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Backends for EMIR and HERA
Distribution of intermediate frequencies (IFs) to the backends
1. Current IF distribution
2. Historic IF distribution <June 2011>

Backends for EMIR and HERA

Backend	Type	Channel Width	Bandwidth	Receiver (width mode)	Status	Remark
4 MHz	Filterbanks	4 MHz	8 or 9 x 1GHz	EMIR, either HERA1 or HERA2 (wide)		(1)
WILMA	Autocorrelator	2 MHz	16 or 18 x 930 MHz	EMIR, HERA (wide)		(2)
FTS	FFTS	195 kHz	8x4 GHz	EMIR, HERA		(3.1)
FTS	FFTS	50 kHz		EMIR, HERA (narrow)		(3.2)
VESPA	Autocorrelator	3.3 kHz-1.25 MHz	10-512 MHz	EMIR, HERA (narrow)		(4)
XPOL	VESPA	40kHz-1.25MHz	120-640MHz	EMIR		(5)
nbc / continuum	continuum	1 GHz				(6)
bbc	continuum	8 GHz				(7)

See here, for the present status of the backends. For more information on the capabilities of EMIR, see here. In general, several backends can be attached to one receiver. Exceptions are listed below. The pako manual describes in detail how to configure the backends.

4MHz Filterbank: max. 9 parts; use of the 4MHz filterbank excludes the use of VESPA on the same receiver. Frequency switching not available. While the channel spacing is 4MHz, the 3dB width is 5.4MHz and the noise equivalent width is 6.5 MHz
WILMA: The Wideband Line Multiple Autocorrelator for EMIR and HERA

Fast Fourier Transform Spectrometer (FTS): In July 2011, we installed 24 FTS units to cover 32GHz of bandwidth. The resolution is 200 or 50kHz. They are available to all observers since 2-Aug-2011. See the short commissioning report and the document of Gilles Butin on the Spectrum Slicers for FFT Spectrometers. Also see the backend status page. These FTS have been designed by Bernd Klein at the MPIfR/Uni Bonn and manufactured by Radiometer Physics. See Klein et al. 2012, A&A, papers of 2009, 2008, and a presentation of 2011.
The exact frequency ranges are (GP, 21-Jul-2011):

- EMIR wide mode (~200kHz resolution):
  20737 channels (~4050.195MHz) centered at 5975.0MHz.
  First channel at 3950.0MHz, last channel at 8000.0MHz.
  The first 50MHz are "bonus" bandwidth, which will be
  very useful if the outer folding frequency is 15.95GHz.

- EMIR narrow mode (~50kHz resolution):
  37275 channels (~1820.068MHz) centered at 6200.0MHz
  First channel at ~5289.990MHz, last channel at ~7110.010MHz.

- Hera wide mode (~200kHz resolution):
  5377 channels (~1050.195MHz) centered at 609.375MHz.
  First channel at 84.375MHz, last channel at 1134.375MHz.

- Hera narrow mode (~50kHz resolution):
  12814 channels (~625.684MHz) centered at ~397.192MHz.
  First channel at 84.375MHz, last channel at ~710.010MHz.

As long as we keep the current folding frequency for outer bands, 
outer band are always at 15680-inner in MHz, so in the case of EMIR 
narrow mode, 15680-6200 = 9480. (GP, 19-Sep-2011)

For Wilma replace 5975 by 5985. (GP, 13-Jan-2012)

In the winter semester 2010/11 we had offered 8 units covering 2x4GHz of bandwidth with a fixed resolution of 195kHz for EMIR.

VESPA: The Versatile SPectrometer Array. Up to 18000 channels. In connection with HERA (9 pixels) the following combinations of resolution (kHz) and bandwidth (MHz) are possible: (20/40), (40,80), (80, 160), (320,320), (1250, 640); VESPA User Guide (2002), Summary in IRAM Newsletter No. 54 (Dec 2002), local contact: G. Paubert
XPOL: Line and continuum polarimetry is possible at the 30m using a new type of IF polarimeter designated XPOL. The central feature of XPOL is the correlator VESPA where the IF signals from two orthogonally polarized receivers are cross correlated to determine the four Stokes parameters. Further information is provided here.
The old continuum backend, now called narrow band continuum backend nbc with 1GHz width, is still available for HERA, and also for EMIR.
The broad band continuum backend bbc with 8GHz width, fully exploiting the bandwidths of EMIR, is available since 2-Aug-2011. bbc cannot be connected to HERA.

