User Tools

Site Tools


information_for_astronomers:user_guide:signalpathsetup

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
information_for_astronomers:user_guide:signalpathsetup [2014/11/20 15:29]
bwinkel
information_for_astronomers:user_guide:signalpathsetup [2017/01/25 20:24] (current)
akraus
Line 1: Line 1:
 ===== Signal paths to the spectroscopic,​ VLBI, 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 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**.+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 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 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
Line 7: Line 7:
 <​code>​SXXNNNZ</​code>​ <​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. **Notethat 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^Channels^IF^Bandwidth^Attenuation-enabled^Comment^ +
-|097|8+16|VLBA IF|100 MHz|yes| | +
-|185|8+16|VLBA IF|500 MHz|yes| | +
-|128|8+16|Narrowband (SB)|100 MHz|yes| | +
-|134|8+16|Narrowband (SB)|50 MHz|yes|needs change in .front-files| +
-|128|1-7,​9-15|7-Beam IF|100 MHz|yes|exclusively for 21-cm 7-beam| +
-|161|1-7,​9-15|7-Beam IF|300 MHz(*)|yes|exclusively for 21-cm 7-beam| +
-|033|8+16|Optical|2/​2.5 GHz|no|used for UBB/new K-band| +
-|161|8+16|Broadband|1 GHz(+)|yes|mainly for VLBI and pulsars| +
-(*) 300 MHz from frontendMultiFiBa has 2.5 GHz bandpass +
-(+) 1GHz from IF, MultiFiBa has 2.5 GHz bandpass +
- +
-| 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.| +
-| 128 | Applying the internal 100 MHz filter, almost exclusively used for spectroscopy with the 21-cm 7-feed and AFFTS. | +
-| 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! | +
-| 192 | Special mode for using the DFB in polarimetry mode |+
  
 +^Mode^Channels^IF name^IF range^Bandwidth^Attenuation^Comments^
 +^ ^ ^ ^[MHz]^[MHz]^enabled^ ^
 +|216|8+16|VLBA IF|700-800|100|yes| |
 +|185|8+16|VLBA IF|500-1000|500|yes| |
 +|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 One can change the attenuation using the commands
Line 40: Line 35:
 The commands can be sent in the "​MultiFiBa"​ tab within ObsInp. The commands can be sent in the "​MultiFiBa"​ tab within ObsInp.
  
-**Note 1: For spectroscopy observations with the XFFTS, there is 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 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.** +
- +
- +
-===== Wiring schemes for spectroscopy ===== +
- +
-=== 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|}}+Note 2The XFFTSGui will only work correctly, when a spectroscopy core is running on the XFFTS.
  
-=== AFFTS 7-Beam (100 MHz) ===+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.
  
-{{:​information_for_astronomers:​user_guide:​affts_7beam.png?​800|}} 
  
-=== AFFTS channels 8 and 16 (100 MHz) ===+===== 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|}}
  
-{{:​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|}} 
information_for_astronomers/user_guide/signalpathsetup.1416493761.txt.gz · Last modified: 2014/11/20 15:29 by bwinkel