Studio Technologies 5132 2014 - Manual (Page 12)

Issue 5, October 2014 Model 5132 User Guide
Page 12 Studio Technologies, Inc.
Model 5132
Party-Line Interface Module
compatible with the RTS TW-series “mic kill”
protocol. The actual auto nulling process
is performed next. A series of tones will be
sent out the party-line interface channels.
Other Model 5132 circuitry, under software
control, will rapidly perform adjustments to
achieve the best null possible. After the null
adjustments have been made the results
are stored in non-volatile memory. Once
the process is complete the audio input and
output paths are again activated.
If possible, prior to performing an auto null
it’s polite to warn all personnel who are
actively using the connected party-line
intercom devices. The tones sent to the
party-line intercom channels during the
nulling process are not excessively loud or
obnoxious, but most users might want to re-
move their headsets during the process. In
addition to warning users it might be a good
time to ask them to mute any active micro-
phones. While the automatic “mic kill” signal
will apply to many user devices it may not
apply to all. Muting microphones is impor-
tant as obtaining a “deep” null requires that
no extraneous audio signals be present on
the party-line circuit.
Operating Mode
A configurable feature allows Model 5132
units to be selected from two operating
modes. This is provided so that modules
can be used in both standard and non-
standard applications. By default Model
5132 units are configured for what is called
operating mode 1. This is appropriate in
most applications. But special situations
can benefit from using operating mode 2.
Refer to the Technical Notes section of this
guide for details on how to determine the
Model 5132’s selected operating mode and,
if required, how to change it.
Operating mode 1 is appropriate for most
applications and is considered the default.
When a Model 5132 is selected for operat-
ing mode 1 full module operation requires
that current must be drawn from the party-
line interface (when the Model 5132 is
providing party-line power) or a DC voltage
must be present on pin 2 of the party-line
interface (when the Model 5132 is not pro-
viding party-line power). The Pin 2 Status
LED on the front panel provides an indica-
tion that the module is ready for full opera-
tion. If neither of these conditions is met the
two line-level audio outputs are muted, the
auto null function can’t be enabled, and the
Pin 2 Status LED is not lit. Muting the audio
outputs ensures that unwanted audio is not
sent to connected equipment. Preventing
the auto null process from starting keeps
an incorrect auto null from occurring. These
operating requirements are desirable for
most applications and will provide maximum
performance.
But not all legitimate applications will meet
these requirements and that’s why operat-
ing mode 2 is provided. There will be situ-
ations where DC current will not be drawn
from the Model 5132’s party-line interface.
In other cases no DC voltage will be pro-
vided to pin 2 of the party-line interface.
With operating mode 2 the line-level audio
outputs are always enabled and the auto
null function can be used. No current draw
or DC voltage on pin 2 is required for full
module operation to take place.
A specific example where mode 2 would be
appropriate is when an application requires
connecting the Model 5132’s party-line
interface to two separate audio channels
associated with two Clear-Com® single-
channel party-line intercom circuits. These
audio channels would not draw current or