Page 8
DXD8/PTP User Manual (rev 2.15)
5.1 RTC (Real Time Clock)
A backup clock, called the RTC (Real Time Clock) is included in the DXD-8. It is set at the factory (date & time) and runs
continuously, even when the unit is turned off as it is powered by an internal battery.
The DXD uses the date & time information from the RTC just after power up and transfers it to the main TOD (System Time).
When locking to a new reference, if that reference does not have date & time, the TOD simply continues counting along its
current time sequence; if it has date & time, that information is transferred to the TOD.
Although the RTC is set at the factory, it can also be set manually by the operator or be updated automatically (if GPS is
available) via the Real Time Clock menu (menu 7.2).
5.2 Time Jam
Time information can also be received from an external source via the Time Jam mode. This mode is available only when the
reference set in menu 1.1 is one of the BNC inputs as the references available at the BNC inputs do not carry time information,
only rate (Word Clock, AES, Video Sync or 10 MHz). Current choices for Time Jam source are PTP and GPS. The DXD-8’s
System Time will be reset to the time of the Time Jam source before locking to the reference connected to the BNC input selected
in menu 1.1.
5.2.1 TIME JAM TO PTP
When PTP is selected as the source of TIME JAM (menu 1.2), the DXD-8 will first lock its internal
Time of Day clock to PTP. When that is achieved, the DXD-8 will release the PTP Lock and revert
to the BNC source selected in the reference menu.
Reasons to PTP time jam DXD-8’s include:
•Locking to a common video reference (e.g. NTSC) and wanting all of the cross-frame outputs (25 etc.) to be in correct phase
(and epoch), as well as wordclock and AES.
•In a primarily legacy application this is the way to increase the number of legacy outputs and have them all in phase.
•With a timecode license wanting TOD timecode outputs to be in sync, and with correct cross-framing where applicable.
5.2.2 WHAT IS THE SEQUENCE OF A COMPLETE TIME JAM TO PTP?
1. LOCK TO PTP: The DXD-8 Lock status indicates HOLD / PTP SYNC on dark pink background.
2. CONFIRMATION: A message confirms that the date and time information has been transferred to the internal Time of Day
successfully (clearing of this message is required).
3. LOCK TO THE BNC INPUT: The DXD-8 indicates it is locked to the BNC reference, Input a / Video in this example.
4. SYSTEM TIME UPDATED: The System Time now indicates the same time as the PTP source
TIME JAM
A Time Jam to PTP has
completed successfully
Press Any Key to Exit
IMPORTANT NOTE
When using a reference without date & time information such as video sync, there will be a date & time adjustment in
the TOD count so that video frame edges are correctly aligned.
The internal TOD is always creating internal
frame references that are aligned as required with Jan 1, 1970 (PTP epoch)
. To lock to an external
frame edge the DXD has to move the TOD count by up to +/- half a frame to synchronize the internal TOD frame
edge to the incoming edge.
