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Of course everything I know about the DFB came from the FINE MANUAL, Warwick Wilson's SPD command list and DUMMSY command list (UPDATED 090915)

Complete startup from a shutdown machine (both PC and DFB powered off)

• Power up PC (dfb0.ast.man.ac.uk). If you are at a remote site and it seems inaccessible, you may need to ask the controller to help.
• Power up the DFB. The embedded PC on the DFB downloads its system from the PC using tftpboot. It takes approx 30 secs and when complete will have displays on the small display and various flashing LEDS! Again, if you are trying to do this remotely, and there's no communication with l-bcc11 from dfb0, you may need the controller to power cycle the DFB crate
• Log in to the dfb0 as corr and start a vnc session for the controller using the command startvnc6 Open vncsession :6
  If the last shutdown was unclean, a lock file will have been left and vncserver will complain and not start. You can check whether vnc is running using ps -elf | grep vnc, if it isn't, remove the file, and rerun startvnc6
• Start and set up the ATDC
  Type atdc in an 80x24 xterm. and select the defaults for access, then 2 for clock control.
  Follow the instructions to set the time correctly (you will need to dial TIM - the speaking clock or ask the controller to read back his GPS time display or find a reliable synchronised time display from another computer used for observations. (Try the CLOCK program on ARTHUR - use "telnet arthur", login in as pulsar, type clock)
  Select the clock display option and accept the defaults for clock phase monitoring (yes and 600 secs), double check that it is right to the second and the day, month, year etc are correct.
  Finally see if the tick phase (displayed bottom right) is somewhere between 0 and 200 nS. It can be adjusted in 200ns steps by typing s and entering the amount of slide required in nS. Leave the clock running and logout from arthur.
• New startup script
  To start from nothing, in a convenient xterm, type startdfb
  This will start pdfb4, dummsy and dscom in their own windows. You may need to adjust window positions

  (conversely, if any part of the running software has failed or got stuck use stopdfb which will stop any running processes and cleanup everything ready for a restart. This script also reboots the DFB so it may be useful to try this if things don't start. ( The ATDC and SPD are not affected )

  stopstart will run stopdbf then startdfb

• Now start spd with the command restartspd which brings up a new xterm, running spd in the required configuration.
• If the telescope is in operation, you can get the controller to start an observation and if all goes well, the software should start by doing a configuration (a config window will appear, stuff happens, then if successful, it will iconize to the bar at the bottom). If it fails the screen will stay there with an error message (you can try Return, then program to try the config again - but running stopstart is the easiest way out of this)

  If the telescope is observing, ask the controller to start the observation. There will be activity on all the windows, and with luck a "good" spectrum will appear after the third subint (ie ~30secs). If it doesn't work, try typing restart in an xterm window, or for a complete flush out and restart, use the command stopstart

• If the telescope is not observing, you can check that the DFB is properly setup, by going to the PDFB4 gui. Try to reconfigure by selecting a 512MHz file (the BW is the middle term) eg pdfb4_1024_512_1024 and CONFIG. If this is successful, start a run going by typing go in the DSCOM window. Integrations and folding should start, with a spectrum appearing after ~3integrations.
• PDFB4 is the DFB monitor.
  dummsy sends commands to the DFB and gets status info
  dscom is our link between the observing schedule and dummsy. (Our standard configurations are loaded into dscom from ~corr/dscom.dfg)
  
• SPD graphics display - will monitor bandpass and folded data
  

• To run manually - ie without the link to the controllers schedule
• open a few xterms
• Start pdfb4 and use the gui to load a config. Check that the DFB configures without errors (or at least doesn't get stuck and says OK Done at the end) this is shown in a window called CFG. which flashes up for a few seconds then gets minimised.

  

• Start tkds
  you can now run the DFB manually - see Warwick Wilson's dummsy command list

  

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• Manual DFB control through tkds - Folded data
• Configure the DFB - Choose a config file from the pull down list For folded data, choose a file pdfb4_bins_bw_chans and click on the COnfig button. Check that the DFB configures without errors (or at least doesn't get stuck and says OK Done at the end) this is shown in a window called CFG. which flashes up for a few seconds then gets minimised. Our default is pdfb4_1024_512_1024.
  (Pulsars with periods less than ~4 ms need a different config - we use pdfb4_128_512_2048) Work your way down the GUI using the following selections (JB defaults)
  
  • Observer - Your pick :-)
  • Obs Type - PSR WBPSR
  • Source - Name of pulsar including B or J eg B1931+24
    As far as I can see from the src code, if the source name starts with B or J, there will be a call to psrcat to produce a par file (online.eph) and a call to tempo2 in predictor mode ro produce a t2pred file. This is the default behaviour which we are using. See notes about catalogue at the end

    It appears to be possible to supply a polyco file. This will be searched for as Sourcename.polyco if the source does not start with B or J or possibly if some undocumented commands are used. In the code there is a tkds command "POLYCO". Warwick says that using this command will force the software to load a file /home/corr/cor/pulsar/online.polyco.
    Fill in the other fields on this line (coords and epoch). Stick to J2000 if you are using PSRCHIVE, it grumbles about B1950 coordinates. (The software will still run without changing these fields but you'll have misleading info in the data files header.

  • Freqs: We only use one freq. band
    Frequency - 1524.0 Sky frequency in MHz of the centre of the baseband. ie for a 512MHz band, supply the sky frequency equivalent of 256MHz
    Bandwidth - 512. It should match that selected in the Config file or the software will grumble (but run)
    Rest Frequency 1422.405 - "Defines the rest frequency, in decimal MHz, of one spectral line contained in each band"
    Inverted - Yes
    Write Chans - 128-895 This can be "ALL" or a subset of channels to write to the output data files. We are saving disc space and time by only dumping the part with a signal in it. It's a good idea to make the number of channels a power of 2 - some software won't handle it otherwise, and it makes bscrunching easier!.
    
