Validation of the error model against the Cassini 2014 DOY 320 solar conjunction. (Top left) Cassini–Earth LOS projected onto the heliocentric ecliptic plane in units of solar radii ﹩{R}_{{\rm{S}}}﹩, colored by the PFSS-predicted LOS magnetic field component along the ray. (Top right) 1﹩\sigma ﹩ comparison for the three two-way retrieval configurations: empirical 1﹩\sigma ﹩ (blue), predicted 1 ﹩\sigma ﹩ from the forward model using the observed per-channel CNR (purple), and predicted 1﹩\sigma ﹩ from the same forward model using the a priori DSN-design CNR of Section 3 (orange). (Bottom) Measured ﹩\left\langle {B}_{\parallel }\right\rangle ﹩ as a function of tangent-point distance for the single X-up/S-down (black), dual S/X (blue), and single X-up/X-down (red) two-way retrievals, each overlaid with its 3σ envelope obtained by forward-evaluating the error model with the observed per-channel CNR. The PFSS prediction (green) is also shown.