The KFFTspec spectrometer: Current status and future plans for ALMA

We developed a software spectrometer for the Korean radio telescopes that allows spectral line observations at 22/43/86/129 GHz in 512 MHz wide digital basebands produced samplers connected to 10G Ethernet. The spectrometer is configurable for Fourier transform and polyphase filter bank based spectrometry and utilizes graphics cards (GPUs) for signal processing. A current consumer GPU (nVidia TITAN X) is able to process a total bandwidth of between 2-4 GHz (1-2 GHz in Full-Stokes) with 1k-1M spectral channels and near arbitrary integration times. We report here the design and performance of the spectrometer, and describe its ongoing adaption to a new Atacama Submillimeter Telescope Experiment 300-500 GHz focal plane array, and the Atacama Compact Array, where a future scaled up multi-GPU computing cluster will process four 2 GHz wide basebands at dual polarization from 4 antennas each.