A
Anonymous
Guest
Thankyou for the wake-up call!
Try inputting An Introduction to Metal Detector Filters at Google and reading Robert Hoolko.
Burr-Brown provide a useful programme for calculating circuit values - it even graphs responses. Sorry, I have misplaced the reference.
Similarly, they have an interesting paper - ,AB-022 in respect to fast-settling low-pass filters which I have yet to fiddle with.
Low-pass filters can also provide intergration of various samples - the approach adopted by Bruce Candy. In this application I have gone as low as 25htz. There simply doesn't appear any reason to maintaining square-waves in a detected signal - unless of course you want to fiddle with frequency analysis.
Findmall.com/minelabdoc.htm provides useful reading and discloses received signals up to 25khtz are used in the Sovereign design. Harken back to Eric's warning and don't open the window more than necessary to detect that something may be there.
Finally, I have found useful concepts in the design of wow/flutter meters. A particularly useful one is at pp 720 - 726, September '98, Electronics World.
graeme
Try inputting An Introduction to Metal Detector Filters at Google and reading Robert Hoolko.
Burr-Brown provide a useful programme for calculating circuit values - it even graphs responses. Sorry, I have misplaced the reference.
Similarly, they have an interesting paper - ,AB-022 in respect to fast-settling low-pass filters which I have yet to fiddle with.
Low-pass filters can also provide intergration of various samples - the approach adopted by Bruce Candy. In this application I have gone as low as 25htz. There simply doesn't appear any reason to maintaining square-waves in a detected signal - unless of course you want to fiddle with frequency analysis.
Findmall.com/minelabdoc.htm provides useful reading and discloses received signals up to 25khtz are used in the Sovereign design. Harken back to Eric's warning and don't open the window more than necessary to detect that something may be there.
Finally, I have found useful concepts in the design of wow/flutter meters. A particularly useful one is at pp 720 - 726, September '98, Electronics World.
graeme