Title: A single stage, two channel Ka-band to digital, thermal compensating receiver for SWOT
Primary Author: Siqueira, Paul
Organization: University of Massachusetts
Co-Author(s): Russel Tessier, Brandon Heavey, Daniel-Esteban-Fernandez, Anthony Swochak, Vishwas Vijayendra, Vu Duong

In this talk, we will present progress on the creation of a single-stage two channel Ka-band to digital stream downconverter, appropriate for the Surface Water and Ocean Topography (SWOT) mission. In the design of this downconverter, the 200 MHz bandwidth, Ka-band data is downconverted to L-band prior to digital sampling by two, 3 GSamp/sec analog to digital converters. Further downconversion is exercised on-board a Xilinx Virtex-IV chip to provide digital data for downstream processing. Thermal measurements made at point locations on the Ka-band board are fed downstream to the digital architecture so that phase and amplitude effects in the passband can be digitally compensated. To better understand the role of thermal effects on signal performance, a thermal model is created for the L-band board and validated with the point measurements. In this way, thermal distributions can be obtained for a steady state condition as well as for external thermal slewing. In this presentation, we will discuss current progress on the Ka-band downconverter development and demonstrate success our team has had in the digital architecture and thermal modeling aspect of the work.