Studio Technologies 780-03 V.4.15 - Manual (Page 45)

Model 780-03/790 User Guide Issue 1, April 2015
Studio Technologies, Inc. Page 45
for Surround
signals will have a sample rate of 48 kHz.
A Model 780-03 and all of its normally con-
nected input signals will be “locked” to a
main timing reference signal that supports
the 48 kHz sampling rate. But, as an exam-
ple, a signal associated with a portable de-
vice, while at a 48 kHz sampling rate, may
not be synchronized (“genlocked”) to the
“house” reference. Connecting this signal to
the stereo input will cause the SRC function
to “lock” it to the Model 780-03’s rate, thus
allowing it to be monitored over
a loudspeaker system.
Model 780-03 to Control
Console Connections
Figure 8 gives a detailed description of
the signals that connect the Model 780-03
Central Controller to the one or more Model
790 or Model 71 Control Consoles. The
Model 780-03 provides 12 Vdc for use by
the control console’s circuitry. The DC out-
put is current-limited to 100 mA to minimize
the chance that a short-circuit condition
will damage the Model 780-03’s circuitry.
An asynchronous, bi-directional data inter-
face links the connected units. The RS-485
hardware connection scheme operates at a
rate of 115.2 kbit/s and uses an 8-N-1 data
format. The Model 780-03 communicates
with each Model 790 and Model 71 unit
20 times per second, receiving button and
rotary level control information and sending
LED and 4-digit display status data.
“Hot” Disconnection of
Control Consoles
There’s no problem relocating one or more
Model 790 or Model 71 Control Consoles
while the StudioComm system is operating.
You can disconnect the 9-pin interconnect-
ing cable, move the unit (or units), and then
reconnect without issue. Upon discon-
nection of all control consoles the Model
780-03 Central Controller will mute the
internal digital audio channels as well as
saving the current operating parameters.
No clicks, pops, or other noises will occur
when the Model 790 or Model 71 units are
again connected. The control consoles
will go through their standard power-up
sequence and then normal operation will
resume.
Channel Status, User, and
Validity Bits
The non-audio bits that are part of the
AES3 digital audio monitor output channel
data are actively controlled by the Model
780-03’s software. The Channel Status
bits use the Professional Use of Channel
Status block. They indicate a word length
of 24 and the current sample rate. The cor-
rect CRC is also calculated and inserted.
The User bits are always set to 0. When
a valid timing reference (sync) source is
recognized by the system the Validity bits
will be set to 1.
The Model 780-03’s hardware is capable
of routing the C/U/V bit information from
any of the L/R inputs, as well as the sync
input, to the main logic device (FPGA)
and then on to the digital audio transmitter
(DIT) integrated circuits. This is provided
for future use and is not active at this time.