Very large FX correlator system for enhanced ALMA

Sachiko Kawabe Okumura; Yoshihiro Chikada; Munetake Momose

doi:10.1117/12.390450

3 July 2000 Very large FX correlator system for enhanced ALMA

Sachiko Kawabe Okumura, Yoshihiro Chikada, Munetake Momose

Proceedings Volume 4015, Radio Telescopes; (2000) https://doi.org/10.1117/12.390450
Event: Astronomical Telescopes and Instrumentation, 2000, Munich, Germany

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.

Citation Download Citation

Sachiko Kawabe Okumura, Yoshihiro Chikada, and Munetake Momose "Very large FX correlator system for enhanced ALMA", Proc. SPIE 4015, Radio Telescopes, (3 July 2000); https://doi.org/10.1117/12.390450

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