FORMAT is used to specify the recording format. Note that it is couched in terms of tracks despite the switch to disks because the concept isstill used in Mark5A and in Mark5A+ playback of Mark5B. Options are:
- Set to DAR type for first stage default.
VLBA formats - VLBA type systems:
VLBA - Let SCHED choose the fan out.
VLBA1:1 - 1 bitstream on 1 tape track. VLBA format.
VLBA1:2 - 1 bitstream on 2 tape tracks (fan out).
VLBA1:4 - 1 bitstream on 4 tape tracks (fan out).
VLBA2:1 - 2 bitstreams on 1 tape track (fan in).
VLBA4:1 - 4 bitstreams on 1 tape track (fan in).
MKIV formats -Mark IV (and VLBA4) systems:
MKIV - Let SCHED choose the fan out.
MKIV1:1 - 1 bitstream on 1 tape track. Mark IV format.
MKIV1:2 - 1 bitstream on 2 tape tracks (fan out).
MKIV1:4 - 1 bitstream on 4 tape tracks (fan out).
MKIV2:1 - 2 bitstreams on 1 tape track (fan in).
MKIV4:1 - 4 bitstreams on 1 tape track (fan in).
MARKIII format - Mark III and VLBA systems.
MARKIII - Mark III tape format. No fan in or out.
S2 - Canadian S2 record systems.
S2 - All S2 recordings.
Others:
MARKII - No action. Use for Mark II and single dish.
NONE - No tape to be used, as for pointing.
Note on track assignments: Track assignments are an easy thing to get wrong. SCHED will make track assignments automatically for some modes if they are not specified in the setup file. Most users should take advantage of this facility. Automatic track assignments will be made for MARKIII modes with 1 bit only, and for VLBA1:1, VLBA1:2, and VLBA1:4 modes with 1 or 2 bits. The barrel roll is on by default (can be controlled with BARREL) in VLBA modes and off in MARKIII mode. The roll is within 8 or 16 track groups, advancing one track for each frame.
The fan in modes, VLBA2:1 and VLBA4:1 were never implemented, so this paragraph is only retained for historical reasons. If using a fain in mode, give the same track assignment to 2 or 4 channels. In the fan in modes, if there are 2 bits per sample, the two bits will be put on the same track so there will be one channel per track for VLBA2:1 mode and two channels per track for VLBA4:1 mode.
For the fan out modes, VLBA1:2, VLBA1:4, MKIV1:2, and MKIV1:4, give the first track assignment for the baseband channel. Sequential formatter track assignments are used for the other tracks associated with that baseband channel. The resulting recorder track assignments are then given below:
VLBA1:2, MKIV1:2:
forward, track for 1st bit - 3 7 11 15 19 23 27 31
forward, track for 2nd bit - 5 9 13 17 21 25 29 33
reverse, track for 1st bit - 2 6 10 14 18 22 26 30
reverse, track for 2nd bit - 4 8 12 16 20 24 28 32
VLBA1:4, MKIV1:4:
forward, track for 1st bit - 3 11 19 27
forward, track for 2nd bit - 5 13 21 29
forward, track for 3rd bit - 7 15 23 31
forward, track for 4th bit - 9 17 25 33
reverse, track for 1st bit - 2 10 18 26
reverse, track for 2nd bit - 4 12 20 28
reverse, track for 3rd bit - 6 14 22 30
reverse, track for 4th bit - 8 16 24 32
Note that MkIII modes are obsolete.
Format NONE is used for VLBA testing, such as single dish pointing. When specified for VLBA data, the on-line system does not touch the formatter. This includes not readjusting the pcal detection. Format NONE will mainly be used by VLBA staff for testing and in high frequency projects that do reference pointing. If the reference pointing scan uses this format, no formatter reconfigures are done which can prevent the significant data loss that can happen at reconfigures.
Note that it is not necessary to specify FORMAT. FORMAT will be set equal to DAR in the station catalog.. Stations with DAR = VLBA4 will write Mark IV format on the tape. When the default format is taken, the barrel roll is turned off for formats other than VLBA.