ABSTRACT
This chapter describes the subsystem for instrument control and onboard data handling of a spaceborne hyperspectral sensor. First, it describes the functions of the subsystem, including (1) controlling the spectrometers (e.g., for spectral regions in shortwave infrared [SWIR], visible and near-infrared [VNIR], and panchromatic [PAN]) in the Optical Head, (2) receiving, formatting, and packetizing data from the spectrometers, (3) interfacing with the Processing, Formatting, and Control Unit (PFCU) for sending science data packets, (4) sending telemetry for monitoring temperatures and voltages in the units and for monitoring the unit on/off status, (5) interfacing with the spacecraft to receive the supply voltage, (6) controlling the power supply distribution to the spectrometers, and (7) performing the system built-in tests. The chapter then presents the hardware configuration of the subsystem that incorporates dual redundant PFCU and a solid-state Mass Memory Unit (MMU). The chapter also provides a detailed description on the PFCU, which is the central controller of the instrument, and therefore redundant boards are often used. Onboard data compression technologies used by five spaceborne hyperspectral sensors are then discussed. In particular, vector quantization based near-lossless data compression technology and the Consultative Committee for Space Data Systems (CCSDS) recommended data compression standards are introduced. The later sections of the chapter describe the MMU, proximity electronics and service module electronics, and electrical interfaces to the spacecraft and data downlink.
