UHF communications with CubeL: the path to nominal operations

Abstract

CubeL (aka PIXL 1) is a 3U cubesat serving in-orbit-demonstration purposes. Its main payload is OSIRIS, a miniaturized optical terminal designed by DLR and Tesat-Spacecom which is capable of transmitting up to 100Mbps. CubeL is also the first COTS cubesat operated by the German Space Operations Center (GSOC). For this, a standard UHF transceiver using CSP, the Cubesat Space Protocol, has been installed on the spacecraft. And a brand new UHF ground station was installed on GSOC’s roof in Oberpfaffenhofen, Germany. The UHF station consists of a steerable double cross Yagi antenna linked to a transceiver of the same design as the one on board the spacecraft. This transceiver also relies on CSP and secures the compatibility between spacecraft and ground station. After introducing the CubeL spacecraft, its on-board UHF communication systems, and the new UHF ground station, we will present the challenges encountered by GSOC to operate CubeL with the UHF link. Among others, we will detail how the geometry of the ground antenna and various misalignments affect the link quality and what this means for daily operations. Effects of phase misalignment on the antenna and their impact will be detailed too. And the consequences of the World Radiocommunication Conference 2019 (WRC-2019), more specifically the addition of the article 5.264A, on operations with the UHF communication link will be analysed in detail. GSOC’s strategy to tackle those obstacles and restore nominal operations with CubeL will be described. To conclude, we will discuss if this UHF link is viable in today’s conditions.