Tait TB9100, Инструкция по установке и эксплуатации

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TB9100 Installation and Operation Manual Technical Description 101
© Tait Electronics Limited May 2006
From the Digital
Line
The digital line can receive calls that were made in digital P25 or analog FM
mode. Digital P25 calls arrive in IMBE format. Analog FM calls arrive in
G.711 format.
Figure 8.8 shows a call being received on the digital line.
1. Speech packets arrive from the network in either IMBE or G.711 for-
mat.
2. The RTP frame information is extracted and the speech packets are
passed directly to the voter.
From the Control
Panel Microphone
The control panel microphone can be used to make a call in either P25
digital or analog FM mode. Refer to
“Microphone Operation” on page 68
for details of how to set the mode for a control panel transmission. Calls
made from the control panel participate in the base station voting.
The signal path (not illustrated) is similar to the path for the analog line.
1. The ADC at the control panel interface converts audio speech sam-
ples to digital samples. A buffer adjacent to the ADC collects the indi-
vidual digital samples into packets. Header data is added.
2. The packet switch routes the packets to the appropriate encoder; the
IMBE encoder for digital P25 packets or the G.711 encoder for
analog FM packets.
3. The encoder passes the packets to the voter.
Figure 8.8 Path from digital line to voter
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