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B.11. Changing to Pulsar Binned mode

IMPORTANT: In order for CABB to fold pulsar data correctly, a predictor file is needed:

  • On caccc1, type:

    caccc1> psrpred

  • Choose the pulsar name, e.g.:

    psrpred> J1302-6350 or

    psrpred> J0835-4510 for Vela

  • follow the defaults thereafter

To change modes it is necessary to:

  • stop the current scan

  • cccversion: pulsar mode works in any version.

  • in cacor, open the edit menu

    select the edit button in the cacor gui,

    • select the appropriate config

      edit> get psr32_2f_favg4

      The psr32_2f_favg4 config has 4 “frequencies”. F1 and F3 are continuum bands with 2048 1MHz wide channels. F2 and F4 are the pulsar data - the continuum data is averaged into 4MHz wide channels, then each channel binned into time bins as defined by the predictor file.

    • and program the correlator

      edit> prog

      Check that all blocks program correctly. If any blocks report an error, they need to be programmed again, e.g.:

      edit> prog 8 or edit> prog 8 27

    • if you are having problems with a block you can try

      edit> prog N cal which just reprograms the calibration (sometimes works)

    • <CR> to return out of the edit menu

  • Calband will be set to the default values - which is what is required

  • start observing a strong calibrator, e.g.

    caobs> track 1

  • Check for rear transition module (rtm) problems

    F1 and F2 Datalinks (separate tabs in the CACOR gui) should not have red error messages, and the 1ms values are in the range 2000 - 13000 (i.e. not 260 000). Fix with:

    cacor> rtminit

  • Check (from non-binned autocorrelations (F1, F3) in spd) for “big humps”. To fix, reprogram the relevant block.

    To determine the block, note antenna, frequency (1 or 2), and polarization (A or B) - then read off the block from the relevant Datalink tab on the CABB GUI.

  • Check (in spd) individual baseline amplitudes and phases for discontinuities and fix by reprogramming relevant blocks

  • Check for memory problems - every second cycle is obviously bad. Fix with:

    cacor> reset mem

  • Setup standard flagging

    cacor> fflag f1 birdies

    cacor> fflag f2 birdies

    NOTE: all flagging is cleared every time you exit from the edit menu

  • Check that tvch is set to appropriate values

  • Check that delavg is set to an appropriate value

  • Standard setup follows (i.e. check sampler levels, and for fringes, then dcal, acal, pcal etc.)

  • Note: As of end October, 2013, there is a bug in the cacor software that means that the Tsys is not being calculated correctly for the second (F3) frequency.