A Wideband Digital FFT Spectrometer System for ground based Sub-mm Wave Telescope

This paper presents design of a wideband digital Fast Fourier Transform (FFT) spectrometer system for ground based sub-mm telescope, to be deployed at Hanle. The proposed telescope is a survey instrument working on the principle of heterodyne spectroscopy, observing radiations emitted from rotational transitions of CO from molecular clouds, J: 2→1 at 230GHz and J: 3→2 at 345GHz, with an angular resolution of 1'. At these frequencies, this will be first of its kind comprehensive survey of Milky Way and nearby galaxies from the northern hemisphere. The FFT spectrometer provides 4GHz instantaneous bandwidth and 1MHz spectral resolution for the receiver chains at 230 GHz and 345 GHz. Current paper discusses spectrometer design aspects, hardware configuration, methodology, system specifications and FPGA implementation architecture. Simulations results for spectral line profiles and spectrometer methodology are also discussed along with the novel elements proposed for the instrument design and development.