JVC VR 601 - Manual (Page 44)

44
PRE- ALARM:
This option determines that images prior to an alarm occurs will be recorded in the hard-disk drive.
When an alarm is triggered the device will record the image prior to the alarm for 5 seconds in NTSC
(**20 fields/sec) or 6 seconds in PAL (**17 fields/sec).
ON: Enables this function.
OFF: Disables this function.
NOTE: If the device is already under recording mode before alarm occur, the pre-alarm
recording would not take effect.
** : For NTSC and Mux Off Mode, recording rate 20F/S would be actually 15 F/S
For PAL and Mux Off Mode, recording rate 17F/S would be actually 12.5 F/S.
( This adjustment is to avoid image shaking during playback at the same speed )