Studio Technologies 76DA V.4.00 - Manual (Page 45)

Model 76DA/77 User Guide Issue 3, July 2012
Studio Technologies, Inc. Page 45
for Surround
this function it’s really not the case. Sev-
eral semiconductor companies provide
“single-chip” SRC solutions and an excel-
lent one from AKM was selected for the
Model 76DA. The technical capabilities of
the Model 76DA’s SRC function is stated in
this way: the sample rate of an input signal
can range from 1/6 to six times the Model
76DA’s output sample rate, with the ad-
ditional restriction that it must be no less
than 8 kHz and no more than 216 kHz. The
Model 76DA’s output sample rate is de-
termined by the selected timing reference
(sync) signal and, if required, a config-
ured value. If a word clock, DRS (AES11),
or AES3id signal is the designated sync
source its rate will be the Model 76DA’s
output sample rate. If a video sync signal
is connected, the Model 76DA’s sample
rate is selected as part of the configuration
process.
So in practice what can the SRC function
accomplish? If the output sample rate is
48 kHz then a signal connected to stereo
input C can have a sample rate from 8 to
216 kHz. Or, as another example, if the
Model 76DA’s output sample rate is 96
kHz a signal connected to stereo input C
can have its sample rate range from 16 to
216 kHz.
As useful as allowing one disparate
sample rate to be converted to another,
it may be the ability of the Model 76DA’s
SRC function to re-synchronize a signal
that proves most valuable. For example,
in typical post-production and broadcast
applications all signals will have a sample
rate of 48 kHz. A Model 76DA and all of its
normally connected input signals will be
“locked” to the main timing reference signal
that supports the 48 kHz sampling rate.
But, as an example, a signal associated
with a portable device, while at a 48 kHz
sampling rate, may not be synchronized
(“genlocked”) to the “house” reference.
Connecting this signal to stereo input C will
cause the SRC function to “lock” it to the
Model 76DA’s rate, thus allowing it to be
monitored over a loudspeaker system. In
addition, the stereo input C direct monitor
output can be connected to other devices
that find need for the now-synchronized
signal. In some cases it may be useful to
connect the stereo input C direct monitor
output to the input of a signal router, allow-
ing an entire facility to access the signal.
Model 76DA to Control
Console Connections
Figure 7 gives a detailed description of the
signals that connect the Model 76DA Cen-
tral Controller to the one or more Model
77 or Model 71 Control Consoles. The
Model 76DA provides a +12 volt DC power
source for use by the control console’s
circuitry. The DC output is current-limited
to minimize the chance that a short-circuit
condition will damage the Model 76DA’s
circuitry. An asynchronous, bi-directional
data interface 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 76DA
communicates with each Model 77 and
Model 71 unit 20 times per second, receiv-
ing button and rotary level control informa-
tion and sending LED and 4-digit display
status data.
“Hot” Disconnection of
Control Consoles
There’s no problem relocating one or
more Model 77 or Model 71 Control
Consoles while the StudioComm system
is operating. You can disconnect the 9-pin