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--- information_for_astronomers:user_guide:signalpathsetup [2012/06/12 13:58]
127.0.0.1 external edit
+++ information_for_astronomers:user_guide:signalpathsetup [2017/01/25 20:24] (current)
akraus
@@ Line 1: / Line 1: @@
-===== Signal paths to the spectroscopic and pulsar backends =====
+===== Signal paths to the spectroscopic, VLBI, and pulsar backends =====
-There are several IF chains going to the Faraday room (where the backends live), most importantly the VLBA and narrow-band (SB) IF. Furthermore, the 21-cm 7-feed system has its own IF; and some receivers provide a 2 GHz IF. All IFs are usually used with different bandwidth setups and need different attenuation to bring the power to a level which is appropriate for the backend ADCs. This is done using the so-called **MultiFiBa**.
+There are several IF chains going to the Faraday room (where the backends live), most importantly the VLBA and narrow-band (SB) IF. Furthermore, the 21-cm 7-feed system has its own IF; and some receivers provide a 2+ GHz IF over optical fibers. All IFs are usually used with different bandwidth setups and need different attenuation to bring the power to a level which is appropriate for the backend ADCs. This is done using the so-called **MultiFiBa**.
-The various IFs are fed into the 16-channel MultiFiBa, which allows to apply several internal bandpass filters and attenuation. For each channel the **mode** can be changed with the command
+The various IFs coming from the receivers are fed into the 16-channel MultiFiBa, which allows to apply several internal bandpass filters and attenuation. Channels 1-7 and 9-15 is almost exclusively used for the 21-cm 7-Beam system. All other receivers are attached to channels 8+16. For each channel the **mode** can be changed with the command
 <code>SXXNNNZ</code>
-where XX stands for the channel which one would like to change and NNN is a three-byte code for the mode. XX can be 01 to 16, or 99 (for all channels. Typical modes are:
+where XX stands for the channel which one would like to change and NNN is a three-byte code for the mode. XX can be 01 to 16, or 99 (for all channels. **Note, that the MultiFiBa got a very slow processing unit, so sometimes it may take a while until the requested mode is set.** Typical modes are:
-^Mode^Comment^
+^Mode^Channels^IF name^IF range^Bandwidth^Attenuation^Comments^
-| 000 | Bypass through the MultiFiBa, used for the 2 GHz modes. When using this mode, one can not use the MultiFiBa for leveling, but has to use the so-called XIF.|
+^ ^ ^ ^[MHz]^[MHz]^enabled^ ^
-| 128 | Applying the internal 100 MHz filter, almost exclusively used for spectroscopy with the 21-cm 7-feed and AFFTS. |
+|216|8+16|VLBA IF|700-800|100|yes| |
-| 161 | No filter applied for channels 01-07 and 09-15 (used for 21-cm 7-feed pulsar search with the EFFTS/AFFTS)), while channels 08 and 16 are fed into the (X)FFTS filterbox (used for spectroscopy with the XFFTS in 100 and 500 MHz bandwidth mode).\\ Note that the (X)FFTS filterbox provides 100 and 500 MHz bandwidth filters and allows to switch between VLBA and narrow-band (SB) IF, **both has to be set using ObsInp!** The latter is mandatory for everything which uses the XFFTS! |
+|185|8+16|VLBA IF|500-1000|500|yes| |
-| 192 | Special mode for using the DFB in polarimetry mode |
+|000|8+16|Narrowband (SB)|100-200|100|yes| |
+|006|8+16|Narrowband (SB)|150-200|50|yes|needs change in .front-files (ULO)|
+|128|1-7,9-15|7-Beam IF|100-200|100|yes|exclusively for 21-cm 7-beam|
+|161|1-7,9-15|7-Beam IF|0-300|300(*)|yes|exclusively for 21-cm 7-beam|
+|033|8+16|Optical|0-2500|2500|no|used for UBB/new K-band|
+|161|8+16|Baseband|0-1000|1000(+)|yes|mainly for VLBI and pulsars|
+(*) 300 MHz from 7-Beam Rx/IF, MultiFiBa only applies 2.5 GHz lowpass\\
+(+) 1GHz from IF, MultiFiBa only applies 2.5 GHz lowpass
 One can change the attenuation using the commands
@@ Line 24: / Line 31: @@
 sets the attenuation in all channels to 10dB.
 <code>A03-030</code>
-decreases attenuation in channel 3 by 3dB.
+decreases attenuation in channel 3 by 3dB. **However, not all signal paths are internally going through the attenuation unit of the MultiFiBa (as indicated in the table above).**
 The commands can be sent in the "MultiFiBa" tab within ObsInp.
-**Note 1: For spectroscopy observations with the XFFTS, there is a software [[information_for_astronomers:user_guide:xffts|XFFTSGui]] which can be used to set the MultiFiBa modes and levels (as well as XIF attenuation values!).**
+Note 1: For standard spectroscopy observations with the XFFTS (using MultiFiBa channels 8+16), there is the software [[information_for_astronomers:user_guide:xffts|XFFTSGui]] which can be used to set the MultiFiBa modes and levels.
-**Note 2: The XFFTSGui will only work, if a spectroscopy core is running on the XFFTS.**
+Note 2: The XFFTSGui will only work correctly, when a spectroscopy core is running on the XFFTS.
-**Note 3: If, for some reason, you want to set the MultiFiBa manually, you should also close the XFFTSGui, as there might occur problems, when multiple clients connect to it.**
+Note 3: If, for some reason, you want to set the MultiFiBa manually, you should also close the XFFTSGui, as there may occur problems, when multiple clients connect to the former.
-===== Wiring schemes for spectroscopy =====
+===== MultiFiBa technical scheme =====
+{{:information_for_astronomers:user_guide:bsb_multifiba_rev.4_20141120.png?1000|}}\\
+{{:information_for_astronomers:user_guide:bsb_multifiba_rev.4_20141120.pdf|}}
-=== XFFTS 100/500 MHz Bandwidths ===
-{{:information_for_astronomers:user_guide:xffts_100_500mhz.png?800|}}
-=== XFFTS 2 GHz Bandwidth ===
-{{:information_for_astronomers:user_guide:xffts_2ghz.png?800|}}
-=== AFFTS 7-Beam (100 MHz) ===
-{{:information_for_astronomers:user_guide:affts_7beam.png?800|}}
-=== AFFTS channels 8 and 16 (100 MHz) ===
-{{:information_for_astronomers:user_guide:affts_8_16_100mhz.png?800|}}
-===== Pictures =====
-{{:information_for_astronomers:user_guide:xffts_photo.png?518|}}\\
-{{:information_for_astronomers:user_guide:affts_photo.png?556|}}\\
-{{:information_for_astronomers:user_guide:multifiba1_rename.png?768|}}\\
-{{:information_for_astronomers:user_guide:multifiba2_rename.png?576|}}

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