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Proceedings Paper

Very large FX correlator system for enhanced ALMA
Author(s): Sachiko Kawabe Okumura; Yoshihiro Chikada; Munetake Momose
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Paper Abstract

We are proposing a very large FX correlator system as an enhanced ALMA correlator. Maximum bandwidth per IF is 4096 MHz. Spectral channels per baseline per IF is 128 X 1024. The possible number of correlation is a few thousands per IF. This correlator system realizes both high spectral resolution (< 0.1 km/s at 100 GHz) and wideband (> 1000 km/s at 850 GHz) observations up to 850 GHz. We have started the design and development of a minimum test system of the very large FX correlator in order to overcome several technical issues. This test system consists of two 2-bit A/D converters and one FX spectro-correlator. This correlator system has the bandwidth of 2048 MHz, 'half' bandwidth of the final specifications. But the spectral resolving point is the same as the final one. For the A/D converter, we are now measuring the sampling performance of high-speed sample-hold circuit at the clock of 8 GHz. For the FX correlator, we have finished the coefficient error estimation for the finite word length of FFT. More than 9-bit FFT calculation will make the coefficient error less than 3%. We also apply a new function, re-quantization. It reduces the number of connection between F and X parts with almost keeping the sensitivity.

Paper Details

Date Published: 3 July 2000
PDF: 9 pages
Proc. SPIE 4015, Radio Telescopes, (3 July 2000); doi: 10.1117/12.390450
Show Author Affiliations
Sachiko Kawabe Okumura, Nobeyama Radio Observatory (Japan)
Yoshihiro Chikada, National Astronomical Observatory (Japan)
Munetake Momose, Ibaraki Univ. (Japan)

Published in SPIE Proceedings Vol. 4015:
Radio Telescopes
Harvey R. Butcher, Editor(s)

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