Localization and CRLB validity with Doppler and bearing measurements

The passive localization of a moving narrowband source by stationary sensors deployed at arbitrary locations which can make both Doppler and bearing measurements is discussed. In this problem, important considerations are the relative contributions of Doppler and bearing measurements, and the localization accuracy attainable. A standard approach is to use the Cramer-Rao lower bound (CRLB) to estimate the localization errors. However, it is known that at large enough noise levels, the CRLB fails to be accurate gauge of the attainable accuracy. The authors extend their previous results with Doppler to the case where bearing measurements are also available, and show how this approach can be used to determine the maximum-likelihood location, evaluate localization errors, and indicate departures from the CRLB