TD 90227GB
2006-09-18/ Ver. C
System Installation
On Site Paging System
4
bus without modem must not exceed 500 metres. If the SP-bus is 1-way, the length can be
increased to max 3 km with bus amplifier T938BA.
D-bus 3 km
Terminal
Transmitter
Slave
Driver
Slave
Transmitter
Central
Unit
SP-bus 500 m
Figure 2. Max D- and SP-bus length.
In HF installations a Power Divider is required between every transmitter for driving the
Slave Transmitters, and in UHF systems a Slave Driver is used between the Terminal
Transmitter and the first Slave Transmitter in series. The Slave transmitters have one output
and they can be connected in series or used as line amplifiers. However, in most cases it is
also advisable to connect an antenna to the line amplifier, especially in speech systems
where speech quality depends directly on coverage.
Slave transmitters are connected with coaxial cable RG-8 or RG-213 with a maximum
length of 700 metres. Distances exceeding this require line amplifiers. A separate power
supply feeds the slave, but if the slave is mounted close to other units the power can be
taken from one of them.
D-bus 3 km
Terminal
Transmitter
Slave
Driver
Slave
Transmitter
Central
Unit
SP-bus 500 m
700 m
Slave
Transmitter
700 m
Power
Divider
700 m
Power
Divider
700 m
D-bus 3 km
Terminal
Transmitter
Slave
Transmitter
Central
Unit
SP-bus 500 m
Slave
Transmitter
HF
UHF
Slave
Transmitter
700 m
Slave
Transmitter
700 m
Figure 3. Max coaxial cable length.
Equipment for Slave Transmitters
• Power Divider MPT-50, with one output used in HF installations.
• Slave Driver U952DR, with two outputs used in UHF installations.