Decelerate phase-shifted signal in order to evaluate with lower-cost components. e.g. for laser distance measurement.
Add both input signals to a slightly faster or slower frequency.
The result is an amplitude modulated harmonic, which is then rectified and smoothed.
The output has two slower frequencies with an equivalent phase shift.
https://www.youtube.com/watch?v=pcw3Ue3cLUo&t=677s
http://www.electronicdeveloper.de/FilterAktivAllPass.aspx
The left circuit is a simple phase shifter to test the devider circuit.
an other solution http://everycircuit.com/circuit/5252526659338240
