Is Kelly Lochbaum Ladder Filter LTI? I am a bit confused about the Kelly Lochbaum Ladder Filter. Image below taken from here.



My question is, is this an LTI (linear time-invariant) filter? I thought that it was LTI, but I am not sure anymore.
As long as the graph consists only of delays, add/subtract and multiply-with-a-constant, then the system will be LTI.

In this case, if the coefficients $k_1 ... k_m$ don't change with time, the system is LTI.