No I didn't, I actually understood the explanation as best I can. (Thanks to Nikodemuz's great clarification :thumbup:). We're not talking about ground returns here, which do indeed have a doppler shift, and are filtered out as well as the radial velocity contacts which have the same doppler shift, we are talking about the so-called 0 relative airspeed doppler filter. It's apparently a real thing and in Naquii's last post he explains why these co-speed tail chase returns are dropped.