Avid Technology Digidesign USD User Manual page 39

Pilot Tone
The USD can resolve to an external Pilot
Tone signal for clock reference, for syn-
chronizing to (or transferring audio from)
certain types of open-reel audio tape re-
corders. Pilot Tone is basically a 60 Hz
(NTSC) or 50 Hz (PAL) sine wave tone. Pilot
Tone is used on location film shoots to es-
tablish a common sync reference between
a film or video camera with a portable 1/4"
analog ATR. Pilot Tone contains no posi-
tional information; it provides only clock
reference.
USD decides whether to use 60 Hz or 50 Hz
as the pilot tone reference frequency ac-
cording to the setting of the Video Format.
When set to PAL, the pilot tone frequency
is assumed to be 50 Hz. When set to NTSC,
60 Hz is assumed.
To resolve the USD to Pilot Tone:
From Pro Tools:
In the USD Setup area of the Pro Tools
Session Setup window, click on the Clock
Reference pop-up and choose Pilot Tone.
Using the front panel controls:
Connect your Pilot Tone reference source
1
to the USD Bi-Phase/Tach/GPI/Pilot port.
Using the front panel Clock Reference
2
switch, select Pilot.
Using USD Setup:
Connect your Pilot Tone reference source
1
to the USD's Bi-Phase/Tach/GPI/Pilot port.
Select Pilot Tone under the USD Setup's
2
Clock Ref pop-up menu.
If the Pilot Tone reference source is not
valid for any reason (such as a poor con-
nection or other signal transmission prob-
lem), the Locked LED on the far-right of
the USD front panel will flash on and off.
For additional Pilot Tone information, see
"Pilot Tone" on page 70 in Appendix A.
Bi-Phase/Tach and Clock Reference
The USD is able to resolve to Bi-Phase/Tach
information for use as a clock reference. Bi-
Phase/Tach can synthesize positional refer-
ence, but you must provide a reference start
address (see "Bi-Phase Position Trimming"
on page 44 for other requirements).
To configure Bi-Phase/Tach for the USD clock
reference:
Using USD Setup:
Select Bi-Phase/Tach under USD Setup's
1
Clock Ref pop-up menu.
Select the appropriate Pulse Per Frame
2
and Input Signals parameters, as described
in "Bi-Phase/Tach Starting Frame" on
page 42 and "Bi-Phase/Tach Signal" on
page 43.
Typically, when you use Bi-Phase/Tach as
the clock reference you will also be using it
as the positional reference (see "Bi-
Phase/Tach Positional Reference" on
page 42.).
Chapter 4: Using the USD 35