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information_for_astronomers:user_guide:vlbi [2014/08/18 15:36]
ubach
information_for_astronomers:user_guide:vlbi [2014/08/18 16:41]
ubach
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   * There are two new digital VLBI systems installed at Effelsberg   * There are two new digital VLBI systems installed at Effelsberg
     * **A DBBC with a Mark5B+ disk recorder**. In digital down converter mode (DDC) it provides 8 tunable base band converters (BBCs) with upper (USB) and lower side band (LSB) at bandwidth of 1 to 16 MHz. The recording rate depends on the number of selected base band channels, the maximum data rate is 1024 Mbps using 16x16 MHz channels. The DBBC can be also operated in a poly-phase filter bank mode (PFB) that provides 16 or 32 BB channels at fixed frequencies (8/16 dual or 16/32 single pol. of 32 MHz bandwidth) and a recording rate of 2048 or 4096 Mbps. It is recommended to use the DBBC for any EVN, global VLBI, and geo observations that are correlated in Bonn or JIVE. Projects that are correlated in Socorro might want to use the RDBE instead, however also DBBC data can be correlated at Socorro. The SCHED station code is EFLSBERG.     * **A DBBC with a Mark5B+ disk recorder**. In digital down converter mode (DDC) it provides 8 tunable base band converters (BBCs) with upper (USB) and lower side band (LSB) at bandwidth of 1 to 16 MHz. The recording rate depends on the number of selected base band channels, the maximum data rate is 1024 Mbps using 16x16 MHz channels. The DBBC can be also operated in a poly-phase filter bank mode (PFB) that provides 16 or 32 BB channels at fixed frequencies (8/16 dual or 16/32 single pol. of 32 MHz bandwidth) and a recording rate of 2048 or 4096 Mbps. It is recommended to use the DBBC for any EVN, global VLBI, and geo observations that are correlated in Bonn or JIVE. Projects that are correlated in Socorro might want to use the RDBE instead, however also DBBC data can be correlated at Socorro. The SCHED station code is EFLSBERG.
-    * **The NRAOs RDBE with a Mark5C disk recorder**. It can be used in a poly-phase filter bank mode (PFB) that provides 16 BB channels at fixed frequencies (8 dual or 16 single pol. of 32 MHz bandwidth) and a recording rate of 2048 Mbps. There is also a digital down converter mode (DDC) available that provides either 4 or 8 tunable base band channels at variable bandwidth between 1 and 128 MHz and corresponding recording rates. The maximum recording rate is 2 Gbps (4x128 MHz or 8x64MHz). The BB channels can be either LSB or USB. The SCHED station code is EB_RDBE. More details on the RDBE modes and scheduling of EB+VLBA and HSA observations can be found on the Wiki pages below and the NRAO [[https://​science.nrao.edu/​facilities/​vlba/​proposing/​|proposal web page]] and the [[https://​science.nrao.edu/​facilities/​vlba/​proposing/​HSA|HSA web page]].+    * **The NRAOs RDBE with a Mark5C disk recorder**. It can be used in a poly-phase filter bank mode (PFB) that provides 16 BB channels at fixed frequencies (8 dual or 16 single pol. of 32 MHz bandwidth) and a recording rate of 2048 Mbps. There is also a digital down converter mode (DDC) available that provides either 4 or 8 tunable base band channels at variable bandwidth between 1 and 128 MHz and corresponding recording rates. The maximum recording rate is 2 Gbps (4x128 MHz or 8x64MHz). The BB channels can be either LSB or USB. The SCHED station code is EB_RDBE. More details on the RDBE modes and scheduling of VLBA+EB and High Sensitivity Array (HSAobservations can be found on the Wiki pages below and the NRAO [[https://​science.nrao.edu/​facilities/​vlba/​proposing/​|proposal web page]] and the [[https://​science.nrao.edu/​facilities/​vlba/​proposing/​HSA|HSA web page]].
   * Since the resolution of the Effelsberg antenna is higher than that of the usual VLBI antennas it is recommended to introduce same gaps for pointing checks in the schedule at least for frequencies of 5 GHz and higher. Gaps of 6-8 minutes on a bright source should be sufficient for a pointing. If the VLBI source itself isn't bright enough 10 minutes are better to allow for a source change.\\ At 6cm and 3.6cm a pointing every 4 hours is sufficient, at shorter wavelength a gap every 2 hours is recommended.   * Since the resolution of the Effelsberg antenna is higher than that of the usual VLBI antennas it is recommended to introduce same gaps for pointing checks in the schedule at least for frequencies of 5 GHz and higher. Gaps of 6-8 minutes on a bright source should be sufficient for a pointing. If the VLBI source itself isn't bright enough 10 minutes are better to allow for a source change.\\ At 6cm and 3.6cm a pointing every 4 hours is sufficient, at shorter wavelength a gap every 2 hours is recommended.
   * Driving speeds of 25 deg/min in azimuth and 15 deg/min in elevation are the usual settings in the station catalogue from SCHED and produce realistic results.   * Driving speeds of 25 deg/min in azimuth and 15 deg/min in elevation are the usual settings in the station catalogue from SCHED and produce realistic results.
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   * VLBI Friend at Effelsberg is Uwe Bach (ubach at mpifr.de).   * VLBI Friend at Effelsberg is Uwe Bach (ubach at mpifr.de).
  
 +===== Instructions for Effelsberg observations using the RDBE =====
 +
 +  * [[EB-HSA|Using Effelsberg as part of the High Sensitivity Array (HSA)]] ​
information_for_astronomers/user_guide/vlbi.txt ยท Last modified: 2014/08/18 16:41 by ubach