DigiDesign SYNC HD, Руководство пользователя

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Chapter 5: Additional Operational Information 65
Example Fader Start Application
In a typical scenario, the Fader Start feature con-
trols playback of a CD player. The CD player
outputs are routed into a Pro Tools stereo Aux
Input. As the Aux channel fader is moved above
–120 dB, playback of the CD player is automati-
cally triggered. Likewise, as the fader is moved
below –120 dB, playback is automatically
stopped.
To configure Pro Tools tracks for Fader Start Play
and Stop:
1
Use the New Track dialog to create two new
auxiliary input tracks. If you already have aux
tracks, you will use the first and second (top-
most in the Edit window, left-most in the Mix
window).
2
When the first visible aux input in a Pro Tools
session is above –120 dB, GPI Relay output 3
(Fader Start #1) will be enabled; otherwise, it will
be disabled.
Similarly, when the second visible aux input in a
Pro Tools session is above –120 dB, GPI Relay
output #4 (Fader Start #2) will be enabled; oth-
erwise, it will be disabled.
If you rearrange channel strips in the Pro Tools
Mix or Edit windows, the two GPI outputs will
update dynamically to reflect the current state.
The Fader Start channel must be in a Show Track
state (not hidden). See “GPI Relay Wiring for
Fader-Start” on page 92 for additional GPI infor-
mation.
Calibrating the SYNC HD
Oscillator
The SYNC HD provides a feature for calibrating
the frequency of the on-board crystal oscillator.
This allows the SYNC HD to be used as an ex-
tremely accurate frequency reference while in
Internal/VSO mode.
With normal usage, the SYNC HD should never
require recalibrating. Each unit is factory cali-
brated to /– 5 ppm (parts per million).
You may want to recalibrate the SYNC HD in
the following situations:
• If greater than 5 ppm accuracy is required.
• If the unit needs to be matched to a unique
(nonstandard) frequency.
• To precisely compensate for component ag-
ing.
– and –
• To restore the original factory setting.
Oscillator Resolution and Stability
SYNC HD calibration units are in 1/64th of a
sample period. What this means is that the
SYNC HD can theoretically be calibrated to
about 1/3 of a ppm. The unit will maintain cali-
bration across a wide range in temperature.
Long-term drift should be less than 1 ppm per
year due to aging of the crystal. To put this in
perspective, most digital audio products are ac-
curate to within 20 to 50 ppm and drift with
temperature. The SYNC HD’s accuracy is possi-
ble because it contains a low-jitter, high-stability
temperature controlled crystal oscillator.
To rearrange tracks, drag the Track Name
left or right in the Mix window, or up or
down in the Edit window. See the
Pro Tools
Reference Guide for more information.
Oscillator recalibration does not occur dur-
ing firmware updating or when resetting the
SYNC HD to factory defaults (see “Restor-
ing Factory Settings” on page 66).