  • Commands: These are the Jodrell defaults
    fold For folded data :-)
    site 8 for Lovell
    cycle 10 - cycle time (default), needs to be at least twice the pulse period. Range 2s to 30s.
    avg 1Number of cycles to average before writing to file
    fo Filename.rf Open a file
  PSRCYCLE 36 Optional - the DFB will stop after that number of cycles. I use this when I'm using the AVG command to make sure I get a whole number of averages done. There seems to be some problem with the data dumped from an incomplete subint.
  
  • GO starts the dfb on the next 10sec line - activity happens in the pdfb4 window!
    .
    .
    .
    .
    
  • STOP The DFB takes 1-2 cycle times to empty its buffers, finally a STOP will appear in the pdfb4 window. (HALT will do an untidy but immediate stop).
  • fc Close the data file
• PSRCAL Needs investigation, but I have driven the noise diode in phase with the pulsar period to produce a folded data profile of the noise diode.
• I'll write up Search data later - but basically you need to use a srch_bw_bin config file, set WBPSR,SSET (search set mode),SNB,SNP,SSAMT,(AVG 1,CYCLE 10 maybe) and with no file open, do a short run. This sets dclevels and spans etc. Then use command SEARCH (rather than SSET), open a file, GO ..... STOP, FC

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• SPD
  To view the data live, you can use SPD (See Warwick Wilson's SPD command list
.
I like to run 3 spd's in another vncviewer (currently :2) (this is because the updating of the main page can be a bit slow when checking from home, if everyhting is running on the same viewer).
For folded data, I like to display averaged phase/freq. images for the 2 pols:
• chan 450 700
• auto
• sel bi
The averaged phase bins, dedispersed:
• chan 450 700
• auto
• sel dp (In manual mode, the DM will have to be set using the PSRDM xx command. At Jodrell, this ) set manually
and the bandpass (for each cycle)for the 2 pols.
• chan 450 700
• sca a 0 2000
• sel aa bb
These settings currently give the best chance of seeing pulses while observing
For search data, bi and dp won't do anything but you can still see the bandpass.

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• Finally, if you want to start observations, tied to the current analogue obs (Jodrell specific), check the hsl software - this gives the DFB PC access to information about the telscope status and pulsar observing. Use ps to see if a program called hsl_shm is running (this should be started automatically at boot time). If it's not running, type hsl_shm in a terminal window and see that there is information coming through, if there isn't the problem may be with goedel which circulates the messages round the JBO network (see if the jblive web pages are running - they use the same info). If all seeems OK Ctrl-C it and restart it as a detached process ....
  hsl_shm >/dev/null &
  
• In (yet) another xterm (there should be one left!) start dscom. This reads the data collected by hsl_shm and configures and runs the DFB according to (currently) hardcoded configurations in parallel with analogue FB observations.
• Useful commands - dscom commands (typed with no echo!) vaxstop and vaxgo stop the analogue filterbank mirroring without exiting dscom
. If you want to exit dscom, type vaxstop, then exit. If you crash out untidyly, you may take out tkds as well.
• if you crash out of pdfb4 or tkds, exit them both and type corkill a couple of times to remove any processes before trying to strt things again.
• bcckill will stop and restart the bcc process - (need to be root)

The Green Shoots of timing analysis - a work in progress!

• a script currently saves data daily to /scratch/wulfgeat_2/nyoung/DFB/ and regular backups to a USB disk are being made. I'll make a tape of the data when I can.
• scripts doscrunch psrname YYMMDD and scrunchall psrname can be used to preprocess data - they (crudely) rip out chunks of bandwidth known to harbour RFI, and leave a clean(er) fits file, scrunched in frequency and time in psrname/scrunch
• If a file 1400.template is available in the scrunch directory, a TOA is produced and added to dbf.tpo in the default format.
• This is be copied to the analogue archive area ... folder /psrdata/timing/psrname/dfb
• To compare observations with analogue FB data, run psrtime (currently only tsttime supports the format correctly) using the command obey dfb.dat to load the dfb data and recent analogue data together.

Known problems

• Catalogue problems. The catalogues are held at /home/corr/psrcat
  The supplied psrcat holds some VERY out of date ephems. There is are add on catalogues called obs99.db and obscat.db which may or may not be better, but not it appears for things not observed by Parkes. Using the data from these catalgues gave me pulsars (especially the "classics") which were obviously drifting in phase over runs as short as a few minutes.
  I have replaced all the supplied catalogues with one generated from the eph files used on the VAX which I know are up to date.
  Observation will give obscure errors about pulsar period (in pdfb4) if it isn't found in the catalogue under the name used by the VAX (if dscom is running) or by the name entered in tkds. The name should be preceded by a B or J.
  At the start of an observation, tkds runs a catalogue search eg.
  psrcat -e -all J1927+0916 > /home/corr/cor/pulsar/online.eph
  Then runs this though tempo2 in prediction mode to get polycos for folding
  tempo2 -f /home/corr/cor/pulsar/online.eph -pred "8 54843.530968 54843.67713 1284 1560 12 2 12688"
  Run these two commands from a terminal to see if they work. (Check the online.eph produced and see what tempo2 makes of it). If the problem lies with the pulsar name used by the VAX this will have to be fixed in the pulsar observing list and ephemeris files held on the VAX
• Another source of error are that FITS file headers do not have spaces for some ephemeris variables, and the FITS file header writer does not handle this problem gracefully - it fails to write each subint. DM2 and F4 have so far caused this problem. Solved by replacing the catalogue!

If you have any queries please contact ChrisJ or TimI