Model 5601MSC
Model 5601MSC Master SPG/Master Clock System
Page - 42
Revision 2.2
OPERATION
or if the user bits are being used for another purpose, the date decoder must be disabled by setting it to
No Date
. This prevents false date decoding that may trigger spurious
time jam
events or warnings.
When the date decoder is disabled, the date can be manually set using the
Set System Date
menu item
in the
GENERAL
root menu.
The 5601MSC will continuously compare the
system clock
to the incoming VITC timecode. When a
difference of more than 2 milliseconds is detected the 5601MSC will generate a
jam
event, or a jam
warning depending on the
Lock Type
setting. When a
jam
event occurs, the time read from the VITC
input is jammed into the
system clock
. At the same time, the VITC input time is jammed into the
timecode output clocks.
When the incoming VITC is jammed into a particular output timecode clock, it may be adjusted to
maintain color frame alignment and to match the output frame rate. See section 2.3.4.2 for more
information. If a particular timecode output is the same frame rate as the incoming VITC, the time is
copied directly into the output’s clock. If the timecode output is running at a different frame rate than the
VITC input, then the time is rounded to the nearest frame before being jammed into the output’s
timecode clock.
In order to use VITC as a time reference, the frequency reference must be set to
Video.
2.3.3.6. IRIG Time Reference
When the
IRIG
option is installed, the 5601MSC will be able to read IRIG-B timecode that is applied to
the LTC input on the GPIO connector. The IRIG type is auto-detected. Refer to section 2.3.5 for more
information on the IRIG-B formats supported and how to connect IRIG to the LTC input. Only the IRIG-
B124 and IRIG-B127 formats supply complete date information. If other formats are used, the system
date will have to be set manually using the
Set System Date
menu item in the
GENERAL
root menu.
The
system clock
is continuously compared with the incoming IRIG timecode. When a difference of
more than 5.5 milliseconds is detected the 5601MSC will flag that a time
jam
is required. The time
Lock
Type
menu item controls how the 5601MSC responds when a time
jam
is needed. See section 2.3.1 for
more information.
2.3.3.7. SNTP Time Reference
The 5601MSC can jam its
system clock
to an external NTP server. Unlike with other time references,
this synchronization is not continuous and happens once a day. The time
Lock Type
is forced to
Daily
,
and the
Input Jam Time
control sets the time of day the synchronization happens. Up to eight external
NTP servers can be defined. All enabled NTP servers will be contacted and the server response with
the best stratum and dispersion values will be chosen to jam the system clock.