Avid Technology Digidesign USD, Руководство пользователя, Страница: 48 / 96

Universal Slave Driver 44
Bi-Phase/Tach Pulses-per-frame (PPF)
There are several different standards for the
number of pulses-per-frame output by Bi-
Phase or Tach devices. Using USD Setup’s
Pulse Per Frame setting, you can set the
USD to operate from 2 to 254 pulses per
frame. The setting should match the PPF
rate of the external device’s Bi-Phase/Tach
encoder.
To set the pulses per frame value for a Bi-
Phase/Tach signal using the front panel:
1
Using the Set, Down, and Up switches,
select Bi-Phase/Tach Pulses Per Frame (bIPH
PPF):
2
Press the Set switch again. The LED Time
Code Display will switch to display the cur-
rent PPF value.
3
Use the Down and Up switches to scroll
through the parameter values (range is
from 2 to 255 pulses per frame). Holding ei-
ther switch will scrolls at a faster speed.
4
When you have chosen your desired op-
tion, press Set.
Bi-Phase Position Trimming
While using bi-phase as your positional ref-
erence, you can trim the Bi-Phase-to-time
code translation at any time. Each press of
the Up switch will advance the time ad-
dress one frame. Each press of the Down
switch will retard the time address by one
frame. Remember how many presses
you've accumulated so that you can go
back and trim the starting address you pre-
viously programmed in.
Generating and
Regenerating Time Code
The USD generates LTC, VITC, and MTC si-
multaneously, obtaining time addresses
from a variety of sources:
• When the Positional Reference is set to
Generate, the USD generates LTC, VITC,
and MTC from an internal time address
clock. This is referred to as Generator Pre-
set mode.
• When the Positional Reference is LTC,
VITC, or Bi-Phase, the USD generates
LTC, VITC, and MTC based on the time
address of one of those sources. This is
sometimes called re-generation or transla-
tion. For the USD, this is referred to as
Read/Regeneration mode.
☞
For information about using serial time code
with Pro Tools, refer to the
MachineControl
User’s Guide
.
Read/Regeneration Mode
In this mode, the USD regenerates time
code based upon external positional refer-
ence information (LTC or VITC time code,
or a Bi-Phase/Tach signal). Subject to cer-
tain conditions, three types of time code
(LTC, VITC, and MTC) are simultaneously
regenerated from the selected positional
reference.