Title: On-board Processing to Advance the PanFTS Imaging System for GEO-CAPE, Second Year Progress
Presenting Author: Paula Pingree
Organization: Jet Propulsion Laboratory
Co-Author(s): Paula Pingree, Dmitriy Bekker, Jean-Francois Blavier, Maxwell Bryk, Colin Donahue, Megan Fazio, Brian Franklin, Jeffrey Hayden, Ryan Monroe, Matthew Ryan, Stanley Sander, Thomas Werne

Abstract:
The Panchromatic Fourier Transform Spectrometer (PanFTS) is an imaging instrument designed to record atmospheric spectra of the Earth from the vantage point of a geosynchronous orbit. Each observation covers a scene of 128x128 pixels. In order to retrieve multiple chemical families and perform passive vertical profiling, the recorded spectra will cover a wide wavelength range, from the thermal infra-red to the near ultra-violet. The small size of the nadir ground-sampling distance and the desire to re-visit each scene hourly both set the outgoing data rate. These result in a PanFTS design that challenges the downlink capabilities of current radio communication. The PanFTS on-board processing will reduce downlink rates by converting time-domain interferograms to band-limited spectra, hence achieving a factor 20 in data reduction. In this presentation, we report on the second year progress of this AIST-11 task. Our Virtex-5 FPGA implementation to support the PanFTS Focal Plane Array (FPA) control and data interfaces has been validated during the thermal and vacuum tests of the PanFTS Engineering Model. The real-time processing of the interferometer metrology laser signal has allowed us to close the servo loop of the tip/tilt correction of the interferometer mirrors, with a measured residual error below the target of 1 microradian of tip/tilt angle. Several types of FPAs have been interfaced to our Virtex-5 FPGA design. We have developed large Discrete Cosine Transforms (DCTs) simulated for a Virtex-7 FPGA at rates matching the observation scans of PanFTS. These DCTs will soon be incorporated into the FPGA pipeline processing to handle the full FPA array size. The overall processing development will support the observations taken by PanFTS during its deployment at the California Laboratory for Atmospheric Remote Sensing (CLARS, Mount Wilson).