Quantec Zombies 12xx Series, Operation Manual

Page: 36 / 145

Operation Guide Revision 3.7c
©1994 - 2003 Quantec® Tonstudiotechnik GmbH, Munich, Germany
36
Clock Mode - some general notes
Depending on the choice of clock signal source a ZOMBIE operates in either of two modes:
Clock Slave the clock signal is either derived directly from the audio signal
(»Genlock«), or derived from an externally fed word clock
Clock Master
the clock signal is generated through an internal PLL (»Phase
Locked Loop«), which is synchronized either from the internal
crystal oscillator or from an external standard frequency source
The term »clock master« indicates solely that the ZOMBIE does not derive its clock signal directly
from the sample rate, but from a separate external source.
With the exception of synchronization onto the internal quartz crystal oscillator, which does
represent a completely self sufficient system, all other clock master modes are defined externally.
In all ZOMBIES which receive a common clock signal (»House-Sync«), which is lower than the
sample rate, such that the sample rate can be divided by the clock signal to leave a whole number,
fame skew of the audio samples is avoided entirely.
If several ZOMBIEs receive a common signal which is greater than the sample rate, it is still
possible to link the various ZOMBIES without using a sample rate converter, but the common
frame orientation is lost, so that problems are likely to arise, unless the receiver can tolerate a frame
skew of over
25%. That would, for example, be the case if it were equipped with a FIFO receiver
able to cope with several samples simultaneously.
It is easy to avoid this potential problem with frame skew. If one ZOMBIE switches the original
reference clock signal to AES/EBU once, the AES/EBU signal generated by this ZOMBIE can then
be regarded as a secondary reference. If only the signal generated by this device is inputted into the
other digital devices in the studio, all downstream equipment should be accurately synchronized.
The menu items and clock signal sources for the “slave mode” are :
XLR
REF-input (AES11 »Star Clock«) ,(AES3 »Genlock«)
BNC TRUE
Word clock BNC (rising edge, duty cycle not relevant)
BNC INVERTED
Word clock BNC (falling edge, duty cycle not relevant)
BNC INVERTED
Word clock BNC (falling edge, duty cycle not relevant)
from LL
LL-input (»Genlock«), not available on all ZOMBIES
Note on »
XLR
« mode: If a valid signal is present at the REF input, this will be used as the clock
signal source. Otherwise the audio or empty AES/EBU signal of the GL input will be used
(»genlock«).
Note on » from LL « mode : This mode is not available on all ZOMBIES, as it can only operate if
there is no sample rate converter built into the device. The clock signal of the LL cannot be