Receive crosspoint switch, Figure 19 rx board audio and i/o block diagram, 2 receive crosspoint switch – CTI Products TSAM Transmitter Steering & Audio Matrix User Manual
Page 75
TSAM Installation and Maintenance Rev. 2.10
Chapter 8
CTI Products, Inc.
Maintenance Theory
67
The line receiver amplifier, consisting of IC201D and associated components, amplifies the input signal to
the optimum level for the crosspoint switch. Audio into the crosspoint switch is adjusted to a peak level of
0 dBm. This level optimizes signal to noise levels and minimizes cross-talk levels from adjacent wireline
inputs.
Figure 19 RX Board Audio and I/O Block Diagram
8.3.2
Receive Crosspoint Switch
The crosspoint switch device allows any receiver input to be connected to any receive audio output.
The receive crosspoint switch has two receive audio outputs and 10 receive audio inputs (8 receiver + 2
expansion). In normal operation, the TSAM routes audio from the steered site receive input to the Console
1 RX Audio output (C1 RX). Console 1 RX audio is not typically used. This audio path acts as an
intercom from the remote site. The Main channel receive audio comes directly from the system
comparator, and is not routed through the TSAM.
When a site is selected for secondary operation, the audio path from the selected site receive input is
routed to the secondary channel audio output. This output drives the secondary channel receive audio line
to the console.
The crosspoint switch also has inputs from the expansion audio bus and a test tone audio input. On the
master TSAM, receive audio from other TSAMs is picked off the expansion audio bus and routed to the
C1 or C2 RX output. The test tone input is used for factory testing and to generate the warning tone heard
when an attempt is made to key the secondary channel without a secondary site selected.
When the warning tone is generated, the MCU programs the C2 tone generator to alternately generate 480
Hz / 620Hz warning tone. This audio is routed from the receive crosspoint test tone input to the top of
R302 the Alert Tone Level adjustment pot. The wiper of R302 is brought back to the crosspoint switch,