First Deep-Space Flight Demonstration of Regenerative Pseudo-Noise Ranging

Deep-space missions traditionally use sequential, turnaround ranging to measure the distance to the spacecraft. The spacecraft demodulates the uplinked ranging signal (composed of sequential frequency tones) and retransmits it ("turnaround") onto the downlink. Since this operation is bent-pipe, noise on the uplink within the ranging channel bandwidth is also retransmitted. When the received uplink signal-to-noise ratio (SNR) is low, regenerating the ranging signal can increase the retransmitted ranging SNR by 30 dB or more, compared to the bent-pipe method. The Regenerative pseudo-noise (PN) ranging creates this gain by using a PN digital ranging signal on the uplink and detecting that signal in the spacecraft receiver. The PN signal is regenerated digitally, with no uplink noise, and retransmitted to the ground. We report the first deep-space flight demonstration of regenerative ranging on the New Horizons Mission to Pluto. We provide an overview of the technique, including the operational PN ranging capability deployed at NASA's Deep Space Network (DSN). We describe the regenerative ranging implementation on the New Horizons spacecraft. Finally, we report on the operational flight tests, compare their results to the current trajectory (and sequential ranging), and detail how this technique will aid this mission in the future.