Decommissioned backends:

MAMBO2 has been decommissioned mid 2011. ABBA1 and ABBA2 (Adc Bolometer Backend) were the bolometer backends for the MAMBO 1mm camera, i.e. dedicated PCs connected to the bolometers.
The 1MHz filterbank has been decommissioned in 4/2008: max. 4 parts; series, parallel, or mixed mode possible; using the 1MHz filterbank with 1GHz bandwidth excludes the use of VESPA with the same receiver. The filterbank can be shifted in multiples of 32MHz from the center frequency of the connected receiver.

-  ⇤ ← Revision 52 as of 2011-07-27 17:25:41 → 
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+   ← Revision 92 as of 2014-05-21 13:51:46 → ⇥
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-Deletions are marked like this.
+Additions are marked like this.
 Line 8:
-== Backends for EMIR, HERA, MAMBO (after EMIR installation & commissioning in March/April 2009) ==
+== Backends for EMIR and HERA ==
 Line 10:
-|| || Type || Channel Width || Bandwidth || Receiver (width mode) || [[http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus#BackendStatus|Status]] || Remark ||
|| '''4 MHz''' || Filterbanks || 4 MHz || 8 or 9 x 1GHz || EMIR, either HERA1 or HERA2 (wide) || {{attachment:haken.gif}} || (1) ||
+|| Backend || Type || Channel Width || Bandwidth || Receiver (width mode) || [[http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus#BackendStatus|Status]] || Remark ||
|| '''4 MHz''' || Filterbanks || 4 MHz || 8 or 9 x 1GHz || EMIR, either HERA1 or HERA2 (wide) || {{attachment:kreuz.gif}} || (1) ||
 Line 13:
-|| '''FTS'''   || FFTS || 195 kHz || 2x4 GHz || EMIR || {{attachment:kreuz.gif}} || (4.1) ||
|| '''FTS'''   || FFTS || 195 kHz || 8x4 GHz || EMIR, HERA || {{attachment:kreuz.gif}} || (4.2) ||
|| '''FTS'''   || FFTS || 50 kHz || || EMIR, HERA (narrow) || {{attachment:kreuz.gif}} || (4.3) ||
|| '''VESPA''' || Autocorrelator || 3.3 kHz-1.25 MHz || 10-512 MHz || EMIR, HERA (narrow) || {{attachment:haken.gif}} || (5) ||
|| '''XPOL''' || VESPA || 40kHz-1.25MHz || 120-640MHz || EMIR || {{attachment:haken.gif}} || (6) ||
|| '''ABBA2''' || || || || MAMBO2 || {{attachment:kreuz.gif}} || (7) ||
|| '''nbc / continuum''' || continuum || 1 GHz || || || {{attachment:haken.gif}} || (8) ||
|| '''bbc''' || continuum || 8 GHz || || || {{attachment:kreuz.gif}} || (9) ||
+|| '''FTS'''   || FFTS || 195 kHz || 8x4 GHz || EMIR, HERA || {{attachment:haken.gif}} || (3.1) ||
|| '''FTS'''   || FFTS || 50 kHz || || EMIR, HERA (narrow) || {{attachment:haken.gif}} || (3.2) ||
|| '''VESPA''' || Autocorrelator || 3.3 kHz-1.25 MHz || 10-512 MHz || EMIR, HERA (narrow) || {{attachment:haken.gif}} || (4) ||
|| '''XPOL''' || VESPA || 40kHz-1.25MHz || 120-640MHz || EMIR || {{attachment:haken.gif}} || (5) ||
|| '''nbc / continuum''' || continuum || 1 GHz || || || {{attachment:haken.gif}} || (6) ||
|| '''bbc''' || continuum || 8 GHz || || || {{attachment:haken.gif}} || (7) ||
-Line 28:
+Line 26:
-. '''1MHz Filterbank''': max. 4 parts; series, parallel, or mixed mode possible; using the 1MHz filterbank with 1GHz bandwidth excludes the use of VESPA with the same receiver. The filterbank can be shifted in multiples of 32MHz from the center frequency of the connected receiver. '''Deactivated since 4/2008'''
+. '''Fast Fourier Transform Spectrometer (FTS)''': In July 2011, we installed 24 FTS units to cover 32GHz of bandwidth. The resolution is 200 or 50kHz. They are available to all observers since 2-Aug-2011. See the short [[http://www.iram.es/IRAMES/mainWiki/EmirforAstronomers#Upgradeto32GHzFTSsystem.28July2011.29|commissioning report]] and the document of Gilles Butin on the [[attachment:butin-32ghz-fts-4jul2011.pdf|Spectrum Slicers for FFT Spectrometers]]. Also see the [[http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus#BackendStatus|backend status page]]. These FTS have been designed by Bernd Klein at the MPIfR/Uni Bonn and manufactured by Radiometer Physics. See [[http://arxiv.org/abs/1203.3972|Klein et al. 2012, A&A]], papers of [[http://www.nrao.edu/meetings/isstt/papers/2009/2009199201.pdf|2009]], [[http://www.nrao.edu/meetings/isstt/papers/2008/2008192195.pdf|2008]], and a [[http://www.mpifr-bonn.mpg.de/staff/bklein/FFTS/CCAT-MeetingCologne2011_BKlein.pdf|presentation of 2011]]. <<BR>> The exact frequency ranges are (GP, 21-Jul-2011):
-Line 30:
+Line 28:
-. '''Fast Fourier Transform Spectrometer (FTS)''': for the winter semester 2010/11 we offer 8 units covering 2x4GHz of bandwidth with a fixed resolution of 195kHz for EMIR. During July 2011, the FTS and the FTS are upgraded to 32GHz bandwidth with 195 resolution for EMIR and HERA. During this time, none of the FTS units will be available for observations. See the [[http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus#BackendStatus|backend status page]].
+  {{{
- EMIR wide mode (~200kHz resolution):
  20737 channels (~4050.195MHz) centered at 5975.0MHz.
  First channel at 3950.0MHz, last channel at 8000.0MHz.
  The first 50MHz are "bonus" bandwidth, which will be
  very useful if the outer folding frequency is 15.95GHz.

