TD 90227GB
2006-09-18/ Ver. C
System Installation
On Site Paging System
5
Slave Driver U952DR
The Slave Driver has one antenna output and two outputs for driving Slave Transmitters
from an UHF Terminal Transmitter, U952T. It also obtain a proper level at the Slave
Transmitter input. The Slave Driver operates in the 53 - 65 MHz band to reduce coaxial
cable losses.
3.1
Frequency Locked Transmitters
The Reference Module, that contains a highly stable reference tone generator, is placed
near the Central Unit. Each transmitter is fitted with the combined SM/FL (Speech/
Frequency Lock) T952SM/FL module. The SM/FL module uses the reference tone to correct
carrier frequency. A Slave Driver is needed if the Terminal transmitter is to drive Slave
transmitters.
Equipment for frequency locking
• Combined Speech-/ Frequency Lock Module T952SM/FL is to be plugged onto the
Terminal Transmitter’s circuit board.
• Reference Module T938RM with drive circuits for FL-bus, controlled by the Central
Unit.
• Bus Amplifier T938BA = T938RM without ref. tone generator, with drive circuits for the
FL-bus.
• Modem Compensator T938MC compensates for time delay in a T938S modem-pair.
Older transmitters that can be frequency locked are the H950T HF Terminal Transmitter,
with circuit board number 40291 or higher, and U951T UHF Terminal Transmitter. They
both use Frequency Locking Module T950FL.
Systems with frequency locked transmitters fall into two basic categories: those without
modems to the transmitters, and those that have at least one modem-pair. Three twisted-
pairs carry all communication between the central and terminal transmitter site.
3.2
Without Modem to Transmitters
The transmitters are connected to the D-bus and FL-bus. If the max length for the FL-bus is
exceeded, the transmitter’s speech bus must be connected to the FL-bus on the Reference
Module or Bus Amplifier. Several transmitters may be connected to the D-bus provided the