Timeline for Lowpass Filter for Lock-In-Amplifier
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| Apr 30, 2022 at 19:47 | comment | added | Ed V | Maybe this will provide food for thought: dsp.stackexchange.com/a/58540/41790. In my answer there, I just used a simple RC low pass filter instantiation and then the N point smoothing, which is the moving average Dan Boschen recommended. As he said, providing details about what you have and what you want to do with it, is very helpful in getting a useful and valid answer. | |
| Apr 30, 2022 at 19:28 | review | Close votes | |||
| May 17, 2022 at 3:03 | |||||
| Apr 30, 2022 at 3:11 | comment | added | Dan Boschen | A Butterworth is likely not the best choice. A moving average is your best choice for estimating the mean WHEN the noise is AWGN. For other cases (if you have any spectral content as an interference, this would be the worst choice). To answer your question we would need the following details: What is the bandwidth of your signal of interest (what is the highest frequency you want to observe)? What is your input sampling rate? What is your objective use of the resulting signal (This may help illuminate other requirements of interest). What does the spectrum look like if you didn't filter at all | |
| Apr 29, 2022 at 19:53 | comment | added | bilaljo | Thank you for the explanation! But why would be a (moving) average a good choice? I thought its frequency behaviour would make it a bad choice. | |
| Apr 29, 2022 at 17:53 | comment | added | a concerned citizen | An adaptive moving average might be your best bet; or a simple moving average, if the tracked frequency is fixed. A Butterworth is only good because it's flat in the passband, but its attenuation is not that good, and its step response has overshoots. | |
| Apr 29, 2022 at 17:44 | comment | added | Marcus Müller | Well, the choice of bandwidth of the filter depends on the bandwidth of the observed signal, there's no general rule because it really depends. | |
| Apr 29, 2022 at 17:43 | comment | added | Marcus Müller | Butterworth is probably not the filter type you want here, but if you don't care about delay it's probably OK. | |
| S Apr 29, 2022 at 16:27 | review | First questions | |||
| Apr 29, 2022 at 17:43 | |||||
| S Apr 29, 2022 at 16:27 | history | asked | bilaljo | CC BY-SA 4.0 |