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Hi Carl,
I checked this site out and it looks quite interesting. http://www.pulsdetektor.de/
I used GOOGLE to translate pages from German to English abeit a little poor but none the less informative. The Pulse isolation unit based designs on this site are the most interesting I think. My understanding of what they are doing is this;
A free air coil sample is taken to presumably gain a null point reference with no metal near the coil.
Then a small piece of ferrous metal is used to load the coil while taking another in air sample or snap shot. I think the idea is to subtract this reference from the received signal to exclude the metal type. Coil switched voltage looks to be around 30v and peak current would be quite high. I gave up reading after 2 or 3 pages as my brain was hurting from the bad translation.I will revisit it though.
The point is that it would seem that sampling like this and then comparing the difference to recieved signals has a little bit of Corbyn's proccess in it. The Corbyn design I built up worked reasonably well although tweaking the unit over different ground patches was required which became anoying,it is not an orphan here though.
I like the idea of digital sampling but with my experience using the Corbyn analog design,one would need a few reference samples stored to be of much value.
Thinking on this though, it should be possible to take a single digital sample of the ground signal with no metal present, store this as a base reference, then modify the stored decay curve using the received ground signal as the control for further tweakingmodifying the realtime reference. Stability over varying ground in a given area while still maintaining senstivity is what I am thinking about here.
Eg. multi frequency ground exclusion methods are not perfect nor is the Corbyn method of ground simulation exclusion but perhaps using one method to modify the other is not too far fetched....the answer I think is around there somewhere... Hope this makes sense!
Cheers
Brian King
I checked this site out and it looks quite interesting. http://www.pulsdetektor.de/
I used GOOGLE to translate pages from German to English abeit a little poor but none the less informative. The Pulse isolation unit based designs on this site are the most interesting I think. My understanding of what they are doing is this;
A free air coil sample is taken to presumably gain a null point reference with no metal near the coil.
Then a small piece of ferrous metal is used to load the coil while taking another in air sample or snap shot. I think the idea is to subtract this reference from the received signal to exclude the metal type. Coil switched voltage looks to be around 30v and peak current would be quite high. I gave up reading after 2 or 3 pages as my brain was hurting from the bad translation.I will revisit it though.
The point is that it would seem that sampling like this and then comparing the difference to recieved signals has a little bit of Corbyn's proccess in it. The Corbyn design I built up worked reasonably well although tweaking the unit over different ground patches was required which became anoying,it is not an orphan here though.
I like the idea of digital sampling but with my experience using the Corbyn analog design,one would need a few reference samples stored to be of much value.
Thinking on this though, it should be possible to take a single digital sample of the ground signal with no metal present, store this as a base reference, then modify the stored decay curve using the received ground signal as the control for further tweakingmodifying the realtime reference. Stability over varying ground in a given area while still maintaining senstivity is what I am thinking about here.
Eg. multi frequency ground exclusion methods are not perfect nor is the Corbyn method of ground simulation exclusion but perhaps using one method to modify the other is not too far fetched....the answer I think is around there somewhere... Hope this makes sense!
Cheers
Brian King
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