Velocity Ambiguity Resolution using Opposite Chirprates with LFM Radar

High frequency radar observations of satellites are altered by the impacts of range Doppler coupling along with ambiguous Doppler measurements, making the estimation of true range and velocity challenging. This paper investigates the use of combining two coincident detections, from independent chirp transmitters, to instantaneously estimate target parameters. It shows the estimates produced are greatly improved with using chirprates with opposite polarity, even if the two transmit frequencies are closely spaced. The paper includes example results from an opportunistic pass of the International Space Station during a recent trial.