﹩{B}_{\parallel ,{\rm{CA}}}﹩ and ﹩\left\langle {B}_{\parallel }\right\rangle ﹩ as functions of altitude during ingress (left) and egress (right), with 3 ﹩\sigma ﹩ uncertainties for the single two-way S-band link (black) and the dual two-way S/X-band combination (blue). The 3σ envelopes are obtained by forward-evaluating the error model with the a priori DSN-design CNR of Section 3. Altitude is defined above the 1 bar level.