2D Ideal Particle System Function for 1D FFP Motion. Ideal particle system function at different harmonics for 1D FFP motion along the center line in z direction. The column '1D system function' displays the Chebyshev functions plotted in the left part of figure 4. The 2D system function is obtained from a convolution of the Chebyshev functions with the kernels shown in the top row for signal reception in z and x direction, respectively. The dashed lines indicate the edges of the range covered by the FFP motion.