, it would be interesting to hear from the Xterra engineers at Minelab about exactly what they are doing.
Ralph
Hope you and yours had a nice Christmas.
The first machine that comes to mind for me (obviously) is the Nautilus DMC-IIb with its R&C coil tuning capabilities. I think the ability to fine-tune the coil according to variations caused by some of the reasons you mention is very important. Too many times we think of our detectors and their capabilities all lying within the circuitry of the control housing, and don't pay near enough attention to the coil. We assume that the coils are tuned to their "optimum" level, when in fact that is rarely the case. And having that ability to fine-tune the coil I think is one of the major advantages of the Nautilus and likely why most relic hunters who use them consider them as the "best" machines on the market for that purpose with an apparent ability to signal on fringe range and fringe sized targets that others cannot. I'm not sure if other machines have this "coil-tuning" activity being performed to some degree "automatically" within the circuitry as a matter of design or not. I would suspect though that most machine to coil "tuning" is more a matter of just manufacturing the coils to "tolerances" as you suggest. I know Tesoro for instance claims compatability between all of their uMax land machines and coils, even though they have units operating from 10 kHz up to 12 kHz, plus any individual unit tolerances + or - those frequency specifications. That is a pretty wide tolerance to cover with a coil that is "tuned" to the operating frequency, but they seem to be "functional" (as Monte would put it
) from experience. But how could they possibly be tuned for optimal performance with such wide tolerances ? At detectable depths, maybe it is not quite as important......with the term "detectable depths" being a little more than vague terminology. Either it can or it can't..... I think the suggestion (by Matt) that the Minelab Xterra coils have what amounts to a digitizing function at the coil RX point is a matter of which is easier or "cleaner" to transmit from that point back to the main circuits via the coil cable, analog information or digital data.
In any case, it would be interesting to hear from the Xterra engineers at Minelab about exactly what they are doing.
Ralph
Ralph, if there is something really different such as multiple frequency in the Explorer or Sovereign then there are lots of room to play. However, SF is as old a dirt so what can be done? Fine tune the coil, clean drive signal, but there is not going to be some kind of super technology that just astonishes the detecting world as long as it is SF and PI. The greatest change to PI was with the TID time domain Sovereign and Explorer and kin to that the frequency domain DFX and then the others that followed. SF has not changed since it radiated the roaches in our walls. I look at digital, taking up a little slack here and there and we have a better machine.
A
Anonymous
Guest
n/t