Model 5601MSC
Model 5601MSC Master SPG/Master Clock System
Page - 28 Revision 2.2 OPERATION
The SMPTE ST 318 ten-field reference can be generated by the 5601MSC and its predecessor the
5600MSC on any NTSC sync output. It is turned on and off using the Ten Field Ctl menu item (see
section 4.4.2.2.11). The 10field waveform is illustrated below in Figure 2-9. The number of pulses
indicates where in the sequence the frame belongs. It is inserted on lines 15 (field 1) and 278 (field 2).
Figure 2-9: SMPTE ST 318 Ten-field Reference on NTSC line 15
When the 5601MSC is locked to an NTSC reference with a ten-field pulse, the AES, DARS, and
Wordclock outputs can be phase locked properly. The AES/DARS/WC lck menu item located in the
AES Audio menu off the OUTPUT root menu should be set to NTSC/fractional.
In the NTSC ten-field lock diagram above (Figure 2-8), the AES/DARS outputs are displayed as frames.
Each frame is divided into two subframes, labeled X and Y. The X subframe identifies channel 1 (left
channel). The Y subframe identifies channel 2 (right channel). The wordclock output is high during
channel 1 and low during channel 2. Note that the AES/DARS and wordclock outputs can be phased
independently. If the phase of the AES/DARS outputs is changed for any reason, the phase of the
wordclock output should be changed as well to match.
The AES/DARS outputs provide a fixed sample rate of 48kHz (48,000 samples per second). This
means that during a single NTSC frame, 1601.6 AES frames will have been generated. It takes five
NTSC frames to fit a whole number of AES frames (8008 frames). This means that 48kHz AES/DARS
will line up evenly with NTSC sync once out of every five frames, and during the other four frames the
AES/DARS waveforms will appear to be partially shifted. The 10field sequence identifies frame #1 (a
single pulse) as the frame where the AES/DARS waveforms line up perfectly to horizontal sync of line 4
of the NTSC waveform. This is illustrated in lock diagram #2 (Figure 2-8).
Note that the Z preamble (which identifies the start of a 192-frame AES block) will only line up with
NTSC sync once every 120 frames (4.004 seconds). This is in contrast to PAL sync where it will line up
every frame. This essentially renders the AES Coarse phase adjustment meaningless when locked to
an NTSC reference. The alignment of an AES block to analog video sync is not important for proper
reception of an AES signal.
If the NTSC reference is lost, the unit will freerun on the selected oscillator as described in section
2.2.3. Note than when the Genlock Range is set to Wide, the freerun drift upon loss of reference will be
much higher. When the NTSC reference is re-applied the Lock Type menu selection controls how the
5601MSC will respond to re-align its internal oscillator with the reference (see section 2.2.4).
2 3 4 5
Start Pulse
Field
2
Pulse
Line 15
1
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