AP
Thanks for that. My admittedly limited experience is with marine radar where you have a full set of tools to adjust the image. I was hugely impressed to find I could pick up lobster pot buoys (basically a stick with a flag on it attached to a plastic float) using the radar on a cross-channel ferry where you have sea-clutter to contend with.
As you say, if you filter it out you an't going to see it. (Which leads us seductively into the Mode S debate
)