5700MSC-IP
IP Network Grand Master Clock & Video Master Clock System
Revision 0.2 Page - 27
difference of one line of video. At any time during this Slow relock process, the operator can force
the 5700MSC-IP to immediately lock to the reference by performing a frequency jam. This can be
performed by selecting Jam Reference in the Jam Input menu off the INPUT root menu. It can also be
performed remotely through SNMP. Once the Jam Reference has been initiated, the frequency and
phase from the reference is jammed into the main oscillator, forcing it to lock immediately. Performing
a Jam may cause disturbances on all sync and test generator outputs as the phase of the unit is reset.
Careful consideration and testing of Slow lock mode effects should be made, especially when using
multiple 5700MSC-IP units locked to each other. Portable truck systems that may require a cold start
of all equipment should allow for some time for oscillator warm-up and GNSS lock but could require a
manual frequency jam to be performed in order to get units locked up quickly.
When the unit is first started up, or if the frequency reference source is changed by
the user, a frequency jam is always performed. This jam occurs even if the Lock Type
has been set to Slow mode. When locked to GNSS, this initial frequency jam could
occur 5 to 30 minutes after the unit has been restarted, once GNSS lock is fully
established.
If a large shift in the reference occurs while Slow lock mode is enabled, the outputs
of the 5700MSC-IP may be out of phase for a long time while re-locking. The
5700MSC-IP will gradually slew its oscillator to bring it back into phase with the
reference. This slewing action combined with the apparent phase shift may seem to
indicate that the unit is completely unlocked to the reference and freerunning. This
should not be considered a fault. A manual jam can be performed at any time to force
the 5700MSC-IP to lock immediately.
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