Datasheet

Studio Technologies, Inc. Model 44D Audio Interface, Issue 3, Page 3
General Purpose Inputs and
Outputs
The Model 44D allows the sending and receiving of status
signals using high-frequency audio tones that are included
with within the Dante audio channels. When two Model
44D units are interconnected using an Ethernet network
and Dante, two status signals will be transported in each
direction. Each general purpose input (GPI) is compatible
with contact closures provided by equipment such as matrix
intercom systems or routers. A closure on a GPI on one
Model 44D unit will result in the closing (shorting) of a
solid-state relay contact on the other Model 44D. To assist
in implementing specialized GPI and GPO applications a
source of low-current DC power is also provided.
The GPI and GPO functions can be especially useful in
party-line intercom applications where call-light signals
are utilized. Contact closures on matrix intercom systems
can be “repeated” by Model 44D units that are located
anywhere within the associated local area network (LAN).
The Model 44D is also directly compatible with the call-light
signal support provided by the Studio Technologies’ Model
45DC and Model 45DR Intercom Interface units. With a
Model 44D appropriately interconnected with a matrix in
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tercom system full call-light support can be provided to and
from RTS and Clear-Com® party-line intercom circuits.
Pro Audio Quality
The Model 44D’s audio circuitry was designed in the spirit
of professional audio equipment rather than that found in
typical broadcast or commercial audio gear. High-perfor
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mance components are used throughout, providing low-
distortion, low-noise, and high headroom. Care was taken
so that signal integrity is maintained in both the analog
and digital domains.
Audio Meters and Status LEDs
The Model 44D provides four 5-segment LED meters. The
meters, located on the front panel, display the level of the
audio signals associated with the two line inputs and two
line outputs. At the time of installation and setup the meters
are invaluable in helping to confirm correct operation. Dur
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ing normal operation the meters offer direct confirmation of
the unit’s audio signal levels, helping to ensure that optimal
audio quality is maintained. Additional LED indicators are
provided on the front panel, offering status indications of
the incoming power and general purpose output (GPO)
functions.
Tone Generator Mode
For special applications the Model 44D can be configured
to serve as a tone generator. Instead of functioning as an
audio interface device, the Model 44D will generate two
sine-wave audio signals, one 18 kHz and the other 20 kHz.
These signals are available both as line-level analog and
Dante digital audio (transmitter) outputs. The 18 kHz tone
is intended for use with matrix intercom systems that are
used with the Studio Technologies’ Model 5422 Dante
Intercom Audio Engine. This tone will be connected to a
matrix intercom system using either analog or Dante inputs.
The matrix intercom system will be configured such that
it will combine voice audio with the 18 kHz tone to create
specialized IFB signals. These voice-with-tone signals will
be routed, by way of an audio transport system, to Model
5422 interrupt inputs associated with tone operated (TOX)
IFB channels. The Model 5422 will detect the 18 kHz tone
and “trigger” the associated IFB function. In this way high-
performance IFB functions can be implemented for REMI
(remote-production) applications.
The 20 kHz tone is provided for use in applications where
generation of in-band signals that are compatible with the
call function on RTS TW-series party-line (PL) intercom
channels is desired. One example would be for the 20
kHz tone to be connected to an analog or Dante receiver
(input) channel on a matrix intercom system. The intercom
system would be configured such that a button press on an
intercom “key” panel would cause 20 kHz to be sent out an
intercom channel. This would then serve as a call “trigger”
for devices such as a Studio Technologies’ Model 391 Dante
Alerting Unit. Another interesting example would be for the
20 kHz tone to be used to serve as an activation signal for
contact closures. Using Dante subscriptions (routes), the
intercom channel from the matrix interface would be con
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nected to additional Model 44D units. When those units
receive the 20 kHz tone signal they would enable their
associated GPO contact closure.
Both the 18 kHz and 20 kHz tones are precise in terms of
frequency and level accuracy, as well as being very low in
harmonic distortion.
Ethernet Data, PoE, and DC Power
Source
The Model 44D connects to a data network using a standard
100 Mb/s twisted-pair Ethernet interface. The physical
interconnection is made by way of a Neutrik® etherCON