A technical study of digital filter design and performance for the ASTRO‑H satellite's BGO active shield.
This document presents research on optimizing digital filters used in the BGO active shield of the ASTRO‑H X‑ray and soft‑gamma‑ray detectors. It describes the detector architecture, the role of the active shield, and the need for low‑noise signal processing in space.
The study details the design of odd‑ and even‑function digital filters, their implementation in the Avalanche Photo‑Diode Processing and Management Unit (APMU), and experimental results showing improved threshold and noise performance under various test conditions. This manual is written in Japanese.
The BGO active shield surrounds the main detectors and acts as a detector itself, allowing coincidence counting to remove background radiation from outside the field of view and from the detector’s own activation.
Digital filters are employed to process very weak signals and reduce noise components, which is essential for improving background‑rejection performance of the detectors.
The digital filter has a large impact on the detector’s background‑removal capability, influencing the overall sensitivity of the ASTRO‑H mission.