Research on Multipath-Caused MLS Angle-Measurement Error Using Main Lobe Gaussian Replacement Technology

Electromagnetic scattering caused by the site environment of airports will cause multipath effect. In the presence of multipath, the measured angle position, which is derived through the measuring of the time interval between “From” and “To” scanning pulse pairs, will deviate from the actual position, leading lower system guidance accuracy and higher risk. An error research method based on the equivalent replacement of the scanning beaming main lobe is presented. Through the equivalent Gaussian replacement of the beam main-lobe of “From” and “To” pulse, the error formula in the presence of several multipath components is derived. The method is used to calculate the anglemeasuring performance error of the receiver for the special multipath environment and a practical angle-measurement error model is established. The results derived from the replacement model are compared with that of the classical model. The new model can overcome the limitation and deficiency of classical model in exact error calculation. Moreover, the accuracy is more improved than the classical model. The displacement error of envelope peak position and displacement error of envelope peak level caused by multipath effect is further analyzed based on the replacement method.