Positional accuracy of GPS is limited by various error sources like ionosphere, troposphere, clock, instrumental bias, multipath etc. Among these, multipath errors are quite significant, since it should be dynamically modelled with respect to GPS receiver environment. In this paper, multipath error is estimated based on both code and carrier phase measurements using CMC (code minus carrier) method. It is verified with experimental static dual frequency GPS receiver data. The multipath time series data is applied to various Recursive Least Squares (RLS) adaptive filtering algorithms to minimize the multipath error. The results are encouraging and significant reduction of multipath error is observed. The convergence of RLS filters is faster than the conventional Least Mean Squares (LMS) adaptive filters. These RLS filters can also be applied to real time kinematic GPS applications.

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<p><strong>Abstract.</strong> Corner Reflectors (CR) are standard passive radar targets which offer one of the best solutions for SAR calibration. Radar Cross Section (RCS) of corner reflectors plays a vital role for estimation of calibration parameters and hence back scatter coefficient for airborne and spaceborne SAR images. There is a stringent requirement to characterize RCS of corner reflectors by measuring its scattering properties in a controlled environment. RCS characterization of square trihedral corner reflectors, dihedrals including polarization selective dihedrals is addressed. These measurements were carried out at X, C and S band frequencies with wide scan angles at definite sampling interval. The design details of corner reflectors, specifications of Compact Antenna Test Range Facility, technical modalities involved for RCS measurements, variation of measured RCS from theoretical value for trihedral and dihedral reflectors at different frequency bands and polarizations are presented in this paper.</p>

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