Tait TB9100, Installation And Operation Manual

Page: 104 / 144

104 Technical Description TB9100 Installation and Operation Manual
© Tait Electronics Limited May 2006
To the Digital Line
The signal processing on the audio path from the voter to the digital line
(not illustrated) is as follows:
1. The voter switches the winning packets to the RTP processing cir-
cuitry.
2. This circuitry adds RTP frame information to the speech packets and
then puts them on the digital line.
To the Speaker
(Monitoring the
Receiver)
The control panel speaker can be used to monitor the received RF signal
(see
“Speaker Operation” on page 67 ), bypassing the voter. If the call is
analog FM, the packet switch routes the incoming signal directly to the
speaker. If the call is digital P25 (see
Figure 8.11 ), the P25 modem output is
passed through an IMBE decoder (shown with a *).
To the Speaker
(Vote Winner Mode)
The control panel speaker can be used to monitor the voter output (see
“Speaker Operation” on page 67 ). In this case, the signal path (not
illustrated) is as follows:
1. The voter sends the output to the appropriate decoder.
2. The decoder sends its output via the packet switch to the control
panel speaker.
Figure 8.11 Path when monitoring receiver (digital P25 mode)
Packet
Switch
ADC
ADC
ADC
Voter
P25
Modem
Mod/
Demod
IMBE
Enc/Dec
G.711
Enc/Dec
FM Audio
Process
RTP
RF
Interface
Control Panel
Speaker/Microphone
Digital
Network
Analog Line
IMBE G.711
IMBE
IMBE/G.711 IMBE/G.711
Digital
Board DSP
Network
Board RISC
Network
Board DSP
IMBE
Dec*
Buffer
Buffer