3-10 Installing The Hardware - AT&T PagePac Plus AmpliCenter Installation And Use Manual

NOTE: Ground start interface
requires common ground
between paging input and
telephone system by direct line
or other common grounding
methods.

3-10 Installing the Hardware

The Dry Loop 600 Ohm is a four wire interface consisting of a dry audio
pair with a 600 ohm impedance and a control pair. The page input is
activated when the control pair receives a contact closure from the host
equipment, connecting C1 to ground. The Dry Loop page input can also be
activated by the presence of page input audio signals that exceed a set
threshold. This threshold is set by the page VOX adjustment; clockwise
rotation lowers the threshold and makes it more sensitive. Adjust by
experimentation to account for various line loss and noise. This feature is
beneficial for (amplified) microphone sources that don't have a Music/Page
control contact, or for remote AmpliCenters connected by leased pairs so
that another pair is not required for Music/Page switching control.
Dry Loop Hi Impedance is used to interface with parallel multiple inputs.
Input impedance is 100K ohms. Otherwise, the same as the 600 ohm dry
loop operation.
The Ground Start mode is a two wire interface and has a 600 ohm input
impedance. When a trunk is accessed, a momentary ground is sent to the
ring-side of the pair by the host equipment, loop current is detected and
the tip-side pair is closed. Disconnect supervision of the ground start
mode is accomplished by monitoring the loop current.
The Loop Start mode is two wire interface and has a 600 ohm input
impedance. The host equipment draws loop current from the talk-battery
which is supplied by the AmpliCenter. Disconnect supervision of the loop
start mode is accomplished by monitoring the loop current.