Fast Fourier Transform Spectrometer (FFTS)

Spectroscopy allows studies of the physics and chemistry of astronomical objects such as planetary atmospheres, circumstellar envelopes and the interstellar medium of our Milky Way and external galaxies. Today, spectrographs offer usable contiguous bandwidth from a few MHz to 1-2 GHz, with a few thousand spectral channels capable of resolving narrow spectral lines e.g. of masers or thermal line emission of gaseous clouds. Particularly for the new APEX sub-millimeter telescope which operates at sky frequencies of several 100 GHz up to 1.5 THz, a large bandwidth is very important to allow for studies of broader lines even at the highest frequencies. The novel FPGA-based FFTSs offer new perspectives:

Today, complex FPGAs have become very popular for building fast and reconfigurable hardware. State-of-the-art FPGAs include several hundreds of dedicated 18 × 18 bit multipliers which allow up to 8 E10 multiplications and nearly 5 E11 36-bit additions per second, giving these FPGA chips over ~50 times higher performance in digital signal processing than the latest Intel Pentium 4 processors. By parallelization of single processing threads and using the FFT algorithm in a pipelined manner it becomes possible to implement 16K-point Fourier transforms for input data rates up to 2 GBytes/s.

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