Homebrew Lock-In Amplifier

[Picuino]

Interesting documentation about digital filters and Lock-in Amplifiers:
https://www.lakeshore.com/docs/default-source/default-document-library/ab1-00---fir-vs-iir-filtering-for-faster-lock-in-measurements.pdf

https://www.advsolned.com/difference-between-iir-and-fir-filters-a-practical-design-guide/

[zrq]

I just did some very quick and dirty tests using labview and my 3rd gen Focusrite 2x2 sound card to work as a lock-in ampliifer, apparently one can easily get >110 dB dynamic range at 311Hz and 1112 Hz carrier frequency for 1 Hz IF bandwidth, characterized by comparing the demodulated signal strength when (Line) input is open and when the loopback signal reaches full scale. And it appears to be limited by the crosstalk from the internal generator (using the headphone output), particularly at higher carrier frequencies, so by doing a simple "zeroing" it can be even better.