Ryan McKnight and Frank van Graas, Ohio University

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Abstract:

Recent research on pulsar based navigation and timing by organizations such as NASA and ESA has primarily focused on X-ray measurements as opposed to previous research which instead focused primarily on radio-frequency (RF) measurements. X-ray based systems offer the potential for greater accuracy than RF based systems and do not require the large antenna apertures historically considered to be necessary for adequate performance of an RF system. However, recent RF studies have suggested the feasibility of 1-10 microsecond timing performance using an antenna with an effective aperture on the order of 10 square meters, which is more optimistic than many previous results. This level of performance may be sufficient to prove useful for both terrestrial and space applications, particularly in deep space or even cislunar space where navigation and timing performance requirements are typically more relaxed. Such a radio-frequency based solution would not require the large, heavy, complex hardware required to receive X-ray signals and could be particularly advantageous for small spacecraft where size, weight, and cost are of higher concern. This paper serves as a literature review of radio-frequency pulsar observation, timing, and navigation systems. It examines the theoretical relationship of system parameters such as antenna size, amplifier noise figure, observation time, and processing techniques to overall system signal-to-noise ratio (SNR) and measurement performance. It then details the design of a terrestrial experiment to observe pulsars in the radio-frequency band using two small-aperture observing stations and low-cost hardware with the goal of determining experimentally the minimum practical antenna size for radio-frequency pulsar measurements as a function of signal-to-noise ratio, measurement performance, and observation time. Additionally, experimental results of pulsar observations performed by amateur radio operators are discussed and used to provide context to the theoretical results.