My understanding of lock-in used to be only that of an analog lock-in amplifier.
Now, I am thinking about digital lock-in technique.
Reading this has been helpful.
However, I am having trouble identifying the digital lock-in's equivalent for the integration time found in the analog lock-in's multiplier unit.
Is this not the right way to think about the more modern lock-in, which actually doesnt have a multiplier unit but achieves high SNR measurement with the use of a mixer and LPF.
I would like to apply 'the integration of the product of the reference signal and the input signal' picture to the modern lock-in if there is a way. (thinking about the LPF in the time domain may be the way to do exactly that but I can't exactly put my finger on it)