Phase-Based Ranging

Question

I've been reading a lot about Phase-Based Ranging (PBR), and it's all starting to become very intuitive.

BUT; There is one technical, but extremely important, detail that seems to escape me. When the Local Oscillator (LO) replicates the input signal, does it replicate by mirroring the input detected instant of the phase? (I know the wording is weird)

Here is what I'm trying to say:

This "signal" would be detected after $2\pi+\frac{\pi}{3}$ rad. This would make the output signal intentionally out of phase by $\frac{\pi}{3}$.

This makes sense in that it would allow for PBR calculation, but doesn't seem possible to produce (detect) in the real world.

Answer 1

The local oscillator oscillates. It does not see input nor output signals at all. It just generates a steady waveform.

Your use of input and output feel unusual to me. You talk about "outputting a signal intentionally out of phase." The output is typically the thing that radiates outwards towards the object being ranged. It is not made out of phase to match the distance - the distance to the object creates the phase shift. There is also typically an "input" signal received from the object. This is the signal that exhibits a phase shift.

This "input" signal is then compared against the LO to recover the phase difference caused by propagation. Again, the LO never sees this signal. A comparator circuit sees the LO signal and the input signal.