TB7300 Installation and Operation Manual Installation 77
© Tait International Limited December 2022
5.7.9 Setting Up Simplex Operation
Simplex operation allows the base station to use one antenna to either
transmit or receive, so the base station cannot transmit and receive at the
same time. A coaxial relay switches an antenna between base station
receive and transmit automatically.
Simplex operation applies to:
■ P25 firmware: P25 Phase1 conventional and analog conventional
mode
■ DMR firmware: analog conventional mode
In single frequency simplex, only one physical radio frequency is used.
Simplex operates in a single base station context and simulcast and non-
simulcast channel group operation.
When the base station is transmitting, the receiver is disabled.
Pin 24 in the 25-way D-range is configured as the relay driver.
Refer to Connecting General Purpose Inputs and Outputs for pin-out
information.
Warning Switching the PA output while it is operating can dam-
age the PA. It is essential to use a relay that meets the 30 ms operat-
ing time specification.
Warning When the base station is in simplex mode using a single
antenna with a coaxial changeover relay, the isolation of this relay
must be >40dB to avoid damage to the receiver.
The relay operating time interacts with the base station transmit buffer.
Once a transceiver begins receiving a transit stream, it will not begin
transmitting that signal until the relay operating time has passed. To
avoid any confusion, you must allow at least this much time in the trans-
mit buffer setting (Tx delay for non-simulcast operation, and marshal-
ling duration for simulcast operation).
Tait offers an Antenna Relay Kit which comes complete with installation
instructions (402-00119-01).
Configuration Configure > Base station > Programmable I/O “Antenna relay control”
check box.
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