Is this flight software?

No. SIDUS models are educational reimplementations. Cross-check before any flight decision.

Doppler shift

One-way fd = f0 vr/c, two-way 2 fd, and range-rate error from a clock offset.

SIDUS educational calculator. Category satellite. Tags: operations, RF, satellite. Pure SI. Not flight software.

fd = f0 vr / c fd2 = 2 fd

One-way and two-way Doppler

Fundamentals of Astrodynamics and Applications (David A. Vallado): Standard reference for two-body, Lambert, maneuvers, and J2. Equations implemented independently in SIDUS.
Orbital Mechanics for Engineering Students (Howard D. Curtis): Textbook derivations for Hohmann, vis-viva, rocket equation, elements.
Radiometric Tracking Techniques for Deep-Space Navigation (NASA / JPL DESCANSO (Thornton, Border)): DSN two-way range, Doppler, and clock-to-range-rate. Educational SI, not a tracking system.

Read /llms.txt or call https://sidus.tools/api/mcp. Open the interactive page for live SI inputs.