Context. We present the technology and rst scientic results of a new generation of very e xible and sensitive spectrometers, well-suited for the needs of spectral-line radio and (sub)millimeter astronomy: Fast Fourier Transform Spectrometers (FFTS), which are in operation at the Atacama Pathnder EXperiment (APEX) telescope. Aims. The FFTS for APEX is a novel high-resolution 2 1 GHz bandwidth digital spectrometer backend. Due to its high frequency resolution, and the demonstrated capability of operating at high altitude, the FFTS became the facility spectrometer for spectral line observations at APEX. Methods. The FFTS is based on one of the currently most powerful digitizer/analyzer boards available from Acqiris, Switzerland. The board incorporates two 1 Gsamples/s analog-to-digital converters (ADCs) with 8-bit resolution which feed an on-board complex eld programmable gate array (FPGA) chip. The enormous processing power by today’s FPGAs allow for a complete real-time FFT signal processing pipeline to decompose a 1 GHz band into 16384 spectral channels in just one chip. Results. Since May 2005 an MPIfR FFTS has been extensively used in all regular spectroscopic science observations. The performance at APEX was demonstrated to be very reliable and as good as measured in the rst laboratory tests which nally led to the request to provide a second, facility type FFTS for APEX. The unit was delivered and commissioned in March this year. Conclusions. Using a commercially available digitizer board, it was possible to develop a complete FFTS in only a few months. Successful observations at APEX demonstrate that this new generation of FPGA-based spectrometers easily matching and superseding the performance of older technology spectrometers and can built up much more easily. Furthermore, the by now available class of new high-speed ADCs and the continuous increase of FPGA processing power makes it very likely that FFTS can be pushed to broader bandwidth and even more spectral channels in the near future.
[1]
A. Belloche,et al.
APECS : the Atacama pathfinder experiment control system
,
2006
.
[2]
A. Nuttall.
Some windows with very good sidelobe behavior
,
1981
.
[3]
F. Harris.
On the use of windows for harmonic analysis with the discrete Fourier transform
,
1978,
Proceedings of the IEEE.
[4]
Catherine J. Cesarsky,et al.
The Atacama Pathfinder EXperiment (APEX) : a new submillimeter facility for southern skies
,
2006
.
[5]
Bonn,et al.
A Field Programmable Gate Array Spectrometer for Radio Astronomy First Light at the Effelsberg 100-m Telescope
,
2005,
astro-ph/0503067.
[6]
S. Heyminck,et al.
The first-light APEX submillimeter heterodyne instrument FLASH
,
2006
.
[7]
Hansueli Meyer,et al.
A broadband FFT spectrometer for radio and millimeter astronomy
,
2005
.