Front-end signal processing and operation status of the FRB Hawaiʻi outrigger station

Abstract

The FRB telescope array located in Pāhala, Hawaiʻi, will operate as an outrigger station for CHIME (the Canadian Hydrogen Intensity Mapping Experiment), the leading fast radio burst (FRB) detection project led by the Trottier Space Institute at McGill University. The Hawaiʻi station provides a ~4,700 km baseline with CHIME, enabling substantially improved localization accuracy for transient events. The array will comprise ten 6-meter parabolic dishes and twelve log-periodic antenna elements, covering the 400–800 MHz band to match CHIME’s frequency range. All elements will be pointed to overlap with a portion of CHIME’s sky coverage. The analog time-domain signals from each antenna element are continuously digitized and stored in a temporary ring buffer. When CHIME issues an FRB detection trigger, the Hawaiʻi station transfers the relevant ring-buffered data to non-volatile storage for subsequent upload to the CHIME facility for offline correlation. This paper presents the design and performance parameters of the antennas, low-noise amplifiers (LNAs), and fiber-optic transmission systems, which are critical to determining the overall system sensitivity. One of the primary challenges of operating in the 400–800 MHz regime is radio-frequency interference (RFI); therefore, this paper also covers RFI sources, avoidance strategies, and mitigation techniques. A companion paper will describe the back-end signal-processing system.