MINPAUSE is used to specify the minimum time a recording will be stopped between scans. It can be specified for each scan, but usually will be set to one value for the whole schedule. If the start of a scan is less than MINPAUSE (seconds) /sl times the speedup factor from the end of the last recording scan, the recording will be left running between the scans. This action is station dependent -- different stations can have the recording started at different times except when writing a VEX file, in which case simultaneity is enforced. The nominal start time of the scan as displayed in the summary is not affected by MINPAUSE. You can use the option TPSTART in the SUMITEM list to display in the summary how long before the scan start time the recording starts. The recording start time is also given in the sch file.
Short recorder stoppages can cause problems for playback. Every time the recording stops, it must be resynced, which takes 10-20 seconds for the VLBA.
There are a variety of ways to prevent recordings from being stopped between scans. The simplest is to schedule using DUR or explicit times with no specification of an interval between scans. In such cases, SCHED will not schedule any sort of pause in scans or recordings. One can use MINPAUSE to keep the recording going through short gaps. For longer gaps when using MINPAUSE, the recording start time will not be affected. PRESTART, or a negative value for the obsolete parameter PRESCAN, can be used to shift the scan start time forward from the time set by other criteria (such as antennas on-source when using DWELL). The start time is moved by the same amount for all stations and is not moved past the stop time of the most recent scan at any station.
For PCFS (VEX) controled stations, the user should bear in mind that all start times currently (Oct. 2001) must be equal. SCHED will issue a warning if this condition is violated and will try to synchronize recording starts when using MINPAUSE.
In the tape era, it was possible for MINPAUSE to confound your attempts to leave gaps required by VEX files for tape reversals. In such cases, you would need to adjust MINPAUSE on the offending scans. The default should not cause this problem because it does not request continuous tape motion through scans long enough to keep the VEX check routines happy for a reversal.