Android Phone Based Metal Detector - FCMD

[moodz]

AI will give you all sorts of great answers .. but the proof is in the pudding ( or is it the eating ? ).

Anyway here is the frontend response for my sampling scheme from the C code.
The nulls are really sharp mains reduction wont be infinity obviously due to variance in mains frequency.

[moodz]

regarding the loop rates ... 50 Hz is actually better than a fast loop rate.

Below is the comparison of continuous target, 200 hz rate, 50 hz rate and my code cubic interpolation .... giving a smooth signal response that is "near perfect".
If you make your loop faster than needs be for a given target bandwith its just ignoring basic nyquist sampling and shannons sampling theorem.

[Hristo]

This real math science is really trhiling a me amuzment by da way is not correct on target signal response it is not a continius signal so ewretinlg later is no relevant sorry to upset you again tell you just use 250SPS and all be well , and everything will be fine, and you'll be bathing in a chocolate bath.

[moodz]

This real math science is really trhiling a me amuzment by da way is not correct on target signal response it is not a continius signal so ewretinlg later is no relevant sorry to upset you again tell you just use 250SPS and all be well , and everything will be fine, and you'll be bathing in a chocolate bath.

LOL. I am bathing in a chocolate bath ... the signal is just samples .. mine come in at 50 hz ... the integrators fully reset every 20 ms ( ie every cycle ) so theoretically it can detect a target in 20 milliseconds ..

OK how about I put variable loop rate control in ( just for you )

[Carl-NC]

Below is the comparison of continuous target, 200 hz rate, 50 hz rate and my code cubic interpolation

Your Gaussian curve looks slower than it should for 15Hz. This is what I come up with for a 15Hz target response sampled at 50Hz:


In general, the more you sample the more you can filter. The only reason most detectors used a 5ms loop rate is that processors of yore couldn't do much more than that.