Multi/Hyperspectral High Data Rate Image Compression Module

Multi/Hyperspectral High Data Rate Image Compression Module comprising the upper board as nominal and lower board as redundant
Rear view of the nominal board

The module has been developed by TSD in the framework of the PRISMA Hyperspectral Mission program founded by ASI and it is part of the PRISMA Payload Main Electronics Unit, with the name “SDAC (Scientific Data Acquisition and Compression Module)”. PRISMA (PRecursore IperSpettrale della Missione Applicativa) Payload is a Hyperspectral Electro-Optical Instrument, designed for an Earth Observation MiniSatellite (<500Kg) that will operate in a sun synchronous Low Earth Orbit at 615Km, acquiring hyperspectral images in the range from 400 to 2500[nm] and medium resolution panchromatic images. The module is able of acquiring image data, from the SWIR, VNIR and PAN imagers, reassembling & preprocessing them, performing data compression, applying a CCSDS and Reed Solomon encoding and finally transferring them to the equipment that carry out the storage and transmission to Ground. The module is provided with a configurable lossless and lossy (near lossless in particular) compression stage, in order to reduce the volume of data to be stored in the mass memory and the transfer rate at an amount compatible with the mass memory input rate and the downlink capability. The module implements a multispectral-hyperspectral data compression algorithm, that can be considered as an extension of CCSDS 123 loss-less multispectral-hyperspectral compression standard, achieved by adopting a quantization stage and a modified entropy coder, so to be able to operate not only in loss-less mode, but also in near loss-less or lossy mode. The IP core of the compressor and a first HW platform were already developed by TSD in the frame work of the HYDRA ESA Program (in collaboration with Politecnico of Torino).

The HW architecture of the module is based on two independent boards (main and redundant), that work in cold-sparing mode, and they are interconnected by means of a small and reliable interconnection PCB.


Each board is equipped with two FPGAs; a XILINX Virtex XQR5XVFX130-1CN1752V high performan- ce rad-hard reconfigurable FPGA, that operates as primary FPGA, implementing the reassembly of the image data frames, the pre-processing (bin- ning, grouping, etc.) and the lossless and lossy compression algorithm and a MICROSEMI RTA- X2000 rad-hard antifuse FPGA, that operates as secondary FPGA implementing the power mana- gement, the primary FPGA configuration from OTP or Flash memory, the Reed Solomon encoding and the HOTLink data I/F. All the other components present on the board, (transceivers, memories, step-down and linear regulators, clock generators ICs, etc.) are space-grade hi-rel components.


Each board is provided with an aluminum alloy frame, acting as stiffener and main thermal path, specifically designed to take into account in parti- cular of the large package of the primary FPGA and its power dissipation, so to ensure a good and reliable behavior of the module in presence of severe mechanical and thermal environmental conditions.