Studio Technologies 212 2006 - Manual (Page 33)

Model 212 User Guide Issue 3, July 2006
Studio Technologies, Inc. Page 33
header is connected to the common point
of the Model 212’s circuitry. Pin 2 of the
header is connected to the circuitry asso-
ciated with main output pushbutton. Pin 3
of the header is connected to the circuitry
associated with the talkback output push-
button. The input circuitry is “active low,”
with a 10 k ohm resistor connected to
+5 volts acting as a pull up. A combina-
tion of resistors and capacitors provides
ESD protection. A qualified technician can
use these inputs for special applications.
Contact the factory for additional details.
Digital Audio Outputs
As has been previously discussed in this
user guide, the Model 212 is capable of
supporting three digital audio outputs.
Directly accessible on the back panel are
the BNC connectors for the AES3id output
and the bidirectional interface. Accessible
internally for installer-selected applications
is the AES3 output. It’s important to men-
tion that these three outputs are always
active, each sending out the identical
digital audio and control bit stream. While
most applications will use only one of the
outputs, there’s no reason why two, or all
three, can’t be utilized.
In addition, while the bidirectional digital
interface is intended to send and receive
data over a single cable, it can be used
as a standard AES3id output. The only
requirement is that the configuration for
the digital input source must be selected
for something other than the bidirectional
digital interface. This ensures that a stable
clock source will be available for the all the
digital outputs.
Channel Status Bits
Following the AES3 and AES3id stan-
dards, the Model 212 configures the
channel status bits. The unit is defined as
being a professional device, the sample
rate is set to follow the actual sample rate,
and the word length is 24 bits. These set-
tings are made in the Model 212’s soft-
ware and cannot be changed in the field.
This was specifically done to help ensure
reliable operation in the field. The setting
was carefully selected to allow reliable
operation in all intended Model 212
applications.
On-Air MNF Mode
The on-air MNF system mode was cre-
ated specifically to meet the needs of
a well-known weekly sports broadcast.
The event’s technical personnel liked the
digital audio support that the Model 212
provided but needed a second talkback
output. Using the Model 212’s cornuco-
pia of hardware resources, and a slight
addition to the software, a scheme was
devised. A simple wiring harness was cre-
ated that connects the analog microphone
output to the relay contacts, and then on
to a line output card. The line output card,
a standard option from Studio Technolo-
gies, was mounted in one of the spare
connector locations in the back panel. Ac-
cess to the analog mic out, relay contacts,
and line output card was provided by the
existing 3-pin “header” connectors. As
such, no soldering or circuit changes were
required.
To allow the user to enable the analog talk-
back output a third system mode was cre-
ated in the Model 212’s software. The two
pushbutton switches were “re-mapped”