The spatial density of false measurements is known as clutter density in si
gnal rind data processing of targets. It is unknown in practice and its kno
wledge has a significant impact on the effective processing of tar get info
rmation. This paper presents in the first time a number of theoretically so
lid estimators for clutter density based on conditional mean, maximum likel
ihood, and method of moments, respectively. They are computationally highly
efficient and require no knowledge of the probability distribution of the
clutter density. They can be readily incorporated into a variety of tracker
s for performance improvement. Simulation verification of the superiority o
f the proposed estimators to the previously used heuristic ones is also pro
vided.