Abstract: A space-based communications network (10) includes satellites (12) placed in low-earth orbits (14). Satellites (12) engage in bulk communications with central switching offices (CSOs 22) and round control stations (GCSs 24). CSOs (22) and GCSs (24) include a network gateway (30) and any number-of remotely located earth terminals (32). Network gateway may provide telemetry, tracking and control functions for the constellation of satellites. Data are conveyed between the gateway (30) and earth terminals (32) over fiber optic cables (42) which convey a variety of different signals. Opposing unidirectional primary and secondary data communication channels each include signal sets having a gapped clock signal (76) and a data signal (86). The gapped clock signal (76) oscillates in synchronism with the data signal (86) and conveys both data timing and frame timing cable bundles (42) additionally convey LAN signals.