TB9100/P25 CG/P25 TAG Installation and Operation Manual Technical Description 121
© Tait Limited March 2014
■ carrying out the switching to send signals to the RF, analog and control
panel interfaces, based on the voting output.
The network RISC is responsible for the following:
■ inserting header information into P25 signals originating from the
control panel and analog line
■ performing the signal voting and switching
■ inserting RTP (Real-time Transport Protocol) frame information into
IMBE and G.711 speech packets
■ transmitting and receiving RTP frames over the IP network.
Power Supply The reciter operates off a +28 VDC supply. The supply is fed to two separate
power supplies, one on the RF board and a second on the digital board. The
power supply on the RF board also powers some of the circuitry on the
network board.
The power supply on the RF board provides 5.3V and 8.5V regulated
supplies. This 5.3V supply is boosted to 23V and also provides a 3.3V
regulated supply. The power supply on the digital board provides 3.3V and
5.3V regulated supplies. It is also fed through to provide a 2.5V supply.
The network board requires the internal supply voltages of +6 V, +3.3 V,
+1.8 V and +1.6 V. These are all derived from the main +28 V supply rail:
■ the +3.3 V and +1.8 V supplies are acquired from the +28 V supply using
a dual-phase switching converter
■ the +1.6 V supply is acquired from the +3.3 V supply using an adjustable
output switching regulator
■ the +6 V low current auxiliary supply is acquired from the +28 V supply
using a linear regulator.
Reciter Fan
Operation
The reciter fan has a temperature sensor that reads the temperature on the
component side of the digital board.
The reciter fan will operate briefly at start up, after the PMU and PA fans.
This provides a simple diagnostic capability, and the ability to raise or clear
faults.
No configuration is necessary for the reciter fan, it has fixed on/off
thresholds:
■ Fan on threshold: 57
o
C
■ Fan off threshold: 46
o
C
A ‘fan failed’ alarm is raised when the reciter reaches a temperature of
72.5
o
C.
For monitoring purposes, the following information is displayed on the CSS
Monitor Reciter screen:
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