Model 5601MSC
Model 5601MSC Master SPG/Master Clock System
Page - 34
Revision 2.2
OPERATION
The 5601MSC can use either 10MHz or 5MHz continuous wave (CW) frequencies as a reference.
These signals are applied to the reference input BNCs and the frequency is automatically detected by
the 5601MSC. With CW signals, the main oscillator frequency is locked to the incoming reference but
absolutely no phasing information is supplied. The 5601MSC will arbitrarily pick an internal phase
reference point once frequency lock is obtained. Lock diagram #5 (Figure 2-12) illustrates the
generation of signals when locked to a reference that provides no phasing information.
While outputs of the same standard will be phased correctly to each other, they will not be phased
deterministically. The outputs of multiple units locked to a CW reference cannot be guaranteed to be in
phase. Furthermore, if the 5601MSC unit is restarted the phase relationships can change as a new
phasing point is chosen. Likewise if the CW reference is lost, any drift accumulated during the time the
reference is absent cannot be corrected for once the reference is regained.
In order to align the output phase of two 5601MSC units that are locked to a stable CW reference, the
Ten MHz Global Phase
controls can be used. See section 2.1.5 for more information. When the
Ten
MHz Global Phase
is enabled, the 5601MSC outputs can be phased manually to align them with
another source. In this configuration, the unit will maintain a stable phase relationship as long as the
CW reference is uninterrupted and the unit is not restarted. If a restart does occur, the 10MHz Global
Phase controls are automatically disabled and reset to zero at startup.
When a CW reference is used, the phase of the DARS and AES outputs can be anchored to either
NTSC or PAL standards. This is chosen using the
AES/DARS/WC lck
menu item in the
AES Audio
menu. This menu item should be set to the dominant video standard that will be used in the particular
installation.
When the CW reference is lost, the 5601MSC will free-run on its active oscillator, selected by the
Genlock Range
menu item (see section 4.3.2). The
Lock type
menu item controls how the 5601MSC
responds when the reference is regained (see section 2.2.4).
2.2.12.1. Internal Frequency Reference
When
Internal Ref
is selected for the frequency reference, the 5601MSC will free-run on the 10MHz
output of its high-stability OCXO oscillator, regardless of the
Genlock Range
menu item setting. The
locking operation is similar to when locking to CW signals. The 5601MSC will pick an arbitrary phase
reference to generate all outputs. This phase reference will be different between multiple 5601MSC
units set to free-run, and will change if the unit is restarted.
The output phase of a 5601MSC that is running off its internal reference can be adjusted by using the
Internal Global Phase
controls. When enabled, these controls will allow for
temporarily
bringing a free-
running 5601MSC into phase with another piece of equipment. Although the internal oscillator of a
5601MSC is very stable, it will inevitably drift away from another reference due to the slight variation in
frequency of its internal oscillator.
