CTI Products TSAM Transmitter Steering & Audio Matrix - Manual (Page 74)

TSAM Installation and Maintenance Rev. 2.10 Chapter 8
CTI Products, Inc. Maintenance Theory
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8.2.5 TSAM Expansion Bus
The TSAM expansion bus allows up to 8 TSAMs to be connected together to control up to 64 transmitter
sites. Expansion connector P103 on the transmitter board allows multiple TSAM to connect together.
There are five separate busses on the 26 pin expansion connector. These are the SPI expansion bus,
console 1 TX audio, console 1 RX audio, console 2 TX audio, and console 2 TX audio buses.
Transmit Audio Expansion Bus
Transmit audio from the console connects to the Master TSAM (ADDRESS = 0). The master TSAM
inserts control and keying tones and then this audio is the distributed to all connected TSAMs. On the
Master TSAM, jumpers E123, 124, 127, and E128 are in the A position. This routes audio from Master
TSAM TX Audio and Keying Circuit out to the expansion audio bus. All Slave (Expansion) TSAMs have
jumper E123, 124, 127, and E128 in the B position. This picks transmit audio and keying tones off the
expansion bus and routes them through the TX board analog mux to the crosspoint switch. TX expansion
audio is always applied to the crosspoint switch of each slave board. This allows the master to route TX
audio to any transmitter in the system by programming the crosspoint switch on each expansion board.
The slave boards crosspoint switches are programmed through the SPI expansion bus.
The master TSAM is jumpered to send audio out the console 1 and 2 TX audio buses, and receive audio
on the console 1 and 2 RX audio buses. The expansion TSAMs are jumpered in the opposite fashion.
8.3 Receiver Board Electronics
Two circuit boards make up the TSAM, the TSAM-R1 (receiver audio board) board contains all of the RX
audio switching circuitry, RX line receivers, Console receive audio line drivers, and all logic I/O required
for secondary operation. When secondary operation is not used the receiver audio board is not required.
The receiver audio board connects to the transmitter control board via a 50 pin header located on the
TSAM transmitter board. Power, Serial I/O, Audio, and Logic I/O, feed through this connector.
Receiver board circuitry is divided into the following functional blocks:
TSAM-R1 Board
• Receive Audio Line Inputs
• Receive Crosspoint Switch
• Console Audio Line Outputs
• Secondary Mode Logic Inputs
8.3.1 Receive Audio Line Inputs
The receive audio line inputs provide a balanced 600 Ω termination for remote base receive audio lines.
Each circuit contains input transient protection, impedance matching, and audio level setting circuitry.
The wireline receivers have a jumper selectable 10K high impedance input mode. This allows the TSAM
to be connected in parallel with other equipment. Normally the TSAM receive inputs are paralleled with
the system comparator.
Refer to the TSAM-R1 (receiver board) schematic diagram. The first of 8 identical receiver input circuits
is described. The gas discharge tube GT201 provides input transient protection for large transients. R201
provides a 600 ohm termination for impedance matching. R209, R217 R225, R223 make up a jumper
selectable attenuator network. The resistor can be jumpered to provide 3 separate level ranges.
Audio from the attenuator network is coupled via DC blocking cap C209. This cap blocks small dc offsets
present on the input of the line receive amplifier.