The challenge of transmitting super-high-frequency radio signals over short fiber-optic networks on aerospace platforms

This paper addresses the feasibility of transmitting super-high-frequency (3-30 GHz) radio frequency (RF) signals over fiber-optic networks. Fiber-optic media is a preferred selection to transmit the super-high-frequency RF signals because (1) fiber-optic cables are immune to EMI and noise and (2) the associated photonic conversion devices now support enormous increases in signal handling, which are required by modern and future aerospace sensor systems. The benefits and challenges of employing RF over fiber-optic networks using single-mode fiber optics, coupled with wave division multiplexing (WDM) for aerospace platforms, is discussed here. Considerations of signal dynamic range, signal-to-noise ratio, and fidelity associated with RF and super-high-frequency RF signal conversions are also covered. Approaches are also considered for acceptably bounding these parameters for hybrid architectures comprised of legacy networks and for architectures interfaced with fiber-optic networks. Future architectures involving total fiber-optic media provide for communications with RF-to-photonic conversions and photonic-to-RF conversions contained within the subsystem receivers, transmitters, or transceivers associated with the aerospace subsystem. In particular, this paper addresses the use of single-mode fiber-optic networks and postulates designs to consider for modifying or developing modem or future aerospace vehicles, respectively.