  Space-borne gravitational wave detectors, such as (e)LISA, are designed to
operate in the low-frequency band (mHz to Hz), where there is a variety of
gravitational wave sources of great scientific value. To achieve the
extraordinary sensitivity of these detector, the precise synchronization of the
clocks on the separate spacecraft and the accurate determination of the
interspacecraft distances are important ingredients. In our previous paper
(Phys. Rev. D 90, 064016 [2014]), we have described a hybrid-extend Kalman
filter with a full state vector to do this job. In this paper, we explore
several different state vectors and their corresponding (phenomenological)
dynamic models, to reduce the redundancy in the full state vector, to
accelerate the algorithm, and to make the algorithm easily extendable to more
complicated scenarios.
