Wade, AndrewRees, Emily RoseShaddock, DanielMcKenzie, Kirk2023-07-149-14 May 2978-1-943580-91-0http://hdl.handle.net/1885/294241We present an electro-optic technique that generates an independent readout of optical cavity mode frequency spacing. We demonstrate a fractional frequency drift resolution of 1 ppb, sufficient to meet expected future mass change mission requirements.application/pdfen-AU© 2021 OSAReferencing Laser Frequency to Ultra-stable Reference Clocks for Future MCM Missions202110.1364/CLEO_SI.2021.STh1C.22022-05-08