Sound Devices 788T - Manual (Page 72)

Internal
The 788T generates its own clock at the set rate and disregards all external clocks connected. When
set to Internal, the Sample Rate Converters are activated for all incoming AES signals.
Sample Rate Converters
The 788T has high-quality, hardware sample rate converters (SRCs) on each of its AES/EBU digital
inputs. The SRCs apply to AES signals when the Setup Menu option REC: SYNC REFERENCE is set
to Internal. The 788T’s digital inputs accept AES signals with sampling rates from 32 kHz to 192
kHz. With the sample rate converters active, each digital input can be connected with signals of any
sample rate without having to word clock all of the devices together.
The SRCs are only active when needed; when not needed they are deactivated. To use digital inputs
without the SRCs active, set the REC: SYNC REFERENCE Word Clock Input, Video Input, or to an
AES input pair.
Word Clock Input
When the 788T is set to receive external word clock, the 788T locks to a valid clock signal connected
to the Sync Input connector. If a valid word clock is detected, ‘W’ is displayed in the LCD. If no valid
word clock is detected, the input activity LED rings will fl ash yellow and the Lock indicator, ‘W’
does not appear.
Video Sync
The 788T can lock to valid video sync sources, including composite NTSC, PAL and Tri-level con-
nected to the Sync Input connector. If valid video sync is detected, ‘V’ is displayed in the LCD. If no
valid video sync is detected, the input activity LED rings will fl ash yellow and the Lock indicator, ‘V’
does not appear.
Digital Inputs 1-2, 3-4, 5-6, 7-8
The 788T can be set to derive word clock from valid digital input pairs even if the equivalent num-
bered analog input pair has been selected for recording. For example, sync reference is set to digital
input 1-2 and inputs 1 and 2 are both set to MIC. If a valid digital input sync source is detected, ‘D’
is displayed in the LCD. If a valid digital input is not detected, the Input Activity Ring LED associ-
ated with the selected digital input sync source will fl ash yellow and the Lock indicator, ‘D’ will not
appear.
If digital audio is connected to the 788T from more than one digital source, you must lock these
sources together to a common reference, otherwise differences between the sources’ clocks will cause
unpredictable results. Sample rate conversion is not active for digital inputs unless the sync source is
set to Internal.
788T/788T-SSD User Guide and Technical Information
64
v. 3.02 Features and specifications are subject to change. Visit www.sounddevices.com for the latest documentation.
Sync
hronization and T
imecode
6