Operation of the NRL-SDA optical communication terminal testbed

US Naval Research Lab (NRL) has, since early 2023, been operating an optical communication interoperability testbed for the Space Development Agency’s (SDA) Tranche 1 program. This testbed measures pointing, acquisition, and tracking capabilities, as well as data transfer performance. The testbed has been used to test optical communication terminals (OCT) from four different vendors as well the modem for a ground station. These OCTs are tested both against a government reference modem and each other to ensure compatibility between all the vendor implementations of the SDA OCT standard. Throughout the course of this testing numerous issues have been found, both in interoperability as well as general operability, which would have been difficult or impossible to resolve once the terminals were on orbit. This work will discuss how these issues are detected, the resolution process between NRL, SDA, and the OCT vendor, and the general process of optical interoperability testing.