Citation
Abstract
This article describes a synchronous ranging system to estimate the range between a spacecraft and a ground station from an optical uplink and downlink. Time transfer between the uplink and downlink is achieved by (1) synchronizing the uplink and downlink symbol clocks at the spacecraft, and (2) defining a new protocol data unit, termed ranging codeword, to provide sufficient range ambiguity resolution. The article is divided into three parts. First, it explains the general concept of a synchronous ranging system, including how range estimates can be recovered from phase measurements and how the system operates when used in conjunction with the protocol stack defined by the Consultative Committee for Space Data Systems for high photon efficiency optical links. Secondly, this article derives the necessary equations to estimate the system performance assuming that both the spacecraft and ground station use a photon-counting device to receive the optical system. Finally, the third part of this article describes a software prototype developed at the Jet Propulsion Laboratory to validate the operation of a synchronous ranging system. To do so, I utilize channel conditions representative of the Deep Space Optical Communications experiment on board the Psyche spacecraft and showcase the achievable ranging performance in two scenarios, one with benign channel conditions and one with expected channel conditions at 1 AU.
Keywords
Details
- Volume
- 42-229
- Published
- May 15, 2022
- Pages
- 1–47
- File Size
- 1.4 MB