DigiDesign SYNC HD Manual page 73

• 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 recalibration does not occur dur-
ing firmware updating or when resetting the
SYNC peripheral to factory defaults (see
"Restoring Factory Settings" on page 68).
Oscillator Resolution and Stability
The unit of calibration for SYNC peripherals is
1/64th of a sample period. What this means is
that a SYNC peripheral can theoretically be cal-
ibrated to about 1/3 ppm (0.33 part per million).
The unit will maintain calibration 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 accurate to within 20 to
50 ppm and drift with temperature. The SYNC
peripheral's accuracy is possible because it con-
tains a low-jitter, high-stability temperature-
controlled crystal oscillator.
Warm Up the SYNC Peripheral Before
Recalibrating
Before you begin the calibration procedure,
power on the SYNC peripheral and allow it to
warm up for at least five minutes. The tempera-
ture of the room (or chassis) isn't critical during
the calibration procedure. However, if you need
better than 3 ppm accuracy, it is recommended
that you allow the SYNC peripheral to warm up
for at least 30 minutes and that the chassis be at
normal operating temperature.
The original Oscillator Calibration value is
printed on the factory sticker, on the SYNC pe-
ripheral bottom panel.
To restore the SYNC peripheral oscillator
calibration to its factory setting:
Press Set, then press Up until Video System
1
("VIdEo SY") is displayed in the LED readout.
Press and hold the Up switch. While you con-
2
tinue to hold that switch, press the Clock Refer-
ence switch momentarily, and then release both
switches. The LED Time Code Display reads
OSC CAL.
Press Set. The LED Time Code Display shows
3
the current parameter value, which shows a
sample rate frequency deviation from –0999 to
0999.
Note the Oscillator Calibration value printed
4
on the factory sticker, on the SYNC peripheral
bottom panel.
Use the Down and Up switches to scroll
5
through the parameter values.
When you reach a value that matches the
6
sticker's value, stop scrolling and press Set. The
SYNC peripheral is now calibrated.
Press Set. The LED Time Code Display shows
7
O5C CAL.
Press the Down switch to exit OSC CAL.
8
Chapter 5: Additional Operational Information 67