ToddB64
Elite Member
Hi All !
Using the Teknetics Gamma 6000 digital metal detector as the subject in this post, it seems to me that one should always start the machine setup by First Ground Balancing using the instructions provided in the Gamma manual, in order to get rid of ground mineral affects before activating any other machine settings.
Second, increase the Sensitivity setting as high as possible until you hear EMI (Electromagnetic Interference), and then reduce Sens. until no more EMI is heard. Eliminating EMI will allow you to more clearly hear and analyze the audio signal characteristics of trash and/or good targets.
Third, Threshold. After reading and digesting the information in References #1 and #2 below and also reading the following paragraph concerning gain and threshold settings, decide if you want to add gain alone, or gain and some threshold adjustment as depicted by the graph in REFERENCE #2 . Lowering the Threshold by increasing Sensitivity between 90 and 94 exposes more targets according to BottleCapKing's underlined sentence in REFERENCE #1, second paragraph.
With further reference to Sensitivity, the Gamma manual states "From 05 to 90 gain is changing. Above 90, the threshold level changes. Setting above 94 will be noisy or sound erratic.".
This post comprises my suggestions for the initial Gamma 6000 machine setup and I believe those to be logical and in proper sequence. The balance of setups and the sequence of activating those are left to your preference.
Hope this is helpful !
ToddB64
______________________________________________________________
REFERENCE #1: http://metaldetectingforum.com/showthread.php?t=83973&page=3
Friendly Metal Detector Forums > Detectors and Gear > All About Detectors > by Dsparil, Titled Gain > Thread Page #3.
BottleCapKing Post #21 10-28-16, 01:43 PM
Elite Member
Even with Metal Detectors, gain and sensitivity are not the same thing.
Gain amplifies the signal coming out of the coil before being processed. Sensitivity adjusts the threshold at which the processors consider anything above to be a signal. When you increase sensitivity, you are lowering that threshold. When you decrease sensitivity, you are raising the threshold.
Gain has the problem of also amplifying ground noise. If gain is set too high, you are going to get a lot of noise. Sensitivity, if set too high will make bad targets and ground noise appear to be good targets. So, they both perform specific functions and have distinct consequences if set too high or too low.
_____________________________________________________________
REFERENCE #2 : http://www.fisherlab.com/hobby/dave-johnson-essays.htm
Fisher Gold & Treasure Detectors | Dave Johnson's Essays
Dave Johnson, Chief Designer, FTP & Fisher
Essay Title:
Discrimination mode “Sensitivity” and “Depth” in single-frequency VLF metal detectors
“Sensitivity control” A control labeled “sensitivity”. It actually controls either gain or threshold, or a combination of both, depending on the machine. If both, the higher settings vary threshold and the lower settings vary gain.
ToddB64 Personal Comment: I extracted the above paragraph from Dave Johnson's essays and pasted it here for your reference. I also copied and pasted the graph below from a Digger27 post, to help you visualize what Dave is saying.
Using the Teknetics Gamma 6000 digital metal detector as the subject in this post, it seems to me that one should always start the machine setup by First Ground Balancing using the instructions provided in the Gamma manual, in order to get rid of ground mineral affects before activating any other machine settings.
Second, increase the Sensitivity setting as high as possible until you hear EMI (Electromagnetic Interference), and then reduce Sens. until no more EMI is heard. Eliminating EMI will allow you to more clearly hear and analyze the audio signal characteristics of trash and/or good targets.
Third, Threshold. After reading and digesting the information in References #1 and #2 below and also reading the following paragraph concerning gain and threshold settings, decide if you want to add gain alone, or gain and some threshold adjustment as depicted by the graph in REFERENCE #2 . Lowering the Threshold by increasing Sensitivity between 90 and 94 exposes more targets according to BottleCapKing's underlined sentence in REFERENCE #1, second paragraph.
With further reference to Sensitivity, the Gamma manual states "From 05 to 90 gain is changing. Above 90, the threshold level changes. Setting above 94 will be noisy or sound erratic.".
This post comprises my suggestions for the initial Gamma 6000 machine setup and I believe those to be logical and in proper sequence. The balance of setups and the sequence of activating those are left to your preference.
Hope this is helpful !
ToddB64
______________________________________________________________
REFERENCE #1: http://metaldetectingforum.com/showthread.php?t=83973&page=3
Friendly Metal Detector Forums > Detectors and Gear > All About Detectors > by Dsparil, Titled Gain > Thread Page #3.
BottleCapKing Post #21 10-28-16, 01:43 PM
Elite Member
Even with Metal Detectors, gain and sensitivity are not the same thing.
Gain amplifies the signal coming out of the coil before being processed. Sensitivity adjusts the threshold at which the processors consider anything above to be a signal. When you increase sensitivity, you are lowering that threshold. When you decrease sensitivity, you are raising the threshold.
Gain has the problem of also amplifying ground noise. If gain is set too high, you are going to get a lot of noise. Sensitivity, if set too high will make bad targets and ground noise appear to be good targets. So, they both perform specific functions and have distinct consequences if set too high or too low.
_____________________________________________________________
REFERENCE #2 : http://www.fisherlab.com/hobby/dave-johnson-essays.htm
Fisher Gold & Treasure Detectors | Dave Johnson's Essays
Dave Johnson, Chief Designer, FTP & Fisher
Essay Title:
Discrimination mode “Sensitivity” and “Depth” in single-frequency VLF metal detectors
“Sensitivity control” A control labeled “sensitivity”. It actually controls either gain or threshold, or a combination of both, depending on the machine. If both, the higher settings vary threshold and the lower settings vary gain.
ToddB64 Personal Comment: I extracted the above paragraph from Dave Johnson's essays and pasted it here for your reference. I also copied and pasted the graph below from a Digger27 post, to help you visualize what Dave is saying.
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