- EMIR narrow mode (~50kHz resolution):
  37275 channels (~1820.068MHz) centered at 6200.0MHz
  First channel at ~5289.990MHz, last channel at ~7110.010MHz.

- Hera wide mode (~200kHz resolution):
  5377 channels (~1050.195MHz) centered at 609.375MHz.
  First channel at 84.375MHz, last channel at 1134.375MHz.

- Hera narrow mode (~50kHz resolution):
  12814 channels (~625.684MHz) centered at ~397.192MHz.
  First channel at 84.375MHz, last channel at ~710.010MHz.

As long as we keep the current folding frequency for outer bands, 
outer band are always at 15680-inner in MHz, so in the case of EMIR 
narrow mode, 15680-6200 = 9480. (GP, 19-Sep-2011)

For Wilma replace 5975 by 5985. (GP, 13-Jan-2012)

  }}}

<<BR>>

  In the winter semester 2010/11 we had offered 8 units covering 2x4GHz of bandwidth with a fixed resolution of 195kHz for EMIR.
-Line 34:
+Line 61:
-. '''XPOL''': Line and continuum polarimetry is possible at the 30m using a new type of IF polarimeter designated XPOL. The central feature of XPOL is the correlator VESPA where the IF signals from two orthogonally polarized receivers are cross correlated to determine the four Stokes parameters. A manual is in preparation, contact: C. Thum
+. '''XPOL''': Line and continuum polarimetry is possible at the 30m using a new type of IF polarimeter designated XPOL. The central feature of XPOL is the correlator VESPA where the IF signals from two orthogonally polarized receivers are cross correlated to determine the four Stokes parameters. [[http://www.iram.es/IRAMES/mainWiki/PolarimetryforAstronomers|Further information is provided here.]]

 1. The old continuum backend, now called narrow band continuum backend '''nbc''' with 1GHz width, is still available for HERA, and also for EMIR.

 1. The broad band continuum backend '''bbc''' with 8GHz width, fully exploiting the bandwidths of EMIR, is available since 2-Aug-2011. bbc cannot be connected to HERA. 

Decommissioned backends:
-Line 38:
+Line 71:
-. '''Continuum backend''' with 1GHz width, is still the old system used for the ABCD receivers
+. The 1MHz filterbank has been decommissioned in 4/2008: max. 4 parts; series, parallel, or mixed mode possible; using the 1MHz filterbank with 1GHz bandwidth excludes the use of VESPA with the same receiver. The filterbank can be shifted in multiples of 32MHz from the center frequency of the connected receiver.
-Line 40:
+Line 73:
-. '''Continuum backend''' with 8GHz width, fully exploiting the increased bandwidth of EMIR, is in preparation.
+== Distribution of intermediate frequencies (IFs) to the backends ==
-Line 42:
+Line 75:
-== Distribution of intermediate frequencies (IFs) to the backends (Status: July 2011) ==
+=== Current IF distribution ===
-Line 44:
+Line 77:
-=== IF distribution in preparation for end of July 2011 ===
+{{attachment:FE_to_BE_v2.png}} <<BR>>
'''IF distribution in May 2014'''
-Line 46:
+Line 80:
-{{attachment:fft_be2v2.JPG}} <<BR>>
'''Figure 2''': Planned IF distribution for 2011 

=== Old IF distribution (Status: June 2011) ===
+=== Historic IF distribution <June 2011> ===
-Line 52:
+Line 83:
-'''Figure 1''': IF distribution (16-Dec-2010 SS/CK)
+'''IF distribution 16-Dec-2010 '''