Timeline for How does this FLL work?
Current License: CC BY-SA 4.0
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| Feb 10, 2023 at 22:55 | comment | added | Dan Boschen | The complex conjugate product is required to strip the modulation; so given that it is a complex conjugate multiplication, we know it's correlation in the frequency domain. With no modulation, either would work. What is also missing from the diagram is that it is the real output of the complex conjugate multiplier that is used for the error signal as the input to the loop filter. | |
| Feb 10, 2023 at 22:09 | comment | added | Villere_DSP | Its a great explanation. But what I dont follow is why use convolution to get a correlation. The filter derivative spectrum will give a zero when its both convolved and correlated with the filter spectrum because of its shape. So it makes no difference to a result if one is mirrored and the other conjugated to peform a correlation via convolution, not doing that also gives a zero result ( i.e. normal convolution). The correlation and convolution are equal here for these shapes? | |
| Feb 10, 2023 at 21:59 | history | edited | Dan Boschen | CC BY-SA 4.0 |
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| Feb 10, 2023 at 14:11 | history | edited | Dan Boschen | CC BY-SA 4.0 |
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| Feb 9, 2023 at 18:15 | history | edited | Dan Boschen | CC BY-SA 4.0 |
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| Feb 9, 2023 at 17:47 | comment | added | Dan Boschen | @Villere_DSP Please review to see if I properly addressed your concerns. | |
| Feb 9, 2023 at 17:46 | history | edited | Dan Boschen | CC BY-SA 4.0 |
updated to minimize confusion with cross-correlation and convolution
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| Feb 9, 2023 at 17:31 | comment | added | Dan Boschen | @Villere_DSP Yes you are right. Let me edit that to be clearer. | |
| Feb 9, 2023 at 13:14 | comment | added | Villere_DSP | Hi Dan. But your answer talks about convolving the output spectrums. I follow that convolving the spectrums give the error, but not seeing where cross correlation fits in to your answer as you have no conjugation because convolution in frequency is multiplication in time, not conjugate multiplication in time. | |
| Jul 13, 2021 at 4:41 | history | edited | Dan Boschen | CC BY-SA 4.0 |
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| Sep 26, 2018 at 21:45 | history | edited | Dan Boschen | CC BY-SA 4.0 |
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| Sep 24, 2018 at 12:37 | history | edited | Dan Boschen | CC BY-SA 4.0 |
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| Sep 24, 2018 at 2:52 | history | edited | Dan Boschen | CC BY-SA 4.0 |
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| Sep 24, 2018 at 2:47 | history | answered | Dan Boschen | CC BY-SA 4.0 |