LBA Correlator Schedule File Format

The schedule file is a text file containing information which controls the operation of the S2 tape units and the correlator. Each time a go command is executed in LBABOSS, the active schedule file is opened and the statements contained in it are carried out in the order they appear. The s2file command in LBABOSS defines the active schedule file, which must reside in the cor$sched: area for user CORR on ELLEBA.

Within the schedule file, blank lines and comment lines, those with a semi-colon as the first character in the line, are ignored.

Within a statement, space delimited free formatting is used.

Times within the schedule are specified in UTC and are relative to the reference UTC date defined by the DATE statement - see below. The format is DD/HH:MM:SS.ssss, where DD is days, HH hours, MM minutes and SS.sss seconds.

Basic Setup Statements

This specifies the name of the experiment. This name is written to the observer field in the rpfits file. It is also used in the creation of the polyco filename in pulsar gating mode. If the schedule file does not contain an EXPERIMENT definition it will default to "LBA".

DATE YYYY DDD

This specifies the reference UTC date in the form of year and day number of year. Example:

 DATE 1999 234  

TICK s.sss

This specifies the "tick period" in seconds. The tick period defines the rate at which the antenna delays and fringe rotators are updated. It can be specified to an accuracy of one microsecond and there must be an exact integer number of ticks per correlator integration cycle. As the antenna delay units are capable of making a maximum of one delay step ( 31.25 nanoseconds ) per tick period, the maximum delay rate of any antenna in the array, relative to the reference antenna, must be less than 31.25 nanoseconds per tick period over the entire period of the observation defined in the schedule. If the schedule file does not contain a TICK definition the tick period will be set equal to the correlator blank period.

Note: Due to hardware limitations in the current system, the tick period should not be set to a value less than 0.01 seconds.

SOURCE_LIST Name

This defines the source list for the experiment. A file cor$db:name.tab must be present. If the schedule file does not contain a SOURCE_LIST definition, the default list cor$db:source.tab will be used.

FREQ/BW ffff.ff [-]bbb.bb [ffff.ff [-]bbb.bb]

This specifies observing frequency/bandwidth pairs in MHz. A maximum of two frequencies can be included. They define the centre frequencies of each band. Currently, the second frequency bandwidth must be the same as the first frequency bandwidth. The signs of the bandwidth entries define the sideband, + for upper sideband, - for lower sideband.

ANTENNAS N

This defines the number of antennas in the array. It must be preceeded by a FREQ/BW statement defining the number of frequencies. The ANTENNAS statement must be immediately followed by N lines, not counting blank or comment lines, describing the parameters for each antenna. The order defines the antenna numbers, with the nth entry becoming antenna n which is identified with S2 tape unit n. A typical ANTENNAS entry is :

 ANTENNAS 5 ;	      Freq. 1    Freq. 2 ; Name  Map   Sefd Mode  Sefd Mode  Delay(us) at  T0       rate(us/s)  Freq. offset (Hz)   PKS         50.0  0    60.0  0     0.00      0/00:00:00    0.0   CAT13       80.0  0   100.0  4    -5.171     1/05:37:00    4.6E-6 * MOP   M10  400.0  0   500.0  0     2.950     0/05:38:00    5.7E-6 # HOB       1300.0  1  2000.0  1    52.543     2/00:41:00    0.4E-6          1.1   CED        500.0  0   600.0  0     5.920     0/05:50:00   -2.7E-6  

• The first column must be a valid antenna name with a corresponding entry in the file cor$db:stations.tab.
• The next column contains an optional input signal mapping definition. It defines how the S2 data channels are to be mappped to the correlator data channels. If present it must begin with the character M. The next character defines which S2 data channel is to be connected to correlator channel 0, the next character applies to correlator channel 1, etc. The normal one-to-one mapping defined by M01[23] is the default.
• The next column contains the nominal system noise equivalent flux density (Sefd) at the first observing frequency. This is used to do online amplitude calibration and determines the flux scales of the archived data and the data shown in SPD and TVD.
• The next column describes the input data format and sideband data for the first frequency:
  • 0 = standard ATNF coding - sign before magnitude
  • 1 = non-standard ATNF coding - magnitude before sign - e.g. Hobart pre DAS.
  • 2 = VLBA coding

  Add 4 to the above for sideband inversion.

