Doppler-Only Initial Orbit Determination for an Orbiting Transmitter

View Video Presentation: https://doi.org/10.2514/6.2022-1000.vid Most spacecraft rely on radio frequency transmissions for communication and other mission-critical functions. This work investigates the efficacy of initial orbit determination (IOD) for a transmitter in an unknown orbit, potentially allowing for an inexpensive means of spacecraft navigation. In the case where the transmit frequency is unknown, the Doppler shift between the orbiting transmitter and a receiver may be used to estimate the transmit frequency and thus estimate the range rate. It is found that a time-history of range rate measurements allow for IOD when the receiver state is known and the transmitter is in a near circular orbit. IOD for the full three-dimensional transmitter orbit may be achieved using only a one-dimensional search on the unknown orbit radius.