A CubeSat receiver for the study of VLF-waves at LEO


By dgolden - Posted on 08 July 2020

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TitleA CubeSat receiver for the study of VLF-waves at LEO
Publication TypeConference Paper
VLF Publication Number2019-08
Year of Publication 2019
AuthorsRamos, L. D, Wilson G, Sousa A, Marshall R, Brunetto K, Ballenthin J, Kay R, Patton J, Quigley S, Fennelly J, Starks M, Willet-Gies T, Tullino C. S, Linscott I, Umran I
Abstract

We describe the design of the μBBR (micro Broad Band Receiver), a VLF receiver for the VPM mission. VPM
is an AFRL CubeSat mission that will be launched into a 500 km circular orbit with a 51° inclination where it will
continuously sample the VLF electromagnetic spectrum from 300 Hz to 30 kHz. These waves largely control the state
of the radiation belts and improved understanding of them will lead to improved radiation belt predictive models. The
μBBR consists of a single-axis electric dipole antenna, or dipole antenna assembly (DAA), a single-axis magnetic field
search coil antenna, or search coil boom assembly (SCBA) and a payload electronics module (PEM). It is designed for
high reliability by using radiation-tolerant components. The dipole antenna and search coil are aligned
perpendicular to each other and the spacecraft is operated so as to keep both perpendicular to the background
magnetic field as much as possible. All signal processing is implemented in an FPGA, using fixed-point
arithmetic, without any volatile on-board firmware. Data is sampled at 80 kHz using a GPS-disciplined clock. Two
date products are delivered: a reduced-bandwidth survey mode with 6.5, 13.1, or 26.2 second resolution, and a
commandable full-resolution burst mode. Burst data can be taken in the time or frequency domain, can be selectively
windowed along the time or frequency axes, and can be decimated by a factor of 2, 4, 8, or 16. Such capability is included
because of anticipated data download rate limitations. The VPM spacecraft is scheduled for launch before the end of
2019.