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User manual for Cantar-X1 & X2 v2.15 2008 March 28
p.14
p.14
Cantar becomes a master-clock
As soon as the
int c
icon stops blinking, Cantar starts
generating timecode. This timecode is based on a TCXO
(Temperature Compensated (X)crystal Oscillator), accurate
to ±one frame in nine hours (1 ppm). This high accuracy
makes Cantar THE timecode reference on set.
If you turn ‘ON’ the LTC generator output in AUDIO/TC.14
‘LTC Gen Out’, the LTC output can be used to continuously
sync all equipment through cable or RF. You can also initialize
several Aaton GMTs (low power, high accuracy, timekeepers),
attach them to the cameras and digi-slates and have TC that
matches the Cantar’s TC.
Do not power down a master-clock!
Being on a job on which the free-run time-of-day TC is the
essence (AatonCode camera, HD camera with GMT refer-
ence generator, smart digi-slate), never power down Cantar
during the workday to avoid the loss of its 1 ppm reference
time! While the internal HDD is in sleep mode the total
power consumption is a mere 270mA! Set TECHSET.16
‘HDD Pwr Dwn’ to ‘
Aftr 5min
’, to have the HDD sleep five
minutes after STOP. If you still want to power down Cantar
at lunch time, the blinking
int c
icon at power up will remind
you to re-initialize its own sync clock and all other timekeep-
ing machines on the set.
Method 2
‘int c’
internal
Record-Run
driving clock
Go to AUDIO/TC.16 ‘RecRun Init', [ok]: 01:00:00 is pro-
posed as the first TC of the day (it can be modified). From
now on, at the beginning of each audio file Cantar will
stamp a start-TC incremented by 2 seconds later than the
preceding take’s end-TC. This clocking, called Record-Run,
produces audio files which appear as if they have been
recorded in continuity.
If for some reason Cantar is turned off, the rec-run TC must
be initialized again. To prevent any TC overlap, Cantar
proposes to start on the next hour integer, e.g. if the last
recorded take has been closed at 01:34:15, the next start-
TC proposed to the operator will be 02:00:00.
The Cantar record-run mode lets you use the pre-record buffer
without creating TC overlaps. For example, if the preceding
take ends at 01:45:00, and the pre-record buffer is set at
35 seconds, the next audio file will start at 01:45:02
(two second gap), but the LTC emitted by the generator to
the camera when hitting REC will be 01:45:37.
While Cantar is in ‘Rec-Run’ mode, its reference TC must be
continuously sent to all cameras on the set by wire or RF.
note:
in TEST and PPR, the LTC output is frozen on the end-
TC value, it can thus be used as a master TC to start and
stop another Cantar (‘Remote Roll', p.19).
Method 3
‘int c’ internal clock,
AutoSlate
on clapsticks
If the same TC is not running in Cantar and cameras, the only
way to sync pictures and audio is to use clapsticks; forget
digi-slates, they have too many drawbacks. The Cantar
AutoSlate sample-accurate clapstick detection function puts a
timecode crown over the simplest piece of wood.
Method 4
‘ext c’
slaved
to an external clock
An externally-slaved Cantar stamps the audio files with the
same TC as the one running in the video camera. This
requires a link from the camera to Cantar.
Set AUDIO/TC.12 ‘TC Source’ to '
Ext.Clock
';
ext c
blinks
in the circular screen, meaning that Cantar is waiting to be
slaved to an external LTC, e.g. a video camera.
Cantar,
while set to ‘external clock’, will only jam when you go
to REC; pressing the [TC jam] button will do nothing.
Cantar is usually in REC before the camera, so it monitors
the Lemo 5/SubD 15 incoming LTC and grabs it when
coherent TC is received. That is why
ext c
keeps blinking
until the camera is up to speed.
Before closing the audio file, Cantar stamps the TC by using
the latest valid timecode so as to eliminate spurious transmis-
sion errors and false camera starts. If there is no external
timecode signal, an ‘
LTC Not Detected
’ warning appears in
the rectangular screen and a phone beep is triggered every
four seconds. The beep is muted during ‘w’ (wild track)
tagged takes (see ‘Warning beeps’, p.23). Nevertheless,
the external TC is grabbed if it is received before the take’s
end. Note that external LTC breaks can be used to slave
the REC start and stop (see ‘Remote Roll’, p.19).
STOP 4,
Time&Sync