• If two observing frequencies are defined in the preceeding FREQ/BW statement, as was the case in the example above, the next two columns contain the Sefd and data format for the second frequency.
• The next column contains the antenna delay in microseconds at a specified reference time.
• The next column defines the reference time for the delay setting.
• The next column contains the delay rate in microseconds/second.
• The next column is optional. If present it defines an offset frequency which is applied to the fringe rotators for this antenna. Maximum offset is 16MHz.

A * placed before the antenna name puts the S2 playback unit for that station offline. The antenna will still appear in the rpfits antenna table.

A # placed before the antenna name means that the antenna is a "dummy". The antenna will appear in the rpfits file antenna table but it will not have an S2 playback unit allocated to it, nor will it have any associated delay unit or fringe rotators. This allows a single antenna table to be defined for experiments which have more stations than there are S2 playback units and which must therefore be correlated using multiple passes.

Note: S2 transports are allocated to antennas in the order they appear in the antenna list, excluding "dummy" antennas. Hence, in the above table, the transports allocated are: PKS - 1, CAT13 - 2, MOP - 3, CED - 4. Currently, unlike all the top level software, the PRCC works in transport numbers rather than antenna numbers. When "dummy" antennas are present this needs to be taken into account when viewing the PRCC display. This may be changed in future.

CONFIG ConfigurationName

This specifies the way in which the correlator is to be configured. There is a set of standard configurations which specify such parameters as the number of baselines, the number of frequencies and polarisations and the number of frequency channels. This information is stored in two files, cor$sched:ConfigurationName.bsl on ELLEBA and $cor_menu/ConfigurationName.cfg on LBACCC. If either of these files do not exist the schedule will fail. Each schedule file must contain at least one CONFIG statement.

PSRPH PP.ppp

This statement is used in pulsar gating mode only. The value defines an offset which is applied to the pulsar gating timing. It is in units of the pulsar period and must be in the range 0.0 to 1.0.

S2 Tape Recorder Control Statements

Turn the specified S2 tape units online.

OFFLINE n1 n1 n3 ... nn

Turn the specified S2 tape units offline.

The following statements operate on all the currently online S2 tape units.

MODE S2_Mode

Set the mode of the S2 tape units. S2_Mode must be a valid S2 mode - see the S2 Users Manual.

GROUP n

Set the group number of the S2 tape units.

STOP, REWIND, FF, PLAY

S2 tape motion control.

ALIGN HH:MM:SS

Align the S2 tapes to the specified time. The schedule will not proceed until all online S2 tape units are aligned.

Schedule Execution Control Statements

NEWTAPES

Stop the schedule at this point. This is usually used to stop the schedule at a time where new tapes must be loaded into the S2 tape units.

PAUSE n

Wait for n seconds before proceeding with the schedule. This is generally used to wait for a tape motion command to complete or to skip over a bad data section in one or more of the tapes.

GOTO Label

This causes the following statements to be skipped until the Label: statement is found. Label can be any text string not containing blanks.

Archive File Management Statements

This causes any currently open rpfits file to be closed and a new file Name to be opened. A special case is where Name = CLOSE. In this case a new file is not opened.

CHANNELS F1first F1last [F2first F2last]

This statement is used to define which subset of the available frequency channels is to be archived. All channels between the first and last channels, inclusive, are archived. Values can be defined for each frequency. If a CHANNELS statement does not appear in the schedule, all channels are archived.

Scan Control Statements

The scan information is specified by entries of the following form:

 ; Scan    Source     Start time   Stop time     1    1921-293    0/07:30:10 - 0/07:45:00      2    2036-321    0/07:45:10 - 0/08:30:00      3    VELA_PSR    0/08:30:10 - 0/08:45:00  P  

• The first column contains the scan number. This is not used but must be present.
• The second column specifies the source name which must have a corresponding entry in the current source list.
• The next entries specify the start and stop times of the scan.
• A P character following the stop time specifies the scan to be in pulsar gating mode.