ANCHOR is a novel assimilative model developed at the U.S. Naval
Research Laboratory. It extracts ionospheric parameters from RO and
ionosonde data and assimilates them as point measurements into the maps
of the background parameters using Kalman Filter approach. This paper
introduces the ANCHOR algorithm, discusses its coordinate system and
background, explains the background covariance formation, discusses the
extraction of the ionospheric parameters from the data and the
assimilation process, and, finally, shows the results of the observing
system simulation experiment.