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The new Fast
Fourier Transform Spectrometer
(FFTS) for Effelsberg has been tested
since late 2005 and is now available for observations. The backend is a
modified copy of the FFTS at the APEX telescope in Chile (Klein,
B., et al., 2006, A&A, 454, L29 [pdf]).
Due to
the limited Effelsberg IF bandwidth of 500 MHz the FFTS samples the IF with
1 GS/sec (Nyquist sampling) and 8-bit resolution.
The FFTS has two IF inputs so that in 2 channel receivers both
polarisations can be sampled and processed in parallel.
The technical aspects of the spectrometer are described in Klein, B., et al.,
2006, Proc. of the SPIE,
Vol. 6275, pp. 627511 [pdf].
Currently there are two user modes available:
a) "Narrow IF band" Mode (IF center = 150 MHz)
| Bandwidth
[MHz] |
Number
of
Spectral Channels
|
Channel
Separation
[kHz] |
Spectral
Resolution
(ENBW*)
[kHz] |
| 100
|
16384
|
6.104 |
9.827 |
| 20 |
16384
|
1.221 |
1.965 |
b) "Broad IF band" Mode (IF center = 750 MHz)
| Bandwidth
[MHz] |
Number
of
Spectral Channels
|
Spectral
Resolution
[kHz] |
Spectral
Resolution
(ENBW*)
[kHz] |
| 500 |
16384 |
30.518 |
49.133 |
100
|
16384 |
6.104 |
9.827 |
20
|
16384 |
1.221 |
1.965 |
Note, that the effective bandwidths are about 10% smaller, because of bandpass issues!
* ENBW: Equivalent Noise Bandwidth (Klein, B., et al.,
2006, Proc. of the SPIE)
For further information about the FFTS please contact: Bernd Klein (bklein_at_mpifr-bonn.mpg.de).
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