Originally posted by Carl-NC
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We have a no target, roughly DC point that is a steady as we can make it.
Then, when we move the coil over a target, this DC point varies at a rate of about 3 to 20 Hz, depending on the size of the target, the size of the coil and the sweep speed.
Now when we filter the initial signal, high pass and low pass, how much is the 3 to 20Hz target signal influenced?
When I filter my initial coil signal, I notice that the signal of short TC targets, gets attenuated with a 100kHz low pass filter.
A 150kHz high pass filter would help reducing 50-60Hz power line noise picked up by the coil, but the 3 to 20 Hz target signal remains mostly. I say mostly, because I have noticed that there are some frequency interactions that influence the target signal.
The pulse repetition rate.
The integration time.
And the general interactions of all these frequencies. Could someone explain to me how all this together works?
Tinkerer
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