Model 5601MSC
Model 5601MSC Master SPG/Master Clock System
Page - 92
Revision 2.2
MASTER CLOCK
4.3.4. Selecting the Time Reference
INPUT
The
Reference Src
menu item in the
Time
menu is used to select the type of
time reference to be used by the 5601MSC.
When
GPS
is selected, the 5601MSC system time clock is referenced to
time information that is acquired from the GPS receiver. (
GP
option
required) When the frequency reference is set to
GPS
the time reference is
forced to GPS. See section 2.3.3.1 for more information.
When set to
Modem
the 5601MSC system time is obtained by dialling into a
high-level time service such as the NRC or NIST ACTS (
M
option required).
After a successful modem call, the 5601MSC time locked status will be valid
for a period of ten days. See section 2.3.3.2 for synchronization and section
4.5.6 for the modem configuration menu.
When
Syncro
is selected, the 5601MSC will obtain time from another
5601MSC unit that is connected through a 5601ACO2 automatic
changeover. In the
GENERAL
menu, the
Syncro
menu item must be set to
Slave time
or
Slave menu/time
for this time reference to work. See sections
2.3.3.3 and 4.5.5 for more information.
When set to
LTC
, the 5601MSC system time will be referenced to time
information being read from the LTC input on the GPIO connector. The
frame rate of the incoming LTC is auto-detected and must be either
29.97fps dropframe, or 25fps. See section 2.3.3.4 for more information.
When set to
VITC
the 5601MSC system time will be referenced to time read
from Vertical Interval Time Code off a black burst reference applied to the
REF IN LOOP BNCs. The incoming VITC frame rate can be either 29.97fps
dropframe on NTSC-M, or 25fps on PAL-B. The line to read VITC from is
selected by the
Vitc Line
menu item (see section 4.3.5). The frequency
reference must be set to
Video
in order to use VITC as a time reference.
When the time reference source is set to
None
, the 5601MSC system time
will freerun. The operator must set the system date and time from the
GENERAL
menu using the eyeball and wristwatch method. The time cannot
be guaranteed with any sort of accuracy and the NTP server will report an
unlocked condition, unless spoofed (see sections 2.4 and 4.5.13.1).
When set to IRIG, the 5601MSC will obtain time information from an IRIG-B
signal applied to the LTC input on the GPIO connector. The type of IRIG
expected is set using the
Irig Mode
menu item (see section 2.3.3.6).
When set to SNTP, the 5601MSC will obtain time from one of eight NTP
time servers. The time
Lock Type
is forced to
Daily
. The
Input Jam Time
control specifies when the daily sync will happen. It is similar in properties to
using a modem to do a daily dial up. It is designed this way because NTP is
not an adequate reference to do a genlock, and each SNTP synchronization
may cause the LTC and VITC outputs to change.
Time
Reference Src
GPS
Modem
Syncro
LTC
VITC
None
IRIG
SNTP