  We describe the signal-processing firmware and software for a
frequency-domain multiplexed (FDM) biasing and demodulation system that reads
out Transition Edge Sensor (TES) bolometer arrays for mm-wavelength cosmology
telescopes. This system replaces a mixed-signal readout backend with a much
smaller, more power-efficient system relying on Field-Programmable Gate Arrays
(FPGAs) for control, computation and signal processing. The new system is
sufficiently robust, automated, and power efficient to be flown on
stratospheric balloon-borne telescopes and is being further developed for
satellite applications.
