How does target scintillation affect the tracking accuracy of a radar system?

Target scintillation affects the tracking accuracy of a radar system by causing the apparent angular position of the target to wander randomly around the target's true centroid, an effect known as angular glint. Scintillation occurs because real targets are composed of multiple scattering centers (engines, wings, fuselage, tail) that interfere constructively and destructively as the target's aspect angle changes, causing: amplitude scintillation (the total RCS fluctuates, described by the Swerling models, affecting detection probability and SNR-dependent tracking accuracy) and angular glint (the apparent angle of arrival wanders because the relative phases of the scattering centers shift, moving the phase center of the return signal to locations that can be outside the physical extent of the target). The angular glint error is: sigma_glint approximately L_target / (2 x sqrt(SNR)) for a two-scatterer model, where L_target is the target's cross-range extent. For a 15 m aircraft at SNR = 20 dB: sigma_glint approximately 15 / (2 x 10) = 0.75 m in cross-range. At 10 km range: this corresponds to approximately 0.0043 degrees. Glint dominates the tracking error at short ranges (where SNR is high and thermal noise error is small) while thermal noise dominates at long ranges (where SNR is low). The total tracking error is: sigma_total = sqrt(sigma_thermal^2 + sigma_glint